Cooling methods, depending on the type of cooling medium, are divided into direct cooling and cooling with a liquid coolant (indirect cooling).
With direct cooling, the heat perceived by the cooling devices is transferred directly to the refrigerant boiling in them. During cooling with a refrigerant, the heat in the cooling devices is transferred to an intermediate medium - the coolant, with the help of which it is transferred to the refrigerant located in the evaporator of the refrigeration unit, usually located at some distance from the object being cooled.
With this method of cooling, the removal of heat from the cooled object causes an increase in the temperature of the coolant in the cooling devices without changing its state of aggregation.
The areas of application of one or another method are determined by their features that affect the technological process, as well as economic indicators.
The refrigeration unit with direct cooling is simpler, because it does not have an evaporator for cooling the coolant and a pump for its circulation. As a result, this installation requires lower initial costs compared to the indirect cooling plant, as well as lower energy costs.
At the same time, the direct cooling method also has serious disadvantages, namely:
There is a danger of refrigerant entering the premises (devices) if the density of the system is violated. The danger to people is greatly increased by the use of toxic refrigerants such as ammonia.
Even when using safer refrigerants such as freons, apply direct cooling to rooms where there may be a large number of people is undesirable.
Such a ratio of the advantages and disadvantages of both systems for a long time did not give the prevailing advantages of either of them.
However, due to the emergence and wide application automatic control of the supply of refrigerant to cooling devices, refrigeration units with direct cooling have gained an advantage as more economical in terms of capital and operating costs and more durable.
Depending on the type of cooling devices and the method of organizing air circulation in the refrigerated room, non-contact cooling with heat transfer through the air is divided into battery cooling systems (when using batteries - cooling devices with free air movement), air cooling (when using air coolers - cooling devices in forced air movement) and mixed cooling (when using batteries and air coolers).
The air cooling system is characterized by the forced movement of air in the room and its significantly higher speeds, reaching up to 10 m/s in some devices.
With air cooling, the air mixes better, as a result of which there is no sharp difference in temperature and air humidity by volume.
Higher air velocities inherent in air cooling systems intensify the process of heat exchange both between the cooled body and air, and between air and cooling devices (the heat transfer coefficient during air cooling increases on average three to four times). This reduces the cooling time and thus reduces the processing time.
Benefits inherent refrigeration systems with air coolers are obvious, therefore, the project uses a direct decentralized cooling scheme, air coolers are chosen as cooling devices.
The supply of refrigerant to the throttling devices occurs due to the pressure difference on the low and high pressure sides of the refrigeration unit.
The use of a decentralized chamber cooling system has a number of advantages over a centralized cooling system, such as:
- - independence of cooled objects from each other;
- - more reliable operation, the establishment of an accurate temperature regime;
- - reducing the number of equipment and the length of pipelines;
- - the possibility of using aggregated refrigerating machines and their higher reliability due to the simplification and reduction in the volume of installation work;
- - high factory degree of equipment readiness for installation.
Explanatory note to the graduation project: 18 drawings, 20 tables, 24 sources, 3 sheets of A1 format drawings.
Object of research: regulation of cooling of computer systems.
Subject of study: cooling systems for computer systems.
The first section discusses the general principles of cooling and the operation of various types and types of cooling for computer systems.
The second section focuses on Special attention various types of cooling systems in terms of their improvement, the optimal choice of cooling system is made, according to various criteria.
In the third section, a feasibility study of the development object was carried out, a feasibility study of various cooling systems was carried out.
In the fourth section, calculations of heating, ventilation, natural and artificial lighting are carried out, the obtained values are compared with the normative ones.
FAN, WATER COOLING, AIR COOLING, COMPUTER SYSTEM, NITROGENIC COOLING, PASSIVE COOLING, PELTIER ELEMENT
Introduction
1.3 Hard disk cooling
2.1.1 Fan design
2.2 Passive cooling
2.4 Economy cooling
4. Labor protection
4.1.2 Lighting
4.1.3 Microclimate parameters
4.1.4 Noise and vibration
4.3 Working hours
4.4 Illumination calculation
4.5 Ventilation calculation
4.6 Noise calculation
Link List
List of symbols, symbols, units, abbreviations and terms
ADC - analog-to-digital converter
CMOS - complementary logic on metal-oxide-semiconductor transistors
LSM - least squares method
MPS - microprocessor system
CPU - central processing unit
PWM - pulse width modulation
Introduction
The topic of the thesis is "Adjusting the cooling of computer systems", which will be the subject of the study.
The purpose of the work is to investigate the regulation of cooling of computer systems and the scope.
The objectives of the study are to identify and select the most effective means of cooling computer systems.
The work is divided into stages:
1. Study of the principles of cooling (types and types).
2. Research of new progressive cooling systems.
3. Comparison of technical and economic indicators of various types of cooling.
The relevance of this topic is very high, because. The overall performance of the entire computer system - its productivity and durability - depends on the performance of the cooling properties of the system.
The high speed of modern computers comes at a price: they consume a huge amount of power, which is dissipated in the form of heat. The main parts of a computer - the central processing unit, the graphics processor - require their own cooling systems; gone are the days when these microcircuits were content with a small heatsink. The new system unit is equipped with several fans: at least one in the power supply, one cools the processor, a serious video card is equipped with its own fan. Several fans are installed in the computer case, there are even motherboards with active cooling of chipset chips. Some modern hard drives also heat up to noticeable temperatures.
Most computers are equipped with cooling according to the principle of minimizing cost: one or two noisy case fans are installed, the processor is equipped with a standard cooling system. Cooling is sufficient, cheap, but very noisy.
There is another way out - complex technical solutions: liquid (usually water) cooling, freon cooling, a special aluminum computer case that dissipates heat over its entire surface (in fact, it works like a radiator). For some tasks, it is necessary to use such solutions: for example, for a recording studio, where the computer must be completely silent. For typical home and office use, these specialized systems are prohibitively expensive, starting at hundreds of dollars and up. Such options are very exotic today.
1. Cooling of computer systems
1.1 Cooling principles (types and types)
Cold air is heavy, and therefore descends, while hot air, on the contrary, is light, and therefore tends to rise. This simple theorem plays a key role in the organization of competent cooling. Therefore, air must be provided at least in the lower front of the system unit and exit in its upper back. Moreover, it is not necessary to put the fan on the blower. If the system is not very hot, a simple hole at the air inlet will suffice.
Calculate the required capacity of the case cooling system. For calculations, we use the following formula:
Q \u003d 1.76 * P / (Ti - To), (1.1)
where P - complete thermal power computer system;
Ti - air temperature inside the system case;
To - temperature of fresh air sucked into the system unit from the environment;
Q - performance (flow rate) of the case cooling system.
The total heat output (P) is found by summing the heat outputs of all components. These include the processor, motherboard, RAM, expansion cards, hard drives, ROM / RW drives, PSU. In general, what is installed inside the system unit.
For the temperature in the system (Ti), we need to take the temperature we want inside the system unit. For example - 35 o C.
As To, take the maximum temperature that generally occurs in the hottest time of the year in our climate zone. Let's take 25 o C.
When all the necessary data is received, we substitute them into the formula. For example, if P=300 W, then the calculations will look like this:
Q \u003d 1.76 * 300 / (35-25) \u003d 52.8 CFM
That is, on average, the total number of revolutions of all case fans, including the fan in the PSU, must be at least 53 CFM. If the propellers spin more slowly, this is fraught with burnout of any component of the system and its failure.
Also in the theory of cooling there is such a thing as system impedance. It expresses the resistance exerted by the air flow moving inside the case. This resistance can turn out to be everything that is not this flow: expansion boards, cables and wires, case fasteners, and so on. That is why it is desirable to tie all the wiring with clamps and place it in some corner of the air so that it does not become an obstacle to the air flow.
Now that we have decided on the total power of the cabinet CO, let's think about exactly how many fans we need and where to place them. Remember that one, but wisely installed fan will bring more benefits than two, but illiterately installed. If when calculating P we got no more than 115 W, then without special need there is no point in installing additional case fans, one fan in the PSU is enough. If the system generates more than 115 watts of heat, you will need to add fans to the case to keep it alive for years to come. At a minimum, you need to put one blow-out fan on the back of the system unit in addition to the fan in the power supply.
Fans are known to be noisy. If the noise is particularly annoying, you can resort to this method of solving the problem: instead of one fast and noisy, put two slower and slower ones. Share the load, so to speak. For example, instead of one 80 mm with 3000 rpm. screw two of the same (or even 120 mm) at 1500 revolutions each. It is preferable to change one smaller diameter to two larger diameters because a large impeller will drive more cubes of air per minute than small blades. In some cases, you can even limit yourself to simply replacing one smaller fan with one larger one.
Cooling can be passive or active.
The passive is simply a heatsink leaning against the surface of the die and attached to a "socket" or "slot". It has not been used for a long time to cool most CPUs, sometimes it is installed on the GPU and is actively used to cool RAM modules, video memory and chipsets. Such cooling is based on natural air convection. The radiator should preferably be copper (it removes heat better than aluminum) and needle-shaped (without points at the end of the needles). The main thing - total area its surface. The larger it is, the more efficient the heat sink. The sole of the heatsink must be smooth, otherwise the contact with the chip (and, consequently, the heat transfer) will be broken. All radiators are characterized by such a characteristic as thermal resistance. It shows how much the temperature of the processor will change when the power consumed by it increases by 1 watt. The lower this resistance, the better. Heatsinks are mounted to the chip either with a special fastener (to the processor socket) or glued with hot glue (on memory chips, chipset). In the first case, you must first apply a thin layer of thermal paste to the surface of the processor (create a thermal interface). The most common thermal pastes are KPT-8 and AlSil.
Active cooling. It can be air, water, cryogenic and nitrogenous.
Figure 1.1 - Air cooling
Air. It is also called aerogenic. This is passive cooling + cooler, that is, a radiator with a fan mounted on top. A cooler is, as you know, a fan installed on a chip, for example, on a processor or on a graphics core. Absolutely all fans have a lot of characteristics by which you can evaluate their suitability:
Fan dimensions. Expressed as height x width x height. For example, 80x80x20. All values are expressed in mm (millimeters). There is a difference between the size of the fan case (the size of the cooler, written as length x width) and the size of the actual square in which the circumference of the impeller is inscribed (fan size, length x width). The size of the cooler in all respects is a couple of millimeters higher than the size of the fan. Usually, the cooler dimensions are not 80x80x20, but simply 80x80 (eighty by eighty). Coolers come in sizes 40x40, 50x50, 60x60, 70x70, 80x80 and 120x120. The most common are 40x40, 80x80 and 120x120.
Bearing type. The fan impeller is rotated either by a sleeve bearing (sleeve) or a rolling bearing (ball). Both have their own advantages and disadvantages.
Plain bearing. Its device is as follows: a rotor is inserted into the sleeve lubricated with grease. A fan with such a bearing is simply overgrown with shortcomings, which include: low service life compared to a rolling bearing, which is also reduced when a fan with such a bearing is near a temperature above 50 ° C; impeller imbalance - during friction of the rotor with the sleeve, the latter wears out not evenly (that is, not along all the circles), but only on two sides, as a result of which, in cross section, over time it becomes not a circle, an oval. Because of this, there is a beating of the rotor and, as a result, noise. In addition, over time, the lubricant begins to flow out of the gap between the bushing and the rotor, which obviously does not help stop the beating. Coolers with sleeve bearings have only two advantages - they are very cheap compared to their ball-brothers and are quieter until the sleeve wears out or the lubrication runs out. The latter is solved by disassembling the motor and replacing the lubricant.
Friction bearing. The device is somewhat different: instead of lubrication, balls are placed between the bushing and the rotor, along which the rotor rotates. The sleeve is closed on both sides with special rings, which prevents the balls from spilling out. The disadvantages of such coolers are the opposite of the advantages of sleeve coolers - ball coolers are more expensive and noisier than sleeve coolers. In the pros - resistance to high temperatures transmitted by the radiator, and greater durability.
There is also a combined solution:
A fan that is rotated by both a sleeve- and a ball-bearing. AT this case the second increases durability and reduces noise levels. There are also fans with a plain bearing, but a thread is cut on their rotor, which, when rotated, prevents the lubricant from draining to the bottom, due to which it continuously circulates inside the sleeve.
The number of revolutions per minute. Fan impeller rotation speed. This parameter is measured in RPM (Rotations Per Minute) and the larger this value, the better. As a rule, it is from 1500 to ... it's hard to say how much, since the rpm value is constantly being increased by manufacturers. The faster the fan spins, the louder it makes noise. Here you have to choose: either speed, cold and noise, or silence and high temperatures. The operation of any fan can be slowed down by reducing the voltage supplied to the motor. This can be done by connecting to channel 7 or even 5 V instead of 12 V, or by soldering a 10-70 Ohm resistor into the break in the fan power wire. But when too low a voltage (below 6 V) is applied, the fan may simply not have enough power, and it will not start spinning and will not provide proper cooling.
Air volume per minute. Also called efficiency. Measured in CFM (Cubic Feet per Minute). The higher the CFM, the louder the fan noise.
Noise level. Measured in dB. Depends on the value of the two previous parameters. Noise can be mechanical or aerodynamic. Mechanical noise is affected by RPM and CFM. Aerodynamic depends on the angle of the impeller bend. The higher it is, the stronger the air beats against the blades and the louder the rumble.
Power connection method. PC Plug (directly to the PSU) or Molex (to the motherboard).
The next type of cooling is water cooling. It consists of a water block, a radiator, a tank with water or refrigerant, a pump and connecting hoses. The water block with two connectors (fittings) for the inlet and outlet hose is installed on the processor. Chilled water (refrigerant) is pumped from the pump to the radiator through the inlet hose, passes through it and moves through the outlet hose, being heated by the heat of the processor, to the second radiator (on which the fan is installed) to give off the heat taken from the CPU.
Figure 1.2 - Water cooling
After that, the water flows back into the pump, and the pumping cycle is repeated. Water CO has only two parameters: tank volume and pump power. The first is measured in l (liters), and the power is in l / h. The higher the power, the higher the noise produced by the pump. Water cooling has an advantage over air cooling, since the coolant used has a much higher heat capacity than air, and therefore removes heat from the heating elements more efficiently. But, in spite of everything, water cooling is not very common due to its high cost relative to air cooling and the danger short circuit in case of depressurization and leakage.
cryogenic cooling. CO, which cools the chip with a special gas - freon. It consists of a compressor, condenser, filter, capillary, evaporator and suction tube. It works as follows: gaseous freon enters the compressor and is pumped there. Further, the gas under pressure enters the condenser, where it turns into a liquid and releases energy in the form of heat. This energy is dissipated by the capacitor into the environment. Further, freon, already being a liquid, flows into the filter, where it is cleaned of random debris that can enter the capillary and, clogging it, disable the cooling system. Through the capillary, liquid freon enters the evaporator, where, under the influence of the heat transferred from the evaporator, it begins to boil, actively absorbing the thermal energy received from the processor, and returns through the suction tube to the compressor and the cycle repeats.
Figure 1.3 - Cryogenic cooling
It is not common due to its high cost and the need to replenish freon, since it disappears over time and has to be added to the cooling system. It is also effective during overclocking, as it is able to create sub-zero temperatures.
nitrogen cooling. The entire cooling system consists of a medium-sized container filled with liquid nitrogen. Nothing and nowhere should not be let down, not diverted. When heated by the processor, liquid nitrogen evaporates, and, reaching the "ceiling" of the container, it becomes liquid and again falls to the bottom and evaporates again. Nitrogen cooling, as well as freon cooling, is able to provide sub-zero temperatures (approximately -196 ° C). The inconvenience is that liquid nitrogen, as well as freon, has the ability to boil away, and you have to add it in considerable quantities. In addition, nitrogen cooling is quite expensive.
Figure 1.4 - Nitrogen cooling
The principle of operation of the Peltier element is based on the operation of p- and n-type semiconductors.
Another cooling device consisting of two semiconductor wafers. When an electric current is passed through them, one plate begins to freeze, and the other, on the contrary, radiates heat. Moreover, the temperature interval between the temperatures of the two plates is always the same. The Peltier element is used as follows: the "freezing" side is attached to the processor.
Figure 1.5 - Peltier element
The danger of using it is due to the fact that if the element is installed incorrectly, there is a possibility of condensation, which will lead to equipment failure. So when using the Peltier element, you should be extremely careful.
1.2 Cooling processors and video cards
The CPU and GPU are the most powerful sources of heat inside a modern computer. Many different designs of cooling systems for these components have been developed, the variety of design solutions is amazing.
As a rule, a significant limiting factor when choosing a cooler for a processor and video card is the cost: highly efficient and quiet cooling systems are very expensive. From what was said in the section on cooling principles (Section 1.1), it follows that it is better to use cooling systems with the largest possible radiators, preferably copper ones. Due to the high cost of copper, often used combined scheme: copper core pressed into aluminum heatsink; copper helps to distribute heat more efficiently. It is better to use low speed cooling fans: they are quieter. To maintain acceptable performance, large-sized fans (up to x120 mm) are used. So, for example, the processor cooler Zalman CNPS7700-AlCu looks like.
Often, heat pipes are used to build a large radiator - hermetically sealed and specially arranged metal pipes (usually copper). They transfer heat very efficiently from one end to the other: thus, even the farthest fins of a large heatsink work effectively in cooling. So, for example, the popular cooler Scythe Ninja is arranged
To cool modern high-performance GPUs, the same methods are used: large radiators, copper core cooling systems or all-copper radiators, heat pipes to transfer heat to additional radiators.
Recommendations for choosing here are the same: use slow and large-sized fans, the largest possible heatsinks. So, for example, the popular cooling systems for Zalman VF700 and Zalman VF900 video cards look like this.
Usually, the fans of video card cooling systems only mixed the air inside the system unit, which is not very effective in terms of cooling the entire computer.
Only very recently, cooling systems have been used to cool video cards that take hot air out of the case: the first were Arctic Cooling Silencer and a similar design, IceQ from the HIS brand.
Similar cooling systems are installed on the most powerful modern video cards (nVidia GeForce 8800, ATI x1800XT and older). Such a design is often more justified, in terms of the proper organization of air flows inside the computer case, than traditional schemes.
1.3 Hard disk cooling
Like any other component of a computer, HDD tends to heat up during operation. And although the issue of cooling this component is not particularly acute, however, with severe overheating, the life of the drive is significantly reduced. In addition, many users face the problem of HDD noise and vibration. And if there is a huge selection of appropriate coolers on the market for organizing processor and video card cooling with a minimum noise level, then there is no list of cooling systems of this class for hard drives.
A typical HDD cooler is a plate with a fan (or two) that is screwed on from the bottom of the drive. These coolers are the cheapest and most efficient. Of course, the noise from the extra fans in system unit increases.
To combat the above problem, as well as for additional cooling of hard drives, Scythe produces two CO models - Himuro and Quite Drive. By right, we can say that these devices stand out against the background of similar systems. Their design is similar - a radiator case, inside which the drive is installed. The housing dampens vibration and noise, and by combining these characteristics, these models are perhaps the most successful on the market. And if the Quite Drive has already managed to win the recognition of consumers, then Himuro is a relatively new model.
If we measure the heating during hard work, then the temperature of a modern HDD can reach 50-60 degrees Celsius. For the electrical part, this, of course, is not very scary, although its service life is also reduced - modern microcircuits have a clear temperature regime. Yes, and the manufacturer has to think about heat removal from the elements (especially from the motor driver) during design. But the plates in the HDA are very sensitive to elevated temperatures. This is expressed in direct proportion to the number of hours of time between failures of the operating mode. If these modes do not correspond to the nominal ones, then the service life may decrease several times. We risk losing not only the device, but also the data stored on it. Moreover, the increased temperature leads to the appearance of "bad" sectors on the plates, and the recovery of information in such cases may become impossible.
The most important thing is the optimum operating temperature of the hard drive. Looking at Table 1.1, everything will immediately become clear.
Table 1.1 - Hard disk operation depending on temperature
| Temperature, °С |
Bounce rate |
MTBF reduction temperature coefficient |
Corrected MTBF |
1.4 Cooling the system unit
Modern standards for the design of computer cases, among other things, regulate the way the cooling system is built. Starting from systems based on Intel Pentium II, which were launched in 1997, computer cooling technology is being introduced with a through air flow directed from the front wall of the case to the back (additionally, air for cooling is sucked in through the left wall) (Figure 1.11).
At least one fan is installed in the computer's power supply (many modern models have two fans, which can significantly reduce the rotation speed of each of them, and, therefore, the noise during operation). Additional fans can be installed anywhere inside the computer case to increase airflow. Be sure to follow the rule: on the front and left side walls, air is forced into the case, on the rear wall, hot air is thrown out. You also need to make sure that the flow of hot air from the rear wall of the computer does not fall directly into the air intake on the left wall of the computer (this happens at certain positions of the system unit relative to the walls of the room and furniture). Which fans to install depends primarily on the availability of appropriate mounts in the walls of the case. Fan noise is mainly determined by fan speed, so slow (quiet) fan models are recommended. With equal installation dimensions and rotational speed, the fans on the rear wall of the case are subjectively noisier than the front ones: firstly, they are farther from the user, and secondly, there are almost transparent grilles at the back of the case, while various decorative elements are at the front. Often noise is created due to air flow around the elements of the front panel: if the amount of air flow transferred exceeds a certain limit, eddy turbulent flows form on the front panel of the computer case, which create a characteristic noise (it resembles the hiss of a vacuum cleaner, but much quieter).
2. Adjusting the cooling of computer systems
2.1 Air cooling of computer systems
Fans are used to move air in cooling systems.
2.1.1 Fan design
The fan consists of a housing (usually in the form of a frame), an electric motor and an impeller mounted with bearings on the same axis as the motor (Figure 2.1).
Figure 2.1 - Fan (disassembled)
The reliability of the fan depends on the type of bearings installed. Manufacturers claim this typical MTBF (number of years based on 24/7 operation) (Table 2.1).
Taking into account the obsolescence of computer equipment (for home and office use it is 2-3 years), fans with ball bearings can be considered "eternal": their life is not less than the typical life of a computer. For more serious applications, where the computer must work around the clock for many years, it is worth choosing more reliable fans.
Table 2.1 - Dependence of fan operation on bearing brand
Many have come across old fans in which the plain bearings have worn out their life: the impeller shaft rattles and vibrates during operation, making a characteristic growling sound. In principle, such a bearing can be repaired by lubricating it with solid lubricant - but how many will agree to repair a fan that costs only a couple of dollars?
2.1.2 Fan specifications
Fans vary in size and thickness: commonly found in computers are 40x40x10mm for cooling graphics cards and hard drive pockets, as well as 80x80x25, 92x92x25, 120x120x25mm for case cooling. Also, fans differ in the type and design of the installed electric motors: they consume different current and provide different impeller rotation speeds. The performance depends on the size of the fan and the speed of rotation of the impeller blades: the generated static pressure and the maximum volume of air transferred.
The volume of air carried by a fan (flow rate) is measured in cubic meters per minute or cubic feet per minute. The performance of the fan, indicated in the characteristics, is measured at zero pressure: the fan operates in an open space. Inside the computer case, the fan blows into the system unit of a certain size, so it creates excess pressure in the serviced volume. Naturally, the volumetric efficiency will be approximately inversely proportional to the pressure generated. The specific type of flow characteristic depends on the shape of the used impeller and other parameters of a particular model. For example, the corresponding graph for the GlacialTech SilentBlade GT80252BDL fan (Figure 2.2).
Figure 2.2 - SilentBlade GT80252BDL fan performance
The general view of the SilentBlade II GT80252-BDLA1 fan is shown in Figure 2.3, and its specifications are below.
Figure 2.3 - General view of the SilentBlade II GT80252-BDLA1 fan
SilentBlade II GT80252-BDLA1 fan specifications
PC Case Cooling Fan
Low noise
Supply voltage 12 V
Bearing 2 x Rolling
Rotation speed 1700 (± 10%) rpm.
Air flow 26.3 CFM
Dimensions 80 x 80 x 25 mm
Power connector 3-pin + 4-pin connector
Black color
From this follows a simple conclusion: the more intense the fans in the back of the computer case, the more air can be pumped through the entire system, and the more efficient the cooling will be.
The noise level generated by the fan during operation depends on its various characteristics. It is easy to establish the relationship between performance and fan noise. On the website of a large manufacturer of popular Titan cooling systems, in the case fans section, we see that many fans of the same size are equipped with different electric motors that are designed for different rotation speeds. Since the same impeller is used, we obtain the data we are interested in: the characteristics of the same fan at different rotation speeds. We compile a table for the three most common sizes: thickness 25 mm, 80 × 80 × 25 mm, 92 × 92 × 25 mm and 120 × 120 × 25 mm (Tables 2.2).
Table 2.2 - Noise level various fans Titan
Bold font indicates the most popular types of fans.
Having calculated the coefficient of proportionality of the air flow and the noise level to the speed, we see an almost complete match. To clear our conscience, we consider deviations from the average: less than 5%. Thus, we got three linear dependencies, 5 points each. We consider the hypothesis confirmed.
The volumetric efficiency of the fan is proportional to the number of revolutions of the impeller, the same is true for the noise level.
Using the obtained hypothesis, we can extrapolate the obtained results using the least squares method (LSM): in the table, these values are marked in italics. However, it must be remembered that the scope of this model is limited. The investigated dependence is linear in a certain range of rotation speeds; it is logical to assume that the linear nature of the dependence will remain in some neighborhood of this range; but at very high and very low speeds, the picture can change significantly.
Now consider the line of fans from another manufacturer: GlacialTech SilentBlade 80x80x25mm, 92x92x25mm and 120x120x25mm. Let's make a similar table 2.3.
Table 2.3 - Noise level of various GlacialTech fans
Calculated data are marked in italics.
General view of fans of this series is shown in Figure 2.4.
Figure 2.4 - General view of GlacialTech fans
As mentioned above, at fan speeds that differ significantly from those studied, the linear model may be incorrect. The values obtained by extrapolation should be understood as a rough estimate.
Let's pay attention to two circumstances. Firstly, GlacialTech fans are slower, and secondly, they are more efficient. This is obviously the result of using an impeller with a more complex shape of the blades: even at the same speed, the GlacialTech fan carries more air than the Titan (see the gain column). And the noise level at the same speed is approximately equal: the proportion is observed even for fans from different manufacturers with various form impellers.
You need to understand that real noise characteristics the fan depends on its technical design, the pressure created, the volume of air pumped, on the type and shape of obstacles in the way of air flows; that is, on the type of computer case. Since there are many different enclosures used, it is not possible to directly apply the measurements measured in ideal conditions quantitative characteristics of fans - they can only be compared with each other for different models of fans.
2.1.3 Monitoring and control of fans
Most modern motherboards allow you to control the speed of fans connected to some three- or four-pin connectors. Moreover, some of the connectors support software control of the speed of rotation of the connected fan. Not all connectors on the board provide such capabilities: for example, the popular Asus A8N-E motherboard has five connectors for powering fans, only three of them support rotation speed control (CPU, CHIP, CHA1), and only one fan speed control (CPU); Asus P5B motherboard has four connectors, all four support rotation speed control, rotation speed control has two channels: CPU, CASE1 / 2 (the speed of two case fans changes synchronously). The number of connectors with the ability to control or control the speed of rotation does not depend on the chipset or southbridge used, but on the specific model of the motherboard: models from different manufacturers may differ in this regard. Often, motherboard designers deliberately deprive cheaper models of fan speed control capabilities. For example, the Asus P4P800 SE motherboard for Intel Pentiun 4 processors is able to regulate the speed of the processor cooler, while its cheaper version Asus P4P800-X is not. In this case, you can use special devices that are able to control the speed of several fans (and usually provide for the connection of a number of temperature sensors) - there are more and more of them on the modern market.
Fan speeds can be controlled using BIOS Setup. As a rule, if the motherboard supports changing the fan speed, here in the BIOS Setup you can configure the parameters of the speed control algorithm. The set of parameters is different for different motherboards; usually the algorithm uses the readings of thermal sensors built into the processor and motherboard. There are a number of programs for various operating systems that allow you to control and adjust the speed of fans, as well as monitor the temperature of various components inside the computer. Manufacturers of some motherboards bundle their products with proprietary programs for Windows: Asus PC Probe, MSI CoreCenter, Abit µGuru, Gigabyte EasyTune, Foxconn SuperStep, etc. Several universal programs are distributed, among them: Hmonitor (shareware, $20-30), MotherBoard Monitor (distributed free of charge, not updated since 2004). The most popular program of this class is SpeedFan (Figure 2.5).
Figure 2.5 - Program SpeedFan
2.2 Passive cooling
Passive cooling systems are called those that do not contain fans. Individual computer components can be content with passive cooling, provided that their heatsinks are placed in sufficient airflow created by "foreign" fans: for example, a chipset chip is often cooled by a large heatsink located near the CPU cooler. Passive cooling systems for video cards are also popular, for example, Zalman ZM80D-HP (Figure 2.6).
Figure 2.6 - Passive cooling of video cards
Obviously, the more heat sinks one fan has to blow through, the more flow resistance it needs to overcome; thus, with an increase in the number of radiators, it is often necessary to increase the speed of rotation of the impeller. More efficient use of many low-speed fans large diameter, and passive cooling systems should preferably be avoided. Despite the fact that passive heatsinks for processors, video cards with passive cooling, even power supplies without fans (FSP Zen) are produced, trying to build a computer without fans at all from all these components will surely lead to constant overheating. Because a modern high-performance computer dissipates too much heat to be cooled only by passive systems. Due to the low thermal conductivity of air, it is difficult to organize effective passive cooling for the entire computer, except to turn the entire computer case into a radiator, as is done in Zalman TNN 500A (Figure 2.7).
Perhaps, completely passive cooling will be enough for low-power specialized computers (for Internet access, for listening to music and watching videos, etc.)
Figure 2.7 - Zalman TNN 500A Computer Radiator Case
2.3 Water cooling of computer systems
The most common approach to cooling computer systems is to assemble a system, often with a dozen fans, all with an optimized impeller and hydrodynamic bearings. The textolite of printed circuit boards can hardly withstand kilograms of copper from high-performance radiators pierced with heat pipes. The result of all these fancy improvements drops off in direct proportion to the power of the system, as the temperature inside the case rises rapidly with increasing power, and in top-end configurations, pumping air through the case still causes significant noise. A deadlock situation arises when each component of the system is quite silent, say 18-20 dB, but put together they give 30-35 dB of even more unpleasant noise, due to the different spectrum and the resulting interference. It is worth noting the increased complexity of cleaning from dust of a similar design. If a regular system is easy to clean once every six months with a conventional vacuum cleaner, then it is very difficult to clean all these thin-ribbed designs of modern coolers. For some reason, manufacturers do not pay enough attention to the problem of dust in cases, only some cases are equipped with very inefficient dust filters. Meanwhile, dust crushed by fans not only harms cooling, settling on the surface of radiators, but is also very harmful to human health, since it is not retained by the bronchi and is removed from the lungs for a very long time. Some sources believe that the harm from fine dust is comparable to the harm from passive smoking. CD / DVD and FDD drives suffer greatly from dust, there was even a card reader clogged with dust to the point of complete impossibility of operation.
Water cooling systems are well-deserved popularity. The principle of their operation is based on the circulation of the coolant. Computer components that need to be cooled heat the water, and the water in turn is cooled in the heatsink. In this case, the radiator can be located outside the case, and even be passive (Figure 2.8).
Figure 2.8 - One of the most advanced water cooling systems
The disadvantage of water cooling is:
1. noise - the higher the power, the higher the noise emitted by the pump.
2. In spite of everything, water cooling is not very common due to its high cost relative to air cooling and the danger of a short circuit in case of depressurization and leakage.
2.4 Economy cooling
A typical home or office computer, in the absence of resource-intensive tasks, is usually only 10% loaded - anyone can verify this by launching the Windows Task Manager and watching the CPU (Central Processing Unit) Load History. Thus, with the old approach, about 90% of the processor time flew to the wind: the CPU was busy executing commands that no one needed. Newer operating systems (Windows 2000 and later) act smarter in a similar situation: using the HLT (Halt, stop) command, the processor is completely stopped for a short time - this obviously allows you to reduce power consumption and processor temperature in the absence of resource-intensive tasks.
Experienced computer scientists can recall a number of "software processor cooling" programs: when running under Windows 95/98/ME, they stopped the processor using HLT, instead of repeating meaningless NOPs, which lowered the processor temperature in the absence of computational tasks. Accordingly, the use of such programs under Windows 2000 and newer operating systems is meaningless.
Modern processors consume so much energy (which means: they dissipate it in the form of heat, that is, they heat up) that the developers have created additional technical measures to combat possible overheating, as well as tools that increase the efficiency of saving mechanisms when the computer is idle.
2.4.1 CPU thermal protection
To protect the processor from overheating and failure, the so-called thermal throttling is used (usually not translated: throttling). The essence of this mechanism is simple: if the processor temperature exceeds the allowable one, the processor is forcibly stopped by the HLT command so that the crystal has the opportunity to cool down. In early implementations of this mechanism, through BIOS Setup, it was possible to configure how much time the processor would be idle (CPU Throttling Duty Cycle: xx%); new implementations "slow down" the processor automatically until the temperature of the crystal drops to an acceptable level. Of course, the user is interested in the fact that the processor does not cool down (literally!), but does useful work - for this you need to use a fairly efficient cooling system. You can check whether the processor's thermal protection mechanism (throttling) is enabled using special utilities, such as ThrottleWatch (Figure 2.9).
Figure 2.9 - ThrottleWatch Utilities
In this case, the processor is not cooled satisfactorily: as soon as the processor load increases, the throttling mechanism is triggered.
2.4.2 Minimizing energy consumption
Almost all modern processors support special technologies to reduce energy consumption (and, accordingly, heating). Different manufacturers call these technologies differently, for example: Enhanced Intel SpeedStep Technology (EIST), AMD Cool'n'Quiet (CnQ, C&Q) - but they work, in fact, the same way. When the computer is idle and the processor is not loaded with computing tasks, the clock frequency and voltage of the processor decreases. Both of these reduce the power consumption of the processor, which in turn reduces heat dissipation. As soon as the processor load increases, the full speed of the processor is automatically restored: the operation of such a power saving scheme is completely transparent to the user and running programs. To enable such a system, you need:
Enable the use of supported technology in BIOS Setup;
Install the appropriate drivers in the OS you are using (usually this is a processor driver);
In the Windows Control Panel, in the Power Management section, on the Power Schemes tab, select the Minimal Power Management scheme from the list.
You can check that the processor frequency is changing using any program that displays the processor clock speed: from specialized CPU-Z types, up to the Windows Control Panel (Control Panel), System section (Figure 2.10).
Figure 2.10 - Windows Control Panels
AMD Cool "n" Quiet in action: Current CPU clock (994 MHz) is lower than nominal (1.8 GHz).
Often, motherboard manufacturers additionally complete their products with visual programs that clearly demonstrate the operation of the mechanism for changing the frequency and voltage of the processor, for example, Asus Cool&Quiet (Figure 2.11).
Figure 2.11 - Panel Asus Cool&Quiet
The processor frequency changes from maximum (in the presence of computational load) to some minimum (in the absence of CPU load).
2.4.3 RMClock utility
During the development of a set of programs for complex testing of CPU RightMark processors, the RMClock utility (RightMark CPU Clock / Power Utility) was created: it is designed to monitor, configure and manage the power-saving capabilities of modern processors. The utility supports all modern processors and a variety of power consumption management systems (frequency, voltage ...). The program allows you to monitor the occurrence of throttling, changes in the frequency and voltage of the processor. Using RMClock, you can configure and use everything that standard tools allow: BIOS Setup, power management by the OS using the processor driver. But the possibilities of this utility are much broader: with its help, you can configure a number of parameters that are not available for configuration in a standard way. This is especially important when using overclocked systems, when the processor runs faster than the nominal frequency.
RightMark CPU Clock Utility (RMClock) is a small utility that monitors clock speed, throttling, CPU usage, CPU voltage and temperature in real time. It is also capable of managing the performance and power consumption of processors that support power management features. In automatic control mode, it constantly monitors the level of processor utilization and automatically changes its clock speed, processor core voltage and / or throttling level in accordance with the concept of "performance on demand".
Figure 2.12 RightMark CPU Clock Utility (RMClock)
A similar method is used by video card developers: the full power of the GPU is needed only in 3D mode, and a modern graphics chip can cope with a desktop in 2D mode even at a reduced frequency. Many modern video cards are tuned so that the graphics chip serves the desktop (2D mode) with reduced frequency, power consumption and heat dissipation; accordingly, the cooling fan spins more slowly and makes less noise. The video card only starts to work at full capacity when running 3D applications, such as computer games. Similar logic can be implemented programmatically, using various utilities for fine-tuning and overclocking video cards. For example, this is how the automatic overclocking settings in the ATI Tray Tools program for the HIS X800GTO IceQ II video card look like (Figure 2.13).
Figure 2.13 - ATI Tray Tools for HIS X800GTO IceQ II video card
Ray Adams created a new ATI Tray Tools utility (Figure 2.14).
Figure 2.14 - New ATI Tray Tools
2.5 Prospects for the development of cooling systems
Historically, power supplies have been deprived of noiseless cooling systems. This is largely due to the fact that they dissipate 15-25% of the energy consumed by the computer. All this power is allocated to different, active and passive components of the power supply. Power diodes and inverter switches, transformers and chokes heat up... The traditional layout of the power supply requires rethinking with the transition to external cooling. Power supplies with the ability to connect to a water cooling system are produced by only one company.
The production of water-cooled computer systems begins, two-circuit, three-circuit and for extra computer networks are used multi-loop systems cooling.
To test the efficiency of the cooling system, two software configurations were used.
Idle - loaded desktop operating system Windows Vista Ultimate x64 SP1.
In both modes, the standard Koolance water cooling system was used, without connecting to cold water.
Idle Water and 3D Water - cold water with a temperature of about 17 degrees was supplied to the external circuit heat exchanger, the fans of the standard cooling system did not work.
Idle Air and 3D Air - a standard, single-slot, cooling system for the ATI Radeon HD 3870 video card and a Neon 775 processor cooler from GIGABYTE were used.
The coolant in the first four tests is the water of the internal cooling circuit, and in the two latest tests- air inside the system unit. To obtain stable results, all tests were performed within an hour, and the maximum temperature readings were taken using the HWMonitor program.
Studies have shown that water cooling is much more efficient than air cooling. In particular, in an air-cooled system, during downtime, heating parameters similar to those of a loaded water-cooled system are recorded! The system, cooled by air during the 3D test, quickly warmed up the air inside the system unit to a temperature above 45 degrees. Not surprisingly, the temperature of the processors approached 80 degrees, and the fans were noisy at full power.
When evaluating the economic effect, it turned out that the price of converting a computer to water cooling increased by only 1200 UAH, and the efficiency increased by 100%.
In order to save water, it is possible to manufacture a three-circuit cooling system in which the heat exchanger is mounted directly on the main pipe cold water, and the liquid of this intermediate system is pumped by a separate pump. A very interesting possibility is to place a Peltier-effect semiconductor refrigerator between the first and second circuits.
The use of such progressive solutions makes it possible to achieve record performance in the absence of noise.
3. Feasibility study of the research object
3.1 Analysis of different types of cooling
We investigate the technical and economic characteristics of the above types of cooling (Table 3.1).
Table 3.1 - Technical and economic characteristics of various types of cooling
|
cooling |
Noise level, dB |
Cost, UAH |
Safety |
Simplicity designs |
additional information |
| Passive |
missing |
fastening |
|||
| Air: fan |
partial |
installation of additional fans |
|||
| Air: |
partial |
installation of additional coolers |
Electricity consumption energy, increased noise levels, periodic bearing lubrication |
||
|
cooling |
Noise level, dB |
Cost, UAH |
Safety |
Simplicity designs |
additional information |
| Water cooling |
Water intrusion on electrical units |
Complexity of installation, water supply, pump installation |
Moisture ingress, constant inspection of fittings, valves |
||
| cryogenic cooling |
Condensation |
Difficulty of installation |
Condensation, constant viewing of blocks, refilling with freon, sub-zero temperatures |
||
| Nitrogen cooling |
missing |
Condensation formation, nitrogen leakage |
Difficulty of installation, tightness |
Condensation formation, constant viewing of blocks, filling with nitrogen, sub-zero temperatures |
|
| The Peltier element |
missing |
Formation of condensate. |
Difficulty of installation |
Additional heating |
After analyzing table 3.1 by price, we conclude (Figure 3.1):
Figure 3.1 - Analysis of the cost of various types of cooling:
1- passive cooling; 2- air-fan; 3 - air-cooler; 4 - water; 5- cryogenic; 6- nitrogenous; 7 - Peltier element.
In terms of cost, the cheapest type of cooling is passive, the cost of a radiator is determined by the amount of copper in it and the configuration, the most expensive is water cooling and contains many alterations to the computer case, the Peltier element occupies an average position in terms of cost, but it is not profitable due to abundant consumption electrical energy and generation of heat on the semiconductor, which will cause condensation to form; the most advantageous position is occupied by air cooling - ease of installation, low cost, design reliability, low power consumption, the only drawback of fans is a relatively high noise level.
It is beneficial to use a mixed cooling system, but both positive and negative factors will appear when used. When using, for example, air cooling (increasing the number of fans), not only does the noise level of the fans themselves increase, the “resonance” effect appears, since fans are on the same chassis.
When installing additional air cooling, you should also provide a filter system that will protect this computer from dust. It is possible to develop a system automatic shutdown electric fans when cooling computer blocks to a predetermined value, using a program for monitoring the temperature of blocks or additional devices(thermostats, thermostats).
Consider how much it will cost to improve the cooling of computer systems with the installation of one additional fan.
The primary initial data for determining the cost of the project are indicators that are used at the enterprise GPO "MONOLIT" in Kharkov.
These figures are summarized in Table 3.2.
Table 3.2 - Data of the enterprise GPO "MONOLIT" Kharkov.
as of 01.01.2010
| Expenditure |
Conditional designation |
Value |
|
| Development (design) of design documentation |
|||
| The tariff rate of the designer - technologist |
|||
| Tariff rate for service personnel |
|||
| Electricity tariff |
|||
| The power of a computer, modem, printer, etc. |
|||
| Cost of computer, printer, modem for base and new product (IBMPentium/32/200/ SVG) |
|||
| Depreciation deductions |
|||
| The cost of 1 hour of using a computer |
|||
| Additional salary rate |
|||
| Contribution to social events |
|||
| General production (overhead) expenses |
|||
| Transport and procurement costs |
|||
| Maintenance time of computer systems |
|||
| Depreciation rate on a computer |
|||
| Deduction for retention and repair of computers |
|||
3.2 Calculation of costs at the stage of design (development) of the design documentation of a new product
a) The complexity of developing a design documentation for a new product
To determine the complexity of the design work, first of all, a list of all stages and types of work that must be performed (logically, in an orderly and sequential manner) is compiled. It is necessary to determine the qualification level (positions) of the performers.
The cost of developing a design documentation represents the remuneration of the developers of the electrical circuit diagram, designers and technologists.
Calculation of costs for design documentation is derived by the method of costing, which is based on the labor intensity and wages of developers.
a) The complexity of developing a design documentation for a product ( T) is calculated by the formula:
where T atz- labor costs for the analysis of the terms of reference (TOR), man/hour;
T res- labor costs for the development of electrical circuits, man / hour;
T rk
T RT
T okd
T widz- labor costs for the manufacture and testing of a prototype, man/hour.
Table 3.3 - Calculation of wages for the development of product design documentation
Wage for the development of product design documentation FROM is determined by the formula:
where is the developer's hourly rate, UAH
The complexity of developing a design documentation for a product (determined in hryvnias with two decimal places (00.00 UAH)
b) Calculation of material costs for the development of design documentation
Material costs M in, which are necessary for the development (creation) of the design documentation, are given in table 3.4.
Table 3.4 - Calculation of material costs for the development of design documentation
c) Expenses for the use of computers in the development of design documentation (if any).
Expenses for the use of computers in the development of design documentation are calculated based on the cost of one hour of computer operation according to the formula. UAH:
where In g- the cost of one hour of the computer, UAH.
T res- labor costs for the development of electrical circuits, man / hour;
T rk– labor costs for design development, man/hour;
T RT– labor costs for technology development, man/hour;
T okd- labor costs for the design of design documentation, people / hour;
At the same time, the cost of one hour of computer (other technical means - TK) In g
where T e / e – electricity costs, UAH;
to amortization- the value of the 1st hour of computer depreciation, UAH;
Z pers– hourly salary of service personnel, UAH;
T rem – expenses for repairs, purchase of parts, UAH;
Cost of one hour of amortization to amortization determined by the formula, UAH:
at 40 hours working week:
where In tz- the cost of technical means, UAH.
On the- annual depreciation rate (%).
K t- number of weeks per year (52 weeks/year).
G t- number of working hours per week (40 hours/week)
Hourly payment service personnel Z pers calculated by the formula, UAH:
where About cl- monthly salary of service personnel, UAH.
K rg- number of working hours per month (160 hours/month);
H rem- labor costs for computer repair (6% About cl).
Repair costs, purchase of computer parts T rem
where In tz- the cost of technical means, UAH.
H rem- percentage of expenses for repairs, purchase of parts (%);
K t- number of weeks per year (52 weeks/year).
G t- number of working hours per week (36 ¸ 168 hours/week)
Expenses for the use of electricity by computers and technical means T e / e determined by the formula, UAH:
, (3.8)
where In her– the cost of one kWh of electricity, UAH;
W sweat- the power of the computer, printer and scanner (for 1 hour), (kW / h.).
Thus, the cost of one hour of computer operation during the development of design documentation will be (see formula 3.4), UAH:
Expenses for the use of computers in the development, UAH. (see formula 3.3):
d) Calculation of the technological cost of creating a design documentation
The calculation of the technological cost of creating a design documentation for a product is carried out using the costing method (table 3.5).
Table 3.5 - Calculation of technological costs for the creation of product design documentation
Cost of developed design documentation C cd calculated as the sum of points 1–6.
3.3 Calculation of costs at the stage of production of the product
The cost of the product that is being developed is calculated on the basis of the norms of material and labor costs. Among the initial data that are used to calculate the cost of a product, there are norms for the consumption of raw materials and basic materials per product (table 3.6).
Table 3.6 - Calculation of the cost of raw materials and basic materials for one product
| materials |
Cost rate |
Wholesale price UAH/unit. |
Actual costs |
|
| Solder POS - 61 (GOST 21930 - 76), kg |
||||
| Lacquer EP-9114 (GOST 2785-76), kg |
||||
| Transport and procurement costs (4%) |
||||
In the course of calculating the cost of a product, as the initial data, they use the specifications of materials, purchased components for the product and semi-finished products, which are used in the manufacture of one product (table 3.7).
Table 3.7 - List of components for improving PC cooling
We calculate the wages of the main production workers on the basis of labor intensity norms by type of work and hourly rates of workers. Costing and pricing are calculated in table 3.9.
Table 3.9 - Calculation of the cost price and determination of the price of the product according to the new design documentation
total cost for the preparation of design documentation and modernization of cooling is UAH 346.58.
4. Labor protection
Scientific and technological progress has made serious changes in the conditions of production activities of knowledge workers. Their work has become more intense, strenuous, requiring significant expenditure of mental, emotional and physical energy. This required a comprehensive solution to the problems of ergonomics, hygiene and labor organization, regulation of work and rest regimes.
Currently, computer technology is widely used in all areas of human activity. When working with a computer, a person is exposed to a number of dangerous and harmful production factors: electromagnetic fields (radio frequency range: HF, UHF and SHF), infrared and ionizing radiation, noise and vibration, static electricity, etc.
Working with a computer is characterized by significant mental stress and neuro-emotional stress for operators, high intensity of visual work and a fairly large load on the muscles of the hands when working with a computer keyboard. Of great importance is the rational design and arrangement of the elements of the workplace, which is important for maintaining the optimal working posture of the human operator.
In the process of working with a computer, it is necessary to observe the correct mode of work and rest. Otherwise, the staff has a significant strain on the visual apparatus with the appearance of complaints of dissatisfaction with work, headaches, irritability, sleep disturbance, fatigue and pain in the eyes, lower back, neck and arms.
4.1 Requirements for production facilities
4.1.1 Coloration and reflectances
The coloring of rooms and furniture should contribute to the creation of favorable conditions for visual perception, good mood.
Light sources such as lamps and windows that reflect off the screen surface significantly impair the accuracy of the characters and cause physiological disturbances that can result in significant stress, especially during prolonged use. Reflection, including reflections from secondary light sources, should be kept to a minimum.
Curtains and screens can be used to protect against excessive brightness of windows.
windows are oriented to the south: - the walls are greenish-blue or light blue; floor - green;
windows are oriented to the north: - the walls are light orange or orange-yellow; floor - reddish-orange;
windows are oriented to the east: - yellow-green walls; the floor is green or reddish-orange;
the windows are oriented to the west: - the walls are yellow-green or bluish-green; the floor is green or reddish-orange.
In the premises where the computer is located, it is necessary to ensure the following values of the reflection coefficient: for the ceiling: 60-70%, for the walls: 40-50%, for the floor: about 30%. For other surfaces and work furniture: 30-40%.
4.1.2 Lighting
Properly designed and executed industrial lighting improves the conditions of visual work, reduces fatigue, increases labor productivity, has a beneficial effect on the working environment, having a positive psychological impact on the worker, increases labor safety and reduces injuries.
Insufficient lighting leads to eye strain, weakens attention, leads to premature fatigue. Excessively bright lighting causes blinding, irritation and pain in the eyes.
Not right direction light in the workplace can create harsh shadows, glare, and disorientate the worker. All these reasons can lead to an accident or occupational diseases, so the correct calculation of illumination is so important.
There are three types of lighting - natural, artificial and combined (natural and artificial together).
Natural Lighting - Room Lighting daylight, penetrating through the light openings in the external enclosing structures of the premises.
Natural lighting is characterized by the fact that it varies widely depending on the time of day, season, nature of the region and a number of other factors.
Artificial lighting is used when working at night and during the day, when it is not possible to provide the normalized values of the coefficient of natural light (cloudy weather, short daylight hours).
Lighting, in which natural lighting, which is insufficient according to the norms, is supplemented by artificial lighting, is called combined lighting.
Artificial lighting is divided into working, emergency, evacuation, security. Working lighting, in turn, can be general or combined. General - lighting, in which the lamps are placed in the upper zone of the room evenly or in relation to the location of the equipment. Combined - lighting, in which local lighting is added to the general one.
According to SNiP II-4-79 indoors computer centers it is necessary to use a combined lighting system.
When performing work of the category of high visual accuracy (the smallest size of the object of distinction is 0.3 ... …1.0 mm) KEO must be at least 1.0%. As sources of artificial lighting, fluorescent lamps of the LB or DRL type are usually used, which are combined in pairs into lamps, which should be evenly spaced above the work surfaces.
The requirements for lighting in rooms where computers are installed are as follows: when performing visual work high precision general illumination should be 300 lux, and combined - 750 lux; similar requirements when performing work of medium accuracy - 200 and 300 lx, respectively.
In addition, the entire field of view should be illuminated fairly evenly - this is the main hygienic requirement. In other words, the degree of illumination of the room and the brightness of the computer screen should be approximately the same, because. bright light in the area of peripheral vision significantly increases eye strain and, as a result, leads to their rapid fatigue.
4.1.3 Microclimate parameters
Microclimate parameters can vary widely, while a necessary condition for human life is to maintain a constant body temperature due to thermoregulation, i.e. the body's ability to regulate heat transfer to the environment. The principle of microclimate regulation is the creation of optimal conditions for the heat exchange of the human body with the environment.
Computer Engineering is a source of significant heat generation, which can lead to an increase in temperature and a decrease in relative humidity in room. In rooms where computers are installed, the certain parameters microclimate. The sanitary norms SN-245-71 set the values of microclimate parameters that create comfortable conditions. These norms are set depending on the time of year, nature labor process and the nature of the production premises (see table. 4.1)
Table 4.1 - Microclimate parameters for rooms where computers are installed
The volume of premises in which employees of computer centers are located should not be less than 19.5 m 3 / person, taking into account the maximum number of simultaneously working per shift. The norms for supplying fresh air to the premises where computers are located are given in Table. 4.2.
Table 4.2 - Norms for supplying fresh air to rooms where computers are located
To ensure comfortable conditions, both organizational methods (rational organization of work depending on the time of year and day, alternation of work and rest) and technical means (ventilation, air conditioning, heating system) are used.
4.1.4 Noise and vibration
Noise worsens working conditions, having a harmful effect on the human body. Those working in conditions of prolonged noise exposure experience irritability, headaches, dizziness, memory loss, increased fatigue, loss of appetite, ear pain, etc. Such disturbances in the functioning of a number of organs and systems of the human body can cause negative changes in emotional state person up to stressful. Under the influence of noise, concentration of attention decreases, physiological functions are disturbed, fatigue appears due to increased energy costs and neuropsychic stress, and speech commutation worsens. All this reduces the working capacity of a person and his productivity, quality and safety of work. Prolonged exposure to intense noise [above 80 dB(A)] on human hearing results in partial or complete hearing loss.
In table. 4.3 indicates the maximum sound levels depending on the category of severity and intensity of labor, which are safe in terms of maintaining health and performance.
Table 4.3 - Limit sound levels, dB, at workplaces
The noise level at the workplace of mathematicians-programmers and video operators should not exceed 50 dBA, and in the information processing rooms on computers - 65 dBA. To reduce the noise level, the walls and ceiling of the rooms where computers are installed can be lined sound-absorbing materials. The level of vibration in the premises of computer centers can be reduced by installing equipment on special vibration isolators.
4.1.5 Electromagnetic and ionizing radiation
Most scientists believe that both short-term and long-term exposure to all types of radiation from the monitor screen is not dangerous to the health of personnel servicing computers. However, there is no exhaustive data on the danger of exposure to radiation from monitors for those working with computers, and research in this direction continues.
Permissible values of the parameters of non-ionizing electromagnetic radiation from a computer monitor are presented in Table. 4.4.
The maximum level of X-ray radiation at the workplace of a computer operator usually does not exceed 10 microrem/h, and the intensity of ultraviolet and infrared radiation from the monitor screen lies within 10-100 mW/m 2 .
Table 4.4 - Permissible values for the parameters of non-ionizing electromagnetic radiation (in accordance with SanPiN 2.2.2.542-96)
To reduce the impact of these types of radiation, it is recommended to use monitors with a reduced level of radiation (MPR-II, TCO-92, TCO-99), install protective screens, and also observe regulated work and rest schedules.
4.2 Ergonomic requirements for the workplace
The design of workplaces equipped with video terminals is one of the important issues ergonomic design in the field of computer technology.
The workplace and the relative position of all its elements must comply with anthropometric, physical and psychological requirements. The nature of the work is also important. In particular, when organizing a programmer's workplace, the following basic conditions must be met: optimal placement equipment included in the workplace and sufficient workspace, allowing to carry out all the necessary movements and movements.
Ergonomic aspects of designing video terminal workstations, in particular, are: height working surface, legroom dimensions, requirements for the location of documents in the workplace (availability and dimensions of the document stand, the possibility of various placement of documents, the distance from the user's eyes to the screen, document, keyboard, etc.), characteristics of the desk chair, surface requirements desktop, adjustability of workplace elements.
The main elements of the programmer's workplace are a table and an armchair.
The main working position is the sitting position.
The sitting posture causes minimal programmer fatigue.
Rational layout the workplace provides for a clear order and consistency in the placement of objects, means of labor and documentation. What is required to perform work more often is located in the zone of easy reach of the workspace.
Motor field - the space of the workplace, in which human motor actions can be carried out.
The maximum reach of the hands is part of the motor field of the workplace, limited by arcs described by the maximum arms outstretched when moving them in the shoulder joint.
The optimal zone is a part of the motor field of the workplace, limited by arcs described by the forearms when moving in the elbow joints with support at the point of the elbow and with a relatively immobile shoulder.
On fig. 4.1 shows an example of the placement of the main and peripheral components of a PC on the programmer's desktop.
For comfortable work, the table must meet the following conditions:
The height of the table should be chosen taking into account the ability to sit freely, in a comfortable position, if necessary, leaning on the armrests;
The lower part of the table should be designed so that the programmer can sit comfortably without being forced to tuck his legs in;
The surface of the table must have properties that exclude the appearance of glare in the field of view of the programmer;
The design of the table should provide for the presence of drawers (at least 3 for storing documentation, listings, stationery);
The height of the surface on which the keyboard is installed should be about 650mm.
Great importance is attached to the characteristics of the working chair. So, the recommended seat height above floor level is within 420-
550mm. The seat surface is soft, the front edge is rounded and the backrest angle is adjustable.
Figure 4.1 - Placement of the main and peripheral components of the PC on the programmer's desktop:
1 - scanner, 2 - monitor, 3 - printer, 4 - desktop surface, 5 - keyboard, 6 - mouse.
When designing, it is necessary to provide for the possibility of various placement of documents: on the side of the video terminal, between the monitor and keyboard, etc. In addition, in cases where the video terminal has low quality images, for example, flickering is noticeable, the distance from the eyes to the screen is made larger (about 700mm) than the distance from the eye to the document (300-450mm). In general, with a high image quality on the video terminal, the distance from the user's eyes to the screen, document and keyboard can be equal.
The screen position is determined by:
Reading distance (0.6 - 0.7m);
The reading angle, the direction of view 20˚ below the horizontal to the center of the screen, with the screen perpendicular to this direction.
It should also be possible to adjust the screen:
Height +3 cm;
Tilt from -10˚ to +20˚ relative to the vertical;
In the left and right directions.
Great importance is also attached to the correct working posture of the user.
With an uncomfortable working position, pain in the muscles, joints and tendons may appear. The requirements for the working posture of the video terminal user are as follows:
The head should not be tilted more than 20˚,
Shoulders should be relaxed
Elbows - at an angle of 80˚-100˚,
Forearms and hands - in a horizontal position.
The reason for the incorrect posture of users is due to the following factors: there is no good document stand, the keyboard is too high and the documents are too low, there is nowhere to put hands and arms, there is not enough legroom.
In order to overcome these shortcomings, general recommendations: better mobile keyboard; special devices should be provided for adjusting the height of the table, keyboard and screen, as well as a palm rest.
The size of characters, the density of their placement, the contrast and the ratio of the brightness of characters and the background of the screen are essential for productive and high-quality work on a computer. If the distance from the operator's eyes to the display screen is 60-80 cm, then the height of the sign must be at least 3 mm, the optimal ratio of the width and height of the sign is 3:4, and the distance between the signs is 15-20% of their height. The ratio of the brightness of the screen background and characters is from 1:2 to 1:15.
When using a computer, doctors advise installing a monitor at a distance of 50-60 cm from the eyes. Experts also believe that top part The video display should be at eye level or slightly below. When a person looks straight ahead, his eyes open wider than when he looks down. Due to this, the field of view is significantly increased, causing dehydration of the eyes. In addition, if the screen is set high and the eyes are wide open, the blinking function is impaired. This means that the eyes do not close completely, are not washed with tear fluid, do not receive sufficient moisture, which leads to their rapid fatigue.
The creation of favorable working conditions and the correct aesthetic design of workplaces in production is of great importance, both to facilitate labor and to increase its attractiveness, which positively affects labor productivity.
4.3 Working hours
As has been repeatedly noted, when working with a personal computer, a very important role is played by the observance of the correct regime of work and rest. Otherwise, the staff has a significant strain on the visual apparatus with the appearance of complaints of dissatisfaction with work, headaches, irritability, sleep disturbance, fatigue and pain in the eyes, lower back, neck and arms.
In table. 4.5 provides information on regulated breaks that must be taken when working on a computer, depending on the duration of the work shift, types and categories of work with VDT (video display terminal) and PC (in accordance with SanNiP 2.2.2 542-96 " Hygiene requirements to video display terminals, personal electronic computers and work organization”).
Table 4.5 - Time of regulated breaks when working on a computer
Note. Break times are given subject to the specified Sanitary regulations and norms. If the actual working conditions do not meet the requirements of the Sanitary Rules and Norms, the time of regulated breaks should be increased by 30%.
In accordance with SanNiP 2.2.2 546-96, all types of labor activity related to the use of a computer are divided into three groups: group A: work on reading information from the screen of a VDT or PC with a preliminary request; group B: work on entering information; group B: creative work in the mode of dialogue with a computer.
The effectiveness of breaks is increased when combined with industrial gymnastics or organizing a special room for staff rest with comfortable upholstered furniture, an aquarium, a green area, etc.
4.4 Illumination calculation
The calculation of the illumination of the workplace is reduced to the choice of a lighting system, the definition required number fixtures, their type and placement. Based on this, we calculate the parameters of artificial lighting.
4.4.1 Calculation of artificial lighting
Usually artificial lighting It is carried out by means of electric light sources of two types: incandescent lamps and fluorescent lamps. We will use fluorescent lamps, which, compared with incandescent lamps, have a number of significant advantages:
By spectral composition light they are close to daylight, natural light;
Possess more high efficiency(1.5-2 times higher than the efficiency of incandescent lamps);
They have increased light output (3-4 times higher than that of incandescent lamps);
Longer service life.
The calculation of lighting is made for a room with an area of 15m 2, the width of which is 5m, the height is 3m. Let's use the luminous flux method.
To determine the number of fixtures, we determine the luminous flux incident on the surface according to the formula:
F = E∙S∙Z∙К / n, (4.1)
where F is the calculated luminous flux, Lm;
E - normalized minimum illumination, Lux (determined according to the table). The work of a programmer, in accordance with this table, can be classified as precision work, therefore, the minimum illumination will be E = 300 Lx;
S is the area of the illuminated room (in our case, S = 15m 2);
Z is the ratio of the average illumination to the minimum (usually taken equal to 1.1-1.15, let Z = 1.1);
K is a safety factor that takes into account the decrease in the luminous flux of the lamp as a result of lamp contamination during operation (its value depends on the type of room and the nature of the work carried out in it, and in our case K = 1.5);
n - coefficient of use, (expressed as the ratio of the luminous flux incident on the calculated surface to the total flux of all lamps and is calculated in fractions of a unit; depends on the characteristics of the lamp, the size of the room, the color of the walls and ceiling, characterized by the coefficients of reflection from the walls (RS) and the ceiling (RP)), the value of the RS and RP coefficients were indicated above: RS=40%, RP=60%. The value of n is determined from the table of coefficients for the use of various lamps.
To do this, calculate the room index using the formula:
I = A∙B / h (A+B), (4.2)
where h is the calculated suspension height, h = 2.92 m;
A - room width, A = 3 m;
B is the length of the room, B = 5 m.
Substituting the values we get:
Knowing the room index I, according to table 7 we find n = 0.22.
We substitute all the values into formula (4.1) to determine the luminous flux F, we obtain F = 33750 Lm.
For lighting, we select fluorescent lamps of the LB40-1 type, the luminous flux of which F l \u003d 4320 Lm.
We calculate the required number of lamps using the formula:
N \u003d F / F l, (4.3)
where N is the number of lamps to be determined;
F - luminous flux, F = 33750 Lm;
F l - luminous flux of the lamp, F l \u003d 4320 Lm.
When choosing lighting fixtures, we use OD-type fixtures. Each luminaire comes with two lamps.
This means that four lamps of the OD type are required for a room with an area of \u200b\u200bS \u003d 15 m 2.
4.4.2 Calculation of natural lighting of premises
The organization of proper lighting of workplaces, processing areas and industrial premises is of great sanitary and hygienic importance, it helps to increase work productivity, reduce injuries, and improve product quality. Conversely, insufficient lighting complicates the execution of the technological process and can be the cause of an accident and diseases of the organs of vision.
Lighting must meet the following basic requirements:
Be uniform and fairly strong;
Do not create various shadows at work places, contrasts between the illuminated workplace and the environment;
Do not create unnecessary brightness and brilliance in the field of view of workers;
Give the correct direction of the light flux;
All production facilities must have light cuts that provide sufficient natural lighting. Without natural lighting, there may be conference rooms, exhibition halls, locker rooms, sanitary facilities, waiting rooms medical institutions, personal hygiene rooms, corridors and aisles.
The coefficient of natural lighting in accordance with DNB B 25.28.2006, for our third zone of the light climate is 1.5.
Based on this, we will calculate required area window openings.
The calculation of the area of windows with side lighting is determined by the formula:
S o \u003d (L n * K z. * N 0 * S n * K building) / (100 * T 0 * r1) (4.4)
where: L n – normalized value of KEO
K z - safety factor (equal to 1.2)
N 0 - light characteristic of windows
S n - area of sufficient natural light
To zd. - coefficient taking into account the shading of windows by opposing buildings
r1 - coefficient taking into account the increase in KEO with side lighting
T 0 - total light transmission coefficient, which is calculated by the formula:
T 0 = T 1 * T 2 * T 3 * T 4 * T 5, (4.5)
where T 1 is the light transmission coefficient of the material;
T 2 - coefficient taking into account the loss of light in the bindings of the light opening;
T 3 - coefficient taking into account light losses in load-bearing structures;
T 4 - coefficient taking into account the loss of light in sun protection devices;
T 5 - the coefficient that takes into account the loss of light in the protective grid installed under the lanterns, is taken equal to 1;
Now you should calculate the side lighting for the area adjacent to the outer wall. According to the category of visual work, it is necessary to determine the value of KEO. KEO \u003d 1.5, the normalized value of KEO, taking into account the light climate, must be calculated using the formula:
L n \u003d l * m * c, (4.6)
where l – KEO value (l=1.5);
m – coefficient of light climate (m=1);
c – climate sunshine factor (c=1)
Now you should determine the ratio of the length of the room L n to the depth of the room B:
L n /B=3/5 =0.6;
The ratio of the depth of the room B to the height from the level of the conditional work surface to the top of the window h 1 (in this case h 1 = 1.8):
B / h 1 \u003d 5 / 1.8 \u003d 2.77.
Light characteristic light openings N 0 =9.
The value of T 0 =0.8*0.7*1*1*1=0.56.
L n for the 4th category of visual work is 1.5 when washing windows twice a year.
We determine r1, r1=1.5.
Now you should determine the value of S p:
S p \u003d L n * B \u003d 3 * 10 \u003d 30 m 2.
S o \u003d (1.5 * 1.2 * 9 * 30 * 1) / (100 * 0.56 * 1.5) \u003d 486/84 \u003d 5.78 m 2;
We accept the number of windows 1 piece:
S 1 \u003d 5.78 m 2 area of one window
The height of one window is 2.4 m, the width is 2.4 m.
4.5 Ventilation calculation
Depending on the method of air movement, ventilation can be natural and forced.
The parameters of the air entering the intake openings and openings of local exhausts of technological and other devices located in working area, should be taken in accordance with GOST 12.1.005-76. With a room size of 3 by 5 meters and a height of 3 meters, its volume is 45 cubic meters. Therefore, ventilation should provide an air flow rate of 90 cubic meters per hour. In the summer, it is necessary to provide for the installation of an air conditioner in order to avoid exceeding the temperature in the room for the stable operation of the equipment. It is necessary to pay due attention to the amount of dust in the air, as this directly affects the reliability and service life of the computer.
The power (more precisely, the cooling power) of the air conditioner is its main characteristic, it depends on what volume of the room it is designed for. For approximate calculations, 1 kW per 10 m 2 is taken with a ceiling height of 2.8 - 3 m (in accordance with SNiP 2.04.05-86 "Heating, ventilation and air conditioning").
To calculate the heat inflows of this room, a simplified method was used:
where: Q - Heat gains
S - Room area
h - Room height
q - Coefficient equal to 30-40 W / m 3 (in this case 35 W / m 3)
For a room of 15 m 2 and a height of 3 m, the heat inflows will be:
Q=15 3 35=1575 W
In addition, heat dissipation from office equipment and people should be taken into account, it is considered (in accordance with SNiP 2.04.05-86 "Heating, ventilation and air conditioning") that in a calm state a person emits 0.1 kW of heat, a computer or a copier 0.3 kW, By adding these values to the total heat inputs, the required cooling capacity can be obtained.
Q add \u003d (H S opera) + (С S comp) + (P S print) (4.9)
where: Q add - The sum of additional heat inflows
C - Computer Heat Dissipation
H - Heat dissipation of the operator
D - Printer Heat Dissipation
S comp - Number of workstations
S print - Number of printers
S operas - Number of operators
Additional heat inflows of the room will be:
Q add1 \u003d (0.1 2) + (0.3 2) + (0.3 1) \u003d 1.1 (kW)
The total sum of heat gains is equal to:
Q total1 \u003d 1575 + 1100 \u003d 2675 (W)
In accordance with these calculations, it is necessary to choose the appropriate power and number of air conditioners.
For the room for which the calculation is carried out, air conditioners with a rated power of 3.0 kW should be used.
4.6 Noise calculation
One of the unfavorable factors of the production environment in the information and computing center is the high level of noise generated by printing devices, air conditioning equipment, fans of cooling systems in the computers themselves.
To address questions about the need and feasibility of noise reduction, it is necessary to know the noise levels at the operator's workplace.
The noise level arising from several incoherent sources operating simultaneously is calculated based on the principle of energy summation of radiation individual sources:
∑L = 10 lg (Li∙n), (4.10)
where Li is the sound pressure level of the i-th noise source;
n is the number of noise sources.
The obtained calculation results are compared with the permissible value of the noise level for a given workplace. If the calculation results are higher allowable value noise levels, special noise reduction measures are required. These include: lining the walls and ceiling of the hall with sound-absorbing materials, reducing noise at the source, correct layout equipment and rational organization of the operator's workplace.
The sound pressure levels of noise sources acting on the operator at his workplace are presented in Table. 4.6.
Table 4.6 - Sound pressure levels of various sources
Usually workplace operator is equipped with the following equipment: hard drive in the system unit, fan(s) of PC cooling systems, monitor, keyboard, printer and scanner.
Substituting the values of the sound pressure level for each type of equipment into formula (4.4), we obtain:
∑L=10 lg(104+104.5+101.7+101+104.5+104.2)=49.5 dB
The obtained value does not exceed the permissible noise level for the operator's workplace, equal to 65 dB (GOST 12.1.003-83). And if you consider that it is unlikely that such peripheral devices as a scanner and a printer will be used simultaneously, then this figure will be even lower. In addition, when the printer is working, the direct presence of the operator is not necessary, because. The printer is equipped with an automatic sheet feeder.
The paper deals with an actual topic - the regulation of cooling of computer systems.
In the course of the work, the theoretical issues of cooling computer systems, the movement of air flows with various cooling systems, Comparative characteristics use of active and passive cooling systems.
The performance of computer systems increases, which means that the heating of the circuit elements of computer systems also increases, and as a result, the temperature inside the computer increases. With an increase in temperature, failures of some elements also begin.
The paper discusses various types of cooling of computer systems, ranging from the simplest - passive and ending with the most expensive view cooling using Peltier elements.
Air cooling of the computer, at the present stage, is the most acceptable for the average user. But air cooling has a number of disadvantages. The first is the noise level. The more fans we add to the system, the higher the noise level. The second disadvantage is the influx of external dust.
At the present stage, water, cryogenic and nitrogen cooling are used. But each type of cooling has a number of advantages and disadvantages. After conducting a feasibility study of various types of cooling, we decided to add a fan to the computer system and calculated the cost of installing an additional fan and a thermal switch that turns off the fan when the temperature inside the computer drops.
The total cost for the development of design documentation and installation of the fan amounted to UAH 346.58.
In the last section of the work, the issues of labor protection are considered.
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The cooling method largely determines the design of radio-electronic equipment (REA), therefore, even on early stage design, i.e. at the stage of a technical proposal or draft design, it is necessary to select a REA cooling system. For a preliminary assessment and selection of a cooling method, it is necessary to determine two main indicators /1, p.119/.
The first indicator is overheating relative to the environment Tc of the case of the least heat-resistant element, for which the allowable temperature has a minimum value. This indicator is determined by the formula
υс = Ti min - Tc (2.1)
where Ti min - allowable body temperature of the least heat-resistant element;
Тс - ambient temperature (specified in the technical specifications).
Since all the elements are the same according to the terms of reference, but different powers are allocated to them, the third transistor will have the largest heat release. For these elements, the minimum value of the allowable temperature is T min = 373 K.
Substituting the value Tc = 323 K and the selected minimum value of the allowable temperature T min = 373 K into formula (2.1), we obtain
υс = 373 - 323 = 50 K
The second indicator q is equal to the density of the heat flux passing through the conditional surface area Ap of heat transfer
q = Фkн1/Ап (2.2)
where F is the total power dissipated in the block;
kn1 - coefficient taking into account air pressure;
Ap - conditional area of the heat exchange surface.
The conditional area of the heat exchange surface Ap is determined by the following formula
An = 2 (2.3)
where L1, L2, L3 are the horizontal and vertical dimensions of the block specified in the terms of reference, in meters;
Kz - fill factor.
In this case, we have the following values: L1 = 0.34 m, L2 = 0.17 m, L3 = 0.1 m, Kz = 0.31.
Substituting these values into formula (2.3), we obtain
Ap \u003d 2H \u003d 0.15 m2
Knowing that the power is F = 34 W, kn1 = 1.2 at H1 = 0.05 MPa and Ap = 0.15 m2, we calculate the second indicator using formula (2.2) and obtain
q \u003d 34 × 1.2 / 0.15 \u003d 272 W / m2
log q = 2.4 (2.4)
The indicators υс = 50 K and lg q = 2.4 obtained as a result of calculations are the coordinates of the point.
Figure 2 - Areas of reasonable application various ways cooling.
Where 1 - free air; 2 - free and forced air; 3 - forced air; 4 - forced air and liquid; 5 - forced evaporation; 6 - forced liquid and free evaporation; 7 - forced liquid, free and forced evaporation; 8 - free forced and free evaporative; 9 - free and forced evaporation.
From Figure 2, we find that this point falls on the border of areas 1 and 2. Thus, it is possible to use both free and forced cooling. Let us dwell on the choice of free air cooling.
Figure 3 - Probability curves for REA in a perforated case with free air cooling
From Figure 3 we find the probability of normal cooling for the chosen cooling method. From the graph we find that the probability p=0.8. Therefore, a similar cooling method can be chosen, but attention should be paid to the analysis of the thermal regime in the future.
