Automatic control of ventilation systems optimizes their performance. Automation for ventilation is of particular importance in the construction of large buildings. Here, ventilation structures are located on large areas, and it is problematic to control the operation of all equipment in manual mode. It is important to properly set up the automatic system. This will guarantee her quality work and make it easier to manage devices.
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The main tasks of automation
Design modern systems ventilation is rather complicated. It consists of many devices, each of which has its own purpose in ensuring the functioning of the system. In order for the operation of the devices to be of high quality, it must be controlled, seeking to coordinate the actions of all units. This is what automation is for. It greatly facilitates the work with the system and ensures the smooth operation of devices without the direct participation of a person.
Control over the operation of mechanisms is carried out by special sensors installed on them. This allows the operator to control the system remotely from a single center without having to contact each instrument directly.
Automation of ventilation and air conditioning systems
A complex of sensors collects information from ventilation mechanisms and transmits it to the control center monitor. Here it is analyzed by a specialist, after which, in case of serious malfunctions, the workflow is corrected.
If necessary, the system can independently connect additional units and control devices to optimize the operating mode. This may be necessary during weather changes, which can lead to an increased load on the mechanisms, due to which the latter may fail.
In case of an emergency, the automation itself will disconnect the devices from the power supply.Automation of the ventilation system optimizes the operation of the complex, reduces the amount service personnel up to 1-2 people. This reduces the cost of additional workers.
Working mode
The control room for supply ventilation is the control room. Shield provides three modes of its functionality:
- manual;
- automatic autonomous;
- auto.
First option implies manual control over the system. It is carried out by the operator on duty in the control room.In the second case starting and stopping ventilation, as well as the transfer of functional data is carried out independently of the readings collected from adjacent engineering systems. Information about the work is received by the dispatcher.
In completely automatic mode ventilation is included in the overall automated control, which synchronizes all the functions responsible for the life support of the building, its system automation and dispatching.
System nodes
Installing such systems is not easy, so only experienced specialists should be engaged in setting up an automation center. Automatic ventilation divided into control nodes:
- touch sensors;
- regulators;
- executive mechanics.
Touch sensors
The first group of devices collects information about the environment - temperature, pressure, humidity level, etc., as well as the state of ventilation units. Collected by sensors the data is sent to the control center for analysis.
Information is collected by pressure switches, thermostats and hygrostats. These control elements are installed at the nodal points of the system and upon reaching the operating parameters of the devices specified by the program or environment connect or disconnect contacts, starting or stopping mechanisms. Thus, the optimum mode of temperature and air humidity inside the channel or room is maintained.Parameters are controlled by sensors that record humidity, temperature, pressure and level carbon dioxide.
Speed controllers and frequency converters
The second group of devices processes the received information. Comparing the readings of the sensors with each other and with the norms laid down in the control program, they correct the operation of the system by disabling or enabling the corresponding functions, which is provided by the actuators.
Correction of working functions occurs with the help of speed controllers and frequency converters. Speed controllers are installed to service fans and can control one or a whole group of them. When installing this control unit, it must be remembered that the strength of the current passing through the corrective unit should not be more than the amount allowed for it. Therefore, when choosing a regulator, it is necessary to take into account what maximum current it is designed for.
With the help of frequency converters, safe starts of engines are carried out, the power of which is not limited. But the most important function of the converters is to control the speed of rotation of the motor with the help of changing frequencies of the supply voltage. This provides smooth speed control without affecting mechanical characteristics. This adjustment process minimum loss power.
Such advantages of frequency converters, despite their high cost, make them more and more popular.
Air conditioning systems (ACS) are designed to create and automatically maintain the necessary air parameters in the premises (temperature, relative humidity, cleanliness, movement speed, etc.). Depending on the purpose of the SLE, they are divided into technological, ensuring the state air environment that meets the requirements of a particular technological process, and comfortable, creating favorable conditions for a person. Depending on the design, air conditioners are divided into sectional and modular, and according to the equipment for generating heat and cold, they are divided into autonomous and non-autonomous. Autonomous air conditioners are supplied from the outside only with electricity. For the operation of non-autonomous air conditioners, it is necessary to supply heat and coolant from the outside, as well as electricity to drive the motors of fans and pumps.
Let us first consider the basic principles of automating a comfort air conditioning unit designed to maintain a given temperature and humidity in a room (Fig. 8.5).
For winter conditions air is processed according to the following scheme. outside air is first heated in the utilizer U from the point H 3 to the point U 3 , and then in the air heater of the first stage from the point U 3 to the value / k. As a result of adiabatic humidification at a constant enthalpy, the air acquires parameters corresponding to the point K g In the air heater of the second stage, the air is heated up to point R 3 and is supplied to the room.
As the enthalpy of the outside air increases, its heating in the first stage air heater decreases, and when the enthalpy is reached 1 TO heating must be turned off. A transitional regime begins, which is characterized by a constant internal temperature / 3 and varies depending on the enthalpy of the outdoor air and the relative humidity inside the room.
Based on the conditions of comfort, fluctuations in relative humidity within 40-60% are permissible. When the enthalpy of outdoor air is higher than / n in the manned room, it is advisable
Rice. 8.5.
a - technology system SKKV; b - air treatment processes
in /-b diagram
maintain maximum comfortable conditions relative humidity (up to 60%), while allowing significant fluctuations in the internal temperature. Since fluctuations in indoor temperature are associated with changes in the enthalpy of outdoor air, in warm time a certain “dynamic” climate is created, characterized by the best conditions for human well-being than static at constant temperature. At the same time, some savings in cold consumption are provided. With an enthalpy of outside air / n, only adiabatic humidification is provided. At this time, the air heater of the second stage is affected by a relative humidity sensor cp installed in the room, with the help of which, when the humidity deviates upwards, the flow of heat carrier into the air heater increases. The dotted line in fig. 8.5 (from Hp to /l) indicates that the sensor must be set to 57-58% in order to avoid an increase in the value of f above 60%. This is due to the inadmissibility of a higher relative humidity and the desire to maintain the set operating temperature difference between the indoor and supply air.
The summer mode of operation of the air conditioning system begins when the outside air reaches enthalpy / l. At this time, submission is required cold water into the irrigation chamber to maintain air parameters K l. For this purpose, a temperature sensor is installed behind the irrigation chamber, with the help of which, as the temperature rises, the supply of cold water to the chamber increases. Since the air temperature behind the nozzle chamber is not the same, moisture droplets can be carried out and get on the temperature meter. In addition, taking into account the negative effect of radiant heat from the second heating air heater, it is advisable to carry out regulation according to the signals of the temperature sensor installed in the room. The advantages of this method include the fact that it also takes into account the heat storage capacity of the room. The temperature meter installed in the room is adjusted to the temperature value determined by the point t l, and affects the supply of cold water to the irrigation chamber.
The automation system built on the basis of the scheme of such air treatment is shown in fig. 8.6. AT winter period for irrigation
Rice. 8.6.
air conditioning
With the help of a proportional controller, the set temperature is maintained by the body chamber (pos. 1). The meter, set to the temperature / p 3 , acts on the actuator of the regulating body on the coolant return pipeline to the air heater of the first heating gearbox. The irrigation chamber provides adiabatic humidification of the outside air up to 90-95%. As the enthalpy of the outside air increases, its heating decreases, and at enthalpy / k, the first heating is turned off.
The indoor air temperature is controlled by a two-position regulator (pos. 2). Temperature sensor installed in the room and configured to maintain the temperature (3 , acts through a prohibition-allowing device (pos. 3) to the air heater of the gearbox of the second heating. A disable device is included in the circuit to switch indoor temperature control to relative humidity control. This switchover takes place when the relative humidity in the room approaches 60%. At this moment, the air temperature behind the irrigation chamber will rise to the value / p p. The signal from this sensor is sent to the prohibition-permissive device, which switches the indoor temperature sensor to the relative humidity sensor.
In warm weather indoors, using a proportional regulator (pos. 6) constant relative humidity is maintained at varying temperatures. Humidity sensor, as in winter time, through an intermediate relay RP and a prohibition-permissive device acts on the air heater of the second stage. When the relative humidity rises above 60%, the second heater is switched on and the temperature reaches a value at which the relative humidity becomes less than 60% and corresponds to a certain enthalpy of the outside air.
Summer mode, which requires the use of cold water, occurs at an indoor temperature corresponding to the average summer comfort. At this moment, the second temperature sensor, set to 1 L. The temperature regulator (pos. 5) affects the supply of cold water to the irrigation chamber. In the room, two parameters are stabilized at once: temperature and relative humidity. Two regulators act on different regulatory bodies at once, which allows maintaining relative humidity with an accuracy of ± 5% and consuming a minimum of cold. Improving the accuracy of stabilization of microclimate parameters can also be achieved by synthesis of stabilization with correction for deviations from the specified temperature and relative humidity in the room. This is ensured by the transition from single-circuit to double-circuit cascade stabilization systems, which, in essence, should be the main systems for controlling temperature and air humidity.
The operation of cascade systems is based on the regulation of not one, but two regulators, and the regulator that controls the deviation of the main regulated variable from the set value does not act on the regulatory body of the object, but on the auxiliary regulator setpoint. This controller maintains at a given level some auxiliary value of the intermediate point of the regulated object. Since the inertia of the controlled section of the first control loop is small, relatively high speed can be achieved in this loop. The first circuit is called stabilizing, the second - corrective. Functional diagram cascade system for direct-flow SCR is shown in fig. 8.7.
The first system ensures stabilization of the air temperature after the air heater of the second heating with correction
Rice. 8.7.
air conditioning process
according to the air temperature in the control object (room) by changing the coolant flow in the air heater (TC 2 controller). The corrective action is carried out using the corrective controller TS 2 . Thus, the air temperature control system after the second heating air heater includes an air temperature control circuit by changing the coolant flow rate and a correction circuit that changes the TS 2 controller setting depending on the change in the air temperature in the room.
The second stabilization system includes a dew point temperature sensing element installed after the spray chamber, and a TS controller that sequentially controls the actuators of the valves of the spray chamber, the first heating air heater, and the mixing and regulating valves. air valves outdoor and recirculated air.
The corrective action on the TC controller is carried out with the help of the MS humidity controller, the sensor of which is installed in the room.
AT last years in the implementation of the considered principles of automation of air conditioning systems, microprocessor controllers are increasingly used.
Among the directions of development technical progress automation stands out. It saves a person from performing routine, and often dangerous processes, significantly reduces the complexity of operations in production or at home, and allows you to optimize all areas of life.
You can automate almost any function of technology and area - including ventilation. This is relevant mainly for large complexes - industrial, industrial, warehouse, trade - but today it is increasingly used in the organization of life support systems in homes. Ventilation is a complex system that uses many types of sensitive engineering equipment, and its automation is a non-banal and responsible task. However, it has many advantages, and they should be used.
Well organized automation ventilation systems‒ this is a complex of a high degree of rationality, relieving users from manual control of indicators in the environment and their change. In business spaces, crowded places, sports, industrial complexes full automation is relevant, including ventilation systems:
- modular;
- firefighters.
Quality components and skillful organization automatic systems will keep people in the building safe, as well as:
- ensure work in accordance with established algorithms;
- to achieve compliance of indicators with the established values;
- stop systems in emergency situations;
- control the condition and performance of all elements;
- visualize parameters, implement remote control ventilation and so on.
Advantages of organizing automated ventilation systems
It is impossible to consider that automation is an extra and costly option. It allows you to significantly "unload" a person at work and at home, improve the quality of life and work, ensure a much higher level of safety than with manual control. Among the main advantages that distinguishes automation ventilation equipment worth mentioning:
- reduction of costs for electricity, energy carriers, maintenance of engineering, personnel - practice shows that with automation (turning on / off groups of equipment, for example), 10-20% savings in heat and cold consumption can be achieved;
- efficient organization of air exchange in the premises - with the help of automation, you can set the necessary cleaning parameters, temperatures, flow rates, while ensuring a simple and quick achievement of a favorable microclimate;
- reliable protection in emergency situations - integrated system, including warning, fire extinguishing, smoke neutralization devices, will allow you to quickly respond to an emergency;
- full control (including remote) and controllability of the system - with the help of automated installations, you can regulate the operation of fans, monitor how dirty the filters are, whether there is overheating or overcooling of the elements, and so on.
Automation will allow you to determine if the set fan speeds have been violated. It maintains the set parameters, climate conditions and controls all devices. How safe, reliable and durable the system depends on the quality of its assembly and components.
Design features of automated ventilation complexes
Automation for ventilation systems is regulated by existing regulations - these are TU, SNiPs and others. It is a set of elements and algorithms that ensure functional compliance with the set parameters.
What to pay attention to when designing
- Schematic diagrams of automation in engineering models are laid at the design stage. Then they choose the principle of operation and the level of "replacement" of a person by electronics.
- Automation control is organized using special cabinets into which regulators and control elements are inserted. They must be located in a convenient and accessible location so that maintenance can be carried out without interference.
- It is recommended to install in any automated scheme control devices- in supply and exhaust ventilation complexes, air conditioning system. The choice of model depends on the purpose of the object and economic and technical feasibility.
What equipment is required
The basic set of equipment that is included in automated ventilation systems usually includes:
- Sensors are elements that take readings from a controlled object and provide the user and control system information about his condition. They support feedback, providing information on the level of pressure and humidity, temperatures, and are selected depending on the desired accuracy, requirements and range.
- Regulators / controllers are elements that coordinate the work of executing devices and control them based on the data provided by the sensors.
- Executing devices are equipment of mechanical, electronic, hydraulic types that perform direct functions. These are electric drives of fire-air valve parts and heat exchangers, relays that monitor pressure drops, pumps.
Characteristics of the components of an automated installation
All parts and mechanisms that make up automation ventilation units, have their own characteristics and are divided into types.
So, for example, sensors can be related to indoor or outdoor devices, they are mounted with an overlay on pipelines, in channels. Among them stand out:
- temperature - can functionally set limits, installed in rooms or outside;
- humidity - indoor and outdoor, connected to devices for measuring relative parameters, installed at points where the temperature and air speed are unchanged, far from heating structures and direct rays of the sun;
- pressure - relay and analog types, can measure absolute values or differences (two points);
- flow - to find out at what speed the gas / liquid moves in pipes or air ducts.
Control devices are placed on automation boards, where a set of control and execution elements is combined. They are produced using sophisticated equipment, without fail with certification, global and famous brands: Phoenix Contact, Siemens, Schneider Electric, Legrand, General Electric and many others. When creating them, it is important that the devices ensure safety, as well as convenient and ergonomic operation.
Full information about the automation of the ventilation system in each specific case can be obtained from EcoEnergoVent specialists.
Air conditioning: Automatic maintenance in enclosed spaces of all or individual air parameters (temperature, relative humidity, purity, speed of movement and quality) in order to ensure, as a rule, optimal meteorological conditions that are most favorable for people's well-being, conducting the technological process, and ensuring the safety of valuables (SP 60.13330.2012 ).
Air conditioning systems are divided into three main groups:
split system. This is an air conditioning system consisting of two blocks: external (compressor-condensing unit) and internal (evaporative). The principle of operation of the system is based on the removal of heat from the air-conditioned room and its transfer to the street. A split system, like any air conditioning system, works on the same physical principles as a household refrigerator.
Central air conditioning systems combined with ventilation systems. The main task of such systems is to maintain the appropriate parameters of the air environment: temperature, relative humidity, cleanliness and air mobility in all rooms of the facility using one or more technological installations, due to the distribution of flows using a piping system.
At the same time, the correct composition of the air is maintained more by ventilation than by air conditioning. Forced ventilation responsible for the flow fresh air, exhaust - for extracting harmful impurities.
The supply unit is used to process air and supply it to the serviced premises. Air treatment refers to its purification from dust and other contaminants, cooling, heating, dehumidification or humidification.
Multizone systems. They are used for objects large quantity rooms where there is a need for individual air temperature control and special requirements for room comfort, for example, server rooms or technological equipment requiring a large heat sink. Structurally, the multizone system consists of one or more outdoor units connected by refrigerant pipelines, electric cables power and control with necessary number internal blocks of wall, floor and ceiling, cassette and channel execution.
The most common multi-zone systems are chillers, fan coil units, central air conditioners.
The automation system allows the air conditioning system to provide the necessary, sometimes significantly different, parameters in the premises, while avoiding excessive energy consumption (VRV and VRF systems).
Possible design error: Do not separate northern and southern contours heating and air conditioning in large buildings. As a result, one half of the workers are in comfort, while the other half either freezes or overheats.
Components of the system
The control of a central air conditioning system combined with a ventilation system can be decomposed into the control of the following parts:
In multi-zone air conditioning systems, they control the operating modes of the outdoor (central) unit, the operating modes of each of the indoor units, and the distribution of refrigeration power along the circuits. In these systems, each indoor unit is equipped with an electronic expansion valve that regulates the amount of incoming refrigerant from the common circuit depending on the heat load on this unit. As a result, the system is better than conventional household split systems maintains the set temperature.
What parameters can be controlled
Automation of ventilation and air conditioning systems allows them to perform the following functions:
- Regulate the temperature and humidity of the air entering the system of supply channels;
- Maintain air parameters within sanitary norms with multiple management tools;
- Switch air conditioning and ventilation systems to energy-saving operating modes during low-load hours;
- If necessary, transfer systems to non-standard and emergency modes of operation;
- Display of technological parameters of individual nodes of the ventilation system on local control panels;
- Notify the operator if the parameters of individual devices and assemblies fail or go beyond the settings, as well as if any components of the ventilation system are in working order, although according to the regulations they must be turned off.
Technical means of automation of ventilation and air conditioning systems include:
- Primary converters (sensors);
- Secondary appliances;
- Automatic regulators and control computers;
- Executive mechanisms and regulatory bodies;
- Electrical control equipment for electric drives.
The operating parameters of the devices and the readings of the sensors, the monitoring of which is necessary for the correct and economical operation of the system, are displayed on local control panels and on the consoles of the dispatching system. Control of intermediate parameters can be displayed on the monitor automatically, when leaving the specified range, or through nested menus for each of the subsystems.
Supply ventilation systems are equipped with devices for measuring:
- Air temperatures in serviced premises, outdoors, and at intermediate points;
- Temperature and pressure of water (steam or refrigerant) before and after air heaters (air conditioners), compressors, circulation pumps, heat exchangers and other critical points of the technological process;
- Air pressure drops on the filters of ventilation units;
- Energy parameters of the system units.
Air conditioning units are additionally equipped with devices for measuring the pressure and temperature of cold water or brine from a refrigeration station, as well as temperature and humidity devices during air processing.
In the central air conditioning system, the room temperature is controlled by changing the air exchange rate (temperature supply air set for the system as a whole). In multi-zone systems, it is possible to more accurately set the temperature for each of the rooms by changing the mode of the indoor units with refrigerant or heat carrier (closers).
Sensors
The air conditioning system uses the following types sensors:
- Temperature control sensors supply air and indoor air;
- Concentration control sensors in the indoor air of carbon dioxide CO2;
- Humidity control sensors air;
- Sensors for monitoring the condition and operation of equipment(pressure and air flow velocity in air ducts, temperature sensors, pressure or flow sensors for devices with liquid circulating through pipelines, etc.).
The output signals from the sensors are sent to the control cabinet for analysis of the received data and selection corresponding algorithm operation of the air conditioning system.
Temperature controllers
Temperature controllers are the control element of the system and are mechanical and electronic. Using the thermostat, the user can set the conditions that he considers comfortable
Mechanical thermostats. They consist of a thermal head (sensing element) and a valve. When the air temperature in the refrigerated room changes, the sensitive element reacts to this and moves the regulator valve stem. This change in stroke regulates the supply of cold air.
Electronic thermostats. This is automatic devices, control panels that maintain the set temperature in the room. In the air cooling system, they automatically control indoor unit(by changing the refrigerant flow rate or fan speed), the purpose of their operation is to create indoor temperature regime, set by the user.
Mechanical and electronic air thermostats differ only in the way they set the temperature. Their temperature control mechanism is identical - according to a signal transmitted via cable line. This is their difference from regulators on radiator batteries.
Actuator drives
To the actuators of the air conditioning system- air valves and dampers, fans, pumps, compressors, as well as heaters, coolers, etc. electric or pneumatic actuators are connected, through which the system is controlled. They allow:
- Stepwise or smoothly (when using frequency converters) adjust the fan speed;
- Manage the condition of air valves and dampers;
- The performance of duct heaters and coolers is regulated;
- Regulate the performance of circulation pumps;
- Humidifiers and dehumidifiers, etc. are controlled.
The analysis of signals from the sensors, the choice of the operation algorithm, the transmission of the command to the drive and the control of the execution of the command takes place in the controllers and servers of the automation system.
Control of electric motors of compressors, pumps and fans, especially with a power of more than 1 kW, is most economically carried out with the help of frequency converters. The figure shows a possible economic effect from the use of inverters in air conditioning systems.
Air conditioning automation boards
Automation boards are a tool designed to control the air conditioning and ventilation system. The main element of the control panel is a microprocessor controller. Automation system controllers are produced freely programmable, which allows them to be used in systems of various sizes and purposes.
When connecting sensors to the automation panel of the air conditioning system, the type of signal transmitted by the converter is taken into account - analog, discrete or threshold. Expansion modules that control device drives are selected based on the type of control signal and control protocol.
After programming, the controller brings the system to the specified parameters and the time cycle of operation, then the system can function, in a fully automatic mode, the following is carried out:
- Analysis of the readings received from the sensors, data processing and making adjustments to the operation of the equipment to maintain the specified parameters of the environment inside the room;
- Output of information about the system to the operator;
- Monitoring the operation and condition of air conditioning equipment with displaying information on display boards;
- Protect equipment from short circuit, overheating, avoidance of incorrect operating modes, etc.;
- Monitoring the timely replacement of filters and maintenance.
Design of air conditioning automation system
The air conditioning automation project is carried out taking into account technological requirements OF design specialists:
- Refrigerating machines, circulation pumps, two- and three-way valves, and other equipment are subject to automation;
- Summer, winter, transitional, emergency modes of operation of systems are taken into account;
- Provides synchronization of work refrigeration machines, circulation pump valves;
- Provide switching of the main and reserve pumps, for uniform expenditure of a resource;
- They provide for the transfer of information to the building management system and reactions when an alarm signal is received from the fire alarm system.
A typical composition of an air conditioning automation project contains sheets:
System operating modes. Work in the building automation and dispatching system
Control panels can operate in three main control modes:
Manual mode. Using a remote control connected to the automation board, it can be placed directly on the board, or it can be on/off buttons. The operator manually, directly on the switchboard, or remotely selects the operating mode of the system depending on the parameters of the room environment.
Auto offline mode . In this case, switching on, switching off, and selecting the operating mode of the system occurs autonomously, without taking into account the data of other climate systems, with notification of the dispatching system.
Auto mode taking into account the algorithms of the building management system. In this mode, the heating operation is synchronized with other life support systems of the building. More about
