Creating a system of free cooling with power accounting under control of Impulse 112 controllers

Free cooling system is designed to save energy, which is consumed to cool the air in technological rooms. The principle of operation is as follows: at a low outside air temperature (18 ˚C and below) the ventilation system is forced to take outside air into the room, reducing the overall temperature of the air in it.

Principle of operation

Free cooling system is designed to save energy, which is consumed to cool the air in technological rooms.

The principle of operation is as follows: at a low outside air temperature (18 ˚C and below) the ventilation system is forced to take outside air into the room, reducing the overall temperature of the air in it.

[sensors_div]This makes the compressor of the the air conditioner to stop, which makes it possible to save on energy supply. To prevent excessive cooling at very low temperatures (between 15 ˚C and below) the outside air is mixed with the recirculated air. Admixing percentage varies depending on the ambient temperature (the lower it is, the more inside air is used in the mixture). The condensate that is created when mixed, discharged through the drainage system.

System structure

The air intake subsystem

  • 1. Duct air intake fan. It enforces the supply of fresh air.
  • 2. The air cleaning filter. It cleans out the solids from the air.
  • 3. Drip pan. Catches condensate that forms when air is mixed.
  • 4. Control dampers with electric drives (2 pcs.). Manages the mixing of the recirculated air.
  • 5. Duct temperature sensor. Designed to control the temperature of the air in the duct.
  • 6. The throttle valve to control the flow of air. Carry out control of airflow to the branch ducts.
  • 7. The system of ducts made of galvanized steel with thermal insulation coating. It provides air distribution.

Air exhaust subsystem

  • 1. The fan that forces the air out to the street.
  • 2. Gravity grid. Performs automatic channel shutdown when the fan is off.


Automation subsystem

System logic description

When the outside temperature at the external sensor falls down to the configured level (18 ˚C and below) both fans (supply and exhaust) of the free cooling system are automatically started. The room temperature begins to fall, resulting in a shutdown of air conditioning compressors (following the settings of the air conditioning system). Fans of indoor units of the air conditioners continue to operate (at this time we are mentioning the precision air conditioners).

If the temperature in the refrigerated room falls below the temperature, setup on internal thermal sensors, the free cooling system is switched off (regardless of the temperature of outside air). When the temperature the temperature in the room rises above the setting on the internal thermal sensor, the free cooling system is switched on again. Also, the free cooling system is switched off when the temperature at the external sensor rises above the set temperature.

If the free cooling system fans get abruptly disabled, the room temperature begins to rise. Upon reaching the triggering value at the air conditioning system, the air conditioning is turned on. When the outside air temperature reaches the set lower limit (15 ˚C and below) for the outside air (at a signal from the channel sensor), the air begins to get mixed. The regulating valve on the street air intake begins to shut and the recirculation flaps start to open. The extent of the closing / opening of the two flaps is regulated based on the data from the duct temperature sensor. As soon as the temperature reaches the set level for the duct, closing of the first and second dampers stops. Thus the desired level of flow of the admixed air is regulated.

The control logic of the free cooling system is built using the logic triggers of the "Impulse 112" controller. Triggers connect the outside temperature and the room temperature values with control logic of the relay module SDOG2-OW-8R contacts: to enable or disable the fans and to control the dampers.

Furthermore, the controller transmits data about the actual use of the electric power (received from the electricity meters) to the central control and dispatch panel, together with the information on the state of contact sensors and controls.

Integration with the electricity meters

Thanks to the use of of two electricity meters in the scheme, it is possible to estimate how much money saving the free cooling system brings. This can be done by comparing energy use in the time when free cooling system is used, and when the cooling is made by the air conditioners.

This is a screenshot of a part of the dispatch panel that shows the current figures for one of the energy meters in the «Impulse-dispatch» software:

This is a screenshot of a part of the dispatch panel that shows the current state of the relays in the «Impulse-dispatch» software:

This is a screenshot of a part of the dispatch panel that shows the figures for the sensors of temperature and humidity in the «Impulse-dispatch» software:

CONTACTS

  • Our Address: Ukraine, Kyiv 02660
    str. Chervonotkatska 94
  • Email: office@xcs.com.ua
  • Web-site: impulse112.com
    xcs.com.ua
  • Phone number: +38 044 451 87 42