Capacitors are designed such that they can reject the system heat load in conditions of maximum air or water temperature. In cold weather, condensation temperature falls with the cooling medium, and this may cause difficulties in the correct operation of the plant. In particular, pressure through the expansion valve may be too low to extend the necessary mass flow. In such circumstances, artificial means should be used to maintain the pressure, always remembering that the condensing pressure must be kept as low as for practical energy.
Different systems are used:
Air-cooled condensers, having two or more fans, perhaps, pressure switch or thermostatic control to stop the fans one by one, as stated in the article. This method is simple, cheap and effective.
The fans on these capacitors can be installed with two-speed motors or other cruise control. It should be borne in mind that, if one fan a couple of stops, the noise level will decrease by 3 dB, but if both fans fall to half of the speed, the noise drops to 15 dB.
This method is particularly useful in residential areas, where more noise will be tolerated during the daytime with air condensation warm, but a low speed fan can be used at night.
Evaporative condensers and cooling towers with two or more fans to separate the actuator can be controlled in the same way. If one motor the actuators are several fans on the same shaft, cruise control or dampers required. Evaporative condensers and cooling towers shall be equipped with antifreeze, thermostats, which will stop all the fans before the water reaches the freezing point.
The flow of cooling air can be limited by the artboard, screens or winter enclosures, provided that, if not automatically, maintenance personnel are aware of their presence and will restore the flow of air when the weather gets warm.
Water consumption can be limited by means of the control valves. One such device is controlled directly by the head and the electrical or pneumatic regulating or leak valves can be used for this purpose.
A set pressure of the safety valve can be installed via a capacitor, so that the hot gas will pass directly to the receiver in cooler weather. This capacitor will be partially filled with liquid refrigerant, thus reducing the heat exchanger surface is available for condensation. Sufficient refrigerant must be available for this, without much rest of the circuit.
Where a complex system is served by two or more capacitors, full capacitor can be disabled by a pressure switch.
in Addition to these requirements, pressure, winter precautions to prevent freezing of the water until the plant refuses to heat. They usually take the form of electric boilers in tank with water, together with lagging and you can trace heating exposed pipes. In some systems, evaporative condenser itself can be within the building to the outside air. In severe climatic conditions, the external tanks must be isolated to save heat provided immersion heater.....
Condensers and cooling towers