Principle of Evaporative Free Air Cooling
Freecool® uses an evaporative heat exchange process to cool air. This process takes advantage of the principle that “free” latent heat is generated as a result of water evaporation. This evaporative heat exchange system simply reduces the air temperature as it passes through the water filter. When compared to air-conditioning which uses mechanical refrigeration, the operating cost of evaporative heat exchange can be up to 90% less than traditional air conditioning.
Mechanics of Unit
Water is brought into the cooler from the mains water supply and is pumped up to the top of the unit using a circulation pump. The water is then dispersed over CELdek pads manufactured by Munters using a water distribution system which allows the water to flow continually over the pad.
The pads become saturated, air is drawn through the pads and the water evaporates naturally causing the air to cool.
The cool air is then filtered and ducted into the data centre by means of an axial fan.
The hotter the outside temperature and the lower the humidity, the greater will be the cooling effect. On the hottest day in the UK up to 15°C of cooling can be achieved through this process. The air off temperature of a Freecool® system in the UK is always below 23°C, thus providing excellent cooling for data centre and server room applications as well as for comfort cooling.
Why are Running Costs Less than Air Conditioning?
Why do we need to run an air conditioning system when the external ambient temperature is suitable to cool computer equipment ?. By simply bringing in external ambient air and extracting hot exhaust air this will keep a server room computer equipment cool most of the year.
The economics of using evaporative cooling are surprising to most people. An 85% reduction in energy used compared to a conventional air conditioning unit seems too good to be true. This is achieved because in the UK it is cold most of the time.
By using a control system to minimise energy usage of fans coupled with evaporative cooling when outside air temperatures exceed 21ºC, relatively low flow rates of air are required. The only significant energy use when Freecool® is deployed is in the fan for the air movement. By using low energy EC fans typically a 1KW evaporative cooling system can manage a 20KW load in the UK. This cooling coefficient cannot be achieved with any current cooling technology.