These two psychrometric charts show the results of an actual analysis in two distinctly different climates. The target server inlet temperatures were between 65 and 85 degrees F and between 20% and 80% RH. The mechanical system criteria mandated that direct evaporative cooling be used.
The proposed mechanical system consisted of a direct evaporative cooling system with 12" cellulose media, a steam humidifier, DDC controls, and a hot aisle/outside air mixing section. The controls would be configured to modulate the outside air dampers, hot aisle dampers, evap media water flow, and the humidifier to maintain the target conditions.
|Server Inlet Temperatures from Evaporative Cooling System in Pacific Northwest US|
|Server Inlet Temperatures from Evaporative Cooling System in Southeastern US|
While not every location would achieve these results the diversity of climate for these two studies imply that direct evaporative cooling, with creative use of mixing and controls, will work in many more climates than most people expect. To further expand the capabilities of evaporative cooling an indirect evaporative cooling element could be provided to produce even broader temperature control. Although it was not analyzed for this case we would expect that adding an indirect evaporative cooling element to these systems would have eliminated the few hours of excursion above the maximum dry bulb temperature.
As a means to dramatically reduce energy consumption for these data modules the evaporative cooling solutions such as those manufactured by the Aztec division of Mestek would prove to be extremely effective. Since evaporative cooling systems are also relatively simple mechanical systems with no refrigerants maintenance of the systems does not require licensed refrigeration technicians and there are very few elements that could fail...increasing uptime and providing much faster recovery time should a repair be necessary.