ASHRAE Terminology

A Comprehensive Glossary of Terms for the Built Environment
ashrae.org/ashraeterms

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approach

(1) in a water cooling tower or evaporative cooling device, the difference between the average temperature of the circulating water leaving the device and the average wet-bulb temperature of the entering air. (2) in heat exchangers, the temperature difference between the leaving fluids.

evaporative cooler

a cooler that cools indoor air by moisture evaporation, thereby lowering its dry-bulb temperature and raising its wet-bulb temperature, all at a constant energy (adiabatic) level. See also evaporative cooling.

evaporative cooling

two methods using evaporating water to cool air: (1) direct, which is adiabatic and humidifies the air, and (2) indirect, which is not adiabatic and cools the air being treated without adding moisture.

evaporative cooling unit

cools air by moisture evaporation, thereby lowering its dry-bulb temperature and raising its wet-bulb temperature, all at a constant energy level.

indirect evaporative cooler

(1) a heat and mass transfer device used to sensibly cool a primary airstream without addition of moisture, by means of an evaporatively cooled secondary airstream. Since the secondary air provides wet-bulb depression, it represents a heat sink to the primary air. (2) an indirect evaporative cooling device consisting of an indirect evaporative-cooling heat exchanger, a means of delivering and distributing water to the wet passages of the heat exchanger, a basin for collecting water, a recirculating water pump, and the piping that connects the basin and the water distribution system.

indirect evaporative cooler with integrated heat exchanger

an indirect evaporative cooling device with integrated primary (dry) and secondary (wet) air passages in a single sensible and evaporative heat exchanger.

indirect evaporative cooling unit

a packaged, semi-packaged, or component indirect evaporative cooling unit. The term cooling unit is also used interchangeably for evaporative cooling unit or evaporative cooler.

rock bed regenerative cooling system

system of air conditioning in which packed beds of crushed stone or gravel are used for both evaporative cooling and heat energy storage.

spray pond

system for lowering the temperature of water by conductive and evaporative cooling of the water in contact with outside air. Water to be cooled is sprayed by nozzles into the air above a pond of water and allowed to fall into the pond.