Evaporators

Evaporators are the low temperature heat transfer devices in a refrigeration system. In other words, they are the “cold source” in a refrigerated room.

In an industrial refrigeration setting, there are typically one to five evaporator fans per evaporator, and from one to ten or more coils per room. The coils can be quite small or impressively large, as seen relative to the onlookers in the following picture.

The evaporator fans improve the heat transfer and circulate the cold air throughout the room. Evaporator fan motors are fairly small by industrial standards (typically 1/3 Hp to 20 hp), but they are typically quite numerous, operate fully loaded (often into the service factor) and in aggregate are usually the second largest energy user in a refrigeration system (compressors being the largest energy user).

Evaporators are sized for the largest anticipated refrigeration load, a combination of warm summer temperatures and large internal product loads (e.g. cooling fruit from field temperatures to storage temperature). In CA storages, typical refrigeration loads during the holding season are only a small fraction of the design load (less than 25%). In regular storages, the average refrigeration load is typically 50% to 70% of the design load.