Total heat versus sensible heat evaporator selection methods & application

Scope
The purpose of this paper is to provide specifying engineers, purchasers and users of evaporators in industrial refrigeration applications with an explanation of “total heat” versus “sensible heat” selection methods and how the method used can impact coil capacity, fan horsepower, physical size and first cost of the equipment.

This paper provides technical information for engineers, purchasers and users; such that, they have a better understanding of when evaporator selections are appropriate for a total heat capacity unit and which applications are best suited for sensible heat only selections.

Background
Historically, the total heat method of selecting coils has been common place in air conditioning applications where coils are selected at a specific entering air relative humidity. Industrial refrigeration evaporators have typically been selected using the sensible heat capacity of the unit. This has been most evident in North America.

During the last few years, there has been an increase in the use of total heat evaporator selections offered for sale as a result of the globalization within the market. Global manufacturers, who have historically designed and rated their equipment for use in what is often referred to as the commercial refrigeration and light industrial markets, have been pursuing business in the industrial refrigeration market. Because evaporator coil capacity is strongly affected by entering air moisture content, it has become important to realize the potential consequences of a total heat evaporator selection.

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