STG-15 Preventing Freezing in Heat Exchangers

J. W. Palen

Unintentional freezing in a heat exchanger is usually detrimental, causing loss of heat transfer and severe increases in pressure drop. This report addresses heat exchanger design for situations in which the cold fluid inlet temperature is less than the hot fluid freezing (or solidification) temperature. It reviews the basic equations for heat transfer across a series of resistances and then shows how these equations can be used to determine local wall temperature trends as a function of varying process conditions. A brief literature review highlights several instances in which engineers were able to modify their designs to eliminate potential freezing problems. The report presents a set of guidelines and recommends that HTRI Xchanger Suite® include internal checks so that users can better determine and prevent freezing problems in heat exchangers.