Page 402 - Handbook of Energy Engineering Calculations

HEAT-EXCHANGER CHOICE FOR SPECIFIC ENERGY
APPLICATIONS

Determine the type of heat exchanger to use for each of the following
applications: (1) heating oil with steam; (2) cooling internal combustion
engine liquid coolant; (3) evaporating a hot liquid. For each heater chosen,
specify the typical pressure range for which the heater is usually built and the

typical range of the overall coefficient of heat transfer U.

Calculation Procedure:

1. Determine the heat-transfer process involved
In a heat exchanger, one or more of four processes may occur: heating,
cooling, boiling, or condensing. Table 1 lists each of these four processes and

shows the usual heat-transfer fluids involved. Thus, the heat exchangers
being considered here involve (a) oil heater—heating—vapor-liquid; (b)
internal-combustion engine coolant—cooling—gas-liquid; (c) hot-liquid
evaporation—boiling—liquid-liquid.

TABLE 1 Heat-Exchanger Selection Guide *