Power for fans and pumps in heat exchangers of refrigerating plants

摘要

The energy consumption to operate auxiliaries such as fans and pumps in heat exchangers have a significant influence on the total energy demand for operating a refrigerating system. With a starting point in a simple entropy analysis a morepractical approach is adopted for common cases of air coil fans in evaporators or condensers. Examples are given to illustrate how the power for evaporator or condenser fans will affect the capacity and total energy demand of refrigerating systems.It is shown that the two different criteria: - maximum of capacity or - minimum of energy demand (equivalent to maximum system COP) will give different optima for the power to be used in fans or pumps.Simple relations are derived for optimum power in fans or pumps for the two different criteria applicable for many general cases in refrigerating systems.