Chapter 7 - Exergy Analysis of Heat Pump Systems

Abstract

Publisher Summary This chapter presents energy and exergy analyses of an air-source heat pump system. Exergy losses for each component of the system are identified, while the potential for efficiency improvements is described. The idea of using a heat engine in a reverse mode as a heat pump came into common use mainly for refrigeration. They have the advantage of being combustion free, and thus do not generate indoor pollutants like carbon monoxide. More generally, in evaluating the efficiency of heat pump systems, the most commonly used measure is the energy (or first law) efficiency. However, for indicating the possibilities for thermodynamic improvement, energy analysis is inadequate and exergy analysis is needed. The exergy analysis of the air-source heat pump system shown in this chapter identifies improvement potential. Heat pump efficiency is determined by comparing the amount of energy delivered by the heat pump to the amount of energy it consumes. The efficiency measures are usually based on laboratory tests and do not necessarily measure how a heat pump performs in actual use. Comprehensive energy and exergy analyses are presented and applied for evaluating heat pump systems and their components. Actual data are utilized in the analysis. Exergy destructions in the overall heat pump system and its components are quantified. Some concluding remarks that can be drawn from the results are discussed.