Energy Conversion and the Second Law

With the laws of thermodynamic established, this chapter turns to the evaluation of energy conversion systems, focussing on heat engines, refrigerators, and heat pumps operating between two temperature reservoirs. Evaluation of first and second laws shows that heat engine efficiency and coefficient of performance (COP) of refrigerator and heat pump depend only on reservoir temperatures, and are reduced by entropy generation in irreversible processes that occur within the devices. Accordingly, fully reversible engines have maximum performance, given by the Carnot efficiency and Carnot COP. A number of examples highlight determination of performance measures and work losses to irreversibilities.