A Mathematical Description of the Power Loss from Nonequilibrium Regenerative Heat Exchange in the Thermal Machines

摘要

This paper presents the results of the analytical studies on the mechanisms of the losses inception in nonequilibrium regenerative heat exchange between gaseous working medium and the walls of the working cavity, i.e. in the process having the place in the most of the thermal machines. Heat exchange occurs in a significant temperature differential; this process is non-equilibrium, which may lead to tangible power losses in the heat machines. At present, modern design methodologies of the thermal machines do not investigate power losses from nonequilibrium regenerative heat exchange (NRHE) and do not describe them separately from the other types of losses. Lack of the separate consideration the losses from NRHE in the modem methodologies might lead to the notable error in the estimation the indicators of effectiveness, to incorrect constructive solutions and could give a wrong direction of selecting the ways to decrease the losses in the thermal machine. This work gives a qualitative description of the NRHE losses formation mechanism and based on the Guoy-Stodola's theorem excreted an analytical expression for calculating such losses and provides an example of the estimation of the power losses in the aerial two-stage piston compressor. Also, based on the analytical dependence, parameters influencing on the number of losses are determent and recommended its decreasing.