Losses of Power in Thermal Engines in Nonequilibrium Regenerative Heat Exchange

Resumo

The modern design techniques used with most thermal engines do not take into account the power losses caused by nonequilibrium regenerative heat exchange (NRH) separately. A description of the mechanism of power loss initiation in heat exchange of gas with the walls of the working chamber is presented and an analytic technique for calculating these losses is proposed. For this purpose, the rate of entropy generation in regenerative heat exchange is calculated and an analytical relationship for calculating power losses in these types of processes is derived on the basis of the Gui–Stodola theorem. A calculation of the power losses in the VU-3/8 air piston compressor is presented as an example and their contribution to the volume of power consumption is estimated. Factors that affect the scale of the power losses caused by nonequilibrium regenerative heat exchange are identified and analyzed through the use of a novel technique of calculation of the losses. Such a method of analysis is applicable for positive displacement compressors as well as for other types of thermal engines.