压气机效率的正确变比热计算

CORRECT CALCULATION OF VARYING SPECIFIC HEAT COMPRESSOR EFFICIENCY

随着实际压气机压比不断增高，按定比热等熵指数ｋ＝１．４的算法，误差越来越大。文中按照给定或实验测定压比、初温、终温的命题，给出计算效率的正确变比热算法，并按压比５至３０分档作出算例。同时检验出，如简单地按初温终温求ｋ算效率误差很大，几乎与定比热法同一量级。工程中常年用定比热已久，如何给出简便校正方法，尚待研究。

Along with the continuous increase of pressure ratios of real compressors,the error of efficiency calculation with constant specific heat isentropic index k=1.4 becomes greater and greater. In case that the pressure ratio, initial and final temperatures are given or experimentally measured,a correct method of varying specific heat compressor efficiency calculation is given,and results of illustrations for pressure ratios from 5 to 30 by steps are tabulated.An existing paper determining the isentropic index simply through initial and real final temperatures is shown to give appreciable errors in efficiency, being even almost of same order of magnitude as with constant specific heat.In engineering,the constant specific heat practice has been followed habitually for a long time.A simple and convenient way of calibration remains to be studied.