Experimental investigation of heat transfer in a high-pressure reciprocating gas compressor

Heat-transfer processes in a two-stage high-pressure (41.3 MPa) reciprocating gas compressor were investigated experimentally. Heat-transfer correlations were obtained from the measured heat-flux data and flow conditions. The heat fluxes at five locations of the second-stage cylinder of the compressor were measured with heat-flux probes constructed from eroding thermocouples with their backside temperatures measured by a second thermocouple. The exponents of the Reynolds number in the current heat-transfer correlations for different time periods of a complete compression cycle were approximately equal to one. During the compression with discharge process, an additional term containing the Reynolds number was required in the correlation to account for the enhanced heat-transfer rate caused by the increased mass flux flowing in the cylinder. The effects of various parameters of the heat-flux probe on the wall heat flux, deduced from the measured instantaneous surface temperature, were investigated. From the parametric study, it was found that variation of the backside temperature of the heat-flux probe had a strong effect on the deduced wall heat flux. This and the experimental evidence of transient backside temperature indicated the necessity of the measurement of the backside temperature in this study.