Simulation of Compression Heat Pump Cycles Using NH3/H2O Mixtures to Estimate Their Working Domains

Abstract

A computer-aided process design methodology is used to determine the limits of NH3/H2O mixtures in different heat pump cycles from 20 °C to 150 °C. The evaluation is based on a defined parameter set consisting of the coefficient of performance, total heat transfer area and volumetric heat capacity. Simple cycles with two heat flows were chosen to meet good process integration capabilities. The results are shown in a sink outlet/temperature lift matrix considering current technical limits. R1366mzz(Z) in a standard compression cycle with internal heat exchanger serves as a benchmark. To provide temperatures up to 150 °C the lift of the heat pump has to increase to about 80 K of which only the wet compressions cycle with NH3/H2O is capable of. The working domains of NH3/H2O and R1366mzz(Z) are similar, when a two-stage compression for NH3/H2O is applied.