Thermodynamic analysis on feasible operating region of two-stage hybrid absorption-compression heat pump cycles

Abstract

Abstract Ammonia-water hybrid absorption-compression heat pump (HACHP) based on Osenbruck cycle is a promising high-temperature heating technology. However, in the case of large temperature rise, the HACHP is faced with the problem that the compressor discharge temperature is too high, which greatly limits its application. In order to solve this problem, this paper introduces three two-stage HACHP cycles and thermodynamic analysis is conducted respectively. Results show that under the constraints of high pressure of 5000 kPa, compressor discharge temperature of 180 °C and vapor water mass fraction of 5%, the single-stage HACHP cycle cannot meet the heating requirement with the temperature lift of 40K, while three two-stage HACHP cycles can easily meet the needs of heating with the temperature lift of 40 K. When HACHP with flash tank intercooler is especially used, the heating with the temperature lift of 50 K can be achieved. Furthermore, this paper gives some typical combinations of ammonia mass fraction and circulation ratio for realizing high-temperature heating.