Non-Azeotropic Mixtures as Working Fluids in Heat Pumps: A theoretical and experimental study

摘要: Due to the fact that CFC (Chloro-Fluoro-Carbon) fluids will be forbidden as working in heat pumps for environmental reasons, there is an urgent need alternatives. As one alternative type of fluid, non-azeotropic mixtures have been suggested. This thesis deals with such mixtures. It includes HCFC components, spite recently imposed international restrictions these too, since this work started well before those and good data exist The main aim has improve our knowledge about mixture behaviour pump systems, emphasis on thermodynamic differences between pure fluids. A comprehensive computer program simulation systems developed utilized several theoretical investigations. Furthermore, experimental project a full-scale plant carried out. study different methods comparison terms calculated performance done. showed traditional can easily yield misleading results when used Reliable are achieved if comparisons made rigorously, same exchanger area, transport properties included properly. By means program, alternatives CFC12 CFC114 investigated. was found moderate internal glides (less than approximately 10 K) many cases compete COP, even at small external temperature glides. Mixture two-stage cycles investigated detail theoretically. Thermodynamic cycle flash vessel economizer exchanger, both charged mixture, explained. quantified how influence performance. For type, gain more COP going from one-stage fluid does while, vessel, benefit not exist. sensitivity analysis required accuracy levels key factors making predictions within given uncertainty range identified. In order enhance prediction it greatest interest increase transfer coefficient evaporation isentropic efficiency compressor. No major were regarding sensitivities involved estimations An two 1 MW One HCFC22-HCFC142b other CFC12. Variations capacity determined. unfavourable conditions comparable COPs capacities equal conditions. Comparisons theoretically expected three parts, evaporator, condenser