WORKING FLUIDS FOR AN ABSORPTION SYSTEM BASED ON R124 (2-CHLORO-1,1,1,2-TETRAFLUOROETHANE) AND ORGANIC ABSORBENTS

The possibility of using R124 (2-chloro-1,1,1,2,-tetrafluoroethane, CH ClFCF3) and organic absorbents as working fluids in absorption heat pu mps was investigated. Various classes of organic compounds, ail commer cially available, were tested as absorbents for possible combination w ith R124; the absorbents included DMAC (N',N'-dimethylacetamide, C4H9N O), NMP (N-methyl-2-pyrrolidone, C5H9NO), MCL (N-methyl epsilon-caprol actam, C7H13NO), DMEU (dimethylethylene urea, C5H10N2O), and DMETEG (d imethylether tetraethyleneglycol, C10H22O5). To evaluate the performan ce of a candidate refrigerant-absorbent pair in a refrigeration or hea t pump cycle. the thermophysical properties of the pure components and the mixture and the equilibrium and transport properties have to be d etermined. either from experimental data or by prediction methods. The thermal stability of the refrigerant-absorbent must also be tested, A method for the calculation of the concentration in the liquid and gas phases and the excess thermodynamic properties of the mixture as a fu nction of the system temperature and pressure based on our experimenta l setup is described. On the basis of vapor-liquid equilibrium measure ments, density and viscosity measurements and thermostability testing, enthalpy-concentration diagrams were constructed. The performance cha racteristics of the investigated working fluids in terms of the coeffi cient of performance (COP) and the circulation ratio (f) were calculat ed for a single-stage absorption cycle, In terms of overall performanc e (COP, f and stability) R124-DMAC was found to be the superior combin ation, followed by R124-NMP, R124-DMEU and R124-MCL (the three pairs f or which stability problems were found al high temperatures), and fina lly by R124-DMETEG. (C) 1997 Elsevier Science Ltd and IIR.