ABSORPTION SYSTEM BASED ON THE REFRIGERANT R134A

The possibility of using 1,1,1,2-tetrafluoroethane (R134a) as a refrig erant in combination with different organic absorbents, such as dimeth ylether tetraethyleneglycol (DMETEG), N-methyl E-caprolactam (MCL) or dimethyl-ethyleneurea (DMEU), in absorption units was investigated. Th e procedures in this paper are presented for the model working pair R1 34a-DMETEG. Temperature-pressure-concentration curves were constructed on the basis of vapour-liquid equilibrium measurements. Excess thermo dynamic properties of the mixture were calculated, and enthalpy-concen tration diagrams were constructed. The density and viscosity of the wo rking fluids were measured. Thermostability testing of R34a-DMETEG sho wed that no changes were found in either of the phases over the course of the test. The performances of the investigated working fluids were compared in terms of the coefficient of performance (COP) and circula tion ratio (f), which were evaluated by a computerized simulation prog ram based on a single-stage absorption cycle containing a jet ejector as a mixer and preabsorber. The values of the COP for the three combin ations were similar (R134a-DMEU reached 0.49, R134a-MCL 0.47 and R134a -DMETEG 0.46), but the value off for R134a-DMTEG was lower than for th e other two pairs. R134a-DMETEG was therefore the best of the three ca ndidate working pairs.