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All working fluid pairs which are presently used in domestic absorption heat pumps have certain disadvantages. A systematic search for suitable working fluid pairs has therefore been carried out by the University of Essen, Germany. Alcohols and amines as solutions and different halides, nitrates and thiocyanates as solvents have been studied. Up till now binary combinations of the working fluids TFE, R123a, R30, R22, and a large number of solvents have been systematically studied both theoretically and experimentally. All four working fluids had a remarkable solubility in HMPT but the thermal instability of HMPT excludes the application in absorption heat pumps. However, a large number of other promising combinations have been identified. Also ternary combinations have been investigated. Methylamine with aqueous salt solutions as a solvent were not thermally stable up to 200 degrees C. NH-3 with aqueous - salt solutions turned out to be promising. Five of the most promising systems (TFE-NMP, R123a-DTG, Methylamine-Gly, R22-DTrG and NH-3/LiNO-3/H-2O) were investigated in more detail. These investigations comprehended a complete measurement of the properties: vapour pressure, density and viscosity within the temperature range of interest. Also calorific properties and vapour-liquid equilibria of some systems were determined. All measured data were correlated to equations which enabled a construction of diagrams the practical use.

Additional information

Bibliographic Reference: EUR 10725 EN (1986) MF, 19 P., BFR 150, BLOW-UP COPY BFR 200, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
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