Development of High-Temperature Heat Pump Using

four kinds of refrigerant mixtures R22/Rl34a, R22/Rl52a, R22/Rl42b and R22/Rl23, which contain some new halocarbons which are considered to be the alternatives for CFCs, were evaluated in order to realize higher condensing temperature than that using R22 at high temperature operation, and larger heating capacity than that using R22/Rll4 at normal temperature operation. These mixtures were applied to a newly-developed composition changeable rectifying circuit in which the higherboiling-point refrigerant was separated and stored. As a result, the composition changeable high-temperature heat pump indicated the most effective characteristics when using R22/Rl42b as the refrigerant. l. INTRODUCTION Technologies that employ refrigerant mixtures are attracting attention from the aspects of energy saving as well as expansion of the employed temperature range. Refrigerant R22 is widely used for heat pump, but R22 is not suitable for hightemperature heat pump due to the high pressure. Refrigerant mixture of R22/Rll4 is one of Rl2-substitutes and has been partially used for high-temperature heat pump. But Rll4 is now under the regulation and its heating capacity is much smaller than that of R22, so the alternative refrigerant and the new heat pump for high temperature operation are needed. In this paper we examine in detail the characteristics of the basic cycle using non-azeotropic refrigerant mixtures which consist of non-regulated halocarbons (4 types). We also examine,a new composition changeable rectifying circuit with mixed refrigerants. The heat pump composed of the composition changeable rectifying circuir can b~ used fot both high temperature and normal temperature operation. ~e introduce that both the high temperature operation with higher condensing temperature than that using R22 and the normal temperature operation with larger heating capacity than that using R22/Rll4 can be realized in the composition changeable rectifying circuit with the separation. 2. REFRIGERANTS AND CHARGED COMPOSITIONS ln this study the characteristics of the refrigeration cycle both at normal temperature operation and at high temperatun• operation using refrigerant mixtures having different boiling points were carefully considered. Then R22 was selected as the lower-boiling-point refrigerant of the mixtures. Four kinds of mixtures R22/Rl34a, R22/Rl52a, R22/Rl42b, and R22/Rl23 which include the alternative halocarbons, were selected as the refrigerant mixtures. R22/Rll4 was selected as the reference. The charged compositions of the mixtures, as indicated in-Table l, were determined so that the saturated vapor could condense at a temperature of 75'C and at a pressure of approximately 2.6 MPa. Table l. Refrigerant Mixtures and Charged Composition (References) Refrigerant Mixtu~e:s R22/ R22/ R22/ RZ2/ R22/ R22 Rl34a Rl52a Rl42b Rl23 Rll4 Compos1t:ion 50/50 62/38 75/25 87/13 70/30 100 (wt%)