1.3.4.2 Pressure conditions Pressure relationship between the condenser and evaporator pressure is the next major fluid parameter. The reason is mainly that the compressor efficiency,with respect to energy and volume utilization (respectively,isentropic efficiency and delivery degree),is strongly connected to the pressure ratio.In Figure 1.28 the pressure ratio for the most appropriate working fluids plotted as a function of condensing temperature,evaporation temperature is assumed constant 0C. 10 9 NH 8 R134a 6 Propar R12/R22 3 2 1 0 40 50 60 70 80 Condensing temperature [CI Figure 1.28 Pressure ratio as a function of condensing temperature R 717 has higher pressure ratio then R 12 but propane will be more suitable.For ammonia it will compensate more or less due to higher efficiency of compression.For lager systems the result due to the high pressure ratio will be less due to three reasons.First,it throttle losses relatively smaller for a heat pump than for a refrigeration system,and efficiency characteristics will be significantly flatter and the difference in pressure conditions generally(slightly)less.Larger plants which have a relatively high temperature requirements of heat supply(such as heat pumps in district heating systems),which is normal for the two-stage compression/throttling and cooling of the gas pressure in the pressure level. 1.3.4.3 Volumetric heating performance Fluid properties are of great importance to determine 'sucked in'gas volume to the compressor,and thereby the compressor size and construction costs.This volume is determined by the medium's volumetric heat performance,qvol [kj/m3],which is given1.3.4.2 Pressure conditions Pressure relationship between the condenser and evaporator pressure is the next major fluid parameter. The reason is mainly that the compressor efficiency, with respect to energy and volume utilization (respectively, isentropic efficiency and delivery degree), is strongly connected to the pressure ratio. In Figure 1.28 the pressure ratio for the most appropriate working fluids plotted as a function of condensing temperature, evaporation temperature is assumed constant 0 ° C. Figure 1.28 Pressure ratio as a function of condensing temperature R 717 has higher pressure ratio then R 12 but propane will be more suitable. For ammonia it will compensate more or less due to higher efficiency of compression. For lager systems the result due to the high pressure ratio will be less due to three reasons. First, it throttle losses relatively smaller for a heat pump than for a refrigeration system, and efficiency characteristics will be significantly flatter and the difference in pressure conditions generally (slightly) less. Larger plants which have a relatively high temperature requirements of heat supply (such as heat pumps in district heating systems), which is normal for the two-stage compression / throttling and cooling of the gas pressure in the pressure level. 1.3.4.3 Volumetric heating performance Fluid properties are of great importance to determine ‘sucked in’ gas volume to the compressor, and thereby the compressor size and construction costs. This volume is determined by the medium's volumetric heat performance, qvol [kj/m3 ], which is given