Consider an ideal dual-loop heat-powered refrigeration cycle using R-134a as the working fluid, as shown in Fig. P9.135. Saturated vapor at 90◦C leaves the boiler and expands in the turbine to the condenser pressure. Saturated vapor at −15◦C leaves the evaporator and is compressed to the condenser pressure. The ratio of the flows through the two loops is such that the turbine produces just enough power to drive the compressor. The two exiting streams mix together and enter the condenser. Saturated liquid leaving the condenser at 45◦C is then separated into two streams in the necessary proportions. Determine the ratio of the mass flow rate through the power loop to that through the refrigeration loop. Also find the performance of the cycle in terms of the ratio Q_L/Q_H.

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Turbine Compressor Boiler Power Refrigeration loop loop Evaporator Condenser Pump w, Expansion valve FIGURE P9.135