# Assignment #1: Thermodinamics 1 (19 Juni 2019)

1. Each student must solve the following problem:
2. A refrigerator with tetrafluoroethane (Table 9.1, Figure G.2, Smith an Ness six edition) as refrigerant operates with an evaporation temperature of 247.15 K (-26 oC) and a condensation temperature of 300.15 K (27 oC). Saturated liquid refrigerant from the condenser flows through an expansion valve into the evaporator, from which it emerges as saturated vapor.
• (a). For a cooling rate of 5.275 kW, what is the circulation rate of the refrigerant?
• (b). By how much would the circulation rate be reduced if the throttle valve were replaced by a turbine in which the refrigerant expands isentropically?
• (c). Suppose the cycle of (a) is modified by the inclusion of a countercurrent heat exchanger between the condenser and the throttle valve in which heat is transferred to vapor returning from the evaporator. If liquid from the condenser enters the exchanger at 300.15 K (27 oC) and if vapor from the evaporator enters the exchanger at 247.15 K (-26 oC) and leaves at 294.15 K (21 oC), what is the circulation rate of the refrigerant?
3. This assignment must be done by writting by hand in a paper and scanned to PDF document (file name must contain: “NamaMahasiswa_NIM“) and uploaded into the following URL : (), at late : 12 July 2019.
4. Good Luck.