A heat engine cycle is executed with steam in the saturation dome. The pressure of steam is 1 MPa during heat addition, and 0.4 MPa during heat rejection. The highest possible efficiency of this heat engine is (a) 8.0% (b) 15.6% (c) 20.2% (d) 79.8% (e) 100%

A heat pump cycle is executed with R-134a under the saturation dome between the pressure limits of 1.2 and 0.16 MPa. The maximum coefficient of performance of this heat pump is (a) 5.7 (b) 5.2 (c) 4.8 (d) 4.5 (e) 4.1

A heat pump is absorbing heat from the cold outdoors at 5$^\circ{}$C and supplying heat to a house at 25$^\circ{}$C at a rate of 18,000 kJ/h. If the power consumed by the heat pump is 1.9 kW, the coefficient of performance of the heat pump is (a) 1.3 (b) 2.6 (c) 3.0 (d) 3.8 (e) 13.9

The drinking water needs of an office are met by cooling tap water in a refrigerated water fountain from 23 to 6$^\circ{}$C at an average rate of 18 kg/h. If the COP of this refrigerator is 3.1, the required power input to this refrigerator is (a) 1100 W (b) 355 W (c) 195 W (d) 115 W (e) 35 W

A 2.4-m-high 200-m^2 house is maintained at 22$^\circ{}$C by a air-conditioning system whose CPP is 3.2. It is estimated that the kitchen, bath, and other ventilating fans of the house discharge a houseful of conditioned air once every hour. If the average outdoor temperature is 32$^\circ{}$C, the density of air is 1.20 kg/m^3, and the unit cost of electricity is $0.10/kWh, the amount of money "vented out" by the fans in 10 hours is (a)$0.50 (b) $1.6 (c)$5.0 (d) $11.0 (e)$16.0

The label on a washing machine indicates that the washer will use $\$85$ worth of hot water if the water is heated by a 90 percent efficient electric heater at an electricity rate of $\$0.09/kWh$. If the water is heated from 18 to $45^{\circ} \mathrm{C}$, the amount of hot water an average family uses per year is (a) 11.6 tons (b) 15.8 tons (c) 27.1 tons (d) 30.1 tons (e) 33.5 tons

A heat engine receives heat from a source at 1000$^\circ{}$C and rejects the waste heat to a sink at 50$^\circ{}$C. If heat is supplied to this engine at a rate of 100 kJ/s, the maximum power this heat engine can produce is (a) 25.4 kW (b) 55.4 kW (c) 74.6 kW (d) 95.0 kW (e) 100 kW

The label on a washing machine indicates that the washer will use $85 worth of hot water if the water is heated by a 90 percent efficient electric heater at an electricity rate of$0.125/kWh. If the water is heated from 18 to 45$^\circ{}$C, the amount of hot water an average family uses per year is (a) 19.5 tons (b) 21.7 tons (c) 24.1 tons (d) 27.2 tons (e) 30.4 tons

Two Carnot heat engines are operating in series such that the heat sink of the first engine serves as the heat source of the second one. If the source temperature of the first engine is 1300 K and the sink temperature of the second engine is 300 K and the thermal efficiencies of both engines are the same, the temperature of the intermediate reservoir is (a) 625 K (b) 800 K (c) 860 K (d) 453 K (e) 758 K

A 0.2- m$^3$ rigid tank equipped with a pressure regulator contains steam at 2 MPa and 300 degree C. The steam in the tank is now heated. The regulator keeps the steam pressure constant by letting out some steam, but the temperature inside rises. Determine the amount of heat transferred when the steam temperature reaches 500 degree C.

A 0.2-m^3 rigid tank equipped with a pressure regulator contains steam at 2 MPa and 300$^\circ{}$C. The steam in the tank is now heated. The regulator keeps the steam pressure constant by letting out some steam, but the temperature inside rises. Determine the amount of heat transferred when the steam temperature reaches 500$^\circ{}$C.

A typical new household refrigerator consumes about 680 kWh of electricity per year and has a coefficient of performance of 1.4. The amount of heat removed by this refrigerator from the refrigerated space per year is (a) 952 MJ/yr (b) 1749 MJ/yr (c) 2448 MJ/yr (d) 3427 MJ/yr (e) 4048 MJ/yr

In a shower, cold water at 10$^\circ{}$C flowing at a rate of 5 kg/min is mixed with hot water at 60$^\circ{}$C flowing at a rate of 2 kg/min. The exit temperature of the mixture is (a) 24.3$^\circ{}$C (b) 35.0$^\circ{}$C (c) 40.0$^\circ{}$C (d) 44.3$^\circ{}$C (e) 55.2$^\circ{}$C

During a heating process, the temperature of an object rises by 10$^\circ{}$C. This temperature rise is equivalent to a temperature rise of (a) 10$^\circ{}$F (b) 42$^\circ{}$F (c) 18 K (d) 18 R (e) 283 K