Question

# 1. The 2nd law of thermodynamics refers to the quality of energy. 2. Work can convert to heat completely, but heat cannot convert to work completely. 3. The efficiency of a heat engine can be greater than 1. 4. According to Clausius, heat can transfer naturally from cold bodies to hot bodies. 5. The second-law efficiency of a heat engine is always greater than its thermal efficiency. 6. Both the first and second laws of thermodynamics must be satisfied in any real system. 7. The Carnot COP of a heat pump running between 7°C and 23°C is 8. Heat engines with the same 1s* law efficiency will always have the same 2nd law efficiency. 9. An inventor claims to have created a heat engine that produces 10 kW of power for a 15 kW power input, while operating between temperature reservoirs at 27°C and 427°C. Is this claim valid? 10. A manufacturer claims that their refrigerator has a COP of 10 while running between a conditionedspace at 0°C and ambient air at 23°C. Is this claim valid? 11. A heat pump supplies heat to a house at a rate of 30,000 kJ/hr. If the power consumed by the heat pump is 3 kW, determine the coefficient of performance of the heat pump. 12. A Carnot heat engine receives heat from a source at 800°C and rejects heat to a sink at 40°C. The heat is rejected from this engine at a rate of 80 kJ/s. Determine the power output, in kW. 13. An air-conditioner removes heat from a room at 20°C at a rate of 9000 kJ/hr and rejects the heat to the outdoor air at 35°C. If the coefficient of performance of the air-conditioner is 3, determine: a. The power consumed by the air-conditioner. b. The minimum power required if the system is reversible. 14. An A/C unit removes heat from the house at a rate of 1 MJ/min. If the required power input to thisA/C unit is 6 kW, determine: COP of the air-conditioning unit. b. The rate of heat rejection to the outside air, in kW. 15. A heat pump absorbs heat from the cold outdoors at 2° C and supplies heat to a house at 23° C at a rate of 36,000 kJ/hr. a. What is the COP of the heat pump if the power consumed is 1.7 kW? b. What is the maximum COP of the heat pump?  Fig: 1  Fig: 2  Fig: 3  Fig: 4  Fig: 5  Fig: 6  Fig: 7  Fig: 8  Fig: 9  Fig: 10  Fig: 11  Fig: 12  Fig: 13  Fig: 14  Fig: 15  Fig: 16  Fig: 17  Fig: 18  Fig: 19  Fig: 20  Fig: 21