17470948
Description
Flashcards by Julius Kent Balagot, updated more than 1 year ago
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Created by Julius Kent Balagot
about 5 years ago
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| Question | Answer |
| An air-conditioning system operating on the reversed Carnot cycle is required to remove heat from the house at a rate of 32 kJ/s to maintain its temperature constant at 20°C. If the temperature of the outdoors is 35°C, the power required to operate this air-conditioning system is: (a) 0.58 kW (b) 3.20 kW (c) 1.56 kW (d) 2.26 kW (e) 1.64 kW | Answer: (e) 1.64 kW |
| A heat pump is absorbing heat from the cold outdoors at 5°C and supplying heat to a house at 22°C at a rate of 18,000 kJ/h. If the power consumed by the heat pump is 2.5 kW, the coefficient of performance of the heat pump is; (a) 0.5 (b) 1.0 (c) 2.0 (d) 5.0 (e) 17.3 | Answer: (c) 2.0 |
| An automobile engine consumes fuel at a rate of 28 L/h and delivers 60 kW of power to the wheels. If the fuel has a heating value of 44,000 kJ/kg and a density of 0.8 g/cm3, determine the efficiency of this engine. | Answer: Nth = 0.22 (22%) |
| A household refrigerator with a COP of 1.2 removes heat from the refrigerated space at a rate of 60 kJ/min. Determine (a) the electric power consumed by the refrigerator and (b) the rate of heat transfer to the kitchen air. | Answer: (a) Wnet,in = 0.83 kW (b) QH = 110 kJ/min |
| A heat engine operates between a source at 550°C and a sink at 25°C. If heat is supplied to the heat engine at a steady rate of 1200 kJ/min, determine the maximum power output of this heat engine. | Answer: Wnet,out = 12.8 kW |
| A Carnot heat engine operates between a source at 1000 K and a sink at 300 K. If the heat engine is supplied with heat at a rate of 800 kJ/min, determine (a) the thermal efficiency and (b) the power output of this heat engine. | Answer: (a) Nth = 0.7 (70%) (b) Wnet, out = 9.33 kW |
| A geothermal power plant uses geothermal water extracted at 160°C at a rate of 440 kg/s as the heat source and produces 22 MW of net power. If the environment temperature is 25°C, determine (a) the actual thermal efficiency, (b) the maximum possible thermal efficiency, and (c) the actual rate of heat rejection from this power plant. | Answer: (a) 8.76% (b) 31.2 % (c) 229 MW |
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