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27 Nov 2019

A Carnot engine uses hot and cold reservoirs that have temperatures of 1684 and 842 K, respectively. The input heat for this engine is |QH|. The work delivered by the engine is used to operate a Carnot heat pump. The pump removes heat from the 842-K reservoir and puts it into a hot reservoir at a temperature T`. The amount of heat removed from the 842-K reservoir is also |QH|. Find the temperature T`.

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Keith Leannon
Keith LeannonLv2
9 Jan 2019

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

A. Consider two arbitrary heat engines. Engine A hasanefficiency of 60%. Engine B absorbs the same amount ofheat from theheat reservoir as Engine A; however, it exhauststwice as much heatto the cold reservoir as Engine A. Findthe efficiency of EngineB.


B. Consider a nonreversible heat engine that operatesbetweentemperatures Th and Tc, whereTc =1/3 Th. The engine absorbs anamount of heatQh from the heat reservoir in order to doan amount ofwork W.

1) If the engine discards an amount of heat Qc= 3/5Qh to the cold reservoir, determine the efficiencyofthis engine.

2) How much work, in terms of Qh, would beavailableto a Carnot heat engine operating between the same twotemperatures?What would the efficiency of this Carnot enginebe?



C. A freezer with a coefficient of performance of 4 isused toconvert 2kg of water to ice in one hour. The waterstarts at atemperature of 20°C, and the ice that is producedis cooled to atemperature of -5°C.

1) How much heat must be removed from the water for thisprocessto occur?

2) How much electrical energy does the freezer use duringthishour of operation?

3) How much heat is discarded into the room that housesthefreezer?

A. Consider two arbitrary heat engines. Engine A hasanefficiency of 60%. Engine B absorbs the same amount ofheat from theheat reservoir as Engine A; however, it exhauststwice as much heatto the cold reservoir as Engine A. Findthe efficiency of EngineB.


B. Consider a nonreversible heat engine that operatesbetweentemperatures Th and Tc, whereTc =1/3 Th. The engine absorbs anamount of heatQh from the heat reservoir in order to doan amount ofwork W.

1) If the engine discards an amount of heat Qc= 3/5Qh to the cold reservoir, determine the efficiencyofthis engine.

2) How much work, in terms of Qh, would beavailableto a Carnot heat engine operating between the same twotemperatures?What would the efficiency of this Carnot enginebe?


C. A freezer with a coefficient of performance of 4 isused toconvert 2kg of water to ice in one hour. The waterstarts at atemperature of 20°C, and the ice that is producedis cooled to atemperature of -5°C.

1) How much heat must be removed from the water for thisprocessto occur?

2) How much electrical energy does the freezer use duringthishour of operation?

3) How much heat is discarded into the room that housesthefreezer?

Consider a heat engine in contact with a hot and cold reservoir, as shown. If joules of energy are input from the hot reservoir.

(a) What is the maximum amount of work that can be done? Explain.

(b) How much energy in the form of heat is exhausted to the cold reservoir? Explain.

(c) Assume the heat engine and the two reservoirs are isolated from the rest of the universe. Calculate the change in entropy of this isolated system during one cycle of operation. Explain.

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