1.Easy
A heat engine takes in 1600 kJ of heat from a hot reservoir and rejects 1280 kJ to a cold reservoir in each cycle. Find the net work W it produces per cycle.
QH = 1600 kJQL = 1280 kJ
W = kJ
Heat engines & refrigerators worksheet with answers
2.Easy
A heat engine takes in 3700 kJ of heat from a hot reservoir and rejects 2035 kJ to a cold reservoir in each cycle. Find the net work W it produces per cycle.
QH = 3700 kJQL = 2035 kJ
W = kJ
3.Medium
A heat engine works between a hot reservoir at 675 °C and a cold reservoir at 35 °C. It takes in 4800 kJ of heat. Find the most work Wmax it could possibly produce.
TH = 675 °CTL = 35 °CQH = 4800 kJ
Wmax = kJ
4.Medium
A reversible (Carnot) heat engine takes in 1700 kJ of heat from a reservoir at 725 °C and rejects 465 kJ per cycle. Find the temperature TL of the cold reservoir in °C.
TH = 725 °CQH = 1700 kJQL = 465 kJ
TL = °C
5.Hard
A Carnot heat engine receives 130 kW of heat from a source at 500 °C and rejects heat to the surroundings at 25 °C. All of its work drives a Carnot refrigerator that removes heat from a freezer at -15 °C and also rejects heat to the surroundings at 25 °C. Find the rate Q̇L at which heat is removed from the freezer.
TH = 500 °CT0 = 25 °CTL = -15 °CQ̇H = 130 kW
Q̇L = kW
6.Hard
Two Carnot engines work in series. Engine A receives heat from a reservoir at 600 °C and rejects heat to an intermediate reservoir at temperature Tm. Engine B takes all that heat and rejects heat to a reservoir at 15 °C. Both engines produce the same work. Find Tm in °C.
TH = 600 °CTL = 15 °C
Tm = °C
Answer key
- 1. W = 320 kJ
- 2. W = 1665 kJ
- 3. Wmax = 3240 kJ
- 4. TL = −0.1266 °C
- 5. Q̇L = 515.4 kW
- 6. Tm = 307.5 °C
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