1.Easy
A heat engine takes in 3700 kJ of heat from a hot reservoir and rejects 2220 kJ to a cold reservoir in each cycle. Find the net work W it produces per cycle.
QH = 3700 kJQL = 2220 kJ
W = kJ
Heat engines & refrigerators worksheet with answers
2.Easy
A heat engine takes in 3600 kJ of heat from a hot reservoir and rejects 1980 kJ to a cold reservoir in each cycle. Find its thermal efficiency η.
QH = 3600 kJQL = 1980 kJ
η = %
3.Medium
A heat engine works between a hot reservoir at 425 °C and a cold reservoir at 5 °C. It takes in 3000 kJ of heat. Find the most work Wmax it could possibly produce.
TH = 425 °CTL = 5 °CQH = 3000 kJ
Wmax = kJ
4.Medium
A heat engine works between a hot reservoir at 725 °C and a cold reservoir at 30 °C. It takes in 700 kJ of heat. Find the most work Wmax it could possibly produce.
TH = 725 °CTL = 30 °CQH = 700 kJ
Wmax = kJ
5.Hard
Two Carnot engines work in series. Engine A receives heat from a reservoir at 1100 °C and rejects heat to an intermediate reservoir at temperature Tm. Engine B takes all that heat and rejects heat to a reservoir at 20 °C. Both engines produce the same work. Find Tm in °C.
TH = 1100 °CTL = 20 °C
Tm = °C
6.Hard
Two Carnot engines work in series. Engine A receives heat from a reservoir at 1000 °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 have the same thermal efficiency. Find Tm in °C.
TH = 1000 °CTL = 15 °C
Tm = °C
Answer key
- 1. W = 1480 kJ
- 2. η = 45 %
- 3. Wmax = 1805 kJ
- 4. Wmax = 487.4 kJ
- 5. Tm = 560 °C
- 6. Tm = 332.5 °C
Full step-by-step solutions: practise this topic on examproblems.com.