Question

A heat engine (Power Cycle) with a thermal efficiency of 35 percent efficiency produces 750 kJ of work. Heat transfer to the engine is from a reservoir at 550K, and the heat transfer from the engine is released to the surrounding air at 300K. a. Draw a schematic illustrating the heat engine and show the engineering model. (5 points) b. Determine the heat transfer to the engine and the heat transfer from the engine to the air (Actual engine). (10 points) c. If the same heat engine is replaced by a Carnot heat engine that produces the same work output, find the thermal efficiency, the heat-transfer to the heat engine, and the heat transfer from the engine to the low temperature reservoir. (10 points)

Answer 1

Answer:

a) The schematic illustrating is attached

b) The heat transfer to the heat engine is 2142.86 kJ, the heat transfer from the heat engine is 1392.86 kJ

c) The heat transfer to the heat engine is 1648.35 kJ, the heat transfer from the heat engine is 898.35 kJ

Explanation:

b) The heat transfer to the engine and the heat transfer from the engine to the air is:

$Q_{1} =\frac{W}{n}$

Where

W = 750 kJ

n = 35% = 0.25

Replacing:

$Q_{1} =\frac{750}{0.35} =2142.86kJ$

$Q_{2} =Q_{1} -W=2142.86-750=1392.86kJ$

c) The efficiency of Carnot engine is:

$n=1-\frac{300K}{550K} =0.455$

The heat transfer to the heat engine is:

$Q_{1c} =\frac{750}{0.455} =1648.35kJ$

The heat transfer from the heat engine is:

$Q_{2c} =1648.35-750=898.35kJ$