A heat engine cycle is executed with steam in the saturation dome. The pressure of steam is 1 MPa during heat addition, and 0.4 MPa during heat rejection. The highest possible efficiency of this heat engine isQuestion 9Select one:a.8.00%b.15.60%c.20.20%d.79.80%e.100%
Question
A heat engine cycle is executed with steam in the saturation dome. The pressure of steam is 1 MPa during heat addition, and 0.4 MPa during heat rejection. The highest possible efficiency of this heat engine isQuestion 9Select one:a.8.00%b.15.60%c.20.20%d.79.80%e.100%
Solution
The efficiency of a heat engine is given by the formula:
Efficiency = 1 - (Tc/Th)
Where: Tc is the temperature of the cold reservoir (heat rejection) Th is the temperature of the hot reservoir (heat addition)
In this case, we are given the pressures during heat addition and rejection, but not the temperatures. However, we can use the steam tables to find the corresponding saturation temperatures at these pressures.
From the steam tables: At 1 MPa, the saturation temperature Th is approximately 179.9°C or 453.05 K. At 0.4 MPa, the saturation temperature Tc is approximately 143.6°C or 416.75 K.
Substituting these values into the efficiency formula:
Efficiency = 1 - (416.75/453.05) = 0.0802 or 8.02%
So, the highest possible efficiency of this heat engine is approximately 8.02%, which is closest to option a. 8.00%.
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