Project ForgeA heat transformer is a device that transfers a part of the heat, supplied to it at an intermediate temperature, to a high temperature reservoir while rejecting the remaining part to a low temperature heat sink. In such a heat transformer, 100 kJ of heat is supplied at 350 K. The maximum amount of heat in kJ that can be transferred to 400 K, when the rest is rejected to a heat sink at 300 K is
- A12.50
- B14.29
- C33.33
- 57.14
Explanation
Energy balance: Qin=QH+QL, i.e. 100=QH+QL. Maximum QH occurs when the device is fully reversible (zero net entropy change): −100/350+QH/400+QL/300=0. Substituting QL=100−QH and solving gives QH=57.14 kJ.
Source: GATE ME 2007 (2007)
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