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Thermodynamics and engines (A-level only)

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Question 11

A portable cooling thermoelectric box is designed to transport biological specimens at remote research stations. Under typical operating conditions, the temperature of the cold side of the thermoelectric element is maintained at 2 ∘C2\ ^\circ\text{C}2 ∘C while the temperature of the hot side is at 42 ∘C42\ ^\circ\text{C}42 ∘C.

Manufacturer data for this element show that at these temperatures:

  • the rate at which energy is dissipated from the hot side is 95 W95\text{ W}95 W
  • the electrical power supplied to the cooling element is 40 W40\text{ W}40 W
a.

It is claimed that the coefficient of performance (COP) of a thermoelectric refrigerator is much less than the COP of an ideal refrigerator.

Discuss whether this claim is valid for the thermoelectric refrigerator in this question.

[4]
b.

Suggest why a low value of the COP is acceptable for this portable specimen cooler.

[2]

Thermodynamics and engines (A-level only) Questions

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