A portable cryo-therapy sleeve is used by sports physiotherapists to apply rapid localized cooling to athletes' injured joints. Under typical operating conditions, the temperature of the cooling plate (cold side) is maintained at 5 ∘C5\ ^\circ\text{C}5 ∘C while the temperature of the heat-dissipating fins (hot side) is at 55 ∘C55\ ^\circ\text{C}55 ∘C.
Manufacturer data for this cooling unit show that:
It is claimed that the coefficient of performance (COP) of a thermoelectric cooler is much less than the COP of an ideal (reversible) refrigerator operating between the same temperatures.
Discuss whether this claim is valid for the cryo-therapy sleeve under these conditions.
Suggest why a relatively low value of the COP is acceptable for this portable athletic therapy application.
29 exam-style questions on AQA A Level Physics Thermodynamics and engines (A-level only), covering First law of thermodynamics (A-level only), Non-flow processes (A-level only), The $p$ - $V$ diagram (A-level only), Engine cycles (A-level only), Second Law and engines (A-level only), and Reversed heat engines (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.