An active cooling vest for emergency personnel uses a thermoelectric Peltier module to keep the inner lining cool. Under typical operating conditions in a hot environment, the inner cold side of the module is maintained at 14 ∘C14\ ^\circ\text{C}14 ∘C, whilst the outer heat sink (the hot side) is at 54 ∘C54\ ^\circ\text{C}54 ∘C.
Manufacturer specifications for the module under these operating temperatures state that:
An engineer claims that the actual coefficient of performance (COP) of this thermoelectric cooler is less than 20%20\%20% of the COP of an ideal refrigerator operating between the same two temperatures.
Evaluate whether the engineer's claim is valid.
Suggest why a low COP is acceptable for this wearable cooling vest.
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.