The Australian mining town of Coober Pedy in northern South Australia is renowned for its opals. Located approximately 850 km north of Adelaide, the town is exposed to a hot desert climate, and many of the town’s residents live underground to take refuge from the heat. Assume the above ground temperature at Coober Pedy is 48℃, and the below ground temperature is 5℃. (a) An inventor has realized for those living underground a refrigerator to cool the soft drinks in the refrigerated space. The refrigerator is made to reject energy by heat transfer to above the ground and has a remarkable coefficient of performance of 7.0. Evaluate what is the lowest theoretical temperature of the refrigerated space, and if it is worth using it. (b) The same inventor has filed a patent claiming to have devised a process to generate electricity operating between the above ground and below ground temperatures with a thermal efficiency of 15%. Evaluate the inventor’s claim.
The Australian mining town of Coober Pedy in northern South Australia is renowned for its
opals. Located approximately 850 km north of Adelaide, the town is exposed to a hot desert
climate, and many of the town’s residents live underground to take refuge from the heat.
Assume the above ground temperature at Coober Pedy is 48℃, and the below ground
temperature is 5℃.
(a) An inventor has realized for those living underground a refrigerator to cool the soft
drinks in the refrigerated space. The refrigerator is made to reject energy by
transfer
Evaluate what is the lowest theoretical temperature of the refrigerated space, and if
it is worth using it.
(b) The same inventor has filed a patent claiming to have devised a process to generate
electricity operating between the above ground and below ground temperatures
with a thermal efficiency of 15%. Evaluate the inventor’s claim.
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