An ordinary vapor compression cycle is to be operated on methane to cool a chamber to 112 K. Heat is rejected to liquid ethylene at 160 K. The temperatures in the coils are 168 K and 100 K. (ANS. online)
(a) Write the relevant energy and entropy balances for the compression step.
(b) Estimate the minimal work requirement (J/g) for the compressor assuming the ideal gas law.
(c) Estimate the coefficient of performance (COP) for this OVC cycle.
(d) Estimate the COP by the Carnot guideline.
(e) Estimate the minimal work requirement for the compressor using the chart in the text.
