Reference no: EM13103384

In a refrigerator the working fluid remains a gas throughout the cycle. Its working may be described in a greatly simplified form as a sequence of four steps as follows: 1 The fluid passes through the refrigerated compartment, where its temperature rises. During this step its volume remains constant. 2 The fluid passes through the compressor pump, where it is compressed adiabatically. 3 The fluid passes through the pipes behind the refrigerator, where its temperature falls. During this step its volume remains constant. 4 The fluid passes through the expansion valve, where it expands adiabatically. (a) Show these four steps on a P-V diagram, labelling the steps clearly. (7 marks) (b) (i) In which step or steps is work done on the fluid? (ii) In which step or steps is heat transferred to the fluid? (iii) In which step or steps is work done by the fluid? (iv) In which step or steps is heat transferred from the fluid? (4 marks) (c) The temperature inside the refrigerator is 2.0 °C. It stands in a kitchen whose temperature is 22 °C. After a period of an hour, 95 kJ of heat are transferred from the interior of the refrigerator to the kitchen. As a result of this heat transfer, what is the entropy change of (i) the contents of the refrigerator, and (ii) the kitchen? (Assume that the heat transfer is reversible.) (7 marks) (d) State the principle of entropy increase. Are your answers to part (c) compatible with this principle? If not, suggest an explanation (one or two sentences)