Question

1.(9 marks total) Descriptive questions-give briefanswers in words. No calculations are required. You may write your answers in point form if you wish. (a) (2 marks) List the processes that define an ideal Diesel cycle. Sketch a P.v diagram and a T-s diagram for this cycle with all processes labelled. (b) (2 mark) Some homes have natural gas fireplaces, in which the gas fire is separated from the room by a glass wall. Before the gas fire is started, the glass is at room temperature (around 20°C). Shortly after the gas fire is turned on, condensation is observed to form on the glass. Explain why this happens. (c) (2 marks) In a combustion process, the excess air is first set to a negative value (i.e. an air deficit), and is then gradually increased to a large positive value. Describe and explain the changes in efficiency that will result from this. (d) (2 marks) Sketch a simple vapour compression refrigeration cycle and explain how it works (e) (1 mark) A newspaper article describes a unit at Darlington nuclear power station as producing 900 MW per day. Comment on this statement.

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