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# quiz4 - 1 2(7 points Sketch the T – s diagram for an...

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MAE110A Thermodynamics Fall Quarter 2007 http://maecourses.ucsd.edu/mae110a Quiz IV This is a 50 minute closed-book exam; no notes. Please put your name on the top sheet. Answer all three questions. Explain your working and state any assumptions you have made. 1 (3 points) Circle the correct answer. 1. The only processes that occur are those that violate the First Law. that increase the entropy of a system. that are reversible. that occur in the Carnot cycle. that increase the entropy of system and surroundings together. 2. The Rankine cycle is the same as the Carnot cycle. is a gas power cycle. is a refrigeration cycle. has in its simplest form a constant-pressure boiler and condenser. has efficiency greater than one. 3. The ideal vapor refrigeration cycle has a turbine to extract power from the cycle. does not require a hot thermal reservoir. has a throttling device that is reversible. has a throttling device that is irreversible. is the same as the Rankine cycle.

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Unformatted text preview: 1 2 (7 points) Sketch the T – s diagram for an ideal vapor-compression refrigeration cycle. Denote the exit of the evaporator 1, the entrance of the condenser 2, the exit of the condenser 3 and the entrance of the evaporator 4. Derive expressions (all per unit mass of refrigerant) for the heat transfer into the evaporator, the heat transfer out of the condenser and the power input into the compressor. Derive an expression for the coefﬁcient of performance. What is the relation between h 3 and h 4 ? 2 3 (10 points) Steam is the working ﬂuid in an ideal Rankine cycle. Saturated vapor enters the turbine at 8 . 0 MPa and saturated liquid exits the condenser at 0 . 008 MPa. Determine for the cycle (a) the thermal efﬁciency, (b) the mass ﬂow rate of the steam, (c) the rate of heat transfer into the working ﬂuid as it passes through the boiler and from the condensing steam as it passes through the condenser. 3...
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