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Unformatted text preview: Department of Mechanical Science and Engineering ME 300 Thermodynamics Section D Fall 2010 Friday October 1st 8:00AM DCL1320 Exam I  Solution Point Distribution Points Q1 1 Q2 2 Q3 2 Q4 1 Q5 2 Q6 4 Q7 2 Q8 2 Q9 4 P1 16 (a) 4 (b) 3 (c) 4 (d) 1 (e) 4 P2 19 (a) 2 (b) 3 (c) 4 (d) 3 (e) 5 (f) 2 Question 1: Intensive properties per unit volume are called specific properties. True or false? False, properties per unit mass are called specific properties. Question 2: In classical mechanics there are two forms of energy, namely kinetic and potential energy, and the only mode of energy transfer is work. Which additional form of energy and mode of energy transfer is introduced in Thermodynamics? Internal energy and heat transfer. Question 3: Consider the quasiequilibrium process on the right for a closed system. The ideal gas model applies. What type of process is this? Since the polytropic exponent is n=1 it is an isothermal (constant temperature) process. Question 4: For an open system what can cross the system boundary? Circle the right answer. All of the above 1 Question 5: Based on the sign convention what is the correct sign? Circle the correct answer (a) Heat transfer from the system: negative (b) Work done by the system: positive Question 6: For a thermodynamic cycle Q in =280kJ and Q out =380kJ. (a) Is this a power cycle or refrigeration cycle? Show a supporting calculation. W cycle = Q in Q out = 100 kJ W cycle is negative and therefore it is refrigeration/heat pump cycle. (b) Determine the appropriate efficiency or performance of the cycle. Since we dont know if the purpose is for heating or cooling a space the perfromence can be expressed in two ways (both answers are correct!)....
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