In: Mechanical Engineering
For the questions below, answer if the statement is true or false and explain how you reach to your conclusion.
a. The Clausius statement of the second law denies the possibility of transferring energy by heat from a cooler to a hotter body?
b. The COP if a reversible refrigeration cycles is always equal to the COP of an irreversible refrigeration cycle when each operates between the same two thermal reservoirs.
c. The Kelvin–Planck and Clausius statements of the second law of thermodynamics are equivalent because a violation of one statement implies the violation of the other.
d. Mass, energy, entropy, and temperature are examples of extensive properties.
e. For reversible refrigeration and heat pump cycles operating between the same hot and cold reservoirs, the relation between their coefficients of performance is COPR = COPHP + 1.
f. For a reversible heat pump that operates between cold and hot thermal reservoirs at 300°C and 500°C, respectively, the COP is equal to 2.87
g. An experimentalist claims to have raised the temperature of a small amount of water by 150°C by transferring heat from high-pressure steam at 120°C. Is this a reasonable claim? Assume that no refrigerator or heat pump is used in the process.
h. In the absence of any friction and other irreversibilities, can a heat engine have an efficiency of 100%?
i. A heat pump that is used to heat a house has a COP of 2.5 and delivers 2.5 kJ/s to the house for each 1 kWh of electricity it consumes. Is this a violation of the first law of thermodynamics?
j. You visit a department store interested in buying a AC unit that has a COP of at least 4. The manufacturer labels do not show COP values but shows that the EER for the refrigerator you are interested in is 14. Will this refrigerator meet your COP constraint?