Chapter 5, Problem 5.20P

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A solar collector produces a maximum temperature of 98 °C using concentrated sunlight. This energy is used in a heat engine that operates in a 10°C environment. If the solar collector is redesigned to focus the sunlight and reach a higher temperature, what should the maximum temperature be (in °C) to double the efficiency, assuming the heat engine is a Carnot cycle?

A claim states that a power cycle has been invented that produces work of 400KJ and requires energy transfer to the system of 300kJ. Such device is possible. O True O False

thermodynamics

Compare wind, solar, and power generation systems with each other and write down their advantages and disadvantages among themselves in articles.

An inventor claims to have a solar powered heat pump that receives energy as heat from the sun at the rate of 10 kW and extracts energy as heat from the environment at the rate of 7 kW. This system does not require any shaft or electrical power input. If you think this device is impossible, explain why using basic principles to support your argument. If you think it might be possible, what would be the steady-state rate of transfer of energy as heat to the house? (Assume TH = 20 Cand TL = -15 C).

An inventor claims to have devised a refrigeration cycle operating between hot and cold reservoirs at 308 K and 278 K, respectively, that removes an amount of energy QC by heat transfer from the cold reservoir that is a multiple of the net work input—that is, QC = NWcycle, where all quantities are positive. Determine the maximum theoretical value of the number N for any such cycle.

With a 1 kW pump, the energy leakage per unit time is 0.6 kW for a 1 ℃ temperature difference between a house to be heated and the outside environment. Coefficient of performance of the heat pump used to keep this house at a constant temperature of 20 ℃; If it is up to the theoretical heat pump performance coefficient; What is the minimum outdoor temperature ℃ for this heat pump to meet its needs and be used?

A nonpolluting power plant can be constructed using the temperature difference in the ocean. At the surface of the ocean in tropical climates, the average water temperature year-round is 30°C. At a depth of 305 m, the temperature is 5.4°C. Determine the maximum thermal efficiency of such a power plant.