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Chapter 21: Q. 15 (page 595)
What are (a) the thermal efficiency and (b) the heat extracted from the hot reservoir for the heat engine shown in
a.Thermal efficiency heat engine is.
b.The heat extracted from the hot reservoir for the heat engine is.
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The FIGURE shows the Diesel cycle. It is similar to the Otto cycle (see Problem), but there are two important differences. First, the fuel is not admitted until the air is fully compressed at point . Because of the high temperature at the end of adiabatic compression, the fuel begins to burn spontaneously. (There are no spark plugs in a diesel engine!) Second, combustion takes place more slowly, with fuel continuing to be injected. This makes the ignition stage a constant-pressure process. The cycle shown, for one cylinder of a diesel engine, has a displacement localid="1650278379201" of localid="1650278390412" and a compression ratio localid="1650278397535" These are typical values for a diesel truck. The engine operates with intake air localid="1650278425123" at localid="1650278430754" and localid="1650278435051" pressure. The quantity of fuel injected into the cylinder has a heat of combustion of localid="1650278440305" .
. Find , , and at each of the four corners of the cycle. Display your results in a table.
. What is the network done by the cylinder during one full cycle?
. What is the thermal efficiency of this engine?
. What is the power output in kW and horsepower of an eight-cylinder diesel engine running at ?
A refrigerator using helium gas operates on the reversed cycle shown in FIGURE. What are the refrigerator鈥檚 () coefficient of performance and () power input if it operates at cycles per second?
Rank in order, from largest to smallest, the thermal efficiencies to of the four heat engines in FIGURE Q21.5. Explain.
There has long been an interest in using the vast quantities of thermal energy in the oceans to run heat engines. A heat engine needs a temperature difference, a hot side and a cold side. Conveniently, the ocean surface waters are warmer than the deep ocean waters. Suppose you build a floating power plant in the tropics where the surface water temperature is . This would be the hot reservoir of the engine. For the cold reservoir, water would be pumped up from the ocean bottom where it is always . What is the maximum possible efficiency of such a power plant?
The coefficient of performance of a refrigerator is. The compressor usesof energy per cycle.
a. How much heat energy is exhausted per cycle
b. If the hot-reservoir temperature is, what is the lowest possible temperature inof the cold reservoir?
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