Chapter 2: Problem 140
Conduct a literature survey that reviews that concepts of thermal pollution and its current state of the art.
Chapter 2: Problem 140
Conduct a literature survey that reviews that concepts of thermal pollution and its current state of the art.
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Get started for freeAn exercise room has 6 weight-lifting machines that have no motors and 7 treadmills each equipped with a 2.5 -hp (shaft output) motor. The motors operate at an average load factor of \(0.7,\) at which their efficiency is \(0.77 .\) During peak evening hours, all 12 pieces of exercising equipment are used continuously, and there are also two people doing light exercises while waiting in line for one piece of the equipment. Assuming the average rate of heat dissipation from people in an exercise room is \(600 \mathrm{W}\), determine the rate of heat gain of the exercise room from people and the equipment at peak load conditions.
What are the mechanisms of heat transfer?
A room is heated as a result of solar radiation coming in through the windows. Is this a heat or work interaction for the room?
A homeowner is considering these heating systems for heating his house: Electric resistance heating with \(\$ 0.12 /\) \(\mathrm{kWh}\) and \(1 \mathrm{kWh}=3600 \mathrm{kJ},\) gas heating with \(\$ 1.24 /\) therm and 1 therm \(=105,500 \mathrm{kJ},\) and oil heating with \(\$ 2.3 / \mathrm{gal}\) and \(1 \mathrm{gal}\) of oil \(=138,500 \mathrm{kJ}\). Assuming efficiencies of 100 percent for the electric furnace and 87 percent for the gas and oil furnaces, determine the heating system with the lowest energy cost.
The steam requirements of a manufacturing facility are being met by a boiler whose rated heat input is \(5.5 \times 10^{6} \mathrm{Btu} / \mathrm{h}\) The combustion efficiency of the boiler is measured to be 0.7 by a hand-held flue gas analyzer. After tuning up the boiler, the combustion efficiency rises to \(0.8 .\) The boiler operates 4200 hours a year intermittently. Taking the unit cost of energy to be \(\$ 4.35 / 10^{6} \mathrm{Btu}\), determine the annual energy and cost savings as a result of tuning up the boiler.
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