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Unformatted text preview: would be delivered if the element is supplied with
208 V instead of 240 V?
c. Neglecting any losses from the tank, how long would it take for 4800 W
to heat the 52 gallons of water from 60◦ F to 120◦ F? The
conversion between kilowatts of electricity and Btu/hr of heat is
given by 3412 Btu/hr = 1 kW. Also, one Btu heats 1 lb of water by
1◦ F and 1 gallon of water weighs 8.34 lbs. 3. (Masters 3.4) A combinedcycle, naturalgas, power plant has an efficiency
of 52%. Natural gas has an energy density of 55,340 kJ/kg and about
77% of the fuel is carbon.
a. What is the heat rate of this plant expressed as kJ/kWh and
Btu/kWh?
b. Find the emission rate of carbon (kgC/kWh) and carbon dioxide
(kgCO2/kWh). 4. (Masters 3.5) A new coalfired power plant with a heat rate of 9000 Btu/kWh burns coal
with an energy content of 24,000 kJ/kg. The coal content includes 62%
carbon, 2% sulfur and 10% unburnable minerals called ash.
a. What will be the carbon emission rate (g C/kWh)?
b. What will...
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This document was uploaded on 03/25/2014.
 Spring '09

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