HW8S - 1. 6-6C Yes. Because the temperature of the oven...

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1 1. 6-6C Yes. Because the temperature of the oven remains constant no matter how much heat is transferred to the potatoes. 2. 6-28 A coal-burning power plant produces 300 MW of power. The amount of coal consumed during a one- day period and the rate of air flowing through the furnace are to be determined. Assumptions 1 The power plant operates steadily. 2 The kinetic and potential energy changes are zero. Properties The heating value of the coal is given to be 28,000 kJ/kg. Analysis ( a ) The rate and the amount of heat inputs to the power plant are MW 5 . 937 32 . 0 MW 300 th out net, in = = = η W Q ± ± MJ 10 1 . 8 s) 3600 24 ( MJ/s) 5 . 937 ( 7 in in × = × = Δ = t Q Q ± The amount and rate of coal consumed during this period are kg/s 48 . 33 s 3600 24 kg 10 893 . 2 MJ/kg 28 MW 10 1 . 8 6 coal coal 7 HV in coal = × × = Δ = × = × = = t m m q Q m ± kg 10 2.893 6 ( b ) Noting that the air-fuel ratio is 12, the rate of air flowing through the furnace is kg/s 401.8 = = = kg/s) 48 . 33 ( fuel) air/kg kg 12 ( AF) ( coal air m m ± ± 3.
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This note was uploaded on 01/03/2011 for the course MEEN 315 taught by Professor Ramussen during the Fall '07 term at Texas A&M.

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HW8S - 1. 6-6C Yes. Because the temperature of the oven...

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