Engineering, 06.05.2020 02:24 esekvng4551
It is common practice to recover waste heat from an oil or gas-fired furnace by using the exhaust gases to preheat the combustion air. A device commonly used for this purpose consists of a concentric pipe arrangement for which the exhaust gases are passed through the inner pipe, while the cooler combustion air flows through an annular passage around the pipe. Consider conditions for which there is a uniform heat transfer rate per unit length, ?qi???= 1.20 × 105 W/m, from the exhaust gases to the pipe inner surface, while air flows through the annular passage at a rate of m?a?= 2.1 kg/s. The thin-walled inner pipe is of diameter Di= 2 m, while the outer pipe, which is well insulated from the surroundings, is of diameter Do= 2.03 m. The air properties may be taken to be cp= 1030 J/kg·K, ?= 270 × 10-7 N·s/m2, k= 0.041 W/m·K, and P?r= 0.68.(a) If air enters at Ta,1= 300 K and L= 7 m, what is the air outlet temperature Ta,2?(b) If the airflow is fully developed throughout the annular region, what is the temperature of the inner pipe at the inlet (Ts, i,1) and outlet (Ts, i,2) sections of the device? What is the outer surface temperature Ts, o,1 at the inlet?1.)The air outlet temperature Ta,2:2.)The temperature of the inner pipe at the inlet (Ts, i,1):3.)The temperature of the inner pipe at the outlet (Ts, i,2):4.)The outer surface temperature Ts, o,1 at the inlet:
Answers: 2
Engineering, 04.07.2019 18:10
Water in a partially filled large tank is to be supplied to the roof top, which is 8 m above the water level in the tank, through a 2.2-cm-internal-diameter pipe by maintaining a constant air pressure of 300 kpa (gage) in the tank. if the head loss in the piping is 2 m of water, determine the discharge rate of the supply of water to the roof top in liters per second.
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Engineering, 04.07.2019 18:20
Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero
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Engineering, 04.07.2019 18:20
Avolume of 2.65 m3 of air in a rigid, insulated container fitted with a paddle wheel is initially at 264 k, 5.6 bar. the air receives 432 kj by work from the paddle wheel. assuming the ideal gas model with cv = 0.71 kj/kg • k, determine for the air the amount of entropy produced, in kj/k
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Engineering, 04.07.2019 18:20
Modern high speed trains do not have perpendicular expansion gaps where rails are joined end-to-end any more they are mostly welded together but what might happen if there was a spell of particularly hot weather that causes inspection of the tracks?
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It is common practice to recover waste heat from an oil or gas-fired furnace by using the exhaust ga...
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