p8.3-1

# p8.3-1 - Section 8.3: The Effectiveness-NTU Method 8.3-1...

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Section 8.3: The Effectiveness-NTU Method 8.3-1 (8-6 in text) The plant where you work includes a process that results in a stream of hot combustion products at moderate temperature T hg,in = 150°C with mass flow rate hg m ± = 0.25 kg/s. The properties of the combustion products can be assumed to be the same as those for air. You would like to recover the energy associated with this flow in order to reduce the cost of heating the plant and therefore you are evaluating the use of the air-to- air heat exchanger shown in Figure P8.3-1. h c =1mm th w =0.2mm th f =0.1mm p f close-up of channel structure k m =15W/m-K top view front view side view W =20cm , cold air 5C 0.5 kg/s cg in cg T m =− ° = ± , hot gas 150 C 0.25 kg/s hin hg T m = ± cold air, T cg,in hot gas, T h,in T h,out T cg,out L =10cm L flow passages for hot gas (flowing into the page) flow passages for cold gas (flowing into the page) Figure P8.3-1: Air-to-air heat exchanger. The air-to-air heat exchanger is a cross-flow configuration. The length of the heat

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## This note was uploaded on 08/11/2008 for the course ME 364 taught by Professor Rothamer during the Summer '08 term at Wisconsin.

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p8.3-1 - Section 8.3: The Effectiveness-NTU Method 8.3-1...

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