Problem4-81 - PROBLEM 4.81 KNOWN Upper surface of a platen heated by hot fluid through the flow channels is used to heat a process fluid FIND(a The

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PROBLEM 4.81 KNOWN: Upper surface of a platen heated by hot fluid through the flow channels is used to heat a rocess fluid. p FIND: (a) The maximum allowable spacing, W, between channel centerlines that will provide a uniform temperature requirement of 5 ° C on the upper surface of the platen, and (b) Heat rate per unit ength from the flow channel for this condition. l SCHEMATIC: ASSUMPTIONS: (1) Steady-state, two-dimensional conduction with constant properties, and (2) ower surface of platen is adiabatic. L ANALYSIS: As shown in the schematic above for a symmetrical section of the platen-flow channel arrangement, the temperature uniformity requirement will be met when T 1 – T 2 = 5 ° C. The maximum temperature, T 1 , will occur directly over the flow channel centerline, while the minimum surface temperature, T 2 , will occur at the mid-span between channel centerlines. We chose to use FEHT to obtain the temperature distribution and heat rate for guessed values of the channel centerline spacing, W. The following method of solution was used:
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This note was uploaded on 12/07/2010 for the course MAE Heat Trans taught by Professor Lee,j.s. during the Spring '10 term at Seoul National.

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