F-H12 - Abstract This report discuses heat transfer by...

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Abstract This report discuses heat transfer by conduction in four different units, which are: unit #1, unit #2, unit #3, and unit #4. In this experiment we study unit #4 twice: Unit #4a, where the power input was about 750 watts Unit #4b, where the power input was reduced to half of that used in unit #4a. Our objective in this experiment is to calculate the mass flow rate of water and thus the rate of heat transfer for each unit can be also calculated, and to find the barrier resistance between different joint metals. This was achieved by heating one end of the conducting bar. Water was passed over the bar and its incoming and leaving temperature was recorded. For example, the % of error results from comparing Q exp. And Q ther . In units # (3, 4a,4b) were : 23.7 % - for unit 3 53.6 % - for unit 4a 25.9 % - for unit 4b INTRODUCTION Heat transfer accrues in three ways conduction, convection, and radiation. Heat transfer by conduction is best done in solids where the thermal conductivity is high. Heat transfer by conduction accrue as a result of temperature difference between two bodies in contact with each other. So , heat moves from the higher temperature to the lower temperature object. It result from molecular interaction between adjacent molecule. Also, there another mechanism which is caused by free electron which accrue in free metallic solids. THEORETICAL BACKGROUND
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Fourier’s law describes heat transfer by conduction. Q x /A= -kdT/dx ------------------------------------------------------------- 1) Where k is the thermal conductivity of the material which is a function of temperature for the case of solids. and Qx is the rate of heat transfer K = k o (1+ β T) ------------------------------------------------------------2) It is known that any two materials can not have a perfect contact between them , so when heat moves through this empty space there must be a temperature drop because of the resistance of air which has lower thermal conductivity than the solid material . this is called the barrier
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This note was uploaded on 09/27/2011 for the course CHEMICAL E CHE 309 taught by Professor M.elgaily during the Fall '09 term at King Fahd University of Petroleum & Minerals.

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F-H12 - Abstract This report discuses heat transfer by...

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