What is the step-by-step procedure to find out overall heat transfer coefficient (U) of a exchanger from the observed plant data?
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Jim Grant Forum Moderator 118 Posts
Re: How Do You Determine Overall Heat Transfer Coefficient?20 February 2009 at 1:29pmThe exchanger can be evaluated by first performing an energy balance to determine the heat exchanged. I generally recommended you do this on both the hot and cold sides of the exchanger to determine whether there are any errors in the collected data. The heat balance should be within 10%-15% if the instruments are fairly reliable. The next step is to determine the effective mean temperature difference (EMTD) and utilize the simple equation Q = U * A * EMTD -- where Q represents the heat duty, A is the area of the exchanger and EMTD is determined by the fluid temperatures and number of passes in the exchanger. Please refer to the book "Process Heat Transfer" by Hewitt, Shires and Bott (CRC-Press, 1994) for more information.