Thermal Design Guidelines for Optimizing Shell-and-Tube Heat Exchangers
By Satyendra Kumar Singh |
Ensuring optimal performance of shell-and-tube heat exchangers requires knowledge of the controlling fluid, correct exchanger geometry and configuration, as well as proper fluid placement
Satyendra Kumar Singh
Simon India Ltd.
Optimizing the thermal design of a shell-and-tube heat exchanger requires minimizing the heat-transfer area for a given heat duty while remaining within the constraints of given shellside and tubeside pressure drops. The general heat-transfer equation is shown in Equation (1), where the heat-transfer rate (Q) is given in terms of the overall heat-transfer coefficient (U), the heat-transfer surface area (A) and the effective mean temperature difference, (∆T)e.
Q = UA(∆T)e (1)
For a given Q, A can be minimized by maximizing U, (∆T)e or both, subject to the constraints of the shellside and tubeside pressure drops. Additional design constraints may stem from other factors, such as flow-induced vibration, space limitations, and standard tube lengths and diameters as specified by the Tubular Exchangers Manufacturers Association (TEMA) .
Although U can be increased by increasing the shellside or tubeside heat-transfer coefficient (hs or ht, respectively), it can be increased substantially…