S-SS-3-2 Parametric Response Study of Segmentally Baffled Shell-and-Tube Exchanger Performance
An important tool required in the overall optimization of a heat exchanger-pumping system is the relationship between the exchanger constructional parameters and the efficiency of heat exchanger performance.
The purpose of this report is to develop this relationship as quantitatively as possible for the shell side of baffled shell-and-tube exchangers, through the use of a large quantity of artificial "data" points generated by the HTRI Stream Analysis model of shellside flow.
The general equation for shellside heat transfer in terms of pressure drop was derived to be
Nu = Cpd (Npd)1/3
where Nu is the Nusselt number and Npd is the derived pressure drop number containing pressure drop per tuberow, tube diameter, and a physical property group.
The coefficient Cpd is the pressure drop conversion factor which indicates the efficiency with which any exchanger design converts pressure drop to heat transfer. Effects of variations in exchanger geometry on the pressure drop conversion factor were calculated by the Stream Analysis Method for a large number of design configurations, and resulted in determination of optimum design ranges for such parameters as baffle cut, baffle spacing, number of sealing strips, tube layouts, and tube pitch. The effects of baffle-shell and tube-baffle clearances, shellside vs. tubeside flow, and finned tubes on exchanger performance are also discussed.
A generalized method is presented which allows quick manual estimation of the shellside heat transfer coefficient for a given design pressure drop, and also determination of the effects of alternate geometry constructions.
General design recommendations are made for the three cases of industrial significance: high heat transfer, low pressure drop, and most efficient conversion of pressure drop to heat transfer.