Shell and Tube Heat Exchanger Design
The required heat transfer surface area for a shell and tube heat exchanger design is typically found from the basic heat exchanger equation: Q = UA ΔTlm, where:
Q = rate of heat transfer between the two heat exchanger fluids, Btu/hr,
U = overall heat transfer coefficient, BTU/hr-ft2-oF,
A = heat transfer surface area, ft2,
ΔTlm = log mean temperature difference in oF, calculated from the inlet and outlet temperatures of the two fluids.
The basic heat exchanger equation, and the above parameters, are discussed in 'Fundamentals of Heat Exchanger Design'. An example calculation with the basic heat transfer equation is given in 'Preliminary Heat Exchanger Design Example'.
If the required flow rate and temperature change of one of the fluids is known along with the flow rate and one temperature for the other fluid (or both temperatures for the other fluid), an estimate for the heat transfer coefficient, and the shell and tube heat exchanger flow pattern to be used, then the required heat transfer area can be calculated using the basic heat exchanger equation.
After the needed heat transfer surface area is calculated, an appropriate diameter, length and number for the tubes can be determined and the shell can be sized and designed. The tube sheets and baffles will also need to be designed.