S-SS-3-8 Theoretical Method to Evaluate Shellside Temperature Profile Distortion Correction Factor
The theoretical basis for the evaluation of the temperature profile distortion correction factor, δ, is presented. The empirical delta correction is reasonable for well-designed typical exchangers but may be unsafe for units with very close baffle spacing, low crossflow fraction, and low MTD correction factor, F. The theoretical δth, has a better extrapolation potential than the previously used empirical δe, and can be used with all exchanger geometries.
The important parameter in the evaluation of the theoretical delta is the mixing factor, m. This is the parameter which accounts for the effect on the shellside exit temperature due to mixing of the inefficient leakage stream, FFI, with the effective crossflow stream. All the recent HTRI data as well as the data in the HTRI data bank have been used in the development of a generalized correlation for the mixing factor.
The theoretical procedure for delta has been tested against the data, and the results are presented as the error ratio of the predicted over the measured overall heat transfer coefficient versus shellside crossflow Reynolds number.