Temperature difference multipass exchangers

In the field of heat transfer, a good example of this category of shortcut design method is the famous F correction factor to correct the log mean temperature difference of shell and tube heat exchangers for deviations from true countercurrent flow. For multipass heat exchangers, the assumptions are ... 

To determine the true overall temperature difference, the correction factors, F, shown in Figure 10-34 are used to correct for the deviations involved in the construction of multipasses on the shell and tube sides of the exchanger. Note that R of the charts represents the heat capacity rate ratio , and P is the temperature efficiency of the exchanger. 

Bowman RA (1936) Mean Temperature Difference Correction in Multipass Exchangers, Ind Eng Chem, 28 541. 

Use equation for 1-2 multipass. The mean temperature difference for a 1-2 multipass heat exchanger can be calculated from the equation... 

Related Calculations. Mean temperature differences for multipass heat exchangers may also be calculated by using appropriate correction factors for the log mean temperature difference for countercurrent flow... 

Temperature control, 42,45-47 Temperature difference, 172 logarithmic mean, 172 multipass exchangers, 173, 175-177 Temperature profiles, heat exchangers,... 

Mean Temperature Difference 172 Single Pass Exchanger 172 Multipass Exchangers 173 F-Method 173... 

For multipass and cross-flow exchangers, the log-mean temperature difference (LMTD) method is still applicable, i.e., the heat transfer rate is... 

In the majority of industrial operations, higher velocities, shorter tubes, and a more economical exchanger can be achieved with a multipass flow design as shown in Figure 8-1. The flow pattern is however part countercurrent and part co-current. Therefore, the mean temperature difference lies between the countercurrent and co-current log mean temperature differences (LMTD). The mean temperature differences for the... 

If one of the fluids is at constant temperature, as in a condenser, no difference exists among countercurrent flow, parallel flow, or multipass flow, and Eq. (11.15) applies to all of them. In countercurrent flow, AT2, the warm-end approach, may be less than ATj, the cold-end approach. In this case, for convenience and to eliminate negative numbers and logarithms, the subscripts in Eq. (11.15) may be interchanged. The LMTD is not always the correct mean temperature difference to use. It should not be used when U changes appreciably or when AT is not a linear function of q. As an example, consider an exchanger used to cool and condense a superheated vapor, with the temperature diagram shown in Fig. 11.6. 

Correction factor for average temperature difference in crossflow or multipass exchangers, dimensionless... 

Underwood, A.J.V. J. Inst. Petrol. Technol. 20 (1934) 145. The calculation of the mean temperature difference in multipass heat exchangers. 

Nagle, W.M., Mean Temperature Differences in Multipass Heat Exchangers, Ind. Eng. Chem., 25,604-609 (1933). 

Underwood, A.J.V., The Calculation of the Mean Temperature Difference in Multipass Heat Exchangers, J. Inst. Petroleum TechnoL, 20, 145-158 (1934). 

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