Maximum Thermal Effectiveness for 1-2 Shell-and-Tube Heat Exchangers

Maximum Thermal Effectiveness for 1-2 Shell-and-Tube Heat Exchangers 

The maximum value of P, for any R, occurs as Py tends to -oo. Study of the Ft functions above reveals that for Ft to be determinate, 

Condition (3) applies to Eq. (C.2) when R = 1. Both conditions (1) and (2) are always true for a feasible heat exchange with positive temperature differences. 

For condition b to apply, for positive values of i , P 2. However, P 1 for feasible heat exchange. Thus, condition (b) does not apply. Consider now condition (a). Because 

Thus the maximum value of P for any value of R, Pmax is given by 

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