Approximate Values for Overall Heat Transfer Coefficients
Various fluid heat transfer operations can be characterized in a general way by values of the overall coefficient, U. The values given in Perry  cannot be all-inclusive for every situation. However, they are suitable for use in estimating exchanger performance and in checking (approximately) the calculated values and similar non-exact comparison. Table 15-28, 29 and 32 list a variety of applications and the corresponding overall heat transfer coefficient (U) values and fouling factors. In general, these units have performed without difficulty, although the questions that cannot be answered are whether they may have been too large or how too large they may have been.