Methods of Calculating Heat Transfer within the Passages of Heat Exchangers

摘要

Predictions of heat transfer and fluid flow processes within the passages of heat exchangers using: (1) experimental information generalized by dimensional analysis, (2) experimental information generalized by analogies between heat, mass and momentum transfer, (3) the methods of classical mathematics, and (4) numerical methods embodied in computer programs are considered. Practices (1) and (2) are becoming increasingly expensive while practice (3) remains of extremely limited utility. Practice (4) is increasing its power and reducing its costs as new computers, computer programs and experimental information become available. The principles of the numerical approach to within-passage heat transfer and fluid flow are described together with some of the difficulties of implementation and methods of overcoming them. Predictive capability, however, remains insufficient for designers, especially in respect of turbulence complicated by low Reynolds number and two phase phenomena.