THE EFFECT OF HEAT-CONDUCTION RESISTANCES OF TUBES AND SHELLS ON TRANSIENT-BEHAVIOR OF HEAT-EXCHANGERS

With respect to radial heat conduction in tube and shell walls as well as heat loss from the shell to the environment, a predicting method f or transient behaviour of counter and parallel heat exchangers is deve loped. Some parameters such as the Biot number (Bi) and the Fourier nu mber (Fo) of estimating the effect of radial heat conduction are propo sed. If Bi > 0.05, radial heat conduction will remarkably affect dynam ic characteristic of heat exchangers and it should be taken into accou nt. In addition, an approximate approach of considering radial heat co nduction is presented, which reduces much of computing time. There exi sts satisfactory coincidence between accurate and approximate treatmen t of radial heat conduction.