Theoretical solution for the cool-down or warm-up process of a pipeline ora packed bed

For planning the start-up procedure of a pipeline under realistic condition s the cool-down or warm-up behaviour should be known in advance. The relati on between the cool-down or warm-up time and the mass-flow rate in the pipe line should be known in particular. Based on heat balances theoretical rela tions had been derived to enable appropriate estimations. These derived the oretical relations are also valid for the cool-down or warm-up of packed be ds used as heat accumulators, e.g., in regenerators. A simple experimental method is suggested to determine the heat transfer coefficient in a packed bed using the theoretical relation for the gas temperature as a function of time and length. As all variables in the formulae are dimensionless, norma lized diagrams have been developed, which are valid for all the cases discu ssed. (C) 2001 Elsevier Science Ltd. All rights reserved.