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

For planning the start-up procedure of a pipeline under realistic conditions the cool-down or warm-up behaviour should be known in advance. The relation between the cool-down or warm-up time and the mass-flow rate in the pipeline should be known in particular. Based on heat balances theoretical relations had been derived to enable appropriate estimations. These derived theoretical relations are also valid for the cool-down or warm-up of packed beds 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, normalized diagrams have been developed, which are valid for all the cases discussed.