Fluid mass and energy flows in air conditioning systems vary with the changing output demand. In lengthy or complex ductwork and pipework, the accuracy in simulating the dynamic network behaviour is greatly affected by the accuracy in modelling the radial energy losses and the axial transport lag. Transport delay consideration is also vital in the study of heat exchanger dynamics. Reviews the development of transport delay models in fluid conduit flow. A numerical model is recommended in which the thermal behaviour of fluid elements can be traced per physical distance travelled in unit time step. Justification by sensitivity and frequency response analyses were performed. The results of analytical, experimental, as well as intermodel comparisons demonstrate the promising accuracy of the numerical model introduced.

KEYWORDS: year 1996, calculating, accuracy, fluid flow, air conditioning, ducts, pipes, heat loss, temperature distribution