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Modeling the dynamic response of conduits

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journal contribution
posted on 09.10.2008, 14:23 by Victor I. Hanby, Jonathan WrightJonathan Wright, D.W. Fletcher, D.N.T. Jones
A method for the dynamic modeling of a fluid conduit is developed, based on its discretization into a sequence of well-mixed flow nodes. This enables the time delay produced by the fluid flow to be simply modeled in any time domain simulation. An optimal level of discretization, based on the residence time distribution produced by fully developed turbulent flow, is presented. The model is capable of calculating the response to changes in flow rate, fluid inlet temperature, and species concentration. The thermal response is based on a second-order model for each node, taking account of the thermal capacitance of the fluid and of the conduit inner wall. It is demonstrated that the model predicts a time delay, then a rapid initial response due to flow effects, followed by slower dynamics controlled by the thermal inertia of the walls. An intermodel comparison of output for a prototype duct is made with three published models, and an empirical validation is reported.



  • Architecture, Building and Civil Engineering


HANBY, V.I. ... et al, 2002. Modeling the dynamic response of conduits. HVAC & R Research, 8 (1), pp. 1-12


© American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

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This is a journal article [© American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org)]. Reprinted by permission from HVAC&R Research, Vol. 8, Part 1. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission. It is also available at: www.ashrae.org/hvacr-research





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