Paper Conference

Proceedings of SimBuild Conference 2004: 1st conference of IBPSA-USA


Improvement of the ASHRAE Secondary HVAC Toolkit Simple Cooling Coil Model for Simulation

Rahul J. Chillar, Richard J. Liesen
University of Illinois at Urbana Champaign, Dept of Mechanical & Industrial Engineering, 1206 W.Green St, Urbana, IL 61801. USA

Abstract: The simple cooling coil "CCSIM" model of the ASHRAE Secondary HVAC Toolkit approximates the performance of cooling coil as either completely dry or completely wet with wet dry fraction value of 1 or 0. This model also generates an abrupt discontinuity in all output values, such as leaving air temperature, total heat transfer, sensible heat transfer etc., in the wet-dry transition region. This model will fail to work for simulations in the transition range between wet and dry coil sections where a continuous function in output values is necessary. This paper shows how to maintain the simpler input parameters and still have enough information to use the Wet-Dry coil model to eliminate the abrupt discontinuity in the output values in the transition region. This is achieved by addition and amalgamation of certain formulas and modules present in the detailed cooling coil model "CCDET", with the simple cooling coil model. The simplicity of the model in terms of inputs is retained; the discontinuities are eliminated and it also gives value of fraction wet-dry of the simple coil.
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