ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
TRANSIENT MODELLING OF FINNED TUBE HEAT EXCHANGERS
Resumo
A modelling procedure has been developed to predict the performance of air heating or cooling and dehumidifying coils for any single phase heat transfer liquid at various temperatures, flow rates, coil circuits, coil dimensions, and tube and fin arrangements.
The paper describes the procedure for finned tube heat exchangers with application to transient responses as well as the steady state performance. Different tube and circuit arrangements can be modelled for either counter or parallel flow. Finite element techniques are applied to allow for temperature gradients within the fins, varying local heat transfer coefficients, and localised dehumidification.
All heat transfer parameters are derived from the coil dimensions and arrangements, fluid velocities, and the transport properties of the fluids which are derived from a library of algorithms. Mass transfer is computed as a function of vapour and thermal diffusion coefficients. All time lags associated with heat storage and fluid flow are also modelled.
The procedure has been used for the design of close tolerance temperature and humidity air conditioning and for the design of cold air applications to air conditioning.
The paper describes the procedure for finned tube heat exchangers with application to transient responses as well as the steady state performance. Different tube and circuit arrangements can be modelled for either counter or parallel flow. Finite element techniques are applied to allow for temperature gradients within the fins, varying local heat transfer coefficients, and localised dehumidification.
All heat transfer parameters are derived from the coil dimensions and arrangements, fluid velocities, and the transport properties of the fluids which are derived from a library of algorithms. Mass transfer is computed as a function of vapour and thermal diffusion coefficients. All time lags associated with heat storage and fluid flow are also modelled.
The procedure has been used for the design of close tolerance temperature and humidity air conditioning and for the design of cold air applications to air conditioning.