Timothy C. Scott

Modeling Compact Exchangers for HVAC Applications

This paper presents equations for modeling the performance of compact air cooled heat exchangers when only limited supplier catalog performance information is available. Relations for the overall heat transfer coefficient under dry or wet surface operating conditions with water, steam, and refrigerants are presented. Equations for the air and water side pressure drop are also given. The coefficients in these equations may be determined using typical heat transfer vs. air face velocity data without the need for various surface and flow areas or air side convection coefficients. The model may then be used to predict performance at other conditions for which supplier data is not available.Copyright

Cooling Fan Modeling to Support Robust AC/Cooling System Simulation

Advanced design of modern engine cooling and vehicle HVAC components involves sophisticated simulation. In particular, front end air flow models must be able to cover the complete range of conditions from idle to high road speeds involving multiple fans of varying types both powered and unpowered. This paper presents a model for electric radiator cooling fans which covers the complete range of powered and unpowered (freewheel) operation. The model applies equally well to mechanical drive fans.