Practical effectiveness-NTU model for cooling and dehumidifying coil with non-unit Lewis Factor

Abstract This work presents an innovative correlation associating the effectiveness ( e ) of the fully-wet cooling coil with its number of transfer unit (NTU) and vice versa. The thermal performance and design of the fully-wet cooling coil, either chilled water or direct expansion DX coil, can be predicted simply through those correlations with unit and non-unit Lewis factors. The analytical model was constructed on a basis of solving heat and mass transfer equation “enthalpy potential method” simultaneously coupled with the energy equations. The validity of the new correlations was evaluated through calculation of air exit psychometric properties along air flow direction in a cooling coil with the results obtained from literature. Also, the total and sensible cooling capacity can be determined. The main feature of this novel correlation is its simplicity and easiness in calculation by knowing input Lewis number and some other key parameters. Also, the main benefit of this new model is to provide helpful guidelines for optimization of fully-wet cooling coil performance and developing suitable control strategies to achieve higher thermal behavior of the cooling coil during its operation.

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