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Air Enthalpy

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Masud Behnia – One of the best experts on this subject based on the ideXlab platform.

  • cfd simulation of Air to Air Enthalpy heat exchanger variable membrane moisture resistance
    Applied Thermal Engineering, 2015
    Co-Authors: Rafat Alwaked, Graham L. Morrison, Mohammad Shakir Nasif, Masud Behnia

    Abstract:

    Abstract Conjugate heat and mass transfer processes across membrane heat exchangers of variable mass transportation resistance were investigated numerically. One half of flow channel for the hot stream and another for the adjacent cold stream were simulated. Effects of channel height, Reynolds number and flow direction on heat exchanger thermal effectiveness and energy recovered were studied. The validated CFD model showed that values of moisture resistance decrease with the increase in flow rates and/or the decrease in vapour mass fractions on both sides of the membrane. Furthermore, total hydraulic diameter effects on the thermal efficiency within membrane heat exchangers were found strong.

  • CFD simulation of Air to Air Enthalpy heat exchanger
    Energy Conversion and Management, 2013
    Co-Authors: Rafat Al-waked, Mohammad Shakir Nasif, Graham L. Morrison, Masud Behnia

    Abstract:

    Abstract A CFD model which supports conjugate heat and mass transfer problem representation across the membrane of Air-to-Air energy recovery heat exchangers has been developed. The model consists of one flow passage for the hot stream and another for the adjacent cold stream. Only half of each flow passage volume has been modelled on each side of the membrane surface. Three dimensional, steady state and laminar flow studies have been conducted using a commercial CFD package. The volumetric species transport model has been adopted to describe the H 2 O and Air gas mixtures. Mesh dependency has been examined and followed by validation of the CFD model against published data. Furthermore, effects of flow direction at the inlet of the heat exchanger on its thermal effectiveness have been investigated. Simulation results are presented and analysed in terms of sensible effectiveness, latent effectiveness and pressure drop across the membrane heat exchanger. Results have shown that counter-flow configuration has greater sensitivity to the mesh centre perpendicular distance from the membrane when compared to the other two flow configurations (cross-/parallel-flow). However, the lateral mesh element length has shown minimal effect on the thermal effectiveness of the Enthalpy heat exchanger. For the quasi-flow heat exchanger, a perpendicular flow direction to the inlets has been found to produce a higher performance in contrast to the non-perpendicular flow.

  • Modeling of Air to Air Enthalpy Heat Exchanger
    Heat Transfer Engineering, 2012
    Co-Authors: Mohammad Shakir Nasif, Rafat Al-waked, Masud Behnia, Graham L. Morrison

    Abstract:

    The thermal performance of a Z-shaped Enthalpy heat exchanger utilizing 45-gsm Kraft paper as the heat and moisture transfer surface for heating, ventilation, and Air conditioning (HVAC) energy recovery is experimentally investigated through temperature and moisture content measurements. A mathematical model is developed and validated against the experimental results using the effectiveness-NTU method. In this model the paper moisture transfer resistance is determined by paper moisture permeability measurements. Results showed that the paper moisture transfer resistance is not constant and varies with moisture gradient across the paper. Furthermore, the model is used to predict the heat exchanger performance for different heat exchanger flow configurations. The results showed that higher effectiveness values are achieved when the heat exchanger flow path width is reduced. Temperature and moisture distribution in the heat exchanger is also studied using a computational fluid dynamics package (FLUENT). To m…

Rafat Alwaked – One of the best experts on this subject based on the ideXlab platform.

  • cfd simulation of Air to Air Enthalpy heat exchanger variable membrane moisture resistance
    Applied Thermal Engineering, 2015
    Co-Authors: Rafat Alwaked, Graham L. Morrison, Mohammad Shakir Nasif, Masud Behnia

    Abstract:

    Abstract Conjugate heat and mass transfer processes across membrane heat exchangers of variable mass transportation resistance were investigated numerically. One half of flow channel for the hot stream and another for the adjacent cold stream were simulated. Effects of channel height, Reynolds number and flow direction on heat exchanger thermal effectiveness and energy recovered were studied. The validated CFD model showed that values of moisture resistance decrease with the increase in flow rates and/or the decrease in vapour mass fractions on both sides of the membrane. Furthermore, total hydraulic diameter effects on the thermal efficiency within membrane heat exchangers were found strong.

Graham L. Morrison – One of the best experts on this subject based on the ideXlab platform.

  • cfd simulation of Air to Air Enthalpy heat exchanger variable membrane moisture resistance
    Applied Thermal Engineering, 2015
    Co-Authors: Rafat Alwaked, Graham L. Morrison, Mohammad Shakir Nasif, Masud Behnia

    Abstract:

    Abstract Conjugate heat and mass transfer processes across membrane heat exchangers of variable mass transportation resistance were investigated numerically. One half of flow channel for the hot stream and another for the adjacent cold stream were simulated. Effects of channel height, Reynolds number and flow direction on heat exchanger thermal effectiveness and energy recovered were studied. The validated CFD model showed that values of moisture resistance decrease with the increase in flow rates and/or the decrease in vapour mass fractions on both sides of the membrane. Furthermore, total hydraulic diameter effects on the thermal efficiency within membrane heat exchangers were found strong.

  • CFD simulation of Air to Air Enthalpy heat exchanger
    Energy Conversion and Management, 2013
    Co-Authors: Rafat Al-waked, Mohammad Shakir Nasif, Graham L. Morrison, Masud Behnia

    Abstract:

    Abstract A CFD model which supports conjugate heat and mass transfer problem representation across the membrane of Air-to-Air energy recovery heat exchangers has been developed. The model consists of one flow passage for the hot stream and another for the adjacent cold stream. Only half of each flow passage volume has been modelled on each side of the membrane surface. Three dimensional, steady state and laminar flow studies have been conducted using a commercial CFD package. The volumetric species transport model has been adopted to describe the H 2 O and Air gas mixtures. Mesh dependency has been examined and followed by validation of the CFD model against published data. Furthermore, effects of flow direction at the inlet of the heat exchanger on its thermal effectiveness have been investigated. Simulation results are presented and analysed in terms of sensible effectiveness, latent effectiveness and pressure drop across the membrane heat exchanger. Results have shown that counter-flow configuration has greater sensitivity to the mesh centre perpendicular distance from the membrane when compared to the other two flow configurations (cross-/parallel-flow). However, the lateral mesh element length has shown minimal effect on the thermal effectiveness of the Enthalpy heat exchanger. For the quasi-flow heat exchanger, a perpendicular flow direction to the inlets has been found to produce a higher performance in contrast to the non-perpendicular flow.

  • Modeling of Air to Air Enthalpy Heat Exchanger
    Heat Transfer Engineering, 2012
    Co-Authors: Mohammad Shakir Nasif, Rafat Al-waked, Masud Behnia, Graham L. Morrison

    Abstract:

    The thermal performance of a Z-shaped Enthalpy heat exchanger utilizing 45-gsm Kraft paper as the heat and moisture transfer surface for heating, ventilation, and Air conditioning (HVAC) energy recovery is experimentally investigated through temperature and moisture content measurements. A mathematical model is developed and validated against the experimental results using the effectiveness-NTU method. In this model the paper moisture transfer resistance is determined by paper moisture permeability measurements. Results showed that the paper moisture transfer resistance is not constant and varies with moisture gradient across the paper. Furthermore, the model is used to predict the heat exchanger performance for different heat exchanger flow configurations. The results showed that higher effectiveness values are achieved when the heat exchanger flow path width is reduced. Temperature and moisture distribution in the heat exchanger is also studied using a computational fluid dynamics package (FLUENT). To m…