Prediction of Heat Transfer and Air Flow in Solar Heated Ventilation Cavities pp. 137-178
Authors: (Guohui Gan, Department of Architecture and Built Environment, University of Nottingham, Nottingham, United Kingdom)
Abstract: Solar heated ventilation cavities are used to enhance passive cooling of buildings and building-integrated photovoltaics. This chapter is concerned with numerical prediction of buoyancy-driven heat transfer and air flow in vertical cavities for natural ventilation of buildings and inclined cavities for ventilation cooling of building-integrated photovoltaics. Computational fluid dynamics was used to predict the heat transfer and air flow rates in vertical ventilation cavities with various combinations of heat distribution ratios ranging from symmetrical to asymmetrical heating and inlet/outlet openings and also in inclined ventilation cavities with combined convective and radiative heat transfer. The natural ventilation rate and heat transfer rate in a vertical cavity have been found to vary with the total heat flux, heat distribution on the cavity wall surfaces, cavity size and opening positions. It has also been found that reducing asymmetry in heat distribution on the vertical cavity wall surfaces can increase the ventilation rate but would decrease the heat transfer rate. The air flow rate and heat transfer rate in an inclined cavity generally increase with inclination angle while the temperature of PV cells decreases with increasing inclination. General correlations between these variables in the cavities have been obtained and presented in non-dimensional forms.
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