Effect of thermal radiation on convection heat transfer in cooling channel of photovoltaic thermal system

The effect of thermal radiation on convection heat transfer in flat-box type cooling channel of photovoltaic thermal system with tilt angle of 30 degree was studied by 3D numerical simulation under constant heat flux boundary condition. The temperature contours and velocity fields of fluid near the outlet were obtained. The variations of wall temperature and convection Nusselt number along flow direction for all the separate walls composing the cooling channel were compared and analyzed. The results show that due to thermal radiation, the deflection of the maximum velocity region to heated top wall, together with the asymmetry of temperature field is weakened. For natural convection, radiation promotes the formation of multi-vortices. For mixed convection, heat transfer on all the cooling channel walls is enhanced under the condition of lower heat flux while heat transfer on heated top wall is deteriorated when the heat flux is relative high. Also, pressure re-rising is promoted by thermal radiation.

[1]  Reinhard Radermacher,et al.  A high efficiency solar air conditioner using concentrating photovoltaic/thermal collectors , 2012 .

[2]  E. Chénier,et al.  Effect of surface radiation on natural convective flows and onset of flow reversal in asymmetrically heated vertical channels , 2013 .

[3]  E. Sparrow,et al.  Radiation Heat Transfer , 1978 .

[4]  Jie Ji,et al.  Hybrid photovoltaic-thermosyphon water heating system for residential application , 2006 .

[5]  H. Chiu,et al.  Mixed convection heat transfer in inclined rectangular ducts with radiation effects , 2008 .

[6]  Jer‐Huan Jang,et al.  Mixed convection heat transfer in horizontal rectangular ducts with radiation effects , 2007 .

[7]  Swapnil Dubey,et al.  Thermal modeling of a combined system of photovoltaic thermal (PV/T) solar water heater , 2008 .

[8]  Arvind Tiwari,et al.  Performance evaluation of photovoltaic thermal solar air collector for composite climate of India , 2006 .

[9]  Jane H. Davidson,et al.  A model and heat transfer correlation for rooftop integrated photovoltaics with a passive air cooling channel , 2009 .

[10]  Combined heat transfer of radiation and forced convection flow of participating gases in a three-dimensional recess , 2012 .

[11]  M. El-Shaarawi,et al.  Mixed convection with surface radiation between two asymmetrically heated vertical parallel plates , 2012 .

[12]  Andreas K. Athienitis,et al.  Convective Heat Transfer Coefficients in a Building-Integrated Photovoltaic/Thermal System , 2011 .

[13]  Anouar Soufiani,et al.  Combined gas radiation and laminar mixed convection in vertical circular tubes , 2003 .

[14]  Deo Prasad,et al.  Modelling of a photovoltaic heat recovery system and its role in a design decision support tool for building professionals , 2002 .

[15]  Y. Tripanagnostopoulos,et al.  Performance improvement of PV/T solar collectors with natural air flow operation , 2008 .

[16]  K. Sumathy,et al.  Photovoltaic thermal module concepts and their performance analysis: A review , 2010 .