ISEC2005-76140 ......(4)

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NUMERICAL STUDY OF CONJUGATE HEAT TRANSFER IN A BIPV-THERMAL SYSTEM(4)绿色建筑博客9i1r%\9Kr

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2{:v(wh@VU4q~0INTRODUCTION

-r)U h_+Zi(Q0 In recent years, increasing numbers of building integrated photovoltaic (BIPV) systems have been installed in residential and commercial buildings. Such systems may serve not only as a renewable source of electricity, but also as a source of heat. The solar energy absorbed by the PV panel is partially converted to electricity and heat, and the rest of it reflected. The generated heat must be dissipated to a cooling fluid to maintain the proper operating temperature for PV panels and thus to increase electrical conversion efficiency.

Various models and investigations to study BIPV systems or double facades are reported in the literature. A 2-D finite element code was employed in a CFD study by Moshfeg and Sandberg with idealized boundary conditions [1]. In 1996, a 2- D laminar flow model was investigated by Mootz and Bezian [2]. The BIPV model is further improved by introducing the radiation heat transfer in terms of the local surface temperature [3]. However, this [3] study was mainly focused on the laminar flow [3]. Zolner et al. performed detailed experimental investigations and found that the flow was turbulent mixed convection [4]. They report some measurements of the low velocities including different inlet sizes. In 2002, Mei et al. [5] presented a dynamic thermal model integrated to the TRNSYS to study how the BIPV system can help to reduce the building load. However, none of the above studies used the real condition encountered in BIPV/T systems, that is non-uniform temperature profile for the PV panel.
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]f(EzH5TW0 A full scale test facility has been investigated at Concordia University for nearly three years. A test room fa-ade photo taken from outside is shown in Fig. 1. 1-D and 2-D models have been developed to study the thermal behavior in the air cavity [6, 7]. However, the models need the input of convective heat transfer coefficients (hc) for accurate studies. This paper reports on a detailed fluid dynamics investigation, generation of the local convective heat transfer coefficients and prediction of local PV temperatures. Air is drawn into the two side-by-side test sections with the aid of an exhaust fan located at the top in the room. Another part of this project will study integration with HVAC systems and control of the inlet damper and variable speed fan to achieve desired flow rates and supply temperatures.