The analysis of the optimal solution from experimental data essentially comprises of four parts: The fluid dynamics analysis, as in the use of Particle Image Velocimetry, PIV, and their outputted results; the electrical output analysis, in the form of readings and analysis carried out for varying electrical loads; heat flux measurements taken directly in experimentation and using Infrared Thermography; and the combined heat and fluid dynamics effectiveness analysis carried out as described by the publications on transpired solar collectors by researchers at the NREL in the US and at Waterloo University in Canada. The experimental test rig design is along the lines of those used by Murphy [14 ] and Jubran et al, [15 ].

PIV provides velocity data across the flow field, requiring tracer particles or seeding in the flow. The method’s particular advantages are that it is non-intrusive, has high spatial and temporal resolution [16].

Conclusions

Perforating PV panels has been demonstrated as a viable way of increasing cooling by previous testing, Murphy [13]. This is more likely due to the increase in contact area brought about by the hole itself, than the setting up of particular boundary layer flow regimes. Hole geometry and features such as pitch and density along with the
main parameters outlined earlier remain to be examined. Setting up flow regimes such as film cooling could lead to fruitful results, though film cooling effectiveness is a measure of the layers ability to eliminate heat transfer to the hot surrounding environment, rather than promote heat transfer, this could still be useful in the PV problem, at the top of a fagade where the air in the cooling duct would be heated considerably. To date only circular holes at 90° to the panel have been investigated. As shown by Botas et al [17], and Goldstein et al [18], varying the hole parameters will increase film cover effectiveness. Altering hole shapes, compound angles, pitches, densities, etc. have also lead to increased heat transfer depending on how the variable parameters are manipulated.

Depending on the size of the duct behind the panel and the pressure difference used to model the buoyancy effect in a building fagade, the free stream air speed tends to be quite low, <5m/s [1]. The best flow regime to promote heat transfer is turbulent flow. At low velocities, and low Reynolds numbers, this may have to be induced, as discussed in work published by Niami and Gessner [19]. Staggering, perforating and setting up ribbed-grooved walls were found to increase heat transfer by a factor of 3 and more, as well as reducing hot spots. lacovides et al [10], discussed how the inclination of the ribbed turbulators brings about a more evenly mixed flow and heat transfer. The use of ribs would also supplement the ideas of cooling the panels using extended fins to the rear, as carried out by researchers at Brown University, Providence, Rl, on hybrid PV collectors. Dimples have been found to give almost the same heat transfer as ribs with a much lower pressure drop.

In the area of analysis and modeling, conventional CFD mathematics must be carried out on the solution ideas. This will be backed up by CFD computer analysis done on Flotran. Heat transfer measurements are being made using the IR camera and heat flux sensors and thermocouples.