Effect of mounting geometry on convection occurring under a photovoltaic panel and the corresponding efficiency using CFD

Computational fluid dynamics (CFD) is used to model experimental data corresponding to convection occurring under a photovoltaic (PV) panel. Further experimental data is used to validate the model where the satisfactory agreement is received. A standardised condition is set up to allow the effect of varying three geometric parameters to be examined. These are the air gap height (10–500 mm), air gap orientation angle (0–90° from the horizontal) and fluid velocity magnitude (0–3 m/s). The optimum mounting conditions for the PV panel is obtained and maximised electrical efficiency found to favour angles greater than 50° and air gap heights that give an aspect ratio of 60. Mixed convection opposed to natural convection is found to be more effective, with greater efficiencies obtained for larger fluid velocities

Empirical investigation to explore potential gains from the amalgamation of Phase Changing Materials (PCMs) and wood shavings

The reduction of gained heat, heat peak shifting and the mitigation of air temperature fluctuations are some desirable properties that are sought after in any thermal insulation system. It cannot be overstated that these factors, in addition to others, govern the performance of such systems thus their effect on indoor ambient conditions. The effect of such systems extends also to Heating, Ventilation and Air-conditioning (HVAC) systems that are set up to operate optimally in certain conditions. Where literature shows that PCMs and natural materials such as wood-shavings can provide efficient passive insulation for buildings, it is evident that such approaches utilise methods that are of a degree of intricacy which requires specialist knowledge and complex techniques, such as micro-encapsulation for instance. With technical and economic aspects in mind, an amalgam of PCM and wood-shavings has been created for the purpose of being utilised as a feasible thermal insulation. The amalgamation was performed in the simplest of methods, through submerging the wood shavings in PCM. An experimental procedure was devised to test the thermal performance of the amalgam and compare this to the performance of the same un-amalgamated materials. Comparative analysis revealed that no significant thermal gains would be expected from such amalgamation. However, significant reduction in the total weight of the insulation system would be achieved that, in this case, shown to be up to 20.94%. Thus, further reducing possible strains on structural elements due to the application of insulation on buildings. This can be especially beneficial in vernacular architectural approaches where considerably large amounts and thicknesses of insulations are used. In addition, cost reduction could be attained as wood shavings are significantly cheaper compared to the cost of PCMs

Improving indoor conditions of a Thai-style mushroom house by means of an evaporative cooler and continuous ventilation, Renewable Energy 17

Abstract The paper discusses the e}ect of an evaporative cooling process and continuous ventilation for improving the indoor conditions of a conventional Thai!style mushroom house[ A numerical model describing the behaviour of the Thai!style mushroom house model was developed[ It was validated by comparing its output with that of the experiment of a small model of a mushroom house[ It was found that the combination of evaporative cooling and continuous ventilation reduced the temperature and increased the relative humidity of air inside a mush! room house that is suitable for growing Lentinus[ Þ 0888 Elsevier Science Ltd[ All rights reserved