Kamaruzzaman Sopian

Performance analysis of photovoltaic thermal air heaters

The performance of single-pass and double-pass combined photovoltaic thermal collectors are analyzed with steady-state models. The working fluid is air and the models are based on energy conservation at various nodes of the collector. Closed form solutions have been obtained for the differential equations of both the single-pass and double-pass collectors. Comparisons are made between the performances of the two types of combined photovoltaic thermal collectors. The results show that the new design, the double-pass photovoltaic thermal collector, has superior performance. Important parameters for both types of collector are identified, and their effects on the performances of the two types of collectors are presented in detail.

Performance of a double pass photovoltaic thermal solar collector suitable for solar drying systems

The photovoltaic thermal solar collector, sometimes known as the hybrid solar collector generates both thermal and electrical energies simultaneously. A double pass photovoltaic thermal solar collector suitable for solar drying applications has been developed and tested. A steady state closed form solution to determine the outlet and mean photovoltaic panel temperature has been obtained for the differential equations of the upper and lower channels of the collector. Hence, the photovoltaic, thermal and combined photovoltaic thermal efficiencies can be obtained. An experimental setup has been developed. For given sets of operating and design conditions the theoretical and experimental outlet and mean photovoltaic panel temperatures can be obtained. Comparisons are made between the experimental and theoretical results and close agreement between these two values are obtained.

Visible light photocatalytic activity of Fe3+-doped ZnO nanoparticle prepared via sol–gel technique

The optical properties of a ZnO photocatalyst were enhanced with various dopant concentrations of Fe(3+). Doped ZnO nanoparticles were synthesized via a sol-gel method without the use of capping agents or surfactants and was then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultraviolet-visible (UV-Vis) spectroscopy. The results showed that ZnO has a wurtzite, hexagonal structure and that the Fe(3+) ions were well incorporated into the ZnO crystal lattice. As the Fe(3+) concentration increased from 0.25 wt.% to 1 wt.%, the crystal size decreased in comparison with the undoped ZnO. The spectral absorption shifts of the visible light region (red shift) and the band gap decreases for each Fe-ZnO sample were investigated. The photocatalytic activities of the ZnO and Fe-ZnO samples were evaluated based on the degradation of 2-chlorophenol in aqueous solution under solar radiation. The samples with a small concentration of Fe(3+) ions showed enhanced photocatalytic activity with an optimal maximum performance at 0.5 wt.%. The results indicated that toxicity removal of 2-chlorophenol at same line of degradation efficiency. Small crystallite size and low band gap were attributed to high activities of Fe-ZnO samples under various concentrations of Fe(3+) ions compared to undoped ZnO.

Modeling the heating value of Municipal Solid Waste

The most common methods currently being practiced to evaluate the heating value of Municipal Solid Waste (MSW) are by using the equation derived by Dulong, or experimentally by using the bomb calorimeter. There have been numerous other mathematical equations, which were created based on data from the physical composition, proximate or elemental analysis of the MSW. Questions have been raised on the size of the samples used for the experiments and on the applicability of these equations in different parts of the globe. This study was initiated to tackle these problems and also to establish a mathematical model that could calculate the Higher Heating Value of Malaysian MSW. Results showed that the correlation from the physical composition gave the best correlation coefficient when compared to the other correlation created based on the proximate or elemental analysis results. The new equations were also tested against other established equations and produced better results in all the different categories.

The availability of daylight from tropical skies-a case study of Malaysia

In Malaysia, no long-term daylight data are measured. It was only recently that the need to measure the availability of daylight became urgent when the importance of daylighting in buildings was rediscovered. The hourly daylight availability has been simulated for the Malaysian sky using daylight modelling techniques based on empirical and measured solar irradiation and cloud cover data. This paper presents the techniques involved in producing exterior illuminance data. These data were then compared with measured illuminance at Shah Alam and Bangi, Malaysia. The global illuminance levels are generally high, with values exceeding 80,000 lux at noon during the months when solar irradiation is highest. Even during the months when the ground receives less solar irradiation, the peak illuminance can reach 60,000 lux. Applications and uses of such data are in daylighting design, both for visual and thermal comfort, task illuminance and energy-conscious design of buildings. Recommendations are made at the end of the paper on the various climatic data that are required to be measured for overall daylighting design applications.

The wind energy potential of Malaysia

Wind data collected at ten stations in Malaysia were analysed for wind energy potential. The data were collected over a ten-year period (1982–1991). The results were presented as a Weibull distribution and analysis indicated that the station at Mersing has the greatest potential, with a mean power density of 85.61 W/m2 at 10 m above sea level.

Daylighting as a passive solar design strategy in tropical buildings: A case study of Malaysia

The use of daylighting in buildings and architecture is not new. Natural lighting became out of vogue due to the availability of cheap electricity, the predictability and the ability to control illumination levels due to artificial lighting. However, the alarm over rapid depletion of energy resources and the environmental effects of their applications have led designers to reuse daylighting strategies in buildings in order to minimise energy use for lighting and air conditioning as a result of heat gains from the daylight sources and the electrical fixtures. This paper describes a study on the savings achieved by using daylight in passive solar design of buildings and, in this case, the size of windows. Simulated exterior illuminance levels based on long term measured solar irradiation and cloud cover data were used to estimate interior illumination on normal working planes using simple building configurations. Illumination on these planes decreases the need for artificial lighting, thus energy can be saved. A simple algorithm was then used to calculate the overall cooling load to ascertain that the daylighting strategies used do not invoke an increase in thermal gains through walls and glazings. The findings from this study show that at least 10% savings can be produced from simple daylighting strategies.

Modeling of Daily Solar Energy on a Horizontal Surface for Five Main Sites in Malaysia

This paper presents models for global and diffuse solar energy on a horizontal surface for main five sites in Malaysia. The global solar energy is modeled using linear, nonlinear, fuzzy logic, and artificial neural network (ANN) models, while the diffuse solar energy is modeled using linear, nonlinear, and ANN models. Three statistical values are used to evaluate the developed solar energy models, namely, the mean absolute percentage error, MAPE; root mean square error, RMSE; and mean bias error, MBE. The results showed that the ANN models are superior compared with the other models in which the MAPE in calculating the global solar energy in Malaysia by the ANN model is 5.38%, while the MAPE for the linear, nonlinear, and fuzzy logic models are 8.13%, 6.93%, and 6.71%, respectively. The results for the diffuse solar energy showed that the MAPE of the ANN model is 1.53%, while the MAPE of the linear and nonlinear models are 4.35% and 3.74%, respectively. The accurate ANN models can therefore be used to predict solar energy in Malaysia and nearby regions.

Thermal performance of the double-pass solar collector with and without porous media

This paper presents the thermal performance of a double-pass solar collector with and without porous media in the second or lower channel of the collector. The experimental setup has been designed to study the thermal performance over a range of design and operating conditions. Several important relationships between the design and operating conditions have been obtained. These relationships effect the thermal performance of the double-pass solar collector. The relationships include the effect of changes in upper and lower channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature rises on the thermal efficiency of the double-pass solar collector have been studied. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal efficiency of the systems.

Estimates of monthly average daily global solar radiation in Malaysia

Estimates of the monthly average daily global radiation for eight locations in Malaysia has been made using hours of bright sunshine. The data from Bandar Baru Bangi was obtained from the Solar Energy Research Laboratory at the Department of Physics, Universiti Kebangsaan Malaysia while others were obtained from the Meteorological Department. The least square linear regression analysis was used for the eight cities to obtain the relationship between the monthly average daily global radiation and sunshine duration data. The Angstroms correlation obtained for the eight cities can be used for any solar energy application in Malaysia.