Search

This paper presents the results of study on the effect of dust fouling on the transmittance of PV module glass cover. The study included the effect of dust fouling on overall plane glass transmittance, spectral transmittance of anti-reflective coated glass and characterization of the physical and chemical properties of dust particles. Also, micro-adhesion forces of dust particles on flat glass substrates are included. The results indicated a 20% reduction in glass transmittance and a 5g/m² of dust accumulation on the glass cover of PV modules tilted at 26° (Lat of Dhahran) and exposed for 45days. The anti-reflective coated glass exhibited less reduction in transmittance compared to non-coated plane glass. The adhesion forces of particles on flat surfaces increased with increase in particle size due to increase in contact area between the particles and the surface. At high humidity level there is an increase in the vertical adhesion due to the generated capillary forces between dust particles and glass surface. [ABSTRACT FROM AUTHOR]

This technical note communicates the thermal performance of a modified ten-Ton Refrigerant Direct Expansion (10-TR DX) air conditioning unit into a chiller under actual operating conditions. The modified unit achieved higher COP and cooling capacity compared with conventional DX. The increase in the unit cooling capacity is basically attributed to the enhanced heat transfer coefficient of the Plate-and-Frame Heat Exchanger evaporator. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The main criteria to assess a new solar thermal power plant are its performance and cost. Therefore, there is a need to present to the open literature a detailed modeling procedure and cost analyses to help researchers, engineers, and decision makers. The main objectives of this work are to develop a code and to evaluate the optical and thermal efficiencies of parabolic trough collectors (PTCs) solar field considering average hourly, daily, monthly, or annually averaged weather data; in addition to detailed cost analysis of the solar field. In this regard, a computer simulation code was developed using Engineering Equations Solver (EES). This simulation code was validated against Thermoflex code and data previously published in the public literature, and excellent agreements ware observed. The types of the PTC considered in the simulation are EuroTrough solar collector (ET-100) and for LUZ solar collector LS-3. The present study revealed that the maximum optical efficiency that can be reached in Dhahran is 73.5%, whereas the minimum optical efficiency is 61%. This study showed also that the specific cost for a PTC field per unit aperture area and the specific cost of different mechanical works can be cut by about 46% and 48% at 10 hectare and by about 72% and 75% at 160 hectare, respectively, compared to that at 2.8 hectare. On the other hand, the specific civil costs remain constant independent of the plant size. It was found that the ratio of the cost of the PTC to the solar field area decreases significantly as the solar field size increases. This decrement is very significant until the solar field size reaches 60 hectare and then the slope of the decrement is becoming insignificant. Therefore, it is recommended to have a solar field size of 60 hectare or larger. [ABSTRACT FROM AUTHOR]