• Energy Research

This communication presents the experimental study of PCM based thermal management systems for space heating and cooling applications using energy and exergy analysis. Two different types of based thermal management system (TMS-I and TMS-II) using calcium chloride hexahydrate as the heat carrier has been designed, fabricated and studied for space heating and cooling applications at a typical climatic zone in India. In the first experimental arrangement the charging of PCM has been carried out with air conditioning system while discharging has been carried out using electric heater for both the thermal management systems. While in the second arrangement the charging of PCM has been carried out by solar energy and the discharging has been carried out by circulating the cooler ambient air during the night time. In the first experiment, TMS-I is found to be more effective than that of TMS-II while it was found to be reverse in the case of second experiment for both the charging and discharging processes not only for energetic but also for the exergetic performances.

Abstract Photovoltaic (PV) installations in desert areas such as Middle East, Africa, four-season countries and industrial areas suffers from loss in efficiency due to accumulation of dust, snowfall and airborne dirt (both organic and inorganic) from factories. The resultant soiling through dirt accumulation hinders the conversion of light into electricity, consequently degrading the PV performance. Hence, in order to maintain a steady performance, PV panels must be cleaned regularly. However, traditional manual cleaning of the panels is an energy and time consuming process. Moreover, manual cleaning can also create cracks on the PV panel surface due to harsh brushing which will further deteriorate PV performance. In addition, very small particles cannot be removed effectively by manual cleaning process. Therefore, researchers around the globe are promoting the self-cleaning methods, viz., electrostatic method, mechanical method and coating method for PV panel surface cleaning. In this article, attempt has been made to review the progress and achievements in all kinds of self-cleaning methods for PV panels with special focus on super hydrophobic coating based methods for self-cleaning. In this connection, future focus research areas such as development of mini robots and spray coating on self-cleaning have been pointed out.

This communication presents the comparative experimental study of solar cookers based on the exergy analysis. In this study two different types of solar cookers viz. paraboloid type and box type have been evaluated using exergy analysis. The experiments have been carried out with cookers filled with different volume of water viz. one and two liters along with the suitable quantity of rice. Data of temperatures and solar radiation have been measured for different food stuff on clear sky day of the month. It is found that the exergy efficiency increases as the volume of water increases, however, the exergy efficiency of paraboloid solar cooker is found to be higher than that of the box-type solar cooker for all the cases mentioned above. However, it is also found that the exergy efficiency vary with the cooking stuff and water which is due to the fact that the requirement of heating vary with the food stuff.

Abstract In recent years the visible impact of the release from wet cooling tower to the atmosphere has become a matter of greater concern. In the past visible plumes were accepted as the inevitable consequence of industrial activities and a sign of thriving manufacturing industry. Plumes from combustion plant may be visible and colored for a variety of reasons. Some are associated with the combustion process itself, such as excessive quantities of nitrogen dioxide causing a brown tinge to plumes or the release of small particles, and/or aerosols, in the plume which scatter light. These factors can be tackled by modification of the combustion process and the introduction of emission control technology. However, the most common cause of plume visibility, and the reason that chimneys attract public attention, is the presence of condensed water vapor in plumes. In this paper attempt has been made to present an overview of the previous research work on the plume from wet cooling towers, which describes the previous work done of few researchers on the formation, potential and abatement of plumes besides, the numerical analysis of wet cooling towers for a typical set of operating parameters.

Abstract Dry anaerobic digestion (DAD) is an attractive method for the stabilization of solid organic waste with high solid concentration (22–40%). This article provides different aspects for bio-energy production through dry anaerobic digestion suggested by different researchers. Basic fundamental aspects like reactions occurring in the process, microbial species involved in the process, effect of feedstocks and operational parameters like pH, temperature, C/N ratio, VFA concentration, etc. with types of reactors are summarized. A number of scenarios and the effect of changing individual parameters of the environmental impacts of dry anaerobic digestion process for biogas production are considered. Mobility of mass nutrient and energy flow in the above said process are also parts of this review article. We conclude that long term research and development for improvement and optimization of operational parameters in dry anaerobic digestion is necessary.

The integration of photovoltaic (PV) system in power system proved to be potential technology in terms of renewable energy sources. However, photovoltaic system has major drawback of rise in cell temperature, which results in low power production and reduced service life. To overcome the temperature rise in photovoltaic system, the addition of water cooling and phase change materials installed at rear side PV system termed as photovoltaic thermal (PVT) system has been adopted in this study. The organic phase change material (RT-42) having melting temperature of 42 ℃ and water cooling running at 0.45 litre per minute (LPM) under 440 W/m2 irradiation has been taken as input parameters. The photovoltaic system and water cooled photovoltaic system performance has been analysed by using real time solar simulator. Additionally, the PVT-PCM system is assessed by use of TRNSYS simulation. Finally, this study compares the thermal and electrical efficiency of PV, PVT, and PVT-PCM systems. The findings indicated that maximum temperature for PV cells in a PV system was 59 ℃. Water cooling alone reduces the temperature down to 49 ℃, whereas water cooling combined with phase change material (PVT-PCM) lowers it down to 36℃. Further, the heat gain of 189 watt and 191 watt was achieved for PVT and PVT-PCM system. Additionally, the PV, PVT, and PVT-PCM systems achieved electrical efficiencies of 6.1%, 7%, and 9.5%, correspondingly.

Abstract Photovoltaic (PV) systems operate in a paradox; sunlight is the essential input to generate electricity with PV, but they suffer a digression in performance as the operating temperature goes higher. This work is a comprehensive compilation and review of the latest literature regarding research works rendered to achieve improved efficiency through appropriate cooling systems. Most of the research goals were twofold, that is to enhance the efficiency of the solar PV systems and to ensure a longer life at the same time. The passive cooling systems are found to achieve a reduction in PV module temperature in the range of 6–20 °C with an improvement in electrical efficiency up to 15.5% maximum. On the other side, active cooling systems’ performance are better, as may expected, with a reduction in PV module temperature as high as 30 °C with an improvement in electrical efficiency up to 22% maximum along with additional thermal energy output with efficiency reaching as high as 60%. Based on the wide-ranging review, it may be predicted that with the swelling growth of solar PV electricity worldwide, the compatible cooling system is becoming obligatory in order to ensure better energy harvest and utilization.