Applied Mechanics and Materials Vol. 787

Abstract: We demonstrated the construction and performance of dye-sensitized solar cells (DSCs) based on nanoparticles of TiO₂ coated with thin shells of MgO by simple solution growth technique. The XRD patterns confirm the presence of both TiO₂ and MgO in the core-shell structure. The effect of varied shell thickness on the photovoltaic performance of the core-shell structured electrode is also investigated. We found that MgO shells of all thicknesses perform as barriers that improve open-circuit voltage (Voc) of the DSCs only at the expense of a larger decrease in short-circuit current density (Jsc). The energy conversion efficiency was greatly dependent on the thickness of MgO on TiO₂ film, and the highest efficiency of 4.1% was achieved at the optimum MgO shell layer.

Abstract: RETRACTED PAPER: Energy conversion from ocean waves has become the need of the hour in view of the renewable energy awakening occurring all over the world. Energy conversion by Oscillating Water Column (OWC) concept has become an established technology in converting mechanical energy of ocean waves to electrical energy. But the limitations of OWC concept calls for further research and developments to make the technology commercially an attractive one. In this context Boccotti, the Italian scientist advanced the double chamber concept and the implications of the concept still remains to be investigated through model studies. This paper presents the details of a generic study carried out in a physical model device under regular waves.

Abstract: In natural circulation solar water heating, the efficiency of energy storage and solar collector can be improved if the water tank is stratified. Employing Phase Change Material (PCM) in the top of the tank will improve the stratification of the energy storage tank. Current paper studies the use of circular fins around PCM geometry with high surface to volume ratio to improve the efficiency of solar water heater. Heating and cooling tests have been performed in a domestic water heater with flat plate collector under real working conditions. Eventually the temperature distribution along the height of the storage tank, charging energy efficiency, collector efficiency have been calculated and compared. Tests have been simulated in CFD software for validating results. Addition of circular fins around PCM produces up to 5% and 36.48% improvement in tank charging energy efficiency, collector efficiency respectively because of improved heat transfer between PCM and water.

Abstract: Recycling of Printed Circuit Boards (PCB) has been carried out by powdering it into granular size of less than 10 microns. The properties of PCB reveal that it possesses density of 1.3 g/cm³ and Tensile Strength of 310 MPa which is comparatively high when compared to the Polycarbonate material which is normally used in the fabrication of Riot shield. The PCB material was subjected to SEM and EDAX analysis for determining their structure, porosity and material composition. Riot shield fabricated from PCB reduces the environmental effects of E-waste PCBs by the recycling technique, improves the material strength and reduces the weight and cost to a larger extent.

Abstract: A single-slope solar still with the basin area of 1m x1m and slope of 13^○ was fabricated and tested in Anna University, Chennai. Both the inner and outer walls were coated with black paint in order to improve the heat transfer rate. The bottom and side losses of the still are considerably reduced, due to the porous material beneath the basin liner. Effect of solar pond coupled with the still are experimentally investigated on a clear, partially cloudy and cloudy days and found that clear day has the maximum productivity. A model economic analysis calculation for single basin solar still coupled with pond is also done and the results are reported in this paper.

Abstract: In the present work the thermal performance of Phase Change Material (PCM) based solar thermal energy storage system under the influence of different heat transfer fluids (HTF) have been investigated. Water, Ethylene Glycol–water and Copper nanofluid are selected as HTF. Paraffin is used as PCM and encapsulated in cylindrical capsules. The thermal energy storage (TES) tank acts as a storage unit consisting PCM capsules packed in three beds surrounded by water, which acts as sensible heat storage (SHS) material. HTF circulated by a pump transfers heat from solar flat plate collector (FPC) to the TES tank. 25% ethylene glycol -75% water HTF is prepared by mixing ethylene glycol (EG) with water. Copper-distilled water nanofluids (0.3% by weight) are prepared using prolonged sonication with sodium dodecyl benzene sulphonate (SDBS) as the surfactant. Various performance parameters such as charging time, instantaneous heat stored, cumulative heat stored and system efficiency are studied for various HTFs. It is found that the charging time is reduced by 33.3% for copper nanofluid and 22.2% for ethylene glycol- water mixture HTFs. It is also observed that there is an increase in system efficiency and cumulative heat stored with reference to charging time for these HTFs when compared with conventional HTF 1 i.e. water.

Abstract: Many research studies have been carried out to develop small capacity absorption cooling systems as an alternative to conventional vapour compression refrigeration (VCR) systems with respect to performance and economic aspects. The aim of this work is to design a solar assisted single effect absorption cooling system of 5.25 kW cooling capacity to cool a room having floor area of 15 m². Based on the design, an experimental setup is constructed and operated by supplying heat to the generator using solar energy. The performance analysis of the cooling system is carried out by measuring the various operational parameters. The minimum cooling temperature of 16^°C is observed in the evaporator and maximum COP of 0.9 is obtained when the hot water storage tank reaches 90^°C. As per this new design, the operational cost is minimized and the COP obtained is slightly higher when compared to that of earlier similar works.

Abstract: Thermal Energy Storage (TES) has become extremely important in the recent years since it balances the energy demand and improves the efficiency of the solar systems. It is important that the thermal energy storage systems have the necessary characteristics to improve the performance of the storage. Usage of Phase Change Materials (PCM) for energy storage provides a great benefit but, their low thermal conductivity becomes a major drawback. This can be compensated with the use of phase change material in an appropriate design for successful functioning of the system. This review article summarizes the recent designs of thermal energy storage systems containing Phase Change Material that have been adopted for efficient energy storage.

Abstract: In most of the thermal analyses to develop a mathematical model for the conventional single slope passive solar still, it is found that heat capacity of the basin and glass cover are neglected to simplify the mathematical modeling. However all the materials have their own specific heat and according to the specific heat the material store some amount of heat energy within it. As a result the heat transfer between the system components of a solar still and thermal losses from the components will vary depending on their thermal properties like heat capacity, absorptance and thermal conductivity of components. Due to this, the temperature variation of the different components of a solar still is not only the function of solar intensity nevertheless also the function of their thermal properties. Subsequently it is necessary to consider the heat capacity of all the components of a conventional still. In this paper, mathematical modeling was developed to study the effect of heat capacity of basin material and glass cover on distillate yield of single slope passive solar still. The study found that considering the heat capacity of the components increase the distillate yield of the single slope passive solar still.