•The performance of evacuated tube collector with/without storage was investigated.•Evacuated tube collector with phase change material showed better performance.•Designed system is suitable for ...day/night time utilization of hot water.•Thermal cycle test of SA-67 has been studied for long term stability.
This manuscript presents an experimental investigation of heat pipe evacuated tube solar collector with and without phase change material for water heating application under the same weather conditions. In this study, a comparative analysis of two systems has been done in the same weather condition. Where evacuated tubes of the first system (evacuated tube collector-A) were left without phase change material and second system (evacuated tube collector-B) was integrated with SA-67 as phase change material. In order to ensure the thermal and chemical stability of the selected phase change material, thermal cycling treatment was carried out. The results showed that SA-67 has excellent chemical and thermal stability even after 1500 thermal cycling treatment.
In order to analyze the thermal performance of the designed systems, the experiment was conducted with five different water flow rates (8, 12, 16, 20 and 24 L per hour). The daily thermal efficiency of evacuated tube solar collector with and without phase change material was varied in the range of 42–55% and 79–87% respectively. Although, the daily energy efficiency of evacuated tube collector integrated with phase change material was 37.56%, 35.31%, 36.69%, 32.34%, and 32.73% higher than evacuated tube collector without phase change material for water flow rates of 8, 12, 16, 20 and 24 L per hour respectively. The daily thermal efficiency for both systems was maximum at the flow rate of 20 L per hour. The heat transfer parameters for the designed systems have also been evaluated and compared.
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Thermal efficiency of passive building designs can be improved using phase change materials (PCMs). This study was focused on the development and lab-scale thermoregulation performance of wood ...fiber(WF)/capric acid-stearic acid(CA-SA) eutectic mixture as low-cost and eco-friendly composite PCM for thermal energy storage (TES). The composite including 52 wt% PCM showed leak-proof property. The structural/morphological characteristics, TES properties, cycling TES reliability and chemical stability of the leak-proof CPCM were investigated by SEM, FT-IR, XRD, DSC, and TGA techniques. The lab-scale thermoregulation performance of CPCM board was also evaluated experimentally. The SEM results indicated that the eutectic PCM was successfully impregnated with WF as the spectral findings confirmed the good compatibility among its constituents. DSC results demonstrated that the CPCM had a melting temperature of 23.38 °C and latent heat of 92.1 J/g. TGA measurements revealed that the servicing temperature of the CPCM was much over than its thermal decomposition limit. It had stable TES properties and chemical structure after 600 melting-freezing cycles. Furthermore, lab-scale performance test exhibited that the temperature difference at the inside center of CPCM cubic cell and WF cubic cell was ascertained as averagely 2.67 °C during a 72 min-heating period and 1.18 °C during a 100 min-cooling period.
•The wood fiber/CA-SA(52 wt%) composite showed leak-proof property.•The leak-proof CPCM had a melting temperature of 23.38 °C and latent heat of 92.1 J/g.•The CPCM had stable chemical structure and TES properties after 600 thermal cycles.•The functioning temperature of the CPCM was much over than its thermal degradation temperature.•The CPCM board exhibited reasonable thermoregulation performance in lab-scale design.
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•Comprehensive review on heat transfer, device design and limitation of Concentrated Photovoltaic Thermal system.•Component wise thorough discussion on design and limitations of Concentrated ...Photovoltaic Thermal system.•Discussion on economic feasibility and recent novel applications of Concentrated Photovoltaic Thermal system.•Presents recent trends and move in Concentrated Photovoltaic Thermal system research.
The need of the hour in present world scenario is to reduce the emission of greenhouse gases and environmental pollution whilst satisfying the world energy demands. The most promising and readily available source of energy over the whole world is solar energy. One of the ways of taping this energy into useful energy is using Concentrated Photovoltaic Thermal systems. The paper presents the advanced comprehensive review on the design components of Concentrated Photovoltaic Thermal, heat transfer medium, recent application area such as Tissue Dyeing, domestic hot water, Organic Rankine Cycle, and the economic aspect of the Concentrated Photovoltaic Thermal system. Furthermore, the review paper simplifies the classification into two systems namely thermally coupled and thermally decoupled systems. Concentrated Photovoltaic Thermal shows potential to deliver better gains compared to Concentrated Photovoltaic, Photovoltaic and Photovoltaic Thermal. But matching the different components like the heat transfer component and the medium for specific use is an area that requires research. Therefore, this review concentrates more on the advantages and limitations of using different heat transfer components and heat transfer medium. The benefits of this paper would be the understanding of the components of the heat transport system like fins, microchannel, storage tank and underground heat exchangers and the fluid used in the Concentrated Photovoltaic Thermal integrated system like water, air, nanofluids, Phase Change Materials. It is found that the heat transfer device performance is limited due to its large area, thermal losses, mirror effect on the thermal and electrical efficiencies, and the temperature difference between the sink and device. Likewise, the performance of the heat transfer fluid is dependent on the mass flow rate, thermal mass, viscosity, density, time and the required temperature. Finally, for economic feasibility of the Concentrated Photovoltaic Thermal system requires the need for a grid connected system with properly sized system with feed-in-tariff and carbon incentives. Furthermore, the recommendation for heat transfer device, medium and economic aspect is also presented. However, more experimental research is required to further understand the compatibility of each components with Concentrating Photovoltaic Thermal System as presented in way forward.
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•Review of organic phase change materials for thermal energy storage.•Review of the eutectic mixtures of organic PCMs.•Review of the techniques of PCM encapsulations and enhancing the thermal ...conductivity.•Applications of low and medium temperature organic PCMs are listed in detail.•Recommendations are made for future applications of organic PCMs.
Thermal energy storage as sensible or latent heat is an efficient way to conserve the waste heat and excess energy available such as solar radiation. Storage of latent heat using organic phase change materials (PCMs) offers greater energy storage density over a marginal melting and freezing temperature difference in comparison to inorganic materials. These favorable characteristics of organic PCMs make them suitable in a wide range of applications. These materials and their eutectic mixtures have been successfully tested and implemented in many domestic and commercial applications such as, building, electronic devices, refrigeration and air-conditioning, solar air/water heating, textiles, automobiles, food, and space industries.
This review focuses on three aspects: the materials, encapsulation and applications of organic PCMs, and provides an insight on the recent developments in applications of these materials. Organic PCMs have inherent characteristic of low thermal conductivity (0.15–0.35W/mK), hence, a larger surface area is required to enhance the heat transfer rate. Therefore, attention is also given to the thermal conductivity enhancement of the materials, which helps to keep the area of the system to a minimum. Besides, various available techniques for material characterization have also been discussed. It has been found that a wide range of the applications of organic PCMs in buildings and other low and medium temperature solar energy applications are in abundant use but these materials are not yet popular among space applications and virtual data storage media. In addition, it has also been observed that because of the low melting point of organic PCMs, they have not yet been explored for high temperature applications such as in power plants.
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This communication presents a comprehensive review on the solar photovoltaic (SPV) systems for recent advances and their emerging applications in the present and future scenario. Besides, the ...performance study of off grid and grid connected SPV power plant has been discussed and presented in detail. From the literature, it is found that the efficiency of photovoltaic (PV) systems varies from 10% to 23%. Thus, the efficiency is the important factor which needs to be explored further for the best implementation and utilization of this emerging and useful technology around the globe. However, among all the applications discussed here, Building integrated photovoltaics (BIPV), Concentrated photovoltaics (CPV) and photovoltaic thermal (PV/T) are found to be the most technically sound and exhibit that SPV may be a feasible solution for the future energy challenges. Again, the building integrated PV system not only reduces the area requirement, but also cuts the material and infrastructure costs of the building and hence, fulfills the technical thrust for smart building requirements. Recently developed CPV cells are found to be feasible, most promising and cost effective technology having higher efficiency and lesser material requirements than those of the other solar cells. On the other hand, as the PV/T systems produce not only the electricity but also the heat energy are found to be more useful, suitable, and promising for most of the real life applications especially, where both forms of energy are required simultaneously.
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The excessively available solar energy storage is a very useful way to bridge the energy demand and its supply gap. This thermal energy storage (TES) can be done in the form of sensible or latent ...heat energy. The energy storage in the form of latent heat energy is better than the sensible energy storage in terms of operating temperature and storage density. Organic PCMs (O-PCMs) have great potential, especially from low to medium temperature-TES applications due to their several admirable thermal and physical characteristics. An appropriate melting point/enthalpy of O-PCMs is mainly required parameters for TES applications. In this regard, development of eutectic O-PCMs (EO-PCMs) by mixing two or more PCMs customizes the melting temperature and enthalpy so that they can be made suitable for targeted TES applications. However, their low thermal conductivity and leakage issue during the phase transition significantly restrict the practices of EO-PCM. A lot of studies were carried out to solve these changes by preparing them in form stable or shape-stabilized composite form. This review paper provides an insight on the development and thermo-physical properties of eutectic (binary and ternary) EO-PCMs as well as their composites as nano-enhanced and form stable phase change materials (FSPCMs). This paper also highlights recent studies published about the enhancement of thermal conductivity of EO-PCMs and their FSPCMs developed for LHTES practices. The use of EO-PCMs and their form stable composites in various applications, and challenges faced are also discussed. Finally, it outlooks the future directions for development of eutectic organic PCMs and their applications.
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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.
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The solar thermal power plant is one of the promising renewable energy options to substitute the increasing demand of conventional energy. The cost per kW of solar power is higher and the overall ...efficiency of the system is lower. In the present communication, a comprehensive literature review on the scenario of solar thermal power plants and its up-to-date technologies all over the world is presented. Results of the technical and economical feasibility studies by researchers are reported in brief for further reference. It is observed that the solar thermal power plants have come out of the experimental stage to commercial applications. Case studies of typical 50MW solar thermal power plants in the Indian climatic conditions at locations such as Jodhpur and Delhi is highlighted with the help of techno-economic model. Different solar concentrator technologies (parabolic trough, parabolic dish and central power tower) for solar thermal power plants are compared economically. It has been found that the parabolic dish concentrating solar Stirling engine power plant generate electricity at a lower unit cost than the other two solar technologies considering 30 years lifespan and 10% interest rate on investment.
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► Calcium chloride hexahydrate (CaCl2⋅6H2O) as a PCM was used in this study. ► Two different capsulated system (HDPE based panel and balls) were designed. ► The results of CaCl2⋅6H2O are very ...attractive for space air conditioning. ► Energy and exergy analyses for space cooling applications.
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.
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•Low-cost bioflocculant based algal biomass harvesting.•Effect of different concentrations of bioflocculant on algal biomass.•Effect of temperature with optimized concentration on harvesting ...efficiency.•Kinetics and thermodynamic functions to support the experimental data.
In this study, harvesting efficiency (HE) of bioflocculant (egg shell) was observed with variation in flocculent concentrations (0–100mgL−1), temperature (30°C, 35°C 40°C, 45°C and 50°C) and variable contact time (0–50min). It was found maximum (≈95.6%) with 100mgL−1 bioflocculant concentration whereas influence of temperature was also observed with optimized concentration of bioflocculant (100mgL−1) at 40°C (≈98.1%) and 50°C (≈99.3%), in 30min of contact time. Significant changes in algal cell structures were also analyzed after exposure to various temperatures with microscopy, SEM (Scanning electron microscopy) and EDS (Energy dispersive X-ray spectroscopy) images with and without bioflocculant. The experimental data was found to be a good fit with pseudo-second order kinetic model. The thermodynamic functions such as ΔG (Gibbs free energy), ΔH (enthalpy), ΔS (entropy) were also determined. The negative value of ΔG and positive value of ΔH and ΔS shows the spontaneous and endothermic nature of flocculation process.
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