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Due to the intermittent nature of solar energy, researchers and scientists are working to develop thermal energy storage (TES) systems for effective utilization of solar energy. Phase change materials (PCMs) are considered to be promising materials for TES. In this study, organic paraffin RT50 and graphene silver (Gr:Ag) nanopowder are adopted as TES material and thermal property enhancers. Microstructure and morphological behavior as well as chemical, optical, and thermal stability of the prepared composite PCM are visually investigated using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, thermal conductivity analyzer, differential scanning calorimeter (DSC). and thermogravimetric analyzer (TGA). Furthermore, based on the outstanding thermal performance of the composite, an extended investigation on the thermal and chemical properties are evaluated for 500 thermal cycles to ensure their reliability. Results show the thermal conductivity of RT50 improved by 53.85% when Gr:Ag nanopowder is dispersed at a weight percent of 0.8 (RT50-0.8Gr:Ag). The change in latent heat value of the composite sample is less than 3%, which is significant for effective thermal energy storage. The thermal decomposition of RT50 is slightly improved from 300 °C to 330 °C. To ensure a reliable and passive technique for thermal energy storage within solar thermal application devices, such as solar air heaters and solar photovoltaic thermal systems, using nanoparticle enhanced PCMs at the range of a 50 °C melting point are a current research hotspot.

Dispersion of conducting polymer-based nanocomposite in Phase Change Materials (PCMs) tends to enhance the thermophysical properties. Present work aims to synthesize and disperse conducting polyaniline@cobalt nanocomposite within the Paraffin matrix to improve the thermo-physical property. Polyaniline based nanocomposites with 1.0 and 2.0 wt% cobalt (PC1 and PC2) were sonicated with paraffin at different weight ratio of 0.1%, 0.5%, 1%, and 5% and characterization of nanocomposite dispersed phase change material was performed. Thermo-physical properties were analysed by using thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). Thermal conductivity of nanocomposite enhanced paraffin increased with increase in weight% of both PC1 and PC2 till 1% of its weight in paraffin and decreased for 5% of PC1 and PC2 concentration with paraffin. TGA readings observed drop in initial decomposition temperature of PPC1-5% (Paraffin with PC1 in 5% concentration) and PPC2-5% (Paraffin with PC2 in 5% concentration) by an amount of 08% and 12.4% respectively compared with base PCM Paraffin wax. DSC results of PPC1-0.1% and PPC2-0.5% showed 182.04 J/g and 170.86 J/g latent heat of fusion as compared to Paraffin wax. The samples were tested for 200 thermal cycles and the chemical stability and thermal property were compared with the fresh samples.

Coal based thermal power plant expels pollutants consisting hazardous gases that result in to degradation of ecosystem. On the contrary, gasification technologies offer the potential for clean and efficient energy. At optimum gasifier pressure of 2 bar and steam–fuel ratio of 0.25, mole fraction of synthesis gas is analysed for increasing gas–fuel ratio of 0.25, 0.5, 0.75 and 1.0. With increasing gas–fuel ratio from 0.25 to 1.0, the mole fraction of components of synthesis gas does not vary, whereas the heating value and cold-gas efficiency of synthesis gas produced decreases. Considering the emissions, simulated results present co-gasification as better option over conventional systems. Reduction of two-third in kg of CO2 released per kg of fuel was observed with almost three-fourth decrement in kg of CO2 per kWh of power produced. Also, zero SOx and NOx emissions were observed compared to coal based thermal power plants. Simulation of the gasification cycle with varying parameters is carried out using Matrix Laboratory (MATLAB).

Electricity has become a most important parameter for developing countries to improve their growth rate. On an average in India power generation is contributed using coal as fuel up to 75.9%. Higher the calorific value, higher would be the heat liberated from the coal, thus resulting in higher steam generation, which would contribute to increase in power generation. In this article experimental attempt has been made to study the performance of coal used in Indian thermal power plant in terms of calorific value and ash content. Coal used in Chandrapur super thermal power station was blended with charcoal of Prosopis Juliflora in proportion of 100, 80, 60, 40 and 20 percentage. Preparation of coal was also differentiate by crushing the coal manually and using ball miller. Result shows that blending coal with charcoal of Prosopis Juliflora showed increase in calorific value and decrease in ash content.

Air compressors are originating an extensive variety of situations for many processing industries, manufacturing industries and power sector. According to the energy conservation and management point of view the compressor is the main device which attracts the observation of energy engineers in many industries. For analysing the performance of the air compressor it is mandatory to measure the working parameters such as pressure, temperature, mass flow rate of air, motor speed and power. Since the measurement and instrumentation is playing a vital influence on the performance of air compressor. Therefore investigating the error on instrumentation and its influence on performance of air compressor is compulsory to regulate the eminence of experimental set-up. And these error factors will designate the effect of the uncertainty cause on the performance of air compressor. In this research work, a numerical study on uncertainty analysis were done in a double stage reciprocating air compressor with inter cooler setup which is located in sathyamangalam, Tamilnadu, India. The mandatory output for numerous applications were considered and taken for this numerical analysis of double stage reciprocating air compressor with inter cooler as per the local ambient conditions. The pressure ratio is varied from 3 to 7 in the selected experimental setup for the fixed mass flow rate in a double stage reciprocating air compressor with inter cooler. For the corresponding pressure ratios the uncertainty on the performance of air compressor based on the first law and second law analysis were mathematically modelled. Based on the model the uncertainty on the performance of compressor were found for the error of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2% in all the instruments and it was discussed in the result.

In all these days, most of the manufacturing industries are in the urge to produce the components on-time with the appreciable quality due to the increased competitiveness in the global market. Most of the industries follow any one of the three types of the manufacturing process such the way to produce the core product. The traditional way of manufacturing the product in the manufacturing system with the lead time can be optimized by the implication of some constraints in the system. The implication of these constraints in the system converts the traditional way of manufacturing into a flexible manufacturing system. The requirement of flexibility in the manufacturing system and in the demand to manufacture the product on time with the appreciable quality of the product in the global competitiveness, industry moves into set production of the products. Set production of the product in the manufacturing process reduces the lead time in the process flow period. The efficiency of machine utilization in the Takt period of the product requires the manufacturing process to reduce the lead time. The objective of this study is to track down the time for the lot quantity of the product to standard time in order to reduce the bottlenecks in the inventory. It also focuses on the techniques of decision making, dedication to the resources such as the product to be manufactured and also the tools required for manufacturing the product. Trailed by the various techniques used for clustering and grouping to convert the manufacturing system into flexible one this study has been made.

Nowadays compressors are playing a major role in many processing industries, manufacturing industries and power sector. At many cases, the compressors are the ultimate comprehensive one on energy consumption in industries. The major grievance of the compression process is heating effect of air compression process which leads to ineffective compression and constant air supply. Many researchers are showing interest to increase the performance of air compressors. Optimizing the suitable designs, working parameters and fluid properties are the three main ways for improving the performance of air compressors. Energy and second law efficiency analysis are the necessary one to recognize the important of energy consumption and conservation. For analysing the performance of the air compressor it is mandatory to measure the working parameters such as pressure, temperature, mass flow rate of air, speed of the compressor and electrical input power. Since the measurementation and instrumentation is playing a vital influence on the performance of air compressor. Therefore investigating the error on instrumentation and its influence on performance of air compressor is compulsory to regulate the eminence of experimental set-up. And these error factors will designate the effect of the uncertainty cause on the performance of air compressor. Uncertainties are significant in all experimental dealings and must be measured throughout the various points of an experimental analysis. In this research work, a study on energy, second law uncertainty efficiency and analysis were done in a double stage reciprocating air compressor with inter cooler setup which is located in Sathyamangalam, Tamilnadu, India. Based on the local ambient conditions and required output for various applications were taken for this performance analysis of double stage reciprocating air compressor with inter cooler. The discharge pressure from the double stage compression is varied from 3 bar to 7 bar. For the corresponding output pressure, first law and second law efficiency of the system was calculated. For the fixed mass flow rate of air the calculated first law efficiency of the system varies from 38% to 64% and second law efficiency of the system varies from 57% to 67%. For the corresponding pressure ratios the uncertainty on the performance of air compressor based on the first law and second law analysis were mathematically modelled. Based on the model the uncertainty on the performance of compressor were found for the error of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2% in all the instruments and it was discussed in the result.

PV panel or Photovoltaic panels are semi-conducting materials to convert solar energy into electrical energy. According to the Standard Test Conditions, the best operating condition of the PV panel is at 25 °C. For countries like Saudi Arabia, Libya, Yemen and much other have atmospheric temperature of about 40 °C. At this temperature, the performance of the PV panel degrades. In this current paper a heat exchanger is designed numerically in exact dimensions to carry out thermal cooling of the PV panels, with motive to improve the performance of PV panels even at elevated temperatures. Aluminium pipe of 50 m long, 10 cm internal diameter with 40 fins/m length is selected for designing. This increases the efficiency of the panel and the convective heat transfer rate with lower pressure drop.

Vapour Compression Refrigeration (VCR) system with high COP, low input power consumption and minimal exergy losses are of great research hotspot. The current research focuses on analysis of exergy and performance of vapour compression refrigeration (VCR) cycle is in a real-world application. Experiments were carried out in the VCR system using round tube condenser and microchannel condenser along with different refrigerants R134a, and R1234yf. Temperatures were varied from +20°C to 5°C for the evaporator and 40°C to 50°C for the condenser. Among the two refrigerants, experimental results show that refrigerants operating in micro-channel condensers have COP of 6% and 4%greater higher with5% and 3% lower exergy loss compared to the round tube condenser for R134a and R1234yf respectively.R1234yf appears to be a better equivalent for R134a, according to the findings. The efficiency defect in the condenser is the greatest and least in the evaporator for the coolants examined.

Demand and conservation for potable water has become a foremost concern world-wide. Many technologies were adapted for converting the saline water to potable water to meet the required demand on water conservation. In the current research work triangular solar still with rectangular-fins attached to the basin is proposed to enhance the output of potable water from the solar still setup. Solar still with and without rectangular-fins on the basin are fabricated for experimental comparison and evaluation in addition to numerical investigations. Thermal Performance, instantaneous efficiency and potable water output of the proposed solar still & base solar still are investigated during March month for the location of Sathyamangalam. Investigation shows enhancement of water production in the proposed solar still by 41% higher compared to the base still. The maximum distillate output from modified still and base still for a typical day is 3.1 liter and 2.2 liter respectively.

Rapid growth in industrialization has led to high dependency of reliable electric power source for its operation. On the contrary, thermal power plants expel pollutants consisting of hazardous gases that result in degradation of environment and ecosystem. Thus, utmost importance is to generate clean and efficient energy from power plant. This current article resolves the problem of sustainable power production using coal-based thermal power plants, by integrating gasification technologies to the system. The performance of thermal power plant in terms of emission is numerically analyzed with varying gasifier pressure, air-fuel ratio, steam-fuel ratio and flue gas-fuel ratio. Numerical simulation of the gasification cycle with varying parameters is carried out using MATLAB. Optimum performance at gasifier pressure of 2 bar and the steam-fuel ratio of 0.25 was observed with relative air-fuel of 0.075. With increasing flue gas-fuel ratio from 0.25 to 1.00, although the mole fractions of components of syngas don’t differ much, the heating value and cold-gas efficiency of syngas produced decreases for each fuel. Considering the emissions, simulated results present co-gasification as better option over conventional systems. A reduction of two-third in kg of CO2 released per kg of fuel was observed with almost three-fourth decrement in kg of CO2 per kWh of power produced. Also, zero SOx and NOx emissions were observed compared to coal based thermal power plants. It is noted that optimum performance of gasification system at gasifier pressure of 2 bar, air-fuel ratio of 0.1, steam-fuel ratio of 0.25 and flue gas-fuel ratio of 1.00. The proposed cycle presents itself suitable for further research and its application to coal based thermal power plants, providing potential towards supplementary power generation and cleaner exhaust. This research would also significantly contribute to achieve sustainable development goals.

Sustainable development goals not only contributes towards a clean environment but also towards better climatic conditions. Within Asia next to China and India, the Association of Southeast Asian Nations (ASEAN) are the actively developing countries in terms of economy and technologies. On the verge of achieving development, the ASEAN countries highly depend on fossil fuels for their energy needs. The ASEAN countries have taken visionary steps towards increasing the renewable energy mix with the conventional grid without hampering the ongoing development; this study presents the solar energy utilization policies, potential, progresses, and challenges adopted in ASEAN countries; furthermore, in these nations there is a huge potential of solar energy being located near the equator, therefore, they should focus on both solar to electrical and solar to thermal energy applications; however, in order to meet the peak demand and ensure the reliability of renewable energy like solar power, the development of advanced energy storage systems could be the key areas, and concrete efforts are required. Therefore, this article is a spotlight on government policies and goals focusing on energy potential, major progress in terms of energy storage and challenges in implementation of renewable energy systems in ASEAN countries; furthermore the recommended highlights on policies to accelerate the exploitation of renewable energy usage among the people are also discussed in detail, besides, the insights on reduction of carbon footprints over the next decade through incorporation of advanced energy storage systems. The issues discussed in this article will be helpful for exploring the desired energy storage systems and energy policies to be followed, which will eventually attract the stakeholders for small and medium-scale entrepreneurs for the development of renewable energy business in the region, if implemented on the ground.

This article offers a trend of inventions and implementations of photocatalysis process, desalination technologies and solar disinfection techniques adapted particularly for treatment of industrial and domestic wastewater. Photocatalysis treatment of wastewater using solar energy is a promising renewable solution to reduce stresses on global water crisis. Rendering to the United Nation Environment Programme, 1/3 of world population live in water-stressed countries, while by 2025 about 2/3 of world population will face water scarcity. Major pollutants exhibited from numerous sources are critically discussed with focus on potential environmental impacts & hazards. Treatment of wastewater by photocatalysis technique, solar thermal electrochemical process, solar desalination of brackish water and solar advanced oxidation process have been presented and systematically analysed with challenges. Both heterogenous and homogenous photocatalysis techniques employed for wastewater treatment are critically reviewed. For treating domestic wastewater, solar desalination technologies adopted for purifying brackish water into potable water is presented along with key challenges and remedies. Advanced oxidation process using solar energy for degradation of organic pollutant is an important technique to be reviewed due to their effectiveness in wastewater treatment process. Present article focused on three key issues i.e. major pollutants, wastewater treatment techniques and environmental benefits of using solar power for removal of pollutants. The review also provides close ideas on further research needs and major concerns. Drawbacks associated with conventional wastewater treatment options and direct solar energy-based wastewater treatment with energy storage systems to make it convenient during day and night both listed. Although, energy storage systems increase the overall cost of the wastewater treatment plant it also increases the overall efficiency of the system on environmental cost. Cost-efficient wastewater treatment methods using solar power would significantly ensure effective water source utilization, thereby contributing towards sustainable development goals.

Battery Thermal Management System (BTMS) plays a significant role in determining the Electric vehicles (EVs) operating range and battery operating life cycle. Indeed, Phase Change Material (PCM) with outstanding characteristics like passive energy utilization to cool the battery, low cost, and effective operation seems to be an attractive option to be used for BTMS of EVs. However, opting for an exact PCM for the required application of the battery system depends completely on the thermal properties of PCM. Therefore, drawbacks and the advancement of PCM integrated BTMS compared to others should be scrutinized to have a comprehensive assessment on the PCM-integrated BTMS. The present review article majorly focuses on: i) - Advanced thermal properties of organic, inorganic, and eutectic PCM for integration with BTMS; ii) - Secondary assisted PCM cooling system for BTMS; iii) - Experimental development carried out with incorporation of composite PCM with BTMS; iv) - Economic comparative analysis on integrating PCM with EVs; v) - Critical analysis on environmental benefits of PCM based BTMS for EVs. In addition, the key outcomes of utilizing nanoparticle dispersed PCM into battery systems are highlighted. A separate section has been elaborated on the techniques used to overcome the drawbacks of thermal conductivity in PCMs. Finally, critical analysis and consolidation of experimentally hybridized and analyzed composite PCM for performance enhancement of batteries presented in the article would be a hot spot for future research work on EVs.

This paper explicitly deals with the role of thermal energy storage (TES) with respect to energy performance measures in buildings. Buildings constitute about 50% of the total energy consumption worldwide. Thus buildings are directly found to be one of the major perpetrators of the rapid depletion of fossil fuels and greenhouse emissions. This review paper consolidates the list of PCM's for energy efficient buildings along with the thermal properties. A broad spectrum on the role of thermal energy storage techniques i.e. advancements, applications and futuristic solutions with their specific nature and role is summarized in this article. A critical focus has been given to PCM composites, control strategies and PCM based Photo-voltaic Thermal (PV/T) systems which have emerged out as a promising and feasible future solution to be used in building material. The techno-economic aspects of thermal storage systems have been introduced to justify its potential role in mitigating emission challenges. The low off peak energy tariffs and payback periods are certainly found to be economical with thermal energy storage. PCMs are considered to be a potential material to act as thermal batteries for different building applications however, special care has to be considered for an initial investment.

Solar parabolic collectors exploit solar energy for both thermal and power generation applications. But, they demand long arrays of reflective concentrating surfaces with receiver tube throughout the length of axis of the concentrators. For one and half meter long parabolic trough with aluminium sheet as reflective surface, experimental analysis was done attempting to increase the energy transfer rate and reduce the length of arrays. Two absorber tubes were fabricated and distilled water was used as the working fluid in the tubes. The modified absorber tube with hinged blades delivered an average efficiency of 69.33% compared to 60.82% obtained for simple conventional absorber tube. Plots for performance results of the tubes with varying direct normal irradiance and mass flow rates were obtained. Slope and intercept values of 70.887 and -0.419 respectively were obtained for the collector equation of absorber tubes hinged blades compared to slope and intercept values of 61.571 and -0.401 respectively. The present work delivers better performance compared to earlier works Thus, the proposal present its scope for both domestic and industrial applications.

Sun is the most promising renewable resource available to mankind for extracting maximum useful energy. One of the best ways to trap solar energy is to install photovoltaic thermal (PVT) systems whose main novelty is to produce power by photovoltaic conversion and also dissipate the heat evolved to recover thermal energy thereby enhancing the overall efficiency of the system. Implementing this approach in practical application system lags mainly due to the requirement of economic investment. This paper reviews on the economics involved in the installation, operation and maintenance of solar PVT systems. The economic viability of solar PVT systems is evaluated by considering five criteria (energy costs, life cycle costs, profit ratio, cost savings and pay-back period). Furthermore the performances of many PVT systems were compared and the economic evaluation has proved that the PVT system is economically feasible and has greater potential for incorporating in residential/commercial buildings especially for tropical countries like India.

The paper provides a review on solar tracking system for solar cooker and its potential in increasing its efficiency. This paper mainly discusses the solar trackers for increasing the work output. This technique assists in increasing the amount of radiation falling on solar cookers. The types of solar tracking based on their degree of freedom are single axis solar tracking system and dual axis solar tracking system and its classification are discussed in this paper. The solar tracker types based on the actuating systems are also discussed. The tracking system suitable for the solar cooking applications is mentioned in this paper.

Solar thermal systems are playing important role to encounter environmental issues like global warming, in the last two decades they replace conventional systems to create an eco-friendly environment. Lot of research have been undergone on solar thermal systems to improve their performance and efficiency, but still the area is wide open for improvement because of demand on renewable sources increase. As their is need for increasing the performance of solar thermal systems, phase change materials could serve as energy storing device during abundant available of energy. For solar thermal systems the major challenge is energy availability will not be round the clock, in order to clear this hurdle phase change materials backing served as a better support. The biggest challenge of developing countries today is to provide clean drinking water, as there are many conventional systems to convert saline water into drinking water their main disadvantage is pollution of environment due to harmful emissions. Hence, solar thermal systems with phase change materials are considered as best option in production of clean drinking water due to their operation by renewable energy, compactness and zero emissions. Phase change materials are coupled with solar system experimentally, and their behaviour and performance were characterized with results and observation, here the phase change material paraffin wax is embedded in copper tubes coupled with solar system is employed in production of clean drinking water; their performance and efficiency are compared with single slope solar still without phase change material. The thermal stability, corrosive resistance and impressive properties of paraffin wax and thermal conductivity of copper were tied together to single slope solar still for improving performance and efficiency of clean drinking water production. It is observed solar still without phase change material could generate drinking water from saline water only during day time, but the solar still coupled with phase change material embedded in copper tubes showed better results with 11 percent increase in production of drinking water even during dark hours.

Increase in demand for drinking water due to growth in world population and industrialization has lead route for innovating new technologies for purifying sea water. Desalination by conventional energy source increases the emission of greenhouse gases and leads to global warming. As a solution for pollution and water scarcity, solar desalination techniques are incorporated worldwide for converting brackish water into portable water using solar power. Solar power helps water purification via solar thermal systems and also using solar photovoltaic panels which provide electric supply. This review article consolidate the solar thermal energy based small, medium and large scale solar desalination plants for extracting pure water. The environmental benefits and the futuristic challenges of utilizing solar thermal system for purification of water is also highlighted.

The moisture present in the farming yields and in seeds is one of the greatest affecting factors which are playing a major role in storing it for longer days. The quality of products can be increased by preventing the formation of bacteria, yeast, etc. The moisture content present in the groundnut must be between 10 to 15% (weight basis). In this study a numerical analysis was investigated on a solar dryer, which is used to diminish the moisture content present in the groundnut to preserve it for longer days. The performance analyses of forced convection solar dryer with dryer compartment were analysed based on local ambient conditions at sathyamangalam for various required design and operating parameters such as moisture removal rate, air mass flow rate, air inlet, and outlet temperature. The proposed basic solar collector aperture area is about 2 m2 which is made of the copper plate as an absorber plate coated with black powder coating for better absorption. The moisture content present in the freshly harvested groundnut varies from 25-30 % (weight basis). The analysis was done for drying groundnut to remove the moisture content to the required moisture level of 10% by utilizing solar energy. The results from the study illustrate that the Efficiency of dryer is a maximum of 39.2% for the optimized mass flow rate of 0.022 kg/s and also it was found that the dryer overall efficiency and average collector temperature is gradually decreasing for increasing the mass flow rate.

The major challenge in developing countries is to provide drinking water to the people, several techniques are employed but the challenge is to make cost effective and its sustainability over a period. Most of the developing countries work on saline water conversion to neat drinking water, distillation is one of the old and handy techniques in this conversion; where sunlight is used as energy drive for the process because elevating the temperature of saline water is enough for distillation and also for its free of cost availability. Solar still distilled water costs very less than the conventional method of deriving water from saline water and also people need not to worry about the purification of obtained water. Hence various analysis on increasing the performance of solar stills is required to increase the productivity to meet the rising demand for clean drinking water. The experimental work is carried out with three stepped solar stills, one without phase change material, one with paraffin wax as phase change material and other with calcium nitrate as phase change material. Solar stills are integrated with phase change materials to increase the productivity of clean drinking water by storing the solar energy in the form of latent heat to release in the dark hours for enabling solar sill distillation even during night time. There will be change in the total productivity based on the size of solar still, phase change material used, basin design and exergy efficiency, therefore these parameters have to optimized for better yield of neat drinking water from saline water. Experimentation was carried in the month of February and March of 2020 to estimate and compare the yield of three solar stills for the time period of 24 hours, certainly solar stills equipped with phase change materials resulted in higher total production than solar still without phase change material though their day time productivity was low. Solar still equipped with calcium nitrate as phase change material yielded 8.17 % more clean drinking water than the solar still equipped with paraffin as phase change material, though calcium nitrate is economical than paraffin wax but maintenance of solar still with calcium nitrate as phase change material is a hefty task.

Solar parabolic trough collectors are being widely used to exploit solar energy for both thermal and power generation applications. But, these systems require long arrays of reflective troughs with absorber tube running along the axis of parabolic dish. A successful attempt to reduce the length of arrays was accomplished by experimentally analysing the modifications done in absorber tube. Three out of four tubes were fabricated and they were employed to obtain the performance parameters through experimentation conducted at VIT University, Vellore, India. Distilled water was used as the working fluid. Maximum efficiency of 39.12% was acquired at 451.6 W/m 2 of direct normal irradiance (DNI)for absorber tube with internal pin-fins and without glass tube (AFWG t ) compared to 8.15% obtained at same value of DNI and other conditions for simple absorber tube without glass cover (AWG t ). Cylindrical parabolic trough available at the university was utilized, providing the basis for designing and fabrication of the tubes. Plots for varying mass flow rate at interval of 10 minutes were made against instantaneous thermal efficiency and heat utilized, for direct normal irradiance vs. temperature difference across the tubes and instantaneous thermal efficiency. Through the experimentation conducted, better performance was procured compared to earlier works. Thus, the proposal infers that absorber tube with internal fins has good scope for its application, both domestically as well as industrially. It also calls for further research and development of proposed techniques so as to achieve better performance curves.

Solar thermal systems (STSs) are gaining boom in the globalized market since last two decades to combat the menace of global warming. Considerable research has been carried out in the field of solar thermal system for efficiency enhancement. Improvement in terms of efficiency and performance would make solar thermal systems a better option for replacing the conventional energy systems. Phase change Materials (PCMs) have emerged as an alternative to enhance the performance of the solar heating systems by acting as thermal storage batteries. In this review article an attempt has been made to consolidate the global trends and practices that has been underwent incorporating Phase change materials (PCMs) in solar thermal systems. Research on PCM based solar cooker has found to be extinct. PCM based PCM based high temperature power plant applications are on current trends of research. Application of phase change materials for low, medium and high temperature solar thermal systems are comprehensively reviewed and discussed in this article. As well the environmental benefits in terms decline in CO2 emission, due to the use of STS in day-today life and the economic analysis of PCM based STS in terms of cost and payback period is presented.

Background/Objectives: The common assumption made in basic heat exchanger design is that the fluid to be distributed uniformly at the inlet of the exchanger on each fluid side and throughout the core. But in actual practice it doesn't happen. Thus the main objective of this paper is to reduce the non uniformity in the flow of fluid in compact heat exchanger form the header tube to the lateral tube. Methods/Statistical A nalysis: In this work, the flow mal-distribution of heat exchanger at different cross-sectional headers like circular, rectangular, square and triangular header with various flow rates ranging from Re 1000 to 20000 is analyzed. Numerical models and boundary conditions used in the analyses are validated against experimental data. Following the validated procedure, three-dimensional CFD analyses are carried out to study the effect of geometrical variation of headers on flow distribution. For each geometrical variation, analysis is continued till the trend of behavior of flow distribution is completely understood. The results are analyzed to reach the optimum configuration with each variation. Findings: For all the four types of header cross section and for various inlet mass flow rates, the triangular header produces more uniform distribution. With low pressure drop in triangular cross section, the velocity distribution is uniform. Because of uniform velocity distribution in the header the flow maldistribution is minimum in heat exchanger with triangular cross sectional header. Triangular header shows 77%, 45%, and 70% less flow maldistribution when compared to circular, square and rectangular headers respectively. Application/Improvements: Development in the field of renewable energy had made a great revolution in the usage of solar flat plate water heater in each and every home. Implement of this triangular shaped header cross in the core tube of flat plate collector, would increase the efficiency of solar flat plate water heater, which would ultimately improve its usage among the people.

Solar parabolic trough collectors exploit solar energy for power generation in solar thermal power stations. These systems require long arrays of reflective troughs with absorber tube running along the axis of parabolic dish. A successful attempt to reduce the length of arrays was accomplished by experimentally analysing the modifications done in absorber tube. Two out of three tubes were fabricated and they were employed to obtain the performance parameters through experimentation conducted at VIT University, Vellore, India. Distilled water was used as the working fluid. Maximum efficiency of 39.12% was obtained at 451.6 W/m 2 of direct normal irradiance (DNI) for absorber tube with internal pin-fins and without glass tube (AFWG t ) compared to 8.15% obtained at same value of DNI and other conditions for simple absorber tube without glass cover (AWG t ). Cylindrical parabolic trough available at the university was utilized, providing the basis for designing and fabrication of the tubes. Plots for varying mass flow rate at interval of 10 minutes were made against instantaneous thermal efficiency and heat utilized, for direct normal irradiance vs. temperature difference across the tubes and instantaneous thermal efficiency. Through the experimentation conducted, better performance was procured compared to earlier works. Thus, the proposal infers that absorber tube with internal fins has good scope for its application, both domestically as well as industrially. It also calls for further research and development of proposed techniques so as to achieve better performance curves.

An innovative work had been carried to increase the distillate yield of the solar still by replacing the single slope cover by means of parabolic cover. Advantage of pyramid top cover is that the amount of solar radiation entering the system in more when compared to other types of top cover. The top pyramid cover is made up of transparent acrylic sheet of 3 mm thickness of transmittance 88%. Pyramid top cover of diameter 0.75 m and height 0.30 m is designed for the still. It is designed by joining the two portions of the acrylic sheet.