Energy and exergy studies on the receiver models with materials and heat transfer fluids.

This work focuses on meeting the growing demand in solar energy conversion for small-scale applications. In this regard, experimental and CFD research has been done to examine the thermal performance (energy and exergy efficiencies) of a dish collector (reflector and receiver) system with different receiver models. In this work, receivers with uniform absorber cavity areas having cylindrical and hemispherical shapes were modeled for length-to-diameter ratios (L/D) of 1.5, 1, and 0.75. The modeled receivers having coil tube configurations concerning the geometrical shape of the models were tested with two different materials of aluminum and copper. The performance of the receiver models was compared by experimental and CFD methods for the average solar direct normal irradiations of 860 W/m2 by the dish reflector area of almost 12 m2. The supplied average heat flux by the dish reflector was 7 kW/m2 at the absorbing area of the cavity receivers. The energy and exergy efficiencies from the experimental and CFD analyses on the models were determined based on the cavity surface temperature distribution of receiver walls, and heat gain for different mass flow rates by the heat transfer fluid water. The receiver with copper material and L/D ratio of 0.75 has been found as the optimized one among all other models with the maximum obtained energy and exergy efficiencies of 73.64 and 7.31% when water is used as the heat transfer fluid. The performance of the optimized receiver model was also validated with a few other heat transfer fluids such as SiC + water nanofluid and therminol VP1.

Performance evaluation of solar still using evacuated tube collector with and without nanoparticles.

Solar-thermal distillation is recognized as a low-cost, long-term technique of producing high-quality fresh water in the lack of energy and clean water infrastructure. Improvements to distillation have lately been developed by the application of three main phases depending on the transition of sunlight into heat energy, the generation of thermal vapor, and the condensation of vapor into water. The effectiveness of collected distillation water from evacuated tube collectors on nanoparticles was examined along with basic fluids including water and copper oxide, aluminum oxide, and zinc oxide. Additionally, an investigation of the relationship between specific heat and thermal conductivity, as well as between actual and theoretical heat generation, was conducted. For 11 h of operation, 2275 ml of distilled water was collected using evacuated tube collectors without nanoparticles. The efficiency of the nanoparticles compared to water was more than 17.4% CuO, 15.7% Al2O3, and 14.5% ZnO improved and an increase in overall efficiency of 66.6%. As a result of the experiment, the greatest actual heat generation, expressed in kilowatt-hour, exceeds the theoretical value.

Recent advancements in flat plate solar collector using phase change materials and nanofluid: a review.

Solar energy has emerged as one of the most promising sources of renewable energy to replace the current energy market. Flat plate solar collectors (FPSC) not only are one of the easiest collectors to produce and work with but also are cheap and economical. Due to this, extensive research has been done on FPSC to improve its efficiency and reliability. Some of the methods include using nanofluids to improve the heat transfer process, phase change materials to increase and maintain stable temperatures, or integrating the collector with additional components. This review article focuses on analyzing the recent improvements in FPSC, with a particular emphasis on the achieved efficiencies and temperatures in the studies. Additionally, it is aimed at updating the information in the current field, providing a comprehensive overview of the advancements in FPSC technology. Furthermore, the article explores the combined effects of nanofluids and phase change materials in photovoltaic/thermal (PVT) collectors, considering the resulting temperature enhancements. By critically evaluating the efficiency improvements and temperatures achieved through these approaches, this article is aimed at providing valuable insights into the state-of-the-art of FPSC and their potential for advancing solar energy utilization.

A review of environmental friendly green composites: production methods, current progresses, and challenges.

The growing concern about environmental damage and the inability to meet the demand for more versatile, environmentally friendly materials has sparked increasing interest in polymer composites derived from renewable and biodegradable plant-based materials, mainly from forests. These composites are mostly referred to as "green" and they can be widely employed in many industrial applications. Green composites are less harmful to the environment and could be potential substitutes for petroleum-based polymeric materials. It is helpful to limit usage of fossil oil assets by developing biopolymer matrices such as cellulose-reinforced biocomposites using renewable assets such as plant oils, carbohydrates, and proteins. This paper focuses on green composites processing utilizing a variety of naturally available resources, sustainable materials which are not detrimental to the environment, new scientific signs of progress in achieving green sustainable development, as well as nanotechnology and its environmental consequences. Additionally, the environmental impacts of different composite materials are examined in this paper, along with their production from eco-friendly materials. Moreover, the manufacturing aspects of green composites and some concerns related to their production are also discussed. The merits of green composite materials and valid reasons why they are a valuable substitute for the traditionally used composite materials are also covered.

Enhancing the performance of conventional solar still using sensible heat energy storage materials.

The lack of drinkable, safe water is one problem that governments around the world are dealing with. There are many methods for desalinating saltwater, such as solar distillers, which can be used in remote places without access to traditional energy sources to produce distilled water. In this manuscript, two solar stills [conventional solar still (CSS) and CSS with high thermal conductivity material (HTCM)] were researched at the "School of Mechanical Engineering, B.S. Abdur Rahman Crescent Institute of Science and Technology, Vandalur, Chennai, India," under the same climatic condition. The HTCM (silicon carbide) works as a sensible heat energy storage material, which was placed at the basin of the CSS. The silicon carbide used in the present research is used to enhance the freshwater production during lower solar intensity period and furthermore after evening time. It has been found that the maximum fresh water production from the CSS is 1.5 kg/m2 and the CSS with HTCM is 2.9 kg/m2. The daily yield production from the CSS with HTCM is 93.7% higher compared to the CSS. The study also has shown that the maximum daily thermal efficiency of the CSS is 13.43% and the CSS with HTCM is 26.09%. The CSS with HTCM produced 94.3% higher thermal efficiency as compared to the CSS.

Experimental studies of different operating parameters on the photovoltaic thermal system using a flattened geometrical structure.

The efficiency of the photovoltaic (PV) cell reduces with an increase in solar irradiation. The reduction in the efficiency of the photovoltaic (PV) cell can be attributed to the increase in cell temperature. A novel design of a thermal absorber fabricated by a flat spiral tube is used to remove heat and decrease the cell temperature, thus forming the photovoltaic thermal system (PVTS). Water and titanium oxide (TiO2) nanofluid (NF) with a concentration ratio of 0.1% are used as the working fluid in the PVTS. The study has been carried out for the mass flow rates (mf) of 0.05, 0.066, and 0.083 kg/s. The reduction in the cell temperature is obtained to be 5.7 and 11.2 °C due to the cooling effect of water and TiO2 NF, respectively. The percentage increase in electrical efficiency is 2.93 and 5.28% by cooling using water and TiO2 NF, respectively. The hourly variation of the performance of the PVTS shows that TiO2 NF at 0.083 kg/s shows the highest photovoltaic thermal efficiency of 69.2% and thermal and electrical efficiency of 56.45 and 12.75%, respectively. The best coefficient of energy for TiO2 NF is 1.27 for a mf of 0.083 kg/s.

Improving the performance of novel evacuated tube solar collector by using nanofluids: experimental study.

The main focus of the work is to determine the performance efficiency of water-%CuO nanofluids and water at varied flow rate of 0.035 lit/sec, 0.045 lit/sec, and 0.065 lit/sec in an evacuated tube collector integrated with an heat exchanger. A heat exchanger made of copper tube connected to a horizontal pipe for collection of heat from a vertical tube, and a vertical copper tube for collection of heat from an evacuated tube collector for solar radiation were used in the investigation. Water showed no absorption, a low thermal capacity when it was not suitable for high thermal application for improvement in performance, the base fluid with colloidal dispersion of %vol CuO nanofluids in the force convection mode. The evacuated tube collector produced the highest efficiency of water -0.3% vol CuO nanofluids at flow rate 0.035 lit/sec compared to 0.1% and 0.2% vol of CuO nanofluids at flow rate of 0.045, 0.065 lit/sec and water. A comparison to the water CuO nanofluids with the highest effective concentration showed a greater increase in thermal efficiency.The performance of theworking fluid performances was examined for parameters like exit temperature, specific heat, thermal conductivity, energy productivity, and efficiency utilizing.

A comprehensive review on experimental, numerical and optimization analysis of EAHE and GSHP systems.

Geothermal energy is one type of renewable source of energy that can be used as shallow geothermal system for the use of cooling and heating of residential and commercial buildings. In this paper, an intense review is carried out on geothermal heating and cooling for air conditioning with a focus on Earth-Air Heat Exchanger (EAHE) and Ground Source Heat Pump (GSHP) systems. The study is carried out to understand the factors which have a significant effect on the performance of the EAHE and GSHP systems. This paper also focuses on the hybrid work of geothermal heating and cooling system with other forms of energy and provides benefits for designing efficient GSHP and EAHE systems. This study indicates that the important parameters for EAHE and GSHP systems are the thermal conductivity of soil, the water content present in the ground will significantly improve the performance of the systems, and further benefits are discussed in this study.

Analysis of a solar still with photovoltaic modules and electrical heater - Energy and exergy approach.

The availability of drinkable water, along with food and air, is a fundamental human necessity. Because of the presence of higher amounts of salt and pollution, direct use of water from sources such as lakes, sea, rivers, and subsurface water reservoirs is not normally suggested. Solar is still a basic technology that can use solar energy to transform accessible waste or brackish water into drinkable water. Exergy analysis is a strong inferential technique for evaluating the performance of thermal systems. Exergy is becoming more popular as a predictive tool for analysis, and there is a rising interest in using it. In this paper, performance analysis on the aspect of energy and exergy from the proposed solar still (PSS) (conventional solar still with the photovoltaic modules-AC heater) was analyzed on three different water depths (Wd) conditions (1, 2, and 3 cm). Using a solar still with an electric heater, the daily potable water production was found as 8.54, 6.37, and 4.43 kg, for the variations in water depth (Wd) of 1, 2, and 3 cm respectively. The energy and exergy efficiency of the PSS at the Wd of 1, 2, and 3 cm were 75.67, 51.45, and 37.21% and 5.08, 2.29, and 1.03%, respectively. At 1 cm Wd, PSS produced the maximum freshwater yield as compared to the other two water depths. When the Wd is increased from 1 to 2 cm and from 1 to 3 cm, the yield is decreased up to 27.3 and 52.7%, respectively. Similarly, the energy and exergy efficiency is decreased up to 36.8 and 53.2% and 50.4 and 80.6%, respectively. The water cost of the modified solar still is calculated as 0.028 $/kg for the least water thickness.

Performance analysis of a solar dryer integrated with thermal energy storage using PCM-Al2O3 nanofluids.

Solar energy will assist in lowering the price of fossil fuels. The current research is based on a study of a solar dryer with thermal storage that uses water and waste engine oil as the working medium at flow rates of 0.035, 0.045, and 0.065 l/s. A parabolic trough collector was used to collect heat, which was then stored in a thermal energy storage device. The system consisted of rectangular boxes containing stearic acid phase change materials with 0.3vol % Al2O3 nanofluids, which stored heat for the waste engine oil medium is 0.33 times that of the water medium at a rate of flow of 0.035 l/s which was also higher than the flow rates of 0.045 and 0.065 l/s. The parabolic trough reflected solar radiation to the receiver, and the heat was collected in the storage medium before being forced into circulation and transferred to the solar dryer. At a flow rate of 0.035 l/s, the energy output of the solar dryer's waste engine oil medium and water was determined to be roughly 12.4, 14, and 15.1, and 9.8, 10.5, and 11.5 times lower than the crops output of groundnut, ginger, and turmeric, respectively. The energy output in the storage tank and the drying of groundnut, ginger, and turmeric crops with water and waste engine oil medium at varied flow rates of 0.035, 0.045, and 0.065 l/s were studied. Finally, depending on the findings of the tests, this research could be useful in agriculture, notably in the drying of vegetables.

Performance analysis of a novel thermal energy storage integrated solar dryer for drying of coconuts.

The drying of food products is an essential step in the preservation of crops and agricultural by-products that serve as raw materials for numerous end applications. Solar drying with phase change materials (PCMs) is an efficient low-energy consumption process in the post-reaping stage, reducing food deterioration. A customized solar dryer setup was assembled using Cudappah (black) stones as the base of the drying chamber to facilitate the absorption of solar energy on its surface. The organic paraffin wax, with a melting point of 60 ℃, was used as PCM in the solar dryer. The novelty of the study is the application of a PCM in a solar dryer to improve the effectiveness of drying and decrease the absolute drying period and the microbial content in the dried coconut. The study compared the drying characteristics between open sun drying and solar drying without and with PCM (100 and 200 g). The fabricated setup was utilised for drying coconut using a PCM-based solar drying method. The coconut was dried from an initial moisture content of 55.5% to a final moisture content of about 9%. The prototype dryer model minimized the use of the workforce, avoided improper drying, and decreased the absolute drying time. A total plate count (TPC) test was conducted to characterize the microbial content in the dried coconut. The microbial count decreased with the use of 200-g PCM as the use of PCM retained the heat for a longer time in the chamber. The drying time of coconut decreased by about 28 and 52 h on using 100 and 200 g of PCM, respectively, compared to open sun drying. The sensory characteristics like colour, taste, flavour, quality, and texture of the solar-dried coconut sample were superior to the sun-dried coconut sample.

Performance improvements of hemispherical solar still using internal aluminum foil sheet as reflector: energy and exergy analysis.

Various scientists are looking for effective and easy solutions for the augmentation of yield from the hemispherical solar still (HSS). In this study, aluminum foil sheet was used to reflect the intensity, hence augmenting the evaporation rate and daily yield. Experimentations were conducted on two SS: the first SS is HSS; the second SS is HSS with reflective aluminum foil sheet walls (HSS-RAFW). The highest distilled water production from the HSS and HSS-RAFW is 3.36 and 4.1 kg/m2, respectively. Compared to the HSS, the yield of distilled water was augmented by 22.21% when using the HSS-RAFW. The daily energy and exergy efficiencies (EnE and ExE) of the HSS are 26.27 and 1.04%, respectively, and the daily EnE and ExE of the HSS-RAFW are 32.75 and 1.71%, respectively.

Experimental investigation of an active inclined solar panel absorber solar still-energy and exergy analysis.

The objective of the current study is to investigate the performance of the inclined solar panel basin still (ISPBS) incorporated with a spiral tube collector (STC) for various mass flow rates of water (mf). The maximum potable water yield of 8.1, 6.9, and 6.1 kg is obtained for different mass flow rates of 1.8, 3.2, and 4.7 kg/h in each instance. Also, for mf of 1.8, 3.2, and 4.7 kg per hour, the daily average energy and exergy efficiency of the ISPBS is recorded to be 47.9, 39.3, and 31.02 % and 9.8, 7.9, and 5.6 %, in each instance. The average electrical, thermal, and exergy efficiency of the PV panel is noted to be 6.5, 7.1, and 7.5 %; 15.67, 17.1, and 18.04 %; and 20.03, 22.21, and 23.36 % for mf of 1.8, 3.2, and 4.7 kg/h in each instance. The rise in mf causes a drop in the fresh water production yield; thermal, exergy, and overall thermal effectiveness; and an enhancement in the power production of the panel, electrical, thermal, exergy, and overall exergy efficiency of the system. Also, the cost of yield production is noted to be low-cost in AISS at minimum mf of 1.8 kg per hour (0.019 $/l) when compared to the other two mf of 3.2 and 4.7 kg per hour (0.022 and 0.025 $/l).

Energy and exergy analysis of conventional acrylic solar still with and without copper fins.

A detailed exergy analysis of a conventional and copper finned acrylic solar still has been presented in this manuscript. The evaporative, convective, and radiative heat transfer coefficient of water-glass has been calculated. Also energy efficiency, exergy destruction of basin, water, and glass has been determined. Conventional acrylic solar still with fins produced maximum hourly output of 1.24 kg and it produced daily output of 5.08 kg. The conventional acrylic solar still without fins produced maximum hourly output of 0.94 kg and it produced daily output of 3.75 kg. The maximum exergy destruction of the basin, water, and glass for the conventional acrylic solar still with fins are 655.206, 83.35, and 90.48 W/m2, respectively, and conventional acrylic solar still without fins are 616.28, 122.34, and 48.64 W/m2, respectively. The energy and exergy effectiveness of the conventional acrylic solar still with fins are 32 and 2.81%, respectively, and without fins are 24.93 and 1.69%, respectively. The study reveals that exergy destruction of water in the case of still with fins is minimum as related to the exergy destruction of water in the case of still without fins.

Augmenting the productivity of stepped distiller by corrugated and curved liners, CuO/paraffin wax, wick, and vapor suctioning.

This paper aimed to improve the thermal performance of the stepped solar still. So, the effects of using different types of basin liners (corrugated and curved basin liners), jute cloth wick, CuO/paraffin wax, and vapor suction on the stepped solar still performance were investigated. The CuO/paraffin wax was placed into a groove parallel to the basin steps' liner. Also, the stepped distiller was integrated with an external condensation unit. The experimental results revealed that using the corrugated and curved liners increased the productivity of the modified stepped solar still (MSSS) by 42% and 33%, respectively. In addition, using the corrugated liner with wick, corrugated liner with wick and CuO/paraffin wax, corrugated liner with wick, CuO/paraffin wax, and vapor suction improved the freshwater productivity of the distiller by 95%, 127%, and 170%, respectively. At the last studied case (MSSS with corrugated liner, wick, CuO/paraffin wax, and vapor suction), the daily freshwater productivities of the MSSS and conventional still (CSS) were 7000 and 2600 mL/m2·day, respectively. Also, the thermal efficiency of MSSS was calculated as 59% which was obtained at the last studied case. And the efficiency of the CSS was 35%. Besides, the distilled water cost of CSS and MSSS with corrugated liner with wick, CuO/paraffin wax, and vapor suction was 0.023 and 0.014 $/L, respectively.

A relative study on energy and exergy analysis between conventional single slope and novel stepped absorbable plate solar stills.

The innovation of novel absorbing materials using composite materials and nanotechnology is of new trends for many researches. Here, the present study is concerning to enhance the distilled water productivity of a proposed solar still (PSS) using novel absorbing materials. The absorbing material is composed of chitosan (obtained from waste shrimp shells), ethylene diamine tetraacetic acid (EDTA), and Chrysopogon zizaniodes (Vetiver). The combination of these materials is coined as CHEDZ, and it acts as a super absorbent polymer that is coated on the stepped solar still. Evaporation rate increases due to this absorbent, which further increases the yield of the still. In this present study, the PSS is compared with the conventional solar still (CSS) for the use of assessing the yield of freshwater in the same atmospheric circumstance. The experimental setup was performed through the period from December to February 2020 in the Indian climatic condition. The freshwater productivity was improved to 3.05 L/day while the yield of the CSS is 2.47 L/day. The increase in efficiency obtained from a PSS is 39.71% more than the productivity attained from the CSS. The energy efficiency of the PSS is 18.34% and the exergy efficiency is 0.45%.

Recent advancements, technologies, and developments in inclined solar still-a comprehensive review.

People around the world are facing water scarcity, and the demand for freshwater is continuously increasing. The purification of water is the only way to satisfy the need for water. Purification can be done in many ways by purifying seawater or by storing rainwater and letting it to the ground. Different types of solar still are there, which are used to increase the output of water produced. Among others, inclined solar still (ISS) is an outstanding solution as it has a wide exterior area of water, having less depth of water to complement the regular potable water production, even the effectiveness of the inclined solar still. A lot of research had been done by increasing the surface area of water. The day to day collection of water from the ISS was found to be 1-8 kg m- 2. In this review, an analysis was made on the current status of different ISS designs to make advance modifications and research to improve the productivity of the ISS to satisfy the increasing demand for potable water. From this investigation, it is identified that active ISS and hybrid ISS are the most effective as compared to other ISS techniques.

Energy and exergy efficiency analysis of solar still incorporated with copper plate and phosphate pellets as energy storage material.

In this work, a new attempt was made to study the behavior of the conventional solar still (CSS) by adding a black-painted copper plate and phosphate pellets. Therefore, the performance of the three solar stills has been studied and compared. The first is the CSS, and the second is the modified solar still (MSS). The MSS performance was tested using black-coated copper plate (measuring 49 × 49 cm and 0.2 cm thick) with and without phosphate pellets and compared to the CSS in the similar climatic conditions. The results showed that the combination of black coated copper plate and the inclusion of phosphate pellets improved the evaporation rate and daily productivity. During the experiments, yields using black coated copper plate without and with phosphate pellets were 14.96% and 29.53% greater than the CSS. The effectiveness of the CSS, MSS with copper metal plate (MSS-CP), and MSS with copper metal plate with phosphate pellets (MSS-CP and PP) are around 30.23, 35.3, and 41.44%, respectively.

Investigation on the performance enhancement of single-slope solar still using green fibre insulation derived from Artocarpus heterophyllus rags reinforced with Azadirachta indica gum.

The fruits and vegetable waste has become the highest compared with the production rate. These types of wastes had reached up to 70% by 2019-2020 as estimated by Food and Agriculture Organization (FAO). Improvisation of the performance of still using fibre insulation (Artocarpus heterophyllus rags and Azadirachta indica gum (AHRAIG)) has been carried out in this study. Potable water demand in arid areas is a vast problem where fresh water is very expensive. The proposed solar still (PSS) retains the basin temperature and raises the rate of evaporation. Rags are latex-like filament extracted from the waste of the jackfruit peels and an adhesive agent from Azadirachta indica tree. A comparison is made among still without insulation (SWI), still with polystyrene insulation (SPI) and still with fibre insulation (SFI) in producing the fresh water under same ambient conditions. The experiments result a promising yield of 9.3% rate of rise of potable water produced using AHRAIG insulation related to conventional still. The energy efficiency is premeditated as 26.45%, while the exergy efficiency is 4.07%. The production of the potable water reached 2.58 L/m2 for still with polystyrene insulation, 3.26 L/m2 for fibre insulation and 1.93 L/m2 for still without insulation, respectively.