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Water scarcity necessitates a cost-effective and productive solution. This study focused to enhance the productivity of single slope solar still by incorporating the better weight of palm flower powder (micro-sized) in the basin and micro phase change material heat storage bed under the basin. In this aspect, the different quantity of palm powder weights such as 10, 30, 50, 70, 100, 120 and 150 g in the basin was experimentally examined. The absorber basin containing 50 g of palm powder has better productivity of 37.25%, whereas for 10, 30, 70, 100, 120 and 150 g, they were 11.85, 24.78, 36.8, 33.05, 10.25 and - 20.22% respectively. The influence of palm powder with different weight% impregnated in the paraffin wax was analysed. The maximum thermal conductivity of 0.33 W/m K was obtained in the sample containing palm flower powder of 20 wt%. The experimental investigation was carried out with 50 g of micro-sized palm powder in the basin and thermal storage bed under the basin containing 20 wt% of micro phase change material (PCMPFP-SS) and conventional solar still (CSS). The overall distillate output of PCMPFP-SS was 4670 and 4250 mL/m 2 on day 1 and day 2 respectively. On the other hand, the overall distillate output for CSS was 3030 and 2800 mL/m 2 on day 1 and day 2. From the economic analysis, it was found that the cost per litre (CPL) of PCMPFP-SS and CSS was $ 0.025 and $ 0.032 respectively. Moreover, the payback period of PCMPFP-SS was lowered from 5.1 to 4.1 months compared to CSS., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Solar energy is a promising form of energy that has the potential to meet all of the world's energy needs. Only half of the sun's energy reaches the earth's surface, even though it is more enough for meeting the world's energy need. Though there is a great deal of solar energy utilization technologies available, solar parabolic dish collector system got researchers focus because of its higher thermal energy conversion efficiency and its unique advantages. Several researchers have been enlightening new and emerging technologies in several countries. Hence, the authors would like to emphasize the progress in this while exercising an extensive review of different solar concentrating techniques using solar parabolic dish collector in order to produce heat and electrical power using direct and indirect energy conversion devices with wide range of applications. Their design advancement and progress applications in recent years particularly in related field are discussed too., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

India is one of the highly developing countries in the world and it has the second-largest agricultural source of income, which covers 61% of the entire income of the country. The most valuable income group, by giving the appropriate training in this technology, will make their entire country to become one of the most highly developing counties in the world. In recent years, many developing, developed, and underdeveloped countries face shortages of fish, fruits, and vegetables due to natural disasters like earthquakes, tsunami, and any other unexpected events. Now the main issue of this paper is to preserve the food products from post-harvest to consumer-level, which cover 60% of losses due to the unavailability of preservative methods. This paper mainly focused on the conventional methods to advanced solar drying technologies for perseverating fish, fruits, and vegetables and also it discusses the technology used for drying the yield range of fish like Atheriniformes, Catfish, Chilwa, etc. Fruits like banana, mango, and papaya, and vegetables like bitter gourd, cabbage, and cocoa beans have been reviewed and also discussed some problems along with their solutions in concern with food products drying, thereby the selection of dryer for drying products will be made easy by this review article. On the whole, this investigation would help researchers in fish drying to choose the better drying methods for acquiring better results for particular fish, fruits, and vegetables that enable any entrepreneur to select the appropriate method reducing the cost and time., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Agriculture is the main occupation of the majority of people in India. The majority of the population in India is dependent (directly or indirectly) on agriculture as an occupation. The agriculture sector requires more freshwater and power for better yield in the current scenario. Nevertheless, the ever-increasing rate of energy consumption, limited fossil fuels, and rising pollution have made the expansion of renewable resources essential. Due to the suitable solar potential available in India, the deployment of solar energy has been more as compared to other renewable resources. The current study aims to discuss the various technologies, initiatives and policies of solar energy usage in agriculture. This work delivers an assessment of the advancement of solar energy vis-à-vis agricultural applications through the greenhouse concept and photovoltaic approach in India. Various agricultural applications of solar energy, such as solar water desalination system, solar water pumping system, solar crop dryer system for food safety, etc. are discussed as a means to promote solar-based technology. It also highlights the scenario of solar energy in India with important accomplishments, developmental approaches, and future potential. In-depth studies of various policies and government initiatives including those in research and development are also discussed. The current survey on solar technologies will be an aid to agribusiness frameworks to comprehend the statuses, obstructions, and extent of advancement. Finally, some future recommendations for further developments in this approach are discussed. This work sheds light on varied areas of solar energy-assisted agricultural systems as a potentially sustainable and eco-friendly pathway., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The scarcity of clean and safe water is one of the most perilous glitches faced by the world. The pure drinking water resources across the world are depleting progressively due to rapid industrialization and growth in population. The conceivable solution for this problem is converting the available seawater into pure drinking water through several techniques of desalination. In the stream of desalination, many prodigious endeavours are in evolution to increase the reliability of the process by cutting down the principal and maintenance costs. Among several desalination approaches, low-temperature thermal desalination (LTTD) is an intriguing and advancing trend in the desalination process by using low temperatures and pressures in a range similar to ambient temperatures and vacuum pressures. The LTTD technique is operated by taking the energy input from waste heat, thermoclines and renewable energy sources. However, the operating temperatures of the LTTD system are less than 50 °C. The development of this particular LTTD process driven by renewable energy sources has gone through various stages, based on the water-energy demands, environmental concerns and technological progressions. In this article, the historical developments of the LTTD process using several renewable and non-renewable energy sources have been reviewed. Finally, some future recommendations for further developments in this approach are discussed. This article paves the path for the researchers working in desalination to choose an appropriate LTTD approach that is more viable and sustainable than the conventional desalination systems., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The proposed research study aims to improve the productivity of solar still (SS) by using low-cost and eco-friendly materials. The aforementioned objective was achieved by enhancing the evaporation rate of seawater in the absorber basin and the condensation rate over the glass cover of the solar still. In this study, the low-cost and eco-friendly materials used for enhancing the evaporation rate in the solar still were molasses powder (MP), sawdust (SD) and rice husk (RH). In addition to these materials, bamboo straw (BS), banana leaf stem (BL) and rice straw (RS) were used as absorbing materials over the glass cover for enhancing the condensation rate. The experiments were carried out under similar meteorological conditions, and the results of the modified solar still were compared with the conventional solar still (CSS). The productivities of CSS, SSMP, SSRH, SSSD, SSBS, SSBL and SSRS were about 2250 mL/m 2 , 2383 mL/m 2 , 2467 mL/m 2 , 3033 mL/m 2 , 2700 mL/m 2 , 2683 mL/m 2 and 3367 mL/m 2 , respectively. The results of the experimental investigation highlighted that the SSSD had a comparatively better evaporation rate and 34.81% higher yield than CSS. Besides, SSRS had a comparatively better condensation rate and a 51.88% higher yield than CSS. Furthermore, the combination of sawdust (SD) and rice straw (RS) was investigated for the combined enhancement of evaporation and condensation. The solar still with sawdust and rice straw (SSSDRS) showed a 62.88% improvement in productivity with 3633 mL/m 2 when compared to CSS. Also, the economic analysis showed that the cost per litre (CPL) of freshwater obtained from SSSDRS was about ₹ 1.9 ($ 0.025) with a payback period of 4.4 months which was the least when compared to all the considered cases., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Solar parabolic dish concentrators are one of the most efficient solar power conversion technologies. The cavity receivers are the most common type, used for reducing the heat losses from the receiver. In this paper, a novel cavity receiver is proposed, and the objective is to compare the novel modified conical cavity receiver with the existing cavity receivers such as cylindrical, conical and modified cavity receivers. The cavity receivers are designed for the parabolic dish of 4-m diameter which is installed at the National Institute of Technology Puducherry, India. Ray-tracing analysis was carried out to determine the size of the receiver. The analysis was carried out for various orientations of the receivers from 0 to 90° with a step size of 15° and also for the cavity temperatures: 300°C, 400°C, 500°C, 600°C and 700°C. Based on the results obtained, the modified conical cavity receiver is found to be the best design in terms of minimum heat losses compared to other receivers. The next best choices are found to be modified cavity, conical cavity and cylindrical cavity receiver. The whole analysis is conducted with a developed model in COMSOL Multiphysics., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In the current research, the energy and economic performance in single-slope solar still using ball marbles (BMSS) has been investigated and compared the results with conventional solar still (CSS) under the similar weather conditions of Karaikal (10.92° N, 79.83° E), India, during October 2020. The experiments have been conducted on both sunny and cloudy day to evaluate the performance of solar still. The BMSS has increased the evaporation rate and productivity when compared to CSS due to the sensible heat energy stored by the ball marbles in the absorber basin. The potable water yield of the BMSS is improved by 21.23% and 22.86%, respectively, during sunny and cloudy days. The maximum cumulative productivity obtained in the BMSS is 2950 mL/m 2 .day and 2150 mL/m 2 .day, respectively, on sunny and cloudy days. In economic analysis, the payback period (PBP) of the BMSS is 5.7 months, whereas the PBP of the CSS is 6.5 months, respectively. Furthermore, the cost per litre (CPL) potable water produced by BMSS is 8% lower than the CPL of CSS., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The prime intention of the current research is to enhance the freshwater productivity of the solar still (SS) by using Luffa acutangula fibres (LAF). The dried LA fibres were introduced into the absorber basin of a solar still to enhance the wet surface area through its porous structure that leads to augmented evaporation of water from the absorber basin. The effect of the number of LAF in the absorber basin such as 10,13,14,15,16,20 and 25 on freshwater productivity was estimated. The results revealed that SSLAF with 15 fibres in the absorber basin increased the yield by 25.23%. Besides, a solar still with 10,13,14,16,20 and 25 fibres in the absorber basin increased the yield by 12.27%, 17.45%, 22.04%, 22.69%, 14.64% and 4.09% respectively when compared to conventional solar still (CSS). The average thermal efficiency of the SSLAF with 15 LAF was increased by 28.35% whereas, for 10,13,14,16,20 and 25 LAF, the average thermal efficiency was increasedby 11.05%, 16.99%, 22.53%, 19.93%, 11.29% and 3.9% respectively when compared to CSS.The economic analysis resulted that the cost per litre freshwater yield from the SSLAF is 22.5% lower than CSS. Also, the payback period of SSLAF is comparatively lesser than that of CSS.

Solar still is one of the economic and eminent ways of desalinating the available sea/brackish water into potable water. However, the distillate output from the solar still is moderate and various researches are being conducted to improve the productivity of solar still. In this research, a novel bottom finned (solid and hollow) absorber basin is designed and developed to enhance the heat transfer between absorber and phase change material (PCM) which further improves the freshwater productivity from the solar still. The results of the investigation are compared with the conventional solar still. The three single-slope solar stills considered developed for evaluating the effect of modification on the freshwater productivity are (i) conventional solar still (CSS), (ii) solar still with hollow finned absorber inserted in energy storage (SSHFES), and (c) solar still with solid finned absorber inserted in energy storage (SSSFES). The investigation results reported that the SSHFES has greater productivity when compared with the SSSFES and CSS. The freshwater productivity from the SSHFES is 4085 mL/m 2 day, whereas the freshwater productivity from SSSFES and CSS is 3485 mL/m 2 day and 2885 mL/m 2 day, respectively. The efficiency of SSHFES and SSSFES is increased by 41.67% and 20.81% relative to the CSS. It is observed from economic analysis that the cost per liter (CPL) freshwater produced by SSHFES, SSSFES and CSS is about ₹ 2.3 ($ 0.032), ₹ 2.5 ($ 0.034), and ₹2.6 ($ 0.036), respectively. The payback periods of SSHFES, SSSFES, and CSS is 6.3 months, 6.8 months, and 7.1 months, respectively. Also, the enviroeconomic analysis conferred that the carbon credit gained from the SSHFES is $189.28 whereas SSSFES and CSS gained only $158.2 and $132.02. Based on the current study, it is observed that the solar still with hollow finned absorber inserted in energy storage (SSHFES) is effective when compared to others and it is viable for potable water production at cheaper costs., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Research Background: Traditionally, open sun drying method serves to dry the products for long time preservation. Solar drying is also employed to minimise the drying time to achieve the required moisture content. This method inherently contains complex heat and mass transfer mechanisms, which makes difficult to describe drying kinetics at the micro level., Experimental Approach: In this paper, research is carried out to investigate the drying of 5 mm thick slices of red banana ( Musa acuminata 'Red Dacca') in a single slope solar dryer based on natural and forced convection. Based on the experiments, a new semi-empirical thin layer drying kinetics is proposed and compared with other existing models. The proposed model with the correlation coefficient (R 2 ) of 0.997 is in very good agreement with other well-known models. Based on the model, we calculated the moisture diffusivity and activation energy of the red banana drying process., Results and Conclusions: It was found that the moisture diffusivity of the red banana samples was in the range 0.87-1.56·10 -9 m 2 /s for natural convection solar drying and 0.84-2.61·10 -8 m 2 /s for forced convection solar drying. The activation energy of the red banana varied from 24.58 to 45.20 kJ/mol for passive and 22.56 to 35.49 kJ/mol for active drying. Besides, we carried out energy and exergy analyses of red banana in the dryers and found that the average exergy losses in the forced and natural convections were 16.1 and 6.63 kJ/kg and the average exergic efficiency of the natural and forced convection dryers was 57.7 and 70.9%, respectively., Novelty and Scientific Contribution: A single slope direct solar dryer was designed and built to maintain the desired temperature for a specified period in both natural and forced convection mode. A novel drying kinetics model with higher correlation coefficient (R 2 ) than the other drying kinetic models is proposed for the preservation of red bananas., Competing Interests: CONFLICT OF INTEREST The authors declare that they have no conflict of interest.

The single-basin solar still is one of the effective ways of desalinating the seawater at an affordable price. But, the productivity of solar still is low and many kinds of research are under progress to enhance the yield. In this regard, a single-basin solar still with a solid staggered pin finned absorber inserted into a paraffin wax bed is developed to investigate the yield enhancement. This investigation is carried out by varying the seawater depths of the absorber basin from 2 to 4 cm in the developed solar still. The obtained results are compared with conventional solar still without fins and PCM bed. It is observed that the yield obtained in the developed solar still with 2-cm depth is having greater productivity when compared to other cases of seawater depths (3 cm and 4 cm). The yield of modified solar still and conventional solar still at 2-cm water depth is 3750 mL/m 2 and 3017 mL/m 2 respectively. It is also observed that thermal efficiency of the developed single-basin solar still is increased by 12.23%, 22.66% and 24.26% respectively compared to the conventional solar still for the seawater depths of 4 cm, 3 cm and 2 cm. In addition to that, it is observed from the economic analysis, the cost per litre potable water produced from modified solar still and conventional solar still is ₹ 2.1 and ₹ 2.25 respectively. Also, the environmental analysis is carried out to analyse the carbon credit from the developed single-basin solar still and found that the carbon credit gained from modified still and conventional solar still is $ 172.8 and $ 137.9 respectively. Based on this investigation, it is observed that the developed single-basin solar still with solid staggered pin finned absorber inserted into paraffin wax bed can be effectively used for the drinking water production to overcome the water scarcity.