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This study emphasizes the importance of adding fins to the flat absorber plate to augment the thermal performance and yield of potable water produced. The potable water produced from both solar still were compared by considering the similar climatic condition. The results showed that the addition of fins in the absorber plate augments the water temperature and thereby the rate of evaporation from the surface. Linear regression between the experimental and predicted yield was carried out. It was clear that the observed and predicted yield have a deviation of about ± 5%. The total yield produced from the modified absorber was improved by about 46.85% than conventional tubular solar still. Also, results of thermal efficiency exhibited that the solar still using finned absorber was increased while compared to the tubular solar still without fins.

This article conveys the effect of rate of flow by water (mf) over an inclined PV panel basin solar still (IPVPBSS) for improving the distilled water production. In this study, the PV panel is used as a basin of Inclined Solar Still (ISS) and the consequence of flow rate by sea water on yield and power production is experimentally analyzed. Three different flow rates were analyzed for the present study (4.68, 7.56 and 10.08 kg/hr). Results showed that on increasing the rate of flow the distillate output produced from the IPVPBSS decreases, whereas, the power production increases as the panel temperature is an influential parameter. Similarly, the daily thermal efficiency of the IPVPBSS decreases with increasing the flow rate. The daily yield from the IPVPBSS decreases by 27 and 57% for the flow rates of 7.56 and 10.08 kg/hr respectively as compared to that of flow rate of 4.56 kg/hr. Also, from the economic analysis the cost of distilled water and payback period of the IPVPBSS decreases with minimum flow rate of water.

Low-temperature combustion is the individuality of Homogenous charge compression ignition (HCCI) engines where the combustion is achieved at the temperature lower than the temperature at which NOx is formed. By achieving this type of combustion in the engine it is possible to reduce the formation of Thermal NOx and PM. But on the other hand, the performance. In this current study, the combustion parameters of the engine are studied by varying the input parameters of the engine that has been modified to run in HCCI mode. The engine is fuelled with the blends of chicken fat oil biodiesel (CFOB) and gasoline. In the present work, the engine is tested for combustion properties such as in-cylinder pressure, heat release rate and the rate of pressure rise for different blend ratios. The ignition delay has persistently elevated for an increase in the gasoline concentration in blends. Also, the knock is consistently seen at higher engine loads with the blends of gasoline and diesel as well as gasoline with biodiesel. Diesel fuel exhibited lower peak pressure whereas, pure biodiesel exhibits higher peak pressure and the peak cylinder pressure within the engine at higher load varies from 40 to 75 bar. On comparing the heat release rate, the diesel fuel exhibit lower heat release as compared to fuel blended with chicken fat oil. Due to the delay in the start of low-temperature reactions the peaks on the rate of heat release is reduced. During higher engine load conditions, the engine seizes to operate in HCCI mode instead it operates in a conventional pattern which is clearly proved by the heat release curves obtained for the indicated pressure and crank angle data of the particular operating mode of the engine.

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 (TiO

A study has been conducted using a portable emission tester (PET) for the city of Imphal, India using twelve (12) key business locations for determining the combustion by-products (exhaust emissions) & their characteristics from both light and heavy-duty diesel vehicles. The ambient temperature varied from 23.5 to 28 °C and humidity to be 65 ± 15% during the course of the study. Higher values of CxHy and CO, compared to the standard permissible values, have been observed from light duty diesel (LDD) vehicles, with average values of 430 ppm and 465.4 ppm respectively, while NOx has an average value of 99.2 ppm. Similar characteristics are also witnessed from the heavy-duty diesel (HDD) vehicles with CO and CxHy having alarming values of 1585 ppm and 2968 ppm respectively, while NOx have an average value of 140.06 ppm. Using total emission approach, the CO2 emissions have been estimated to be about 38.02*105 tons and 1135*105 tons from LDD and HDD respectively till 2018. With respect to the present study, HDD have the maximum contribution of CxHy, NOx and CO in the atmosphere with values of 76.9%, 69.3% and 58.5% respectively. The authors believed that such alarming emissions from the vehicles would have been controlled if the authorities had performed regular checks and imposed strict laws against heavy emissions from vehicles.

The aim of the present study is to compare the performance of the Inclined Solar Panel Basin (ISPB) still integrated with (active mode) and without (passive mode) Flat Plat Collector (FPC). The maximum yield of 4.3 and 7.9 kg/day is produced from the passive and active mode respectively. The daily thermal and exergy effectiveness of the passive mode is 39.82% and 2.9% and, the active mode is 46.87% and 6.6%, respectively. For the active mode the daily yield, thermal and exergy efficiencies are increased and the panel effectiveness is decreased. An active mode increases the daily fresh water production rate, thermal and exergy effectiveness up to 44.63, 24.91 and 55.68% respectively than the passive mode.

The demand for water and electricity is gradually increasing throughout the years due to the modern lifestyle of humans to complete their daily activities. To make sustainable water and to produce electricity, the proposed experiment was done. In this, hybrid PV/T active solar still was designed and fabricated in which a solar PV powered Peltier system was incorporated. The Peltier used in this still helps in the enhancement of the distilled water production during both evaporation and condensation processes. Various investigations were made on the proposed active hybrid PV/T system to claim this as the best and it was succeeded. Finally, the proposed active hybrid solar PV/T still produces about 30% higher efficiency than the conventional passive still and also resulted in 38% improved efficiency than the actual solar PV system.

Water is a critical component for living existence on earth. Clean water is the need of hour, but the amount of clean water available in earth is drastically reduced due to water pollution caused by industrialization and rapid urbanization. Overall global climatic and seasonal changes also have a significant impact on the reduction of amount of fresh water. The need for clean water is continuously growing due to rise in human residents for the last few decades. Use of contaminated water leads to several water borne diseases and based on the intensity of contamination sometimes it leads to death. There are various processes for obtaining fresh water from contaminated water, but the most economical and preferable method is solar distillation since the process involved in it is similar to natural hydrological cycle which requires only solar energy for its operation. Solar stills are potable and do not require any additional skills for its operation and maintenance which makes it user friendly. Integrated PV/T solar still is used for isolated communities facing electrical energy troubles and a scarcity of good quality water. The daily fresh water produced from passive solar still was found to be 2–5 kg/m 2 whereas from an active solar still integrated with PV/T collector can produced daily yield of about 6–12 kg/m 2 . In this paper, a comprehensive review of integration of solar still and PV module has been presented.

A hybrid photovoltaic/thermal (PV/T) active solar still and a conventional passive solar still with single slope were designed, fabricated and experimented at three different water depths (0.05 m, 0.10 m, and 0.15 m). For the higher production of distillate water, a nickel-chromium (NiCr) heater powered by solar photovoltaic (PV) was incorporated in the proposed hybrid active still. Solar PV module was cooled by the saline water which increases the efficiency of the solar PV as well as the distillate water production. The daily yield from the proposed hybrid active (PV/T) solar still is 6 times more than the conventional passive still. This new system of renewable energy based power and distillate water production is highly self-sustainable in the remote areas. From the experimental study it is clear that, the proposed hybrid active (PV/T) solar still gives an enhanced overall thermal and electrical efficiency, that is nearly 25% higher than the conventional passive one.

In the present work, theoretical performance of humidification–dehumidification desalination unit using a desiccant wheel or heat exchanger in order to increase the thermal performance of the system is investigated. The sensitivity of each parameter including the inlet water and air flow rates ratio, inlet hot water temperature, inlet cooling water temperature, inlet air humidity and regeneration temperature on the fresh water production, Gain output ratio, specific thermal energy, and recovery ratio is studied. Also, the optimum condition of different parameters of desalination units is presented. The results show that the desalination unit with the desiccant wheel is more efficient than the base humidification–dehumidification or use a heat exchanger to provide distillate water. The inlet cooling water temperature and inlet air humidity have a tiny effect on Gain output ratio and specific thermal energy while inlet water and air flow rates ratio, inlet hot water temperature, and regeneration temperature has a measurable effect on Gain output ratio and specific thermal energy. The maximum fresh water production is about 0.4603 kgw/kga, Gain output ratio is about 4.515, recovery ratio is about 46.03% and minimum specific thermal energy is about 0.149 kWh/kg.

Present work is an effort to study the performance of a PV panel integrated solar still to generate power and to do desalination process to meet the water and power scarcity issues. The system performance is experimentally investigated from different aspects such as still productivity, still efficiency, PV panel power production, PV panel efficiency, and exergy efficiency. Results show that the maximum distillate output of 7.3 kg was obtained when inclined solar panel basin solar still with the sidewall and bottom insulation. The freshwater production from inclined solar panel basin solar still with the sidewall and bottom insulation, inclined solar panel basin solar still with Sidewall insulation and inclined solar panel basin solar still without any insulation was 7.3 kg, 4.4 kg and 3.7 kg respectively. The daily energy efficiency and exergy efficiency of inclined solar panel basin solar still with the sidewall and bottom insulation are higher compared to other cases. The daily efficiency of 34.5%, 38.3% and 71.2% and exergy efficiency of 1.3%, 2.3% and 4.5% was recorded for inclined solar panel basin solar still without any insulation, inclined solar panel basin solar still with the sidewall insulation and inclined solar panel basin solar still with sidewall and bottom insulation respectively.

In this research work, a solar air heater with double pass (SAHD) configuration having different porous mediums on its absorber plate is experimentally investigated. The stone pebbles, mild steel and aluminium chips have been used as porous mediums to augment the convective heat transfer (CHT) from plate to the air flowing in channel of SAHD. The experiment is conducted with these three materials at different mass flow rates (MFR) altering from 0.005 to 0.03 kg/s and at distinct solar intensities. The thermal efficiency ( η th ) and thermohydraulic efficiency ( η the ) of SAHD with three porous materials are computed at different MFR to analyse their impact on thermal performance. Findings reveal that SAHD with the porous medium on the absorber plate have higher heat transfer, thermal efficiency and thermohydraulic efficiency as compared to SAHD without porous medium. Out of the three materials used in experimentation, aluminium is found to have maximum influence on the performance of SAHD. The highest enhancement in heat transfer, η th and η the are achieved with aluminium chips as a porous medium. The maximum enhancements in η th and η the obtained are 84% and 74% respectively. The highest η the is attained at MFR of 0.025 kg/s for aluminium chips. The present study concludes that SAHD configuration with the porous medium in its 2nd passage is an efficient design for heat transfer improvement.

A passive solar still combined with a heat storage system was developed and used for desalination of brackish water. The experimental setup mainly consists of an insulated rectangular basin, filled with 19 kg of saline water, painted black and installed south-facing onto the flat roof of a building located in the Meknes city (Latitude: 33°53′36′′ North; Longitude: 5°32′50′′ West). The device was equipped with K-type thermocouples which were connected to a data logger and laptop computer in order to measure and record different temperatures. Emphasis focused on the influence of winter (2020) ambient conditions and storage materials (air, sand and paraffin wax) on the thermal efficiency and pure water productivity of the desalination system. Weather conditions of winter days (sunny, cloudy, rainy, windy, warm, cold) significantly impact the yield of solar still. Heat is stored (or retrieved) as sensible heat for sand unlike paraffin wax (Phase Change Material: PCM) which stores/retrieves heat in both modes: sensible and latent. Temperature melting of the PCM was not reached for unfavorable weather conditions (rainy, cloudy and windy days). The sensible heat storage/retrieval mode is predominant while the latent mode appears for a short period (about 25 min). Latent heat storage mode allows storing a huge amount of heat (> 1 MJ), hence the using of heat storage system (sand and paraffin wax) enhances the overall thermal efficiency by 152.8 and 223.09%, respectively, compared to conventional solar still. In conclusion, a solar distiller coupled with a heat storage system is a promising technology for desalination in arid and semi-arid regions which are confronting to a severe scarcity of fresh water as the same time they have abundant amounts of brackish water.

In this work, the use of micro/Nano-particles of aluminum oxide (Al2O3) with various concentrations in solar still has been reported. Three solar distillers has been fabricated and tested: first distiller is a Conventional Solar Still (CSS), the second distiller is a Modified Solar Still (MSS) contains micro-particles of Al2O3 (MSS – 0.1, 0.2 and 0.3% MP of Al2O3) and the third distiller is a MSS contains Nano-particles of Al2O3 (MSS – 0.1, 0.2 and 0.3% NP of Al2O3). In this experimental study, the micro/Nano-particles of the Al2O3 concentrations are prepared at the concentration ratio of 0.1, 0.2 and 0.3%. From the experimental outputs by adding Nano-particles of Al2O3 with concentrations of 0.1%, 0.2% and 0.3% in the CSS, the productivity of 4.9, 5.47 and 6.12 L/m2 has been observed. However, when using the micro-particles of Al2O3, the MSS productivity is equal to 4.07, 4.54 and 4.96 L/m2 for the concentrations equal to 0.1, 0.2 and 0.3%, respectively. While the maximum productivity of the CSS without micro/Nano-particles of Al2O3 was 3.02 L/m2. Furthermore, the daily increase in yield of 62.25, 81.12 and 102.64% are obtained when using the Nano-particles of Al2O3 with the concentrations of 0.1, 0.2 and 0.3% respectively, as compared to the CSS. By using the micro-particles of Al2O3, the daily increase reaches only 34.77, 50.33 and 64.24% for the concentration equal to 0.1%, 0.2% and 0.3%, respectively as compared to the CSS.

This research primarily concentrates on the use of integrating solar stills. Only few researchers have carried out experiments on still-still basis for improved yield. In the present novel system the yield of fresh water is improved by integrating inclined solar still with triangular pyramid solar still. Effect of water depth and flow rate on the yield of fresh water produced from stills was experimentally investigated. Various water depths such as 0.02 m, 0.04 m, 0.06 m, 0.08 m are maintained in the interior of the basin of pyramidal solar still in case of non-integration whereas 0.02 m depth of water is maintained initially and outlet water of inclined solar still is fed to the triangular pyramidal solar still thereby the water temperature increases which enhances the yield of fresh water. The inclined solar still is maintained at constant flow rate of about 8.33 kg/h. Results show that the yield of solar still is improved by 79.05% in the case of inclined solar still incorporated to triangular pyramid solar still. Results also shows that higher water temperature is achieved in the case of inclined solar still integrated to triangular pyramid solar still at the minimum water depth of dw = 0.02 m.

In this communication, an attempt has been made to find out the effect of water capacity on internal and external heat transfer for a solar distillation system. It is a well-known fact that the distillate output decreases significantly with the increase of water depth in the basin of the solar still. A single slope basin type solar still is fabricated with inner dimensions of 1000mm x 500mm (effective area 0.5 m 2 ) and the glass cover is tilted at 10° with respect to the horizontal. The objective of the present paper is to study the effect of water capacity on the cumulative energy balance of the distillation system. It is inferred that the internal and external heat transfer depends significantly on the water capacity in the basin. It is also observed that the evaporative, radiative and convective heat transfer from water to glass are plays an important role on the performance of the distillation system

Scarceness for water exists in many countries even though three fourth of the earth is covered by water. The reason behind this is the rapid enlargement of industry and populace worldwide. Solar still is the only efficient solution for water trouble in hot climatic conditional areas where there is scarcity of water and electricity. Solar still is a very simple solar device that is used for converting the available salted water into potable water. This paper presents a comparative study of single basin single slope aluminium finned acrylic solar still and single basin single slope galvanised iron solar still. By using acrylic sheet as casing as it has very low thermal conductivity, it reduces the loss of heat from the still basin to the bottom which leads to increase in the rate of evaporation of water. The daily productivity of single basin single slope acrylic solar still is 660ML/0.25M2/day and galvanised iron solar still is 585 ML/ 0.25M2

Shortage for potable water exists in many countries even though three fourth of the earth is sheltered by water. The reason behind this is the express growth of industry and inhabitants worldwide. Solar still is the only efficient solution for water problem in hot climatic conditional areas where there is scarceness of water and electrical energy. Solar still is a very simple solar device that is used for converting the available saline water into potable water. This paper presents a new material acrylic sheet as basin to reduce the bottom heat losses. By using acrylic sheet as covering it reduces the loss of heat from the still to the bottom which leads to increase in the rate of evaporation of water. The daily productivity of single basin single slope acrylic solar still is 660ML/0.25M2/DAY

The present experimental work aims to improve the performance of single basin solar still using two different augmentation approach namely, reduced graphene oxide (RGO) coated absorber plate in solar still and RGO coated absorber plate along with activated carbon pellet as sensible heat energy storage medium. Results showed that utilization of RGO coated absorber plate along with activated carbon pellet in solar still augmented the water yield by 58.15% and full-day average energy efficiency by 64.44%, respectively, compared to conventional solar still. The fractional evaporation exergy was maximum for solar still integrated with RGO coating and activated carbon pellet, owing to the higher water temperature of the basin. The solar still integrated with RGO and activated carbon pellet caused the maximum average full-day exergy efficiency, due to excellent solar-thermal conversion efficiency and high conductivity of RGO along with high energy storage capacity of porous activated carbon. Cost analysis indicated that cost of fresh water produced per liter using RGO and RGO along with activated carbon pellet were lower than conventional solar still by 1.1% and 15.5%, respectively. Exergo-economic and environmental assessments of modified solar stills exhibited a cost-effective method and highly beneficial in reducing the carbon footprint by CO2 mitigation.

Thermal management of heat-generating battery packs involve many operating parameters affecting its performance, efficiency, and maintenance. Heat generation (Qgen), conductivity ratio (Cr), Reynolds number (Re), spacing between the packs (Ws), and coolant Prandtl number (Pr) are the parameters selected as working parameters for conjugate thermal analysis and optimization. The thermal analysis of battery packs is carried out numerically using the finite volume method. Single and multi-objective optimization of thermal management characteristics, namely maximum temperature (Tb, max), average Nusselt number (Nuavg), and coefficient of friction (Fcavg) using Cuckoo search (CS) and artificial bee colony (ABC) algorithm is attempted. For faster numerical analysis, the developed code is parallelized using OpenMP paradigm. 25 coolants having Pr in the range 0.02 to 511.5 belonging to five categories i.e. gases, oils, thermal oils, nanofluids, and liquid metals, are adopted for optimization. Nuavg and Fcavg are not affected by Cr and Qgen, while Tb, max changes significantly. Ws, Pr, and Re impact these characters differently, demanding the need for optimization. Nanofluids and thermal oils have emerged as the best coolants for optimized thermal characteristics at higher heat generations. CS algorithm provided high fitness of objective functions in single-objective optimization, whereas the ABC algorithm converged with high fitness during multi-objective optimization.

In the present work, we conducted some modifications in the design and operation of stepped distiller to improve its performance. The stepped distiller was modified by installing fixed suspended trays over the vertical walls of the steps to increase the evaporative and exposure surface areas. Also, we created a parallel cavity under the steps’ liner to work as a heat storing space. This cavity was filled by a paraffin wax mixed by Al2O3 nanoparticles as a phase change material (PCM). Besides, the stepped solar distiller performance was studied under integrating the distiller with an external condenser. Furthermore, the performance of the stepped solar still was investigated under different fan speeds of zero, 400, 800, 1200, 1600, 2000, 2400, and 2800 rpm. The performance of the solar still was evaluated under the different conditions individually and combined. Results revealed that the stepped solar distiller, either with or without condenser, had better performance than the reference solar still. At the case of using suspended trays only, the stepped distiller recorded a productivity of 4175 mL/m2 a day versus 3800 mL/m2 a day for the reference distiller with an improvement of 9.8%. Moreover, using the suspended trays and Al2O3/paraffin wax mixture in the parallel cavity increased the productivity of the solar still by around 40%, where the productivity was 5740 and 4100 mL/m2 a day for the stepped and reference stills, respectively. In addition, the optimum fan speed obtaining the maximum productivity improvement for the stepped distiller over the conventional still was 2000 rpm, where the productivity of the stepped still was improved by 55% over that of the reference still. At this fan speed of 2000 rpm, the daily distillate of the conventional and stepped distillers was 4000 and 6200 mL/m², respectively. Finally, the average daily thermal efficiency of the stepped solar still was 46%, 48.7%, and 52.4% when using the suspended trays, suspended trays with PCM, suspended trays with PCM and fan at 2000 rpm, respectively. While the average thermal efficiency of the reference basin distiller was ranged between ~ 38 – 41%. Finally, the cost of the distilled water of stepped still and reference still is 0.014 and 0.015 $/L, respectively.

Modified Inclined Solar Stills in passive (PISS) and active mode (AISS) were fabricated and researched in the environmental condition of Chennai, India. In an AISS, Spiral Tube Collector (STC) has been integrated for the extraction of drinking water. The major intention of the current research is to estimate the performance of the PISS and AISS for extracting fresh water from brackish water. The highest distilled water production from the PISS and AISS is 4.4 and 8.3 kg/day, respectively. Furthermore, water quality analysis for brackish water has been carried out. The obtained pH value of the brackish water is 8.7 and for fresh water are 7.6. The water qualities meet EPA standards.

In the present study, solar still performance has been investigated under different operating conditions such as coating the basin liner by TiO2 nanoparticles mixed with Cr2O3 and different combinations of hybrid bond adsorption. The basin liner was a copper sheet which was used to adsorb energy in winter & summer (W&S). The mixture of TiO2 nanoparticles and Cr2O3 was characterized by SEM, FTIR and XRD tests. Results revealed that the average daily productivity of the solar still was 5.39 and 7.89 L during the winter and summer, respectively. The average daily efficiency of the system was 57.16% and 36.69% through the summer and winter, respectively. Based on the analysis, the best performance of the solar still can be achieved during winter and summer conditions of K L University of Andhra Pradesh, India.

Drinking water has become a real global problem, despite the abundance of unsaturated saltwater and colorless, which do not meet the requirements of the World Health Organization. The El Oued, in the southeastern part of Algeria, contains vast quantities of salt water and non-potable water. Solar distillation can be used as a solution to resolve this trouble. To provide drinking water, we use free sunlight to treat salt water. The traditional solar distillation device, which is one mile long (0.5×0.5 m), is designed to confirm the effectiveness of this solution. The traditional single slope solar distillation, its dimensions (0.5×0.5 m), is designed to confirm the effectiveness of this solution. Solar distillation is an environmental, economic and simple technique, but it needs some modifications to increase the distilled water production. In this work, we added aluminum balls inside the solar distillate box. In this work, we added 42 aluminum balls with a diameter of 2 cm inside a solar distillates box; positioned as follows (6 balls x 7 balls). The results showed that aluminum balls increased the distillation of distilled water by about 27.16 %.

The present experimental study deals with the utilization of fumed silicon oxide nanoparticle in black paint at a varied concentration (10–40%) coated on the absorber plate of stepped solar still for augmenting the freshwater yield. The critical parameter for enhanced evaporation depends on the water temperature. From the experimental investigation, it is found that the temperature of the water and absorber are influenced by the absorption rate and the utilization of fumed silicon oxide nanoparticles in black paint which increases the temperature. The average temperature of water and absorber is higher with an optimized concentration of nanoparticle of 20% with black paint is increased by 10.2 and 12.3% respectively whereas, with further increase in nanoparticle concentration with black paint exhibited no significant improvement. Results also showed that the total yield from the solar still is improved by 27.2, 34.2, 18.3, and 18.4% for 10, 20, 30 and 40% respectively while compared to that of ordinary black paint.

The present work investigates about the performance of single slope still (with rehash cooked oil) to enhance the palatable water productivity. The tray with basin contains rehash cooked oil represent the external heat source to increase the temperature of basin water. The performance of proposed solar still with the effects of high heat exchanger rehash cooked oil are studied. In this study, the proposed solar still is compared with conventional solar still for the purpose of evaluating the palatable water productivity under the presence of same ambient condition. The experimental result is obtained during the period from March to May 2019 under the Indian conditions. The production of palatable water reached 3.77 L\m2 for the proposed still, while it is only 3.02 L/m2 for the conventional still. The rate of rise of yield obtained from the single slope solar still with used cooked oil is 57.02% more than the yield obtained from the conventional still in an average. For the proposed still, the energy efficiency is 24.35% and the exergy efficiency is 0.69%.

Direct generation of drinking water from ambient air using sunlight is of great interest for many populations. Here, a new desiccant mechanism using a highly hygroscopic silica gel was tested on the double-slope half-cylindrical basin solar still (DS-HCBSS) to extract the water content from the ambient air. As this mechanism is new to be applied into the solar still, an experimental and predictive study was conducted to investigate the thermal performance of the solar still under this modification. The modification was done in a double-slope half-cylindrical basin solar still, which has four longitudinal fins from inside to increase the surface area. The basin liner of the solar still and the fins were covered by a layer of silica gel with a thickness of 1.5 cm. A parabolic trough solar collector was used to raise the temperature inside the solar still during daytime solar illumination. The productivity of the DS-HCBSS with silica gel was enhanced by about 72% and 166% when longitudinal fins and longitudinal fins with gravels were used, respectively. Moreover, the efficiency of the DS-HCBSS with silica gel was increased by 15% and 35% when longitudinal fins and longitudinal fins with gravels were used, respectively. The best accumulated productivity (400 mL/m2) was recorded for the DS-HCBSS with silica gel, longitudinal fins, and gravels. Finally, a Neuro-fuzzy Inference System (ANFIS) model was employed to predict the process response (productivity) of the investigated systems under different process input factors (ambient temperature and solar irradiance). The predictive model obtained a good agreement with the experimental results. The experimental results revealed that the double-slope half-cylindrical basin solar still with the modification provides a new concept for Air Water Harvesting (AWH) and atmospheric water generation.

Storing of energy in the form of latent or sensible heat is the best method in improving the performance of any thermal application. Desalination using renewable energy is the best method in getting potable water and due to its lower performance and yield it is not commercially available. The present investigation deals with improving potable water produced using nanomaterial in phase change material from a tubular solar still. Three different solar still namely TSS, TSS with PCM and TSS with NPCM were used in the present study and tested under the climatic conditions of Chennai, India. The thermal conductivity of graphene oxide nanoparticle in PCM acts as the key role in improving the thermal performance as the thermal conductivity of NPCM improved by 52% compared to that of PCM without nanoparticle. There is no significant improvement in the thermal conductivity of nano enhanced PCM with concentration beyond 0.3%. With a significant improvement in the thermal conductivity of NPCM, the water temperature increased by 7 °C and 3 °C as compared to TSS loaded with PCM and TSS without PCM respectively. The maximum enhancement in temperature of NPCM is found as 24% and the temperature is higher during off shine hours compared to that of PCM without nanoparticle. Similarly, with improved water temperature using NPCM as energy material, the evaporation rate from the absorber is improved by 41.3%, whereas, the average EHTC for TSS and TSS loaded with PCM alone is improved by 32.76 and 34.32% respectively. The total cumulative yield produced per m2 area from TSS, TSS with PCM, and TSS with NPCM is found to be 2.59, 3.35 and 5.62 kg respectively. Results also revealed that the daily efficiency of TSS with NPCM is improved to about 116.5% and comparatively higher than TSS with PCM and conventional tubular solar still.

Evaporation and condensation rate directly depend on the surface area provided in the solar still. Considering that, pyramid solar still provides greater surface area than basin type still for condensation process and gives out high performance. In this research work, the pyramid solar still is researched by varying the water depth from 1 to 3.5 cm with and without insulation conditions. The performance of the pyramid solar still with insulation is greater than the without insulation. Insulation plays an important role to increase the yield by increasing the water temperature. The yield produced from the pyramid solar still was higher at the lowest water depth of 1 cm for both insulation and un-insulated condition. The freshwater production from the pyramid solar still without insulation is 3.27, 2.93, 2.26, and 1.59 kg/m2 and with insulation is 3.72, 3.40, 2.70, and 2.08 kg/m2 for the water depth of 1, 2, 3, and 3.5 cm, respectively. At 1 cm water depth, the pyramid solar still with and without insulation produced 19.46% and 8.26% higher yield than the single basin type solar still.The daily efficiency of solar still is improved to about 28.5% with insulation whereas, the daily efficiency for solar still without insulation is found as 26.17%.

Solar energy is a need of the hour and very important source for the all living organisms. Due to increment in global warming as well as pollution, solar energy utilization is required and it is replaced by the conventional use of fuels in the world today. Active solar still found higher distillate output due to the use of solar collector i.e. flat plate collector, evacuated tubes. Also the price of solar photovoltaic is also reducing now days. Hence, the main aim of the present review paper is to integrate the active solar still with photovoltaic panel to increase the distillate output as well as improvement in efficiency of solar photovoltaic (PV). Present review paper shows the various researchers have carried out on single slope and double slope active solar still with solar photovoltaic. It is concluded that, the integration of solar photovoltaic (PV) with evacuated tubes with single basin is appropriate for commercial purpose for providing potable water with electricity and it is also good solution for remote location. At last the scope of the future work is also incorporated in review paper.

Scarcity for water exists in many countries even though three-fourth of the earth is covered by water. The reasons for scarcity of water are worldwide rapid growth of industry and immeasurable population. Solar still is the only efficient solution for water problem in hot climatic conditional areas where scarcity of water and electricity occurs. Solar still is a very simple solar device that is used for converting the available brackish water into potable water. Investigation shows that the productivity of basin type solar still is limited. Various literature reported several experimental and numerical investigations on basin type of solar still. An extensive review on different parameters affecting the rate of evaporation and condensation on passive solar still has been carried out in this paper.