Application of heat sinks inside the pyramid solar distiller: experimental study on distiller performance under various operating conditions.

Solar still is a cheap decentralized mode for obtaining potable water from saline water using solar energy, but it has low productivity. Previous studies showed that using pin fins in the absorber can increase the solar still efficiency and yield. The heat sink has better heat transfer properties than those of the pin fin because it has a higher surface area to volume ratio than that of the pin fin. The current study investigates the effect of heat sinks in passive pyramid solar still under two water depths (11 and 30 mm) on the hourly yield, accumulated yield, and efficiency of the distiller. Three cases were compared: conventional solar still (CSS), regular distribution of heat sinks (DHS), and grouped heat sinks in the middle of the solar still basin (GHS). In addition, the effect of atmospheric parameters such as solar radiation, UV index, humidity, dry bulb temperature, and ambient temperature on the solar still parameters such as water, vapor, cover, and feedwater temperature is investigated. Unexpectedly, heat sinks weakly affect the performance of solar still. Therefore, the conclusion of the previous studies that the finned absorber has a favorable impact on the solar still performance is not general and needs further investigation. The highest thermal efficiency was observed for the DHS and GHS at 30-mm water depth, where the efficiency was 35%.

Experimental study of solar air heater performance with evacuated tubes connected in series and involving nano-copper oxide/paraffin wax as thermal storage enhancer.

The investment of solar energy in life applications has become mandatory to maintain a clean environment and reduce the use of fossil fuels. This work aimed to improve the performance of solar air heater (SAH) by using evacuated tube solar collectors ETSC integrated with nano-enhancer phase change material (NE-PCM). To achieve this purpose, a system consisting of 5 linked collecting panels was designed, fabricated, and experimentally investigated. Each panel included a glass-evacuated tube with two concentric aluminum pipes installed inside. NE-PCM was placed between the inlet and outlet air paths inside the evacuated tube to enhance the heat transfer rate. The performance was investigated with and without NE-PCM at five mass flow rates (0.006, 0.008, 0.01, 0.03, and 0.05 kg/s). Experimental results revealed that the highest temperature was 116, 108, 102, 95, and 93 °C, respectively, for the above mass flow rates without adding NE-PCM. The outlet temperature was decreased by 6-15 °C when using NE-PCM. The SAH efficiency was increased by 29.62% compared to the system without NE-PCM at 0.05 kg/s. The maximum thermal efficiency for the system with NE-PCM was 62.66% at 0.05 kg/s, and the pressure drop was 6.79 kPa under the same conditions. As well known, the hot air is used for a variety of purposes including space heating, food processing, drying of fruit, vegetables, dairy, and solar cooking.

The performance enhancement of solar cooker integrated with photovoltaic module and evacuated tubes using ZnO/Acalypha Indica leaf extract: response surface study analysis.

In this study, the effect of employing ZnO/Acalypha Indica leaf extract (ZAE) on the energy absorption of a coated portable solar cooker has been examined using an experimental setup. A prototypical model has been developed to corroborate in associating an investigative outcome per constituents of the experiments. The studied heat transfer process in ZAE is stable for harsh conditions. The design analysis and an estimation of the system performance were done given various parameters including the pressure of the vacuum envelope, bar plate coating digestion, emissivity, and solar rays. The fabricated solar was tested with and without ZAE to investigate the impact of this coating material on the solar cooker's thermal performance. To observe the performance of the new design, two figures of merit (F1 and F2) have been introduced. The factual food cooking assessments were for a family of four people, which operated in ZAE coating (0.8, 1.0, 1.2 µm) of the solar cooker. The values of F1 and F2 for the proposed cooker were obtained as 0.1520 and 0.4235, respectively, which is intact with the BIS values. The results revealed that employing ZAE instead of a thermal NHC-PV solar cooker reduced the time required to boil 2 L of water for about 47 min. The overall thermal energy productivity of the solar cooker with electrical backup was obtained as 42.65%, indicating that the ZAE coating can improve the thermal efficiency by 10.35%.

Effect of basin water depth on the performance of vertical discs' solar still-experimental investigation.

The ability to get clean water is the most urgent birthright for human beings. The scarcity of safe drinking water is a major challenge in both developed and developing countries. Due to overpopulation, industrial revolution advancements, and agricultural evolution, this challenge has become crucially influential. Several studies on solar desalination are being conducted to create novel models that will improve the efficiency and production of these units. Because of their higher evaporation, condensing, exposure, and output rates than traditional stills, vertical distillers have lately piqued the interest of numerous academics. In this study, the scholars investigated the impact of varying water depth at the best rotating speed of discs from their earlier work (1.5 rpm) on the thermal productivity of vertical distillers. Numerous water depths (5, 8, 11, and 14 cm) were studied at 1.5 rpm to specify the best depth. The results indicated that utilizing moving discs enhanced the distillers' productivity. Besides, the peak distiller performance was obtained at 1.5 rpm and 5 cm. Furthermore, the yield of the modified single-stage vertical distiller (MSSVD) and modified double-stage vertical distiller (MDSVD) was increased by 350 and 617.4%, respectively, over the conventional tilted distiller (CTD) productivity of 2.3 L/m2 day. MSSVD and MDSVD had the highest efficacy rates of 48.4 and 77.2%. Lastly, for CTD, CVD, MSSVD, and MDSVD, the pure water cost was 0.025, 0.0477, 0.0180, and 0.0193 $/L, respectively.

Performance improvement of tubular solar still via tilting glass cylinder, nano-coating, and nano-PCM: experimental approach.

Although the solar distillers are one of the economic solutions for addressing the freshwater shortage problem around the world, these devices suffer from low productivity. In this paper, a simple and inexpensive modification was made in the tubular solar still (TSS) to improve its productivity. The adjustment is to tilt the glass cylinder, something to help the droplets move down and collect them as a distillate. The modified inclined TSS was abbreviated by ITSS. Then, three different inclination angles were investigated (2°, 4°, and 6°), and the performance of ITSS with these inclination angles was compared with that of TSS without inclination angle (0°). Moreover, to obtain additional productivity for ITSS, the basin was painted with a mixture of matte black paint with nanomaterials. Three types of nanomaterials were studied (copper oxide nanoparticles, titanium oxide nanoparticles, and silver nanoparticles). For further improvement in ITSS productivity, Ag nanoparticles mixed with phase change material (PCM) were employed beneath the ITSS base to work as thermal energy storage material. Experimental results revealed that the highest average daily productivity rise for ITSS over TSS was observed when tilting ITSS by 6°, where the daily productivity rise and thermal efficiency reached 24% and 37.6%, respectively. Besides, the average increase in daily distillate of ITSS was 34%, 30%, and 28.5% when using Ag, CuO, and TiO2, respectively, compared to that of TSS. Moreover, ITSS with Ag provided the best thermal efficiency compared to the other operating cases, where it was 39.1%. In addition, ITSS-PCM-Ag showed a daily productivity of 62.5% more than that of TSS and a thermal efficiency of 43.5%.

Experimental investigation on dish solar distiller with modified absorber and phase change material under various operating conditions.

The shortage of potable water is a global problem. One of the techniques used to participate solving this problem is the solar distiller. The main demerit of solar distiller is its low output yield. So, this work aims at improving the freshwater productivity of a dish solar distiller by enlarging its absorber surface area and increasing its evaporation rate. As a result, the effect of using three different shapes of absorber liner was investigated: convex dish absorber, stepped absorber, and corrugated surface over the stepped absorber. In addition, the absorber of dish distiller was covered by a cotton wick to enlarge the wetted surface area. Also, different water depths (1.0, 2.0, 3.0, 4.0, and 5.0 cm) in dish distiller with stepped absorber were investigated. Moreover, the distance below basin liner was occupied by energy storing medium (paraffin wax + titanium oxide nanoparticles). The performances of dish distiller, dish distiller with stepped absorber, and dish distiller with corrugated absorber were evaluated and compared to that of a conventional solar distiller. Experimental results revealed that the performance of dish distiller with corrugated absorber, wick, and energy storing material was higher than that of dish distiller with stepped absorber, which was better than that of dish distiller, which was higher than that of conventional distiller. As well, the highest improvement in productivity of dish distiller with stepped absorber was 125% compared to conventional distiller and took place at 2-cm water depth. In addition, the productivity of dish distiller with corrugated absorber and wick was improved by 160% compared to that of conventional distiller. Additionally, the highest performance was obtained for dish distiller with corrugated absorber, wick, and energy storing material, where the productivity was augmented by about 183%, and the thermal efficiency reached 69.5%.

Improving the vertical solar distiller performance using rotating wick discs and integrated condenser.

Freshwater is one of the most essential needs of society. Due to the limited amount of potable water on Earth, guaranteeing the supply of clean water to society is a major challenge. By utilizing abundant sunshine, solar still could be utilized to provide the necessary amount of drinking water in remote locations. The issue of restricted daily production inspires researchers to investigate novel ways for enhancing the thermal performance of desalination techniques while lowering expenses. In this work, the scholars improved a unique distillation method related to solar stills. The authors presented a novel improvement to the vertical distiller design to enhance the exposure area while decreasing the thickness of the water layer as much as possible. Thus, two rotational discs (flat type) covered with wick were integrated into the vertical distiller basin at 1.5 rpm and 5 cm water depth. Furthermore, providing vacuum via a fan with an external condenser. Besides, various rotating speeds (from 400 to 2000 rpm) were tested to determine the perfect fan speed that provides the maximum yield. The experimental findings revealed that the modified vertical distiller produced more pure water than the conventional distiller. Moreover, the rotation of wick discs and vacuum fan enhanced the yield of distillers enormously. Besides, the highest distiller performance was obtained at 1.5 rpm (wick disc speed) and 1600 rpm (fan speed, 10 min ON, and 10 min OFF). Moreover, the daily freshwater output was 19.1 L/m2 day for MDSVD without the fan and 23.65 L/m2 day for MDSVD with the fan. So, the yield of MSSVD without/with vacuum fan was improved by 548.65% and 660.45%, respectively, over that of CTD. The best thermal efficacy for MDSVD without/with vacuum fan was 77.47% and 84.05%, respectively. Lastly, the average cost of freshwater was 0.021, 0.0177, and 0.0164 $/L for CTD, MDSVD without/with vacuum fan, respectively.

Investigating the performance of dish solar distiller with phase change material mixed with Al2O3 nanoparticles under different water depths.

The problem of potable water shortage all over the world made the scientists seek for solutions to overcome this problem. Solar distiller is one of the introduced solutions, but it demerited by the low freshwater output. In this proposed paper, a design modification includes the use of a convex dish absorber instead of the flat absorber liner. The modified solar distiller is nominated by dish solar distiller. The base of dish solar distiller was circular. In addition, a cotton wick was used as a wetting material for facilitating the evaporation process inside the distiller. Besides, the effect of different water heights in the clearance around the dish dome was investigated for 1, 3, 5, 7, 9, and 12 cm. Finally, the space under the dish absorber is filled with a phase change material of paraffin wax mixed with aluminum oxide nanoparticles. Experimental results revealed that the best dish height that provided the highest freshwater productivity was 9 cm, where the average daily yields of dish solar distiller (at 9 cm) and conventional distillers were reported as 4500 and 3000 mL/m2.day, respectively. Then, the productivity of dish solar distiller was improved by around 50% over that of the conventional distiller. In addition, when using the phase change material, the average daily distillate of dish solar distiller was improved by approximately 95% compared to that of the conventional solar still, where the distillate of conventional still and dish solar distiller with phase change material at 9 cm water depth was 3580 and 6980 mL/m2.day, respectively. Besides, the maximum thermal efficiency of dish solar distiller was obtained when using phase change material at 9 cm water depth, where it was 62.4% compared to 30% for the conventional distiller.

Solar still with rotating parts: a review.

Access to freshwater is narrowed down every day in the world. Many diseases of human beings are related to water supplies contaminated or unpurified. Nowadays, there are massive water shortages in developed and developing nations due to unplanned mechanisms and water pollution caused by human behavior. Water desalination with no impact on the environment is the necessity of the hour. The distillation of saline or brackish water using free solar energy such as solar still is one of the techniques of water purification providing ultrapure distilled water. Besides, solar still is an economical and eco-friendly method, particularly in arid areas. Solar distillers also provide renewable equipment for freshwater productivity. The still design was affected by several operating and environmental factors. The low productivity of the solar still is its major drawback, so many researchers have studied various models to enhance solar still productivity. This paper aims to review the numerous studies of solar still incorporated with rotating parts that are deemed to be effective and efficient design because rotating parts break water surface tension, increase evaporation area, and improve the still performance. Throughout this detailed review, the scholars intend to present, clarify, and analyze the status of several solar distillers with various rotary component arrangements such as a fan, rotating wick, shaft, drum, disc... etc. In addition, based on the entire work, it was confirmed and recommended that the solar still with rotating parts should be continuously followed to supply potable water efficiently and economically. Different results showed the importance of part rotation (best daily yield & improvement) such as vertical disc distiller (16.5 L/m2/d & 617.4%), drum distiller (9.22 L/m2/d & 350%), moving wick solar still (9.17 L/m2/d & 315%), shaft still (0.83 L/m2/d & 39.49%), and vibratory distiller (5.8 L/m2/d & 132%). These important results obtain the importance of embedding rotating parts into the solar stills.

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.

Simulation study on thermal performance of a Solar box Cooker using nanocomposite for natural Food invention.

The double glass cover analysis of a solar box cooker has been implemented in an internal heat transfer using MoS2-Fe2O3-Cr2O3 nanomaterials. A nanocomposite material's essential role is its higher surface/volume ratio which agrees in small area size of a high ductility without strength loss and an enhanced optical property. The nanocomposite materials have an average particle size of 0.2 - 0.5 µm. Compared to the overall thermal energy efficiency of the solar cookers used, the samples with and without this study's modification are 56.21-31.77% and 33.90-24.90%. The design used nanomaterials' performance with and without coating materials achieved by the bar plate temperature of about 163.74 °C and 113.34 °C below solar radiation of 1037W/m2. The simulation model is conducted on the fuzzy intelligent logic and Cramer's rules. It agreed with the experimental results by 91%.