Solar Water Heating Research Articles

Investigation on thermo-fluid behavior of flat-plate solar water heater employing titanium dioxide-water nanofluid: An experimental and computational approach

Investigation on thermo-fluid behavior of flat-plate solar water heater employing titanium dioxide-water nanofluid: An experimental and computational approach

Enhancing Energy Efficiency in a Palestinian Dairy Factory Utilizing RETScreen Expert

This paper delves into the intricacies of optimizing energy utilization within a dairy manufacturing facility situated in Palestine through the utilization of RETScreen Expert. An exhaustive energy audit is undertaken to meticulously scrutinize and comprehend the existing energy landscape within the dairy factory. This investigation is specifically oriented towards the evaluation of seven distinct energy efficiency strategies, encompassing aspects such as lighting enhancements, insulation upgrades, the maintenance of steam traps, mitigation of steam leaks, harnessing heat recovery mechanisms, and the installation of a solar water heating system. The study extends its purview to encompass environmental concerns, encompassing the estimation of CO2 emissions, and conducts a comprehensive assessment of the economic feasibility associated with these proposed measures. The findings of this investigation unequivocally reveal the substantial potential for diminishing energy consumption and curtailing CO2 emissions, alongside the concurrent enhancement of economic viability through the judicious implementation of the aforementioned energy efficiency initiatives. In essence, this scholarly work serves as a valuable resource, shedding light on the advantageous outcomes achieved by the incorporation of energy efficiency measures within industrial frameworks. It underscores the imperative of a holistic approach, where both environmental and economic dimensions are harmoniously considered in the decision-making processes pertaining to energy-related initiatives.

Experimental investigation of hybrid vacuum tube solar water heater/parabolic concentrator integrated with phase change material and nanofluid as HTF simultaneously; energy and exergy assessments

ABSTRACT Solar water heaters suffer from fluctuating hot water production due to unpredictable weather changes throughout the day. In this study, the hybrid configuration of a vacuum tube solar water heater with a parabolic solar concentrator, in conjunction with the application of paraffin as a phase change material, is employed as a novel approach to address this problem. Furthermore, the study investigates the utilisation of a nanofluid (0.05%, 0.1%, and 0.2% mass) containing Al2O3 and ZnO nanoparticles dispersed in water-ethylene glycol (base fluid) as the medium fluid to enhance thermal performance. The experimental results revealed that the utilisation of 0.2% mass ZnO and Al2O3 nanofluids led to a considerable increase of 10.74% and 7.25%, respectively, in the maximum reservoir temperature. This resulted in a respective average thermal efficiency improvement of 41.6% and 33.9% compared to the base fluid. Furthermore, the maximum exergy efficiency of the system exhibited a significant increment of 54% and 40.1% compared to the base fluid. Moreover, the incorporation of phase change material in the system effectively minimised temperature fluctuations.

Enhancing Solar Thermal Efficiency: PCM Integration for Compact Energy Storage Systems

The optimal utilization of solar energy presents a challenge in meeting round-the-clock hot water demands while accommodating limited space in modern architectural designs. Solar collectors, operating solely during daylight hours and weather-dependent, necessitate efficient energy storage to meet evening and morning peak hot water consumption in households. Current architectural trends, marked by smaller boiler rooms, further compound the challenge of integrating conventional solar tanks, emphasizing the critical need for compact energy storage solutions. Addressing this challenge, this paper proposes a ground-breaking solution: a solar tank infused with phase change material (PCM). This innovative tank design not only boasts smaller dimensions but also significantly higher heat capacity compared to conventional counterparts. Crucially, the PCM solar tank enables solar collectors to operate at lower temperatures, potentially elevating the overall efficiency of the solar collector system. The proposed storage system comprises two synergistic heat-absorbing units: a solar water heater and a PCM-based heat storage unit. While the solar water heater fulfills the daytime hot water supply, the PCM storage unit accumulates and retains heat throughout the day, ensuring continuous hot water availability during night hours and overcast periods. Leveraging small cylinders filled with paraffin, serving as the PCM, integrated with solar collectors maximizes solar energy absorption and storage. This paper meticulously compares the performance of the PCM-based thermal energy storage system with conventional sensible heat storage systems, presenting insightful conclusions derived from the comparative analysis. The findings underscore the remarkable efficiency and efficacy of the PCM-based solution in meeting the challenges posed by solar energy intermittency and limited space constraints, offering a promising avenue for sustainable and efficient solar energy utilization in residential settings.

Optimizing winter climate control in high-altitude smart greenhouse through renewable energy integration

In the context of food security in mountain regions, this study explores the potential of a Smart Greenhouse (SGH) to address the challenges posed by climate change and limited resources. The SGH utilizes an 8 m2 solar water heating system, weather stations for external temperature and humidity monitoring, as well as internal light, humidity, and temperature sensors to create an optimized environment for crop cultivation. Experiments were conducted with various crops within the SGH during the harsh winter months, typically rendering the cultivable land fallow due to extreme cold conditions. The SGH is equipped with sensors and communication technologies, ensuring continuous data collection and the automated regulation of heating, ventilation, and air conditioning systems. Located in Genekha, Thimphu, this pilot SGH seamlessly integrates renewable energy technology to provide heat during the cold winter season, obviating the need for external heating sources in the summer. The study employed TRNSYS and OpenStudio simulation software to assess the SGH's performance, focusing on temperature and humidity control inside and outside the greenhouse. Additionally, soil pH and nutrient content were examined, and the time required for crop growth and harvesting was recorded. In conclusion, this paper acknowledges some of the current design's limitations and presents recommendations for future enhancements, with a focus on the specific context of improving crop production and food security in mountainous regions.

Experimental investigation on the performance of a Solar-Ocean Thermal Energy Conversion system based on the Organic Rankine Cycle

To improve the performance of the Ocean Thermal Energy Conversion (OTEC) system based on the Organic Rankine Cycle (ORC), a solar-assisted cycle is added, and the power generation experimental setup for the Solar-Ocean Thermal Energy Conversion (S-OTEC) system has been constructed. Through energy and exergy analysis, the effects of solar hot water temperature and working fluid flow rate on the components and system performance are investigated, and the performance differences between S-OTEC and OTEC at the same seawater temperature and working fluid flow rate are compared. The results show that: in the S-OTEC system, as the solar hot water temperature is increased from 54 °C to 72 °C, the isentropic efficiency of the working fluid pump and expander is improved, but the heat transfer coefficient of the heat exchanger is decreased. Futhermore, the thermal efficiency, power generation efficiency, and exergy efficiency increase in the ranges of 2.02–3.26 %, 2.93–3.15 %, and 37.93–41.01 %, respectively. When the working fluid flow rate is increased from 124.33 kg/h to 216.73 kg/h, the isentropic efficiency of the working fluid pump and expander as well as the heat transfer coefficient of the heat exchanger are improved. Additional, the thermal efficiency, power generation efficiency and exergy efficiency increase in the ranges of 2.05–2.75 %, 2.46–2.97 % and 38.01–48.13 %, respectively. What's more, the thermal efficiency, power generation efficiency and exergy efficiency of the S-OTEC system can be increased by 154.32 %, 39.33 % and 27.87 % respectively compared to the OTEC system.

Formation of a black anodic coating on alloy AA5052 by using anodizing in a tri-acid environmentally friendly electrolyte

For the first time, an organic electrolyte has been created, which allowed the formation of black anodized aluminum (Al) by direct anodizing of alloy AA5052. The electrolyte consists of a mixture of three environmentally friendly acids. The structural and optical properties of black anodic coatings were determined before and after thermal treatment. Total reflection tests of black anodized Al have shown that AA5052 samples have a total reflectance value of 5–7% in the visible (VIS) range. The study of specular reflectance on the angle of incidence of the light at a wavelength of 600 nm has shown that sample AA5052 has the highest angular intensity compared to that of AA1050. Thermal treatment reduced the porosity of alloy AA5052 about 2.5 times, but did not affect its optical properties. Black anodized alloy AA5052 has excellent thermal stability both at 100 °C and 200 °C temperatures, i.e. the total reflectance value did not change by more than 5% in the VIS range. Hence, the developed black anodized coatings are suitable for solar water heating systems.

Energetic and exergetic study of a flat plate collector based solar water heater - investigation of the absorber size

Small sized absorber in a flat plate solar collector is beneficial in terms of cost and minimum heat losses. However, its detailed thermal performance compared to standard size collector is still not fully understood. There is a paucity of research to appreciate thermal performance of solar water heating collector with consideration of a small absorber size (below 1m2) and a standard absorber size (2 m2). The present study attempts to investigate the energy and exergy efficiencies of flat plate solar water heating collector with two absorber plate areas (2 m2 and 0.74 m2) to enumerate size of the absorber required for improved first and second law thermal efficiencies of the collector. The efficiencies of these two collector designs are experimentally compared with the help of a test facility available in the site for given operating temperatures and rate of flow. The combined experimental uncertainty due to the measuring instruments and the measured parameters is also ascertained. The obtained results highlight the significance of the larger absorber size (2m2) for higher thermal efficiency, and lower absorber size (0.74m2) for higher exergetic efficiency. The highest thermal efficiency obtained is 77.38% for larger absorber size, and the highest exergy efficiency of 13.21% is obtained for lower absorber size collector. It is demonstrated that larger and lower absorber size of the collector have higher thermal efficiency and higher exergy efficiency, respectively, than some of the published works.

Energy performance assessment of a novel enhanced solar thermal system with topology optimized latent heat thermal energy storage unit for domestic water heating

In this study, we introduce an innovative approach by incorporating a Topology-Optimized Latent Heat Thermal Energy Storage (TO-LHTES) unit with fins into a solar water heating system. Employing EnergyPlus software, we initially assess the energy and power requirements essential for meeting domestic hot water needs within the Moroccan context. Afterward, Computational Fluid Dynamics (CFD) analyses explore diverse Phase Change Materials (RT35, RT50, and RT60) under varying operational conditions, including injected temperature, velocity, and stored temperature. Our investigation extends to different climates, evaluating the energy savings potential. The study's outcomes reveal the remarkable efficacy of the enhanced solar system featuring the TO-LHTES unit, particularly with specific configurations—such as an injected temperature of 20 °C, injected velocity of 0.02 m/s, stored temperature of 80 °C, and RT50 as the chosen Phase change material. Given the poor thermal conductivity of many PCMs, effective heat distribution and storage necessitate innovative methods. While various finned heat exchanger structures have been explored in existing literature, a notable gap exists in non-intuitive heat exchanger concepts specifically tailored for LHTES units. This work contributes by presenting an innovative TO-LHTES unit design, advancing the understanding and applicability of latent heat storage in solar water heating systems. Importantly, a maximum energy savings of 63.2% was achieved.

Study of melting behavior of phase change material in a square enclosure with constant and variable heat flux at different wall heating conditions: A numerical approach

Latent heat thermal energy storage system offers the most promising cost-effective solution in thermal energy storage applications like solar water heaters to building air conditioning, textile industries, pharmaceutical industries, etc. In this article, the melting process of phase change material (PCM) in a square enclosure with constant, linearly increasing, linearly decreasing and sinusoidal heat flux on different sides of the wall is studied. The result shows that double-wall heating has the highest melting rate followed by side-wall heating and bottom-wall heating. This happens because double-wall heating increases the heat transfer area. Between side-wall heating and bottom-wall heating with uniform heat flux, side-wall heating gives a higher melting rate due to the higher length of solid–liquid interface promoting the heat transfer to solid PCM, thus increasing the melting rate. Again, for different heat distributions of side-wall heating the linearly decreasing heat flux provides the highest melting rate. This type of heat distribution actually transfers more heat to the lower part of the container, which counters the effect of convection, resulting in an enhanced melting process. On the other hand, in the case of distributions at bottom-wall heating, linearly increasing heat flux shows the highest melting rate. In addition, for linearly increasing heat flux, the shape of the liquid cavity is triangular, which gives more space and thereby intense natural convective circulation. This enhanced convection heat transfer leads to a higher melting rate.

Innovative twist design for solar water heaters: Experimental findings and implications

More effective use of solar energy in hot water systems is made possible by optimising heat transfer and flow resistance. In light of this, Research has been conducted to enhance convective heat transfer while analysing flow friction characteristics for best performance, resulting in the design of novel inserts known as customised twists, which increase the efficiency of the solar hot water system. A conventional, plain tube heater is used as a baseline for the study on thermal characteristics, heat transportation and flow friction attributes. A thorough analysis and comparison of the thermal behaviour of the system with customised twist inserts that have been modified using rods and spacers of different lengths is performed. As a result of the induced disturbance in the fluid particle flow pattern throughout the length of risers, a significant improvement in the coefficient of convective heat transfer is observed. The study validated the correlations for the convective heat transfer coefficient and the resistance coefficient against previous research findings. The findings indicated that the thermal efficiency of the full-length twist-inserted system is almost three times greater than that of a plain collector while doubling its pressure drop. The findings of this research could be useful in designing low-cost, compact solar water heaters.

Towards a net-zero-energy building with smart control of Trombe walls, underground air ducts, and optimal microgrid composed of renewable energy systems

In recent years, permanent outages and lack of access to electricity have been significant problems in most cities of Iran. The increasing growth of fossil fuel consumption made it necessary to change the design of buildings. Designing a net-zero energy building (with natural ventilation and renewable energy systems) is a solution for reducing fossil fuels. In this paper, dynamic energy modeling of the building for the smart operation of the trapezoidal Trombe wall and underground air ducts is performed. In the first step, the Trombe Zones are considered for heating. Then the combination of the Trombe zones with underground air ducts for cooling is simulated. Then the system combination with a solar hot water system to supply hot water energy is evaluated. Finally, the economic analysis of the optimal hybrid system (with a photovoltaic system, wind turbine, battery, and inverter) for supplying the electricity of the building equipped with both passive energy strategies was evaluated by Homer software. The results show that by integrating the Trombe wall, the heating load is reduced by 44 %, and by integrating a coupled geothermal cooling system with the air duct and the Trombe wall, the cooling load is reduced by 39%. Also, the net present cost over the 25-year life of the optimized renewable system is reduced by about 12.5% due to both passive strategies. The average daily electricity energy demand of the base building is equal to 86.37 kWh and for the passive building, it is equal to 67.49 kWh.

Designing and testing low-cost solar water heater using date palm fibers andstarch.

Solar water heaters are a type of renewable energy technology that converts solar energy into heat to warm water. Solar water heaters are becoming increasingly popular due to their eco-friendliness, cost-effectiveness, and low maintenance requirements. In this study, low-cost solar collectors were developed using date palm waste (dried leaves) as thermal insulation. Date palm waste is a readily available and abundant resource in many regions, and using it in solar collectors can help reduce waste and promote sustainability. Two solar collectors were fabricated using crushed date palm waste, with one collector using the waste alone and the other mixed with starch. Tests were conducted in accordance with the European standard EN 12975-2-2006 and modeled the thermal behavior of the collectors. The results obtained showed that the prototypes of solar collectors performed well and exhibited behavior comparable to that of a commercial solar collector, with a production cost up to three times less. The use of date palm waste as thermal insulation in solar collectors is an innovative approach that aligns with the principles of sustainability and environmental friendliness. Furthermore, it was found that the leveled heating cost (LCOH) and the simple payback period (SPP) were 0.952 US$ kWh-1 and 2.472 years for the prototype without starch and 0.926 US$ kWh-1 and 2.397 years for the prototype with starch.

Facilitating students’ design thinking skills in science class: an exploratory study

ABSTRACT This study aimed to evaluate the effectiveness of a design thinking teaching and learning model on students’ design thinking skills in science class. The study utilised two projects, ‘Making a Simple Solar Water Heater’ and ‘Drawing a 3D Topographic Map of Zhejiang Province,’ based on the 5th-grade science curriculum in China, and involved 45 Grade-5 students from a primary school. The quasi-experimental repeated measure method was used to evaluate the students’ improvement in design thinking skills, with task-based pre-, mid-, and post-tests. Employing quantitative data analysis, the results showed significant improvement in students’ overall performance, with more pronounced improvement between the pre-test and post-test than between the pre-test and mid-test. The analysis of the seven design indexes of students’ design work demonstrated significant improvement in five indicators, except for ‘material’ and ‘shape.’ The study highlights the importance of incorporating design thinking into elementary school curricula to equip students with the necessary competencies for success in the twenty-first-century workforce.

DEVELOPMENT AND INSTALLATION OF SOLAR WATER HEATING SYSTEM FOR FEDPODAM HOSTEL

This paper presents the result of the Development, Installation and Performance evaluation of a 500 liter capacity hot water storage tank with an additional 500 liter capacity cold water storage tank that was, developed, installed and tested at Maryam Abatcha female hostel in the Federal Polytechnic Damaturu, Yobe State, Nigeria which is located at latitude 12.290N and Longitude 11.440E using available materials and thermo syphon principle at an average solar radiation of 630W/m2 to investigate the potential of using solar either directly and indirectly for heating water and to compare its cost with electricity. This design utilized a flat plate collector which was chosen because of the simplicity in construction and ease of maintenance. Two collectors of 1m2 each with single glazing were used as a heat exchanger. The surfaces of the collectors were painted with black paint of absorptivity 0.95 and emissivity of 0.09 to improve its absorption capacity. Readings were taken for a period of nine months starting from March, April, May, June, July, August, September, October and November with minimum ambient temperature of 320C. Maximum hot water temperature inside the tank as 82.30C with an average efficiency of 28.06% in June, with clear sunny atmosphere days and November with lower outlet likely due to cold dusty of the period. Test conducted reveal that the system could satisfy the hot /warm water requirements of the hostel. It was also observed that the water temperature is a function of solar radiation while the cloud cover and dust particles were observed to also affect the performance of solar water heating system thereby reducing its efficiency.

Solar Water Heating Systems: A Review on Contemporary Design and Emergent Technology using PCM for Increased Performance

This study highlighted the specificity of solar water heating systems, investigating their financial benefits and discussing their economic advantages. Several studies have shown that solar water heaters' effective performance and the best cost savings were obtained during the hot seasons. New developments in solar water heaters have been discussed in detail. According to numerous researches, the highest quality performance of solar water heaters and the best cost savings were achieved when the system was integrated with innovative components such as Phase Change Materials (PCMs), heat pipes, and turbulators. Emergent technologies using PCMs have shown excellent results, increasing solar thermal efficiency. This technology presents great potential not only for domestic applications but also on an industrial scale.

Techno-Economic Feasibility of Solar Water Heating Systems in the Winemaking Industry

Techno-Economic Feasibility of Solar Water Heating Systems in the Winemaking Industry

Construction and Comparison of the Efficiency of Water Heating Systems using low Cost Solar Collectors

This work describes the manufacture of two solar water heating (SWH) systems, one using polyvinyl chloride (PVC) pipes and the other using PVC plates, both with approximately the same area of collecting solar thermal energy. The aim is to analyze their efficiencies and discuss physical concepts and their practical applications. Both SWH collectors were placed side by side under the sun, such that they were submitted to the same climatic conditions. This work also draws attention to the importance of using solar radiation1 as an alternative and sustainable source of energy for water heating.

Performance prediction of a solar hot water system with change of circulating pump efficiency in solar collectors

In this study a mathematical model was developed to predict operating performance of the solar collector under specified weather conditions at Jeju Island, Korea. The optimum mass flow rate through collector based on the relationship between the useful heat gain of solar collector and the electricity consumption of solar pump is investigated. Besides, the effect of various parameters such as solar collector area, initial water temperature and volume of storage tank is analyzed. The results of the simulation show that the system performance increased about 1.33% at m = 0 . 442 kg/s with the new coefficient K c = 0 . 17 . Furthermore the system performance is affected strongly by the change of collector area, initial water temperature and volume of storage tank It should give concise information on the aims, the methods, the results and the conclusions of the paper. Its length should not exceed 200 words.

Fermatean Fuzzy Distance ORCA Methodology for Analysis Solar Water Heating Systems

This study presents an in-depth exploration and evaluation of solar water heating systems, focusing on their technological advancements, economic viability, environmental impact, and practical applications. Solar water heating systems stand as innovative solutions, utilizing solar thermal energy to provide a sustainable and renewable source of hot water. The assessment encompasses an analysis of various collector designs, materials, and efficiency metrics, showcasing the evolution and effectiveness of these systems across different climates and settings. Economic evaluations reveal the cost-effectiveness and potential savings associated with solar water heating, emphasizing reduced energy bills and lower carbon footprints. Environmental assessments highlight the systems' significant contribution to mitigating greenhouse gas emissions and reducing reliance on non-renewable energy sources. Furthermore, real-world applications across residential, commercial, and industrial sectors underscore the versatility and scalability of solar water heating systems. Despite their numerous benefits, challenges persist regarding upfront costs, system integration, and technological limitations. However, strategic research, development, and policy interventions present opportunities to overcome these barriers and promote wider adoption. The findings from this comprehensive assessment provide valuable insights into the significance, challenges, and potential pathways for optimizing solar water heating systems towards a sustainable and energy-efficient future. This study used the Fermantean fuzzy sets with the Operational Competitiveness Rating (ORCA) model for analysis of the criteria and alternatives in solar water heating. We used the 12 criteria and 15 options in this study. The sensitivity analysis is conducted to show the stability of the results.