Solar Water Heating Research Articles

Navigating the water–energy nexus amidst the Lebanese economic crisis

ABSTRACT Lebanon's economic crisis has disrupted the country's energy and water sectors, highlighting their interdependence. The methodology involves surveying 150 municipalities across all Lebanese governorates, ensuring a comprehensive coverage of public and private water resources. Data on water and energy were collected before and during the crisis to explore this nexus during periods of economic turmoil. The findings reveal a decline in water provision during the crisis, with the average weekly water supply plummeting from 49 h in 2019 to 22 h in 2023. Concurrently, the use of water tankers has surged from 26 to 44%, indicating a concerning shift in water acquisition methods. Despite the crisis, conventional water sources remain predominant, while unconventional sources account for less than 1% of the total supply. In response to the energy shortage, renewable energy sources have gained traction in residential, commercial, and industrial sectors. The scarcity and rising cost of electricity have driven the adoption of solar photovoltaics in the water sector, reaching 4.8% for extraction from underground reservoirs and 2.8% for distribution. Similarly, the use of solar water heaters has increased from 7.9 to 15.4% in 2023. These findings underscore the interplay between energy and water security during periods of economic instability.

Literature review of potential materials for the construction of an alternative flat-plate solar collector

Through systematic review method the article presents the potential of existing solar energy in Mozambique for use in water heating with the integration of thermal energy storage systems that are currently being investigated. It emphasizes the need for affordable materials in building solar collectors for Mozambique’s homes, leveraging the country’s solar potential to reduce electricity consumption and environmental impact for sustainable development. It explores current research on thermal energy storage systems for solar water heating and reviews alternative materials for solar collectors based on their properties, cost, and availability. The importance of thermal energy storage in solar collectors for efficiency and load balancing is highlighted., it discusses and list the potential alternative materials for the construction of flat plate solar thermal collectors from roofing material, frame, absorber, pipes, and heat storage material according to their thermophysical properties, costs, and availability in the Mozambican market in the context of industrialization.

Thermal Stratification Characteristics of Storage Tanks on Solar Water Heater Inserted with Latent Heat Material

As a latent heat medium, phase change material (PCM) can be applied to heat storage for solar water heaters (SWH). The method used to place PCM is to put it in a capsule. Thermal stratification is critical in generating SWH thermal efficiency. Installation of horizontal capsules in the tank has no known effect on thermal stratification. This paper aims to study the thermal stratification in active-type SWH incorporating PCM. A cylindrical capsule containing the PCM was placed inside the tank. The thermocouple was installed on both the water and PCM sides. The charging process was conducted indoors, and the water flow rate varied from 1, 2, and 3 LPM. Water temperature data for each variation was analyzed to evaluate the thermal stratification. Richardson number analysis proved that thermal stratification was formed in all water flow rates. It was found that a low water flow rate results in high thermal stratification.

Predictors of solar water heater purchasing intention: an empirical analysis of residential behaviors in Hanoi city, Vietnam

Solar energy is a field that has grown rapidly in the world in recent years to solve the energy crisis and respond to climate change. Vietnam is a country with renewables energy potential including solar power and is pursuing net zero emissions target by 2050. This study explores factors affecting the residents’ intention to buy solar water heater in Hanoi, Vietnam. We used theory of planned behaviors and technology acceptance model to build research model and hypotheses. A community survey was conducted with 450 households in 3 districts using cluster sampling method to collect information. We conducted descriptive statistical analysis, Cronbach’s Alpha test, exploring factor analysis, conformity factor analysis and regression to identify and evaluate the impact of factors on solar water heater consumption intention. The results showed that there were significant factors affecting people’s intention to buy solar water heater including attitude, perceived usefulness, price perception, social influence and financial support in which attitude is the most influential factor. Regarding social characteristic of respondents, we also found positively significant relationship between income, education level and intention to use solar heater. Recommendations for government and business included increasing awareness of the benefits and economic feasibility of renewable energy devices to consumers through social media, implementing financial incentives to support clean energy consumption behavior, and strengtheing the emergence of local solar evangelist groups in the communities. Future research can expand to other cities and explore more indirect factors affecting the green energy consumption behavior of Vietnamese residents.

Numerical analysis of the thermal behavior of a solar heat exchanger using multiple phase change materials

Currently, solar energy is the most abundant and cleanest source of renewable energy, making it a good substitute for increasing energy efficiency. Solar water heaters can significantly reduce the cost of electricity consumption in homes and help reduce greenhouse gas emissions. Most homes use water heaters to produce domestic hot water at a temperature between 50 °C and 60 °C. A latent heat phase change module is created to account for variations in energy supply to solve the inherent intermittency problem. The solar water/PCM heat exchanger, a phase change heat storage system, is designed in this work. A numerical analysis was conducted to examine the impact of various cooling temperatures on the solidification thermal cycle of the phase change material. As this temperature range is suitable for its melting. The phase change material (PCM) can be used to effectively control the temperature. Depending on the PCM and its storage capacity, the temperature of the produced water is controlled. Through the tubes, the water used for heat transfer from the solar collector transfers the heat from the sun’s rays to the PCM. During the discharge phase, the heat that has been stored in the PCMs is then transferred to the water and heats it up. In order to quantitatively evaluate the thermal performance of the water heat exchanger, a numerical simulation using the finite volume method was also analyzed.

Analysis of the sustainability of swimming pools: Water and energy cycles

The objective of this article is to conduct a literature review aimed at analyzing recent research conducted between 2018 and March 2023 concerning the water and energy cycles in swimming pools. This review aims to provide updated information by considering the impact of the COVID-19 pandemic on the sector. Additionally, it serves as a complementary review to a previous study that encompassed research up until 2018. Four challenges that the review seeks to analyze and investigate are identified: water balance, energy balance, chemical balance, water treatment, and diverse legislation. Regarding the water balance, the importance of reducing evaporation from swimming pools is highlighted, especially in Mediterranean climates with prolonged drought periods. Various solutions to improve the water balance are analyzed, such as the use of solar covers and the optimization of the water recirculation and filtration system. In relation to the energy balance, it is recognized that the use of pumps and filters consumes a lot of energy. The review emphasizes the importance of optimizing the water recirculation and filtration system, and various ways to improve the energy efficiency of pool heating and air conditioning are examined. In addition, the use of renewable energy technologies, such as solar panels, to reduce the energy demand of pools is considered. In summary, this review updates previous research on the water and energy cycles in swimming pools, with a focus on water and energy balance. The review identifies challenges and solutions to improve the sustainability of pools and highlights the importance of addressing the complexity of applicable legislation. The results of this review are expected to be useful for future research and to promote more sustainable management of swimming pools.

Evaluation of the operational curve for heat storage technology using n-octacosane/low-density as a binding material

Heat storage technology has a critical role for a number of applications involving renewable thermal energy (such as solar water heater). The application of wax (n-octacosane/OCT) as a medium for storing heat brings many positive influences for the system. However, the operational curve is undesirable for the OCT-based energy storage, which makes it necessary to use a binding material. The present work employed LD-class polymer (LDPE) and linear-LDPE as binding materials for OCT. The mixture is prepared through mechanical hot stirring, which comes into two categories: SOCT1 (OCT/LD) and SOCT2 (OCT/LLD). The assessment through the calorimetry method shows an increment in transition temperature for SOCT with a value of 2.1 °C and 5.5 °C. This contributes to the variation of fusion energy for solid-liquid change for both materials, which amounted to 132.05 J/g (SOCT1) and 113.4 J/g (SOCT2). Another assessment related to its chemical and structural phase demonstrates that SOCT has an identical structure to OCT, indicating that SOCT is mixed physically. At the operational level, SOCT is more optimal than OCT according to the indicator related to charge and discharge duration for energy exchange. SOCT1 demonstrates a short plateau line as the indication of a steady transition between 65.4–67.9 °C, while SOCT2 indicates the average heating rate, which is higher than for single OCT. The heat releasing curve for SOCT1 varies at a lower value between 1.92 °C/min and 0.77 °C/min, while SOCT2 has the lowest variation, which is only 0.17 °C/min. Moreover, the self-insulation for SOCT2 has the lowest rate, which is only 0.3 °C/min. The evaluation and analysis from this work show that SOCT is reliable to increase the operational curve of OCT and can be implemented for thermal systems

Role of solar water heater refurbishment in student hostel building to achieve sustainability goals: A techno-economic study

Solar energy technologies are emerging as strong alternatives to their fossil fuel-based conventional counterparts for various applications. Solar water heating system (SWHS) is one of the most adopted technologies all over the world. Moreover, the building sector consumes significant energy from fossil fuels worldwide to meet hot water demand. This fossil fuel consumption can be reduced with the surplus economic and environmental benefits through the refurbishment of SWHSs in residential buildings. Additionally, the student hostels of academic institutes/Universities have great potential to save energy, environment, and money. In view of the same, the technical, economic, and environmental analyses of refurbishing SWHS in the student hostel are presented in the present paper. The analysis is carried out for the hostel named ‘Raman’ of DIT University, located in Dehradun, India. The energy-saving potentials of flat plate collector (FPC)-based and evacuated tube collector (ETC)-based SWHSs to accomplish the hot water demand of selected site are assessed in comparison with electric geyser. Moreover, the economic analysis is also reported in terms of net present value and benefit-to-cost analysis. Whereas the environmental benefit is presented in terms of reduction in equivalent CO2 emissions through implementing both types of considered SWHSs. It is found that the FPC-based and ETC-based SWHSs can fulfil 60.9 % and 67.6 % of the energy demand to heat the required water. Whereas, both of the systems are found economically as well as environmentally beneficial and ETC-based SWHS is recommended for the selected site. The present study may be useful for the energy planning and management of student hostels under academic institutes/Universities.

Thermal Performance Analysis of Thermosyphon Solar Water Heating System Using Overlapped and Reverse Flow

Thermal Performance Analysis of Thermosyphon Solar Water Heating System Using Overlapped and Reverse Flow

DESIGN AND CONSTRUCTION OF A PORTABLE SOLAR WATER HEATER

Solar thermal water heaters are an old technology used a century ago in California. They are now used extensively, in updated form, in many countries. According to government and industry estimates, well-functioning solar water heaters can theoretically displace 50 to 80 percent of the output of a natural gas-fueled household water heater, depending how hot water usage aligns with production and storage capacities. In so doing, they offer tremendous potential for reducing greenhouse gas emissions, fuel consumption, and energy bills. Such performance holds promise for California given its climate change and energy efficiency policy goals, since 40 percent of the natural gas used in California households is used to produce hot water. However, absent programs, only a specialty market for solar water heaters has developed. To encourage wider deployment, the California Solar Initiative—Thermal program offers financial incentives for systems qualifying under a carefully crafted set of specifications. The program has had some limited success since its inception in 2010. Within that context, this research assessed the performance and potential future use of natural gas-displacing solar water heaters in single-family homes in California, attending to a wide range of sociotechnical considerations. This project documented high diversity in user satisfaction and perceived system performance, and a qualified decrease in project costs to below $5,000 per installation. Solar water heating is a technology in progress, not universally suitable but instead appealing to varied niches shaped by household sensibilities, abilities, and hot water use levels. Thus, recent evolution provides a counterpoint to the pessimism, even as serious difficulties remain. The suitability of solar water heating for California households is not purely a matter of cost effectiveness within a typical energy efficiency framework, but also of evolving performance, perceptions, and values in light of ongoing and aspirational energy and social transitions ahead. . Key Words: Solar thermal water heating, renewable energy, domestic hot water, residential natural gas use, sociotechnical energy analysis, energy futures

An experimental study of the effect of solar tracking technology on the performance of a single phase open thermosyphon: a case study

ABSTRACT Recently, an increase in the demand for evacuated tube solar water heaters has been observed in Iraq due to their acceptable thermal efficiency, which reduces the dependence on electrical energy to heat water for domestic uses. The efficiency of the evacuated tube increases with the amount of received solar radiation. Therefore, in the present work, the evacuated tube has been installed at the center of the parabola cylinder to focus more sunlight on its surface. Since the sun has a relative movement concerning the earth, which is variable from one season to another, and during the day from sunrise to sunset, heating water with an evacuated tube solar water heater (ETSWH) has fluctuating temperatures. An effective technique for increasing the efficiency of a solar water heating system is solar tracking technology, which exploits solar radiation continuously during the day. The LDRs were utilized as sensors, and a 12 V linear actuator have been used to guide the position of the modified trough solar water heater (MTSWH). A microcontroller board (Arduino Uno) implements the program code (software part). The MTSWH was experimentally tested, and the results showed that installing a single-phase open thermosyphon evacuated tube at the focus of the parabolic cylinder (MTSWH) increased the thermal efficiency by 16.5%. Moreover, the implementation of solar tracking system led to an increase in the outlet water temperature by 32% and ensured a continuous supply of water throughout the day at high temperatures compared to the conventional trough solar water heater (CTSWH). This study revealed that the MTSWH performance results showed good agreement with previous studies.

Effect of Full Implementation of Domestic Solar Water Heaters on the Electricity Peak Load in Libya

Electricity plays an important role in the contemporary life, and it has become indispensable nowadays. Reducing the peak electricity load and increasing the load factor have been considered as one of the main tasks that have to be accomplished by both electricity generation-side and demand-side managements.The residential sector of Libya consumes over 31% of the total sold electricity, and 29.8% of that is delivered to the electric water heating load. This is an inefficient way of electricity utilization. Usually, the electricity supplier in Libya used to increase the local generation capacity or import electricity from neighboring countries. Both solutions did not resolve the problem. This work attempts to investigate the effect of replacing electric water heaters in the residential sector of Libya by solar water heaters on reducing the electricity peak load and increasing the load factor. The results show that on average 3% of the peak load demand can be saved. This is equivalent to 149.5 MW of reduced power. The study also revealed that the annual amount of energy saved is up to 2.55TWh, and the load factor is improved by 2% (i.e. from 65% to 67%). This saved energy is equivalent to a power plant with a nominal capacity of 448 MW considering a load factor of 0.65.

Enhancing Thermal Efficiency in Solar Water Heaters: The Role of Reflective Walls

Enhancing Thermal Efficiency in Solar Water Heaters: The Role of Reflective Walls

Researchers identify best spots for Californian solar water heaters

Using weather reports, solar-resource availability, and installation data, researchers identified where Californians solar-powered water heaters can best replace gas alternatives.

Energy Savings, Environmental Impacts and Monitoring Results of a Pumped Solar Water Heating System at Katutura Hospital Maternity Ward, Namibia

The SADC region is endowed with solar radiation between 1800-2400 kWh/m2 [1]. Nevertheless only 0.3 % of the worldwide solar thermal capacity is installed in the Sab-Saharan African Countries. Therefore, the main goal of the Southern African Solar Renewable Heating and Cooling Initiative (SOLTRAIN+) project funded by the Austrian Development Agency is to contribute to the transformation of the energy system to a sustainable, affordable and carbon-free system. This will be done by the implementation of Renewable, Heating and Cooling (RHC) systems in the targeted sectors: buildings, industry & commerce, tourism and hospitals, and enable this by a holistic capacity building. RHC technologies are solar thermal, heat pump and energy efficiency. This study therefore intends to evaluate and produce energy balance, based on real data recorded from January 2023 to December 2023 on a 120 m2 collector area with 8000 litres storage tanks, and a 22 kW heat pump, installed at Katutura State Hospital maternity ward.

Enhancing frameworks for utilising Sankey diagrams in modelling the water-energy nexus and circularity

Understanding the connection between water supply and energy consumption in a circular economy is crucial for managing the demands of these resources. Sankey diagrams have the potential to enhance the visualisation of resource flows. However, there is a knowledge gap regarding the effective use of Sankey diagrams to capture the water-energy nexus and circularity of water. This study focused on effectively utilizing Sankey diagrams to model the nexus of water and energy flows and to assess the circularity of water. A comprehensive literature review was conducted on major studies on water material flows and modelling. This was supported by a review of approaches for modelling circularity, which have evolved from the material circularity index. The newly developed framework in this paper models water resource flows at all stages of the water supply chain, embedding the nexus as an interaction and considering resource intensity and material circularity index at each node. A city-level case study in South Africa was then used to apply the recommendations, model circularity, and the water-energy nexus using Sankey diagrams. In terms of circularity, the results indicate that water loss in the study area was very high, accounting for up to 40% of the total water supply and the water recycle rate was still very low, ranging from 3% to 7%. In terms of the nexus, the residential sector was found to have the highest energy intensity for water supply, primarily due to energy demand for water heating. Exploring the use of renewable or solar energy for water heating will be of interest and value. The new approach presented in this study allows for the simultaneous consideration of objectives, enabling a more robust analysis of energy-effective water use and water circularity along the water supply chain.

Analysis Based on Intelligent Model about Intelligent Integrated Design of Additional Building Components and Solar Heat Collection Facilities for Offshore Residences

Using an intelligent model, this paper explores the incorporation of supplementary components in offshore buildings and their utilization within offshore residences. Additionally, it investigates the intelligent integration of solar heat collection systems with residential structures. Based on this computer intelligent method, by the building the 3D model, the potential impacts of additional components of offshore residential buildings on heat collection facilities are analyzed and the means for expanding the usage of additional components by the intelligent integrated design with heat collection facilities are explored. By conducting surveys and studying existing buildings, we analyze practical issues and propose viable solutions through integration with architectural design. This procedure lays down a solid theoretical groundwork to propel the intelligent amalgamation of solar water heaters with residential buildings situated offshore.The computer intelligent method discussed in the paper will enhance the analytical approach and efficiency for evaluating intelligent integrated building designs.

Enhancing Reliability of Empirical Temperature Measurement of a Solar Water Heater System with a Temperature Data Logger

Enhancing Reliability of Empirical Temperature Measurement of a Solar Water Heater System with a Temperature Data Logger

Novel working fluid pair of methanol/betaine-urea for absorption refrigeration system driven by low-temperature heat sources

An absorption refrigeration system (ARS) designed for low-temperature heat sources like industrial waste heat, solar-heated water, or geothermal heat can offer substantial energy-saving benefits. This study explores a novel working fluid pair comprising methanol and betaine-urea (BE-UR), forming a deep eutectic solvent (DES) system. This design capitalizes on methanol's high enthalpy of vaporization, the low heat capacity of the working pair, and the appropriate intensity and strength of the hydrogen bonding network within the solution. The proposed fluid pair shows full solubility of BE-UR in methanol at a mole ratio of 1.81 to 1 (methanol to BE-UR), with an equilibrium vapor pressure dropping to 8.59 kPa at 303.15 K. Molecular dynamics simulations unveil a microscale solution structure, showcasing a hydrogen bond network and unbonded methanol in the concentrated working fluid pair. This configuration enhances the absorption process of methanol vapor in the ARS absorption unit. Aspen Plus simulations predict a coefficient of performance (COP) exceeding 0.85, comparable to H2O/LiBr in single effect-ARS and outperforming NH3/H2O in SE-ARS by approximately 30 %, while maintaining a lower cycle ratio of about 2.

New and effective combination of an absorption desalination systems with adsorption and humidification-dehumidification desalination systems utilizing internal heat recovery methods

The fast growth in population and the need for human comfort leads to a significant rise in freshwater shortage and energy usage. This article provides new and effective combinations between absorption (ABDC), adsorption (ADDC), and humidification-dehumidification (HDH) desalination plants. Four new configurations employing different external and internal heat recovery methods between the plants and their components are proposed to enhance the overall system performance, water production, and utilization of the used energy. In all configurations, the solar water heating system is used to power the ABDC. While the ADDC and HDH were powered by the heat recovery from condensation, absorption, or generation processes. Internal heat recovery methods are also applied between the evaporator and condenser in ABDC and ADDC plants to increase energy utilization. The results are evaluated and compared with standalone ABDC results and with previous related studies at different conditions. The production share percentage (%) from each plant for the suggested configurations with regeneration temperatures is also investigated. The maximum water production is achieved by the fourth configuration (3 m3.day−1 with a gain output ratio (GOR) of 1.316 at 120 °C) when the ADDC is worked by the outlet hot water from the ABDC, and internal heat recovery utilized between the condensation and evaporation components of both ABDC and ADDC. The highest GOR is obtained from the second configuration (1.714 at 90 °C). The finding expressed that the proposed configurations have a better performance than traditional ABDC systems. Also, the proposed configurations express another advantage over traditional ABDC, that the configurations have the potential at low-temperature heat sources (55–65 °C) to improve the water productivity to about 455 % and GOR to about 120 %.