Solar Water Heating System Research Articles

Experiment study on startup characteristics and operation performance of PV/T solar assisted heat pump water heater system driven by direct current variable frequency compressor

The use of renewable energy can alleviate climate warming and environmental pollution. PV/T (photovoltaic/thermal) system has been widely concerned and rapidly developed owing to its capability of generating electric and thermal energy simultaneously. In the article, a PV/T solar assisted heat pump water heater system driven by direct current variable frequency compressor was proposed to meet the growing needs of residents for domestic hot water. This system was tested in different working conditions in Lanzhou, and the startup characteristics and operation performance were evaluated. The results indicate that at the same ambient temperature, low speed is conducive to the continuity of the refrigerant cycle and improves the system performance. In this system, the initial water temperature of the water tank was 23.1 °C and after 2.5 h it reached 53 °C. The average power generation efficiency is 13.64%, the average thermal efficiency is 26.42%, the overall efficiency is 62.69% and the average COP (coefficient of performance) is 4.87. Compared with traditional PV (photovoltaic) modules, the average temperature reduction is 11.2 ℃. With the increase of solar radiation intensity, the electrical power of the system will increase and the electrical efficiency will decrease. The average daily electrical efficiency of PV/T system is 13.64%, which is 6.25% higher than that of uncooled PV panel. In addition, controlling a proper compressor speed is crucial for enhancing system performance. The PV/T collector can remarkably reduce the temperature of PV panel, improve power generation efficiency and comprehensive utilization efficiency of solar energy.

TRNSYS simulation study of the operational energy characteristics of a hot water supply system for the integrated design of solar coupled air source heat pumps

To address the issues with solar water heating systems taking up a lot of space, unstable hot water supply, air source heat pumps susceptible to frost in the winter, and low energy efficiency. The TRNSYS tool is employed in this work to simulate a solar-coupled air source heat pump system. The heat pump operation is first investigated using the inverse Carnot cycle. The performance coefficient is then calculated by the second law of thermodynamics without considering the pipeline's pressure drop and heat loss. The output temperature of the hot water that the heat pump circulates is then determined. The daily hot water needs can be estimated roughly based on information about solar radiation. The heat balance equation for flat plate solar collectors was used to compute the intensity of solar diffused radiation. The Berlage calculation was used to determine the solar radiation received on the collector's surface. After a qualitative analysis of the heat from the heat source, the efficiency of the linked heat pump and the conventional air source heat pump was compared. Analyzing the water temperature change graph for each month's data reveals that the system can achieve 50 °C during the water supply time each month. The heat pump's annual energy consumption is 6252.01 kWh, while the system's annual energy consumption is 9100.47 kWh. The study findings may be used as a guide to improving the design and management of the whole system. In addition, they may improve the solar water supply system's performance.

Stearic acid-modified MOF-based composite phase change materials for solar-thermal energy conversion and storage

The utilization, conversion and storage of clean solar energy serving composite phase change materials (PCMs) formed through combination of shape-stable PCMs and light-absorbing materials becomes one of the most efficacious measures to accomplish sustainable development. In this article, the metal–organic framework (MOF) was functionally modified with stearic acid (SA) by in-situ hydrothermal method for the first time and the prepared SA-modified HKUST-1 (HS) was served as the support material for SA. The morphology and crystal structure of HS displayed unobvious change, while significantly increased the surface and formed a relatively strong hydrogen bond with SA. Therefore, the SA adsorption rate of HS reached as high as 60 wt% without any leakage, which was 20 wt% higher than HKUST-1. TaON and SiW12 were collaboratively employed as light-harvesting materials innovatively, and all PCM composites were fabricated through the simple solution immersion means. It is exciting that the SA/HS/TaON/SiW12 composite PCMs not only exhibited good shape-stability, high latent heat (126.4 J/g) as well as heightened thermal conductivity (grown by 295.9% than SA), but also displayed the outstanding thermal reliability and remarkable solar-thermal energy conversion capability (efficiency reached 96.6%). This work expanded a new orientation of photothermal materials used for utilization of solar energy especially in the application of solar water heater systems.

Performance Evaluation and Optimization of Solar Water Heater Systems: A Comprehensive Experimental Study

Abstract: Solar water heaters are an efficient and sustainable technology for meeting the growing demand for hot water in residential and commercial applications. This abstract presents a comprehensive overview of the performance evaluation of solar water heater systems through an extensive experimental study. The study aims to assess the effectiveness and efficiency of different solar water heater configurations under varying operating conditions. The experimental investigation involved the measurement and analysis of key performance parameters such as solar collector efficiency, heat transfer efficiency, thermal storage capacity, and overall system efficiency. A range of factors including solar radiation intensity, ambient temperature, water flow rate, and collector tilt angle were systematically varied to examine their impact on system performance.

Technical, financial, and emissions analyses of solar water heating systems for supplying sustainable energy for hotels in Ghana

Ghana has the potential to deploy solar energy technologies, with its solar irradiation varying between 4 and 6.5 kWh/m2/day. However, the country's dependence on fossil fuels for generating electricity and heat remains prevalent. This study aims to assess the technical and financial feasibility of installing solar water heating (SWH) systems in hotels within Ghana. RETScreen software is used to conduct the technical, financial, and emission analyses of the SWH system for five cities in Ghana, including Accra, Cape Coast, Kumasi, Tamale, and Wa. The findings show that SWH systems are feasible for Ghanaian hotels, with solar fractions ranging from 61.2% in Kumasi to 78.5% in Wa. Also, installing the SWH system yields a positive net present value for all the cities. The implication is that installing SWH systems in hotels operating in Ghana is financially viable and attractive for investment. In addition, payback periods infer that the SWH systems can generate a return on investment in a reasonable time frame, especially considering the equity payback period. Furthermore, about 58.7 tonnes of carbon dioxide (CO2) emissions could be avoided annually by installing the SWH system in the selected cities. This study's findings suggest that hotels can achieve long-term financial savings on electricity costs by utilising solar energy to heat water. This, in turn, reduces their reliance on fossil fuel consumption while actively pursuing their sustainability objectives. The study findings are crucial in assisting hotel owners in making informed decisions on SWH systems.

Project of Building: Solar Hot Water

The rapid development of urbanization in China has led to an increase in high-rise residential buildings, leading to a surge in the construction industry. However, this prosperity has brought about a significant increase in energy consumption, prompting people's demand for alternative energy. As a solution to this problem, solar hot water systems are becoming increasingly popular in China. The following contents need to be considered in the design of solar hot water systems. The general solar hot water system consists of solar collectors, solar water distribution pipes and water storage tanks. The arrangement of the water storage tank and the water distribution pipe is matched with the design of the building, which has great influence on the operation of the solar energy in the building. With the rapid increase in building height and the increase in residents, the roof area has not changed. The architectural layout will have an impact on the absorption performance of solar radiation. Therefore, in order to optimize the use of solar energy, regional planning should be considered. Different solar radiant intensity and different locations of solar collectors will lead to different collection efficiency and hot water supply conditions of solar water heating systems. Throughout the entire process of architectural design, the application of solar energy technology in buildings also requires consideration of the operating area conditions and architectural style, in harmony with the architectural style.

Overview of solar thermal technology development and applications in West Africa: Focus on hot water and its applications

Solar thermal technologies can help alleviate the sustainable energy access challenge in West Africa by offering complimentary solutions to reduce dependency on wood and fossil fuels. This paper provides a comprehensive regional overview of the water-based solar heating technology sector in West Africa in order to identify crucial factors that could boost a successful deployment of solar water heating systems in the region. Emphasis is placed on solar water heaters (SWHs), solar sorption refrigeration and solar heat for industrial process. The article summarizes the salient characteristics of widely used technological solutions and offers an understanding of the development and applications of solar water heating technology in the region. The review includes trends and research focusing on market, technologies, local manufacturing and policies, and shows that solar water heating potential remains scarcely exploited, with different status in different countries in the region. There are mostly thermosiphon systems with very few pumped systems. Industrial applications are practically inexistent, including concentrated solar heat. Finally, problems lying in the solar thermal sector in West Africa are analysed and measures for solving the problems are suggested.

IoT enabled smart solar water heater system using real time ThingSpeak IoT platform

AbstractThis dissertation aims to reuse the cold water which will initially present inside the water heater and reduce its wastage by sending it back to the water tank. The water heater temperature could be customized based on the number of users either manually or in an automated way using Internet of Things (IoT) techniques. The system is designed and operated using open‐source hardware and an IoT platform. The smart solar water heater with IoT capabilities continuously monitors the tank level, temperature, and pH level, and the data collected by the IoT node is uploaded/published to ThingSpeak. The IoT cloud analyses the sensor value and instructs the control unit of the smart solar system. The IoT enabled solar water heating system efficiency is high for smart homes and Industry 4.0. The main advantages of this model include handling multiple users, reducing the wastage of cold water, and purifying the water based on TDS level and this model aims to make it possible to control the proposed system from anywhere and at any time. The highest efficiency of the respective solar water heater could be well utilized.

Impact of the New Energy Context on the Feasibility of Solar Water Heating Systems in the Agri-Food Industry

The new energy context since 2021 has led to dramatic increases in the energy bills of agribusinesses, affecting the price of foodstuffs. A considerable part of energy consumption is due to the heating of water at high temperatures. The present study analyzed the feasibility of using a Solar Water Heating System (SWHS) with an evacuated tube collector. In particular, the required sizing changes, potential savings and cost-effectiveness were analyzed. The results show that the new energy context makes the SWHS investment highly attractive: a payback of less than 4 years in most of the scenarios analyzed; energy savings of more than 60% in the scenarios with higher irradiation; a reduction in total energy expenditure of more than 50% in the favorable scenarios close to the current reality. The new context especially favors cold and temperate climates, with very sharp drops in payback compared to the previous situation. To achieve these values, it is necessary to design an optimized sizing of the SWHS, reducing the risk of future variations in the price of energy. The results of the study should serve as a reference for decision making in the agroindustrial sector to reduce the energy bill and strategic dependence on fossil fuels from third countries.

Development and Research of a Two-Contour Solar System in the Lorawan Network

This article examines the mechanism for researching and improving the energy efficiency of a solar water heating system (SWH) in a building located in Kazakhstan. In this paper, we use data collected from LoRaWAN to obtain information about various environmental and operational aspects of the system under consideration, which determine the possibilities for improving the efficiency of various SWH subsystems and develop management strategies for the effective operation of the entire system. With the help of data collected by IoT, such as water consumption, the schedule of the heat pump and water pump, the availability of solar energy and electricity consumption, we conduct a comprehensive energy audit to analyze the efficiency of subsystems, as well as the performance of the system as a whole. Based on the findings obtained from the data analysis, appropriate management strategies are developed for various subsystems in order to increase the efficiency of the entire system and reduce the operating costs of SWH.

Integration of emerging PCMs and nano-enhanced PCMs with different solar water heating systems for sustainable energy future: A systematic review

Integration of emerging PCMs and nano-enhanced PCMs with different solar water heating systems for sustainable energy future: A systematic review

Useful energy, economic and reduction of greenhouse gas emissions assessment of solar water heater and solar air heater for heating purposes in Gaza, Palestine

This study investigated the crisis of energy from which Gaza has been suffering over the past years. It ventured to highlight the growing needs for energy and the urging need to use renewable and sustainable sources of energy such as solar thermal energy. Much specifically, it gave much importance to the solar water heater (SWH) as well as the solar air heater (SAH). These two important tools rely on clean and renewable source of energy, and their use in the Gaza Strip would greatly help in bringing about an environmental conservation and sustainable economy. The result obviously shows that both SWH and SAH systems are very suitable for space heating for buildings. The maximum annual heating energy gained is 20360.7 kWh at an inclination angle of the solar collector of 30° for SWH. While for SAH the best value of heating delivered was 19268.9 kWh at a tilt angle of 45°. Besides, the result exposes that the use of SWH and SAH systems can potentially save up to $3461.3 and $3275.7 respectively of energy cost annually. The payback achieved on the investment in SWH and SAH is 4.4 and 4 years respectively. Additionally, the utilization of SWH and SAH systems can ultimately save energy as well as potentially reduce emission of air pollution. For instance, using SWH and SAH can reduce 17306.6 and 16378.57 kg/year of CO2 emissions respectively.

Experimental Study Corrosion Parameters of Copper as an Eco-Friendly Heat Collector for Solar Water Heaters

The corrosion behaviour of copper as a solar collector material was adequately simulated in tests in a solar water heating system. The weight loss technique of corrosion determination was used under exposure conditions ranging from slightly acidic to alkaline. Uniform corrosion was observed and corrosion rates; calculated estimates of the life of a typical collector made of copper were evaluated and found to be below 0.0254 mmpy and the subsequent evaluation of the life of a 3mm thick pipe shows lives of over a hundred years under the varying exposure conditions. A significant fact is that uniform corrosion took place over the period of the test.

Study on collection and retention efficiencies of a new integrated collector storage solar water heating system using a planar thermal diode: an experimental study.

Thermal diodes are a novel method to rectify the heat transfer mechanism and help reduce heat losses in solar thermal collectors during non-collection periods. The current study introduces and analyzes a new planar thermal diode integrated collector storage (ICS) solar water heating system using an experimental approach. This thermal diode ICS system has a simple, affordable structure composed of two parallel plates. Water serves as a phase change material to transfer heat through evaporation and condensation inside the diode. Three scenarios were considered to assess the dynamics of the thermal diode ICS: atmospheric pressure, depressurized thermal diodes, and Ppartial = 0, - 0.2, and - 0.4bar. The water temperature reached 40°C, 46°C, and 42°C in Ppartial = 0, - 0.2, and - 0.4bar, respectively. The heat gain coefficients are 38.61, 40.65, and 39.26 W/K, while the heat loss coefficients are 9.56, 5.16, and 7.03 W/K in Ppartial = 0, - 0.2, and - 0.4bar, respectively. The optimum heat collection and retention efficiencies are 45.3% and 33.5% in Ppartial = - 0.2bar. Hence, there is an optimum partial pressure to achieve the best performance, equal to - 0.2bar. The acquired results illustrate the robustness of the planar thermal diode in reducing heat losses and rectifying the heat transfer mechanism. Furthermore, despite the simple structure of the planar thermal diode, its efficiency is as high as that of other types of thermal diodes analyzed in recent studies.

Influence of heat enhancement technique on the thermal performance of solar water heater for sustainable built environment. Start-of-the-art review

Solar water heater (SWH) is important and low-cost technology for transforming solar radiation into heat energy that is utilized for commercial and industrial purposes. However, due to different advantages, this technology still suffers from poor thermal efficiency and thermal losses from the collector. The various reasons responsible for the poor heat transfer rate of SWH are heat losses from the system and different geometrical shapes of hindrance promoters. The researcher is working on various innovative methods to ameliorate the effectiveness of solar water heating systems (SWHS) by using various heat enhancement methods. The solar thermal conversion efficiency is found to be 70% as compared to solar electrical direct conversion system, which is around 17%. The different heat enhancement techniques, like twisted tape turbulator and their shape, etc., play a very remarkable role in ameliorating the effectiveness of SWHS. This review work abridges the previous research work with different heat enhancement techniques, including the coating effect of pipes, collector design, use of PCM, and different geometrical shapes of turbulence promoters. The twisted tape provides better η as compared to other heat enhancement techniques.

Performance analysis of a novel solar assisted ground source heat pump water heating system with graded thermal energy storage

The solar assisted ground source heat pump system (SAGSHP) is recognized as an efficient, clean and economical renewable energy technology for hot water supply. However, in SAGSHP systems with an all-day hot water supply, the solar collectors can only heat the water tank with intense solar radiation, which wastes moderate and weak solar resources. In addition, as the SAGSHP system draws heat from the soil for a long time, the soil temperature around the borehole decreases, causing the performance of the GSHP to deteriorate. To solve the above problems, a SAGSHP system with graded thermal energy storage (SAGSHP-GTES) was proposed. This paper investigated the performance and feasibility of the SAGSHP-GTES system, using a case study of hot water supply in a campus dormitory in Changsha, China. Firstly, the drawbacks of solar energy utilization in the conventional SAGSHP system were analyzed. Then, the SAGSHP-GTES system was modeled by TRNSYS, and its operational performance was evaluated and compared with the conventional SAGSHP system. Finally, the feasibility and performance of the SAGSHP-GTES system in different climate zones of China were analyzed. The results showed that the conventional SAGSHP system had a poor solar energy utilization efficiency, with an average thermal efficiency of the SC (ηSC) of only around 19.4%. The long period of operation caused the soil temperature to drop from 18.1 °C to 2.78 °C, which led to a decrease in system efficiency and an increase in electricity consumption. By controlling the heat collection of the SC and the graded utilization of solar energy in the SAGSHP-GTES system, a high ηSC of around 42.7% was obtained, which improved the system efficiency while eliminating the problem of soil temperature drop. After 15 years of operation, the soil temperature increased from 18.1 °C to 19.9 °C, which led to an increase in the coefficient of performance of the system (COPsys) from 3.77 kW/kW to 3.84 kW/kW and COPGSHP from 3.45 kW/kW to 3.5 kW/kW, and a reduction in electricity consumption from 51,746 kWh to 50,735 kWh. In addition, the conventional SAGSHP system was not feasible in severe cold zones (Harbin) and cold zones (Beijing) of China, where soil temperatures fell below 0 °C and freezing of the circulating fluid occurred, while the SAGSHP-GTES system showed excellent performance in all climatic zones of China and is a feasible and efficient technology for hot water supply.

Field Study of Novel Storage Tank of Solar Water Heating System

In this paper thermo-hydrodynamic characteristics were investigated experimentally for a new type shell-helical coiled tube heat exchanger used as a storage tank of closed loop solar water heater system. Triple concentric helical coils were made of copper tubes of (12.5mm OD and 10mm ID) with coils diameter of (207, 152.2, 97mm) for outer, middle and inner coils respectively. The experiments were carried out during a clear sky days of (March and April 2012). The parameters studied in this work are: history of average temperature of shell side of the storage tank, collector heat gain, heat rejected from coils to shell side of the storage tank, collector efficiency, thermal effectiveness of the heat exchanger (storage tank), and pressure drop. These parameters were studied at four different circulating mass flow rates of (1.8, 3, 6, 9 l/min) and for two consuming modes of supply water namely no withdrawal, and continuous withdrawal of (1 l/min). The results show that stratification temperature in the storage tank is increased for no withdrawal compared with water withdrawal, also the shell side average temperature increases with increased solar time. Collector efficiency is increased with increasing circulation flow rates, also increases with water withdrawn from storage tank. The pressure drop decreases with the increase of solar radiation .

EXPERIMENTAL INVESTIGATION OF INDIVIDUAL EVACUATED TUBE HEAT PIPE SOLAR WATER HEATING SYSTEMS

lar water heating systems with heat pipes of three diameter groups of 16, 22 and 28.5 mm. The first and third groups had evaporator lengths of 1150, 1300 and 1550 mm. The second group had an additional length of 1800 mm. all heat pipes were of fixed condenser length of 200 mm. Ethanol at 50% fill charge ratio of the evaporator volume was used as the heat pipes working fluid. Each heat pipe condenser section was inserted in a storage tank and the evaporator section inserted into an evacuated glass tube of the Owens- Illinois type. The combined heat pipe and evacuated glass tube form an active solar collector of a unique design.The resulting ten solar water heating systems were tested outdoors under the meteorological conditions of Baghdad, Iraq. Experiments were carried out with no load, intermittent and continuous load conditions. Some tests, at no load, were carried out with and without reflectors. The overall system efficiency was found to improve with load conditions by a maximum of 55%. The system employing an 1800 mm evaporator length and 22 mm heat pipe (HP7) showed the best performance by higher water temperatures, overall useful energy gain and efficiency at various load conditions. System performance was predicted theoretically using electrical analogy derived from an energy balance. An agreement of within 14% was obtained between theoretical and experimental values.

Life cycle assessment of three typical solar energy utilization systems in different regions of China

In the future, solar energy has a major impact on the transformation of energy supply, becoming an attractive option among renewable energy sources. This study compares three typical systems that use solar energy, namely solar water heater (SWH) systems, solar photovoltaic (PV) systems, and photovoltaic/thermal (PVT) systems, under comparable conditions in different regions of China. The comparison is based on a life cycle assessment (LCA), taking into consideration the climate characteristics and energy supply in different regions. The corresponding environmental impact assessment results were obtained using the endpoint method and sensitivity analysis was performed to identify the factors that had a greater impact on the results. The findings indicate that SWH systems are more suitable for the southwest of China, where the power grid structure is dominated by hydropower. PV systems are recommended for northern and northeastern China, where coal power is the main source. In other parts of China, both PVT and PV systems are good options. Taking Shanghai as an example, applying PVT systems in Shanghai can reduce carbon emissions by 11.0% and 55.9% respectively, as well as decrease the environmental impact by 11.1% and 38.9% throughout whole life cycle, compared to PV systems and SWH.

Modeling and Simulation of Indirect Collector Solar Hot Water Heating System Based on TRNSYS

The use of solar energy is one of the important ways of clean energy heating in rural areas in the north, and the collector solar water heating system is an effective way to use solar energy. This paper takes a typical single residential house in a rural area of Shenyang as a research case to design an indirect collector solar hot water heating system. Based on the meteorological data of the winter heating period (November 1 - March 31 of the following year) in Shenyang, TRNSYS software was used to research the heat collection efficiency and scheme design of the heating system. The research results showed that: 1) The best material of the heat exchange coil of the hot water storage tank in the solar water heating system of the indirect collector is stainless steel with a thickness of 0.8mm; 2) The optimal installation angle of solar collectors in Shenyang is 55°; 3) The optimal area of the heat exchanger coil in the hot water storage tank is 4.40m2.