Conventional Solar Water Heater Research Articles

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.

Real-time outdoor experiment and performance analysis of dual-coil heat exchanger integrated thermal energy storage

Integrating a thermal energy storage system into a solar water heater enables a continuous heat supply to ensure hot water is available for household uses throughout the day. This research emphasizes integrating TES units into solar water heating systems. The overall performance of flat plate solar water heaters for a regular (conventional) solar water heating system and a solar water heating system integrated with TES using phase change material (PCM) are analyzed. This innovative design ensures efficient heat capture from the sun, storing it in the phase change material for later use, guaranteeing a sustainable and cost-effective solution for hot water needs. A split PCM tank is integrated within the solar water heating network for the second scenario and is made of a 25 L filled with a phase change material that acts as the thermal storage medium. The PCM tank has a dual-coiled heat exchanger to aid the heat transfer process with paraffin wax as the phase change material. The parameters that are looked into from the conventional and TES-integrated solar water heating systems include the water temperature profiles throughout the entire solar water heating networks and the PCM's temperature distribution throughout the day. A customized water draw schedule is adapted to represent the average hot water usage of a typical household in Kuala Lumpur. Findings reveal that the TES-integrated solar water heating system can be 21 % more efficient than the conventional system due to the lesser heat losses and prolonged hot water supply. The maximum efficiency obtained is about 82 %, and energy can be saved about 50 % from the electric heater. The maximum energy storage is at the 50 °C temperature controller's setting and is feasible for the existing conventional solar water heaters.

Techno-economic assessment and environmental impact of photovoltaic and conventional solar water heating systems in cold climates

Techno-economic assessment and environmental impact of photovoltaic and conventional solar water heating systems in cold climates

Innovative conceptual approach in concentrated solar PV/thermal system using Fresnel lens as the concentrator

ABSTRACT Photovoltaics (PV) is an ever-evolving field. Significant technological advancement in the PV field has been evident in recent years, including PV concentrators to enhance energy density. The present experimental study explores the viability of using a refractive Fresnel lens for electrical and thermal energy through a novel approach, i.e. irradiance bi-focussing method. Unlike in most of the concentrated PV (CPV) studies, real size PV module (polycrystalline) is used here, and its surface temperature was maintained well within 80°C with the help of a self-sustainable (burlap-based) passive cooling technique. Since the concentrated irradiance gets bifurcated and simultaneously received by both PV module (≈⅓) and the thermal collector (≈⅔), the power output from CPV is more than double compared to the reference module, and the maximum thermal efficiency recorded is 48%. Even the exergy analysis upheld the proposed system as the maximum exergy efficiency is ≈ 2.5 times compared to the reference module. Concerning the heat gain, the thermal collector performance is on par with a conventional solar water heater. Hence, such a combi system can entertain a variety of day-to-day energy applications. Further, as the distance between the concentrator and PV module changes the illumination level, it can be optimized based on the cooling and/or PV module type.

Improving the thermal efficiency of a solar water heater by using PCM

The study consists in comparing the thermal behavior of two solar water heaters: a conventional solar water heater and an PCM solar water heater. The aim of this work is to numerically study the importance of phase change materials (PCMs), by analyzing their potential for storing solar energy by latent heat of a phase change material. in an installation to produce domestic hot water. The mathematical model used to simulate the phase change in the PCM is based on the enthalpy formulation of the energy conservation equation. The finite difference method is used for the numerical resolution of the selected model. To validate the mathematical model, a comparison of the numerical predictions made with an analytical solution. The results show that the energy stored by PCM solar water heater is almost 320% more than the energy stored by conventional solar water heater.

Performance evaluation of an enhanced self-storing evacuated tube solar collector in residential water heating application

Phase change materials (PCMs) offer higher levels energy storage density than conventional hot water tanks commonly used with solar hot water systems. The present study aims at investigating the integration of a selected PCM within the structure of an evacuated tube solar hot water system to create some compact thermal storage capacity. Then conventional solar water heater is compared with this novel PCM-based self-storing design. The results show that the proposed self-storing design can maintain the collector output temperature at around 63 °C after 15 h of not receiving any sunlight. That is whilst the output temperature of the normal collector drops down to ambient temperature in the same period. The obtained energy storage efficiency is 57 % and 75 %, and overall thermal efficiency is 49 % and 72 %, for the normal and the self-storing collectors, respectively. For the small-scale system used in this study, the proposed design helps reduce the size of the hot water storage tank required to supply the hot water demand by 55 %. The study also shows that the same design can even yield better performance at larger scales used in practical applications.

Design and Development of Solar Water Heater to Enhance Thermal Efficiency

Abstract: This project is about development of a solar water heater with increased thermal efficiency using nanofluids as enhancement medium compared to conventional solar water heater which uses water as the working medium to overcome the inadequate heating of water in the seasons like rainy and winter. In this project Al₂O₃-H2O nanofluid is used as working medium, where Al₂O₃ is used as nanoparticle and water is used as base fluid. A nanofluid is a fluid containing nanometer sized particles, called nanoparticles. These fluids are engineered colloidal suspensions of nanoparticles in a base fluid. It also includes analysis at various concentrations of Al₂O₃ to determine the performance of the solar water heater.

A novel design for solar collector used for water heating application having nanofluid as working medium: CFD modeling and simulation.

A solar collector is a simple and cheap device that converts solar radiation into valuable heat energy. The thermal performance of the solar collectors can be enhanced significantly with the suspension of nanoparticles in the base fluid. A novel design for a solar-assisted water heater (SWH) is proposed in the current study, and the effect of nanofluid has been investigated on the thermal efficiency of the SWH. The use of nanofluid is one of the prominent methods in comparison to other techniques for improving the performance of solar collectors. Therefore, the base working fluid, i.e., water is mixed with the alumina nanoparticles of average particle size of 30nm, and they are assumed to be spherical. The flow and thermal characteristics of nanofluid through the solar water heater are simulated numerically with the help of the Eulerian-Eulerian two-phase model using the finite volume method (FVM). The commercial package ANSYS Fluent, is used for modeling the problem under transient conditions with a pressure-based solver. In comparison to a conventional flat plate collector, the proposed solar water heater consists of a corrugated absorber-plate and the effect of the radius of curvature has been investigated on the heat transfer and collector efficiency. With the proposed design, the heat transfer area available with the riser tubes increases remarkably and it leads to a 43% and 14% increase in heat transfer augmentation and collector efficiency, in comparison to the conventional solar water heater.

A Comparative Performance Analysis between Serpentine-Flow Solar Water Heater and Photovoltaic Thermal Collector under Malaysian Climate Conditions

Solar energy has increasingly been employed for domestic and industrial water heating. Both conventional solar water heater (SWH) and photovoltaic thermal (PVT) systems suffer from the drawback of poor energy conversion efficiency. In this article, a unique parallel serpentine-flow thermal collector has been designed and developed that has been employed as an isolated SWH and also integrated with a 32-cell monocrystalline photovoltaic (PV) module. Simulation models of both SWH and PVT systems have been built in TRNSYS to study their thermal performance numerically. Thereafter, outdoor experimental investigations have been conducted under the composite climates of Malaysia. Experimental results show very good agreement with the simulation outcomes with disparity less than 2%. At the optimum flow rate, the maximum thermal efficiencies of SWH and PVT are 82.5% and 74.62%, respectively. Superior water outlet temperature was obtained with SWH. Although SWH exhibits superior thermal performance, PVT’s additional electrical output might make it preferable for several applications.

Study on PCM Assisted Constant Temperature Water Heating System

Spread of novel coronavirus across the globe creates panic situations internationally. Major challenge of this pandemic situation is the absence of a specific treatment or vaccine for curing the disease. As per published report of WHO, temperature above 55 ° C is potentially kill Corona virus. This study focuses on design a water heating system that could provide water above the required temperature with minimal input power even during the off-sunshine hours. The thermal performance of Phase Change Material (PCM) integrated solar water heating system providing water temperature above 56 ° C both during the day and the off sunshine hours has been discussed in this present study.The phase change behaviour of paraffin-wax-6035 confined within a copper tube of 100 mm diameter and 1000 mm length and 1 mm thickness, has been studied using CFD analysis. The analysis is carried out for three different cases viz. conventional solar water heating system, modified solar water heating system integrated with bare PCM tube and finned PCM tube of 1 mm fin thickness. The thermal storage capacity of solar water heater is compared based on the thermal storage capacity factor which is calculated to be 1.1149 & 1.1586 for bare PCM tube and finned PCM tube case, respectively with respect to the conventional solar water heater.

Development of Integrated Solar Water Heater Using Phase Change Material

Main barriers for installation of conventional solar water heating system (SWHS) are requirement of large installation area and heavy weight of the heat storage tank consisting water. A storage tank with minimum capacity of 230 liters are needed for household usage and this tank when empty can weigh up to 100 kg while a filled tank could weigh up to 400 kg. In reality, installation of this conventional system require more space and heavy structural support on the roof, which is not available in most houses. As a solution, a form stable light harvesting phase change material (FSLHPCM) integrated compact system is proposed. This new SWHS consists of glass – topped collector cum storage tank filled with FSLHPCM. This new FSLHPCM is form stable, does not leak and exhibit stable latent heat when tested to 1000 thermal cycles. It is capable to not only store heat but can improve the collector efficiency by harvesting the visible light and converting it to heat. The additional light to heat conversion efficiency was 22%. In the new system a maximum 75 liters’ glass-topped collector tank is sufficient to substitute a 230-liter tank. This will reduce installation, renovation and maintenance costs for the SWHS.

A U-Shaped Oscillatory Liquid Piston Compression Air Conditioner Driven by Rotary Displacer Stirling Engine

A rotary displacer, Stirling engine-driven, oscillatory liquid piston-compression air conditioning unit is analyzed, designed, and conceptually proved by experiments on its cooling capability and performance efficiency. The engine itself aims to work compatibly with a conventional solar water heater as its power source, with a rotary displacer to manipulate its operation frequency. A U-shaped, oscillatory liquid piston, with the cylinder chamber vented to low pressure, aims to both reduce the sealing friction and serve as the refrigerant. During the experiments, the engine is fed with an electrically heated hot bath whose temperature profile is determined according to a field test of solar thermal collectors in summer conditions. Experimental results show that the coefficient of performance (COP) of the oscillatory liquid piston air conditioning unit would be in the range of 1.3 to 1.5.

Comparative study on the annual performance between loop thermosyphon solar water heating system and conventional solar water heating system

Loop thermosyphon (LT) is usually introduced to overcome the freezing and corrosion problems associated with the conventional solar water heating (SWH) system. Compared with the conventional SWH system, the LT-SWH system possesses a lower nighttime heat loss because of the thermal diode property of loop thermpsyphon but bigger daytime heat loss because of the secondary heat exchange. However, the effect of above interaction to the system performance is rarely reported based on long-term running. In this study, based on the typical meteorological year data of Fuzhou city, annual performances of above two systems, including the effective number of supplying days, effective heat gain and nighttime heat loss, are comparatively analyzed under two different operational modes. Variations of above mentioned variables with the increment in the set temperature are discussed. The results indicate that, under the discontinuous heating mode, the effective numbers of supplying days of SWH system and LT-SWH system are 139 and 153, respectively. While the numbers of days are respectively 168 and 173 under the continuous heating mode. The SWH system possesses an expected bigger nighttime heat loss ratio with an average annual value of 15.07% corresponding to 6.15% for the LT-SWH system. Particularly, for the LT-SWH system, the different relative magnitudes of heat loss coefficients functioning at different times leads to a smaller temperature drop at night and also a smaller temperature rise at the subsequent day. It generates an unanticipated results that corresponds to the same month from November to April, the two systems have the approximate effective heat gain. The set temperature significantly influences the relative magnitudes of annual effective number of supplying days and annual effective heat gain, the superiority of LT-SWH system gradually diminishes and even reverses with the increment in the set temperature. The bigger daytime heat loss dominating the dominance is responsible for that transition. Combining with a longer static payback period, it is conditional to substitute the conventional SWH system with the LT-SWH system, especially when the water temperature on demand is high.

Calorimetric investigation of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate as salt mixture encapsulated materials for thermal energy storage

The use of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate salt composite as an encapsulated phase change material in solar water heater storage unit for thermal energy storage was experimentally tested and investigated in this research study. A differential scanning calorimetry is performed to determine the properties such as melting temperature, specific heat capacity, and latent heat of the selected mixtures for the proportion 70:30 and 80:20 by weight. For the experimentation, these two samples are stored separately in the aluminum canisters and filled in storage tank to avoid the heat loss directly. The thermal performance of the solar water heater at different zones on collector with and without using encapsulated phase change material in storage tank was tested experimentally. Maximum temperature achieved in solar water collector was 50°C at midpoint and 46°C at outlet of the tank. It is found that even after late evenings 18.00 IST, the average storage tank temperature with phase change material was found to be nearly 2.6 to 3.2 times greater than conventional solar water heater and the average temperature of phase change material is 42°C. The test results shows that sample B 80:20 will produces higher amount of hot water and stores the maximum heat compared to sample A 70:30. The results demonstrate that this encapsulated phase change material cylinder stores higher latent heat of fusion and, it can also be used for indirect solar cooking and other low temperature application even at late evenings.

Exergy analysis of solar thermal energy utilization for buildings: comparison between Multiple source & Multiple use Heat Pump (MMHP) and Solar Water Heater (SWH) systems for winter season

In recent years, there are various utilization methods of solar thermal energy and it is hard to find which system is the best to utilize energy as work from the view point of energy concept alone. Therefore, we conducted exergy analysis of two different solar energy utilization methods: one is a multiple source & multiple use heat pump we have developed; and the other is a conventional solar water heater. In order to clarify the performance gap depending on the solar radiation between the multiple source & multiple use heat pump and the solar water heater, exergy analysis was carried out on a clear-sky day and a daily average under the condition of equal exergy output. The results show that the performance of the solar water heater highly depends on the weather conditions, on the other hand, the multiple source & multiple use heat pump shows high performance regardless of the weather conditions.

VALIDATION OF A HEATING SYSTEM IN THE FARROWING HOUSE USING A CFD APPROACH

ABSTRACT The current heating system for piglets in the farrowing usually uses incandescent lamps and, in some cases, heated floors with electric resistances, which in most cases generates a high energy cost. Thus, the implantation of systems that use renewable energies in the heating of piglets can allow the thermal comfort of the animals without reducing the productive development. The objective of this research was to evaluate a computer model in Computational Fluid Dynamics (CFD), which predicts surface temperature in the heating system of a farrowing house. The study was conducted during the summer season on the swine sector of Federal University of Lavras, Brazil. For this study, a prototype solar heater using alternative materials (ASWH) was developed and compared with a conventional solar water heater (CSWH). Two floors were built of cement to test both heating systems and four thermocouple sensors (K type) with digital display were used in each system to test and evaluate the heating efficiency. Based on the results, the average surface temperature in the ASWH and the CSWH treatments was 27.9 ± 2.6 °C and 27.1 ± 1.9 °C, respectively. Therefore, the experimental data showed no significant differences from the data obtained by the model, enabling the conclusion that it is suitable for predicting the thermal conditions of this type of heating system and could be used in swine factories to predict energy consumption. Thus, this computational model can be used as a useful tool for the design and selection of heating systems used in swine maternity systems.

ANALISA PENGARUH PENAMBAHAN THERMAL ENERGY STORAGE PADA PEMANAS AIR TENAGA SURYA TIPE PLAT DATAR

Abstract: Solar energy, the renewable energy is only available at certain hour. So it is essential to develop efficient, economical solar thermal energy storage. Thermal energy storage (TES) systems provide several alternatives for efficient energy use and conservation. Phase change materials (PCMs) for TES are materials supplying thermal regulation at particular phase change temperatures by absorbing and emitting the heat of the medium. TES in general and PCMs in particular, absorb energy during the heating process as phase change takes place and release energy to the environment in the phase change range during a reverse cooling process. PCMs possesses the ability of latent thermal energy change their state with a certain temperature. Paraffin is the PCM used in this research. Paraffin is being added to a solar water heater to store thermal energy at daylight and supply the stored energy to the heat pipe when the sundown. From this research, it is found that the solar water heater with paraffin need longer heating time than the conventional solar water heater but it could provide steadier heating performance and warm water even when the sun was down.

An Empirical Study on the Thermal Performance and Dynamic Behavior of Wall Integrated Thermosiphon Solar Water Heater

In this study, the evaluation of the dynamic behavior and thermal performance of the “Façade integrated Natural circulation Solar Water Heating System” installed in the residential house was carried out. Experimental tests were performed during the all year around in the rural houses of 166 m2 in size. Facade integrated solar collector of 5 m2 were installed on the south-facing. Electrical heater of 1 kW capacity as an auxiliary heater was installed at the upper part of the heat storage tank. The analyzing results are as follows. (1) Monthly average solar fraction was 51 to 87% and yearly average value is 64%. (2) Hot water supply temperature in December which has the lowest solar altitude is 37 to 76℃. The highest working fluid temperature of solar collector in this period was below 84℃. The temperature difference of working fluid between the collector inlet and outlet has been shown to be around 9 to 26℃. (3) Overheating which is one of the biggest problems during summer did not appear at all, but rather had hot water supply temperature is rather low as 30~47℃ in summer than winter, which is supplied by a small solar load. The solar collecting temperature has been shown to maintain below 55℃. (5) The thermal performance of Facade integrated solar collector can be increase due to the reduction of heat loss to the back of the collector wall integration of the collector is reduced. As a conclusion, Facade integrated natural circulation type Solar Water Heating System is a well-functioning without any pumps or controllers, and it was found that the disadvantages of conventional solar water heaters, hot water or hot water system can be greatly improved.

Carbon Nanotube Dry Spinnable Sheets for Solar Selective Coatings by Lamination

Carbon nanotube, oriented free standing sheets can be laminated on any surface as selective solar absorbers while simultaneously dry spun in a highly controlled process from vertically oriented forests grown by CVD. We have found that properties of a CNT forest strongly correlate with the optical transparency and reflectivity of CNT sheets required for solar selective coatings and can be properly tuned for optimal coatings for solar collectors. We study absorptive and emissive properties of CNT sheets that are laminated by a simple automated and controlled process, developed for coating of cylindrical glass tubes for evacuated solar collectors (ETC). The advantages of Joule heating of CNT coatings are demonstrated and test results described, showing a unique property of fast heating as compared to slow heating in conventional solar water heaters.

Numerical analysis of an integrated storage solar heater

This work aims to evaluate the performance of an integrated phase change material (PCM) solar collector. The dynamic behavior of the system is investigated via a theoretical model based on the first law of thermodynamics and oriented to deliver a maximum outlet water temperature. A parametric study is used to assess the effects of the inlet water temperature, the PCM thicknesses and properties and the mass flow rates on the outlet water temperature and the melt fraction. A comparison with a conventional solar water heater without heat storage is made. Results indicate that charging and discharging processes of PCM offer six stages. It is observed that the complete solidification time is longer than the melting one. The latent heat storage system increases the heating requirements at night. The rise is most enhanced for higher inlet water temperature, melting PCM temperature and PCM thickness and for lower mass flow rate.