Solar Domestic Water Heating Research Articles

Impact of myristic acid on novel designed manifold assimilated with domestic solar water heater: An experimental approach

In this study, myristic acid as heat storage material was assimilated with a novel designed manifold of evacuated tube solar collector (EVTSC). The foremost advantage of this design is that the integration of myristic acid in the manifold does not affect the vacuum tube’s strength and does not occupy extra roof space. Also, the advantageous thermal and chemical properties of myristic acid improve the performance of the system. The proposed system was tested for two different charging operations of storage material i.e. half-day charging operation and whole-day charging operation for water flow of 0.066, 0.133, and 0.20 LPM (liter per minute). These charging operations were selected to optimize the performance of the proposed system for daytime and nighttime hot water demand. The heat transfer analysis of the proposed system during both charging operations is also determined and compared. In addition to this, the machine learning approach is used to predict the hot water temperature. Concerning experimental results, the daily efficiency during HD-CHO is almost 62.42 %, 69.17 %, and 79.12 % respectively for the water flow of 0.066, 0.133, and 0.20 LPM. Whereas, during WD-CHO, daily efficiency was approximately 71.49 %, 80.42 %, and 85.21 % respectively for corresponding flow rates. Furthermore, the daily efficiency of the proposed system during HD-CHO and WD-CHO is found to be 42.85 % and 61 % higher than conventional systems. The higher and lower flow rates during both charging operations are recommended in terms of high daily efficiency and high hot water temperature respectively. Hence, the proposed system is designed to improve thermal performance, fulfill the hot water demand during late evening time, and decrease the overheating concern as compared to the conventional one.

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.

Simulation of a Solar Domestic Water Heating System with Different Collector Efficiences and Different Volumen Storage Tanks.

This paper shows the modeling and dynamic simulation, of a domestic solar water heating installation. The results of simulations performed on an annual basis for a solar system, operated in Santander (Spain), which provides hot water for a family (four persons) are presented. The installation consists in a solar flat collector, a water storage tank, a source of auxiliary energy, and a device for blending water. The mathematical model is used to evaluate the annual variation of the solar fraction respect to the volume of the storage tank, demand hot water temperature required, difference of this temperature and preset storage tank water temperature, and consumption profile of the domestic hot water demand. The results for a number of designs with different storage tank volumes, show that the systems with greater volume yield higher solar fraction values. However, when a larger storage tank volume is used, the solar fraction is less sensitive to a variation of these operation parameters. The results of this simulation may be used to design a solar collector system.

Influence of the Number of Tanks on the Performance of a Domestic Solar Water Heater

Influence of the Number of Tanks on the Performance of a Domestic Solar Water Heater

PCM-based domestic solar water heating in Malaysia: Setbacks and countermeasures

Solar water heating (SWH) systems have yet to be widely employed despite their promising features for hot water production, especially in rural areas. This paper discusses several setbacks to the implementation of SWH systems. Generally, the setbacks are related to weather issues, the collector’s technical damages, and financial constraints. A few potential countermeasures to these setbacks are also listed.

Thermal analysis of a cascaded latent thermal storage tank in a solar domestic water heating system

AbstractTo enhance the thermal characteristics of a solar collector storage system, this study investigates the performance of a rectangular thermal energy storage (TES) tank by incorporating cascade phase change materials (cascade‐PCMs). Three different commercially available PCMs (RT44HC, RT54HC, and RT62HC) with distinct melting temperatures are employed. These cascade‐PCMs are utilized as slabs in vertical rectangular modules, which are integrated into the water TES tank. The heat transfer fluid (HTF) in the flat‐plate solar collector captures solar energy and transfers it to the TES tank, where it is stored as latent thermal energy. A two‐dimensional (2D) numerical model, utilizing the enthalpy‐porosity approach and conservation equations, is developed to analyze the melting and heat transfer processes within the TES tank. The model is validated against previous experimental and numerical data. Performance evaluation of the cascade‐PCMs tank is conducted during a 9‐h charging period (from 8:00 am to 5:00 pm) under Marrakesh weather conditions in Morocco. An optimization study is carried out to determine the optimal height of each cascade‐PCM. The results suggest that an optimal design with heights of 23, 16, and 11 cm for RT44HC, RT54HC, and RT62HC respectively, offers improved melting and storage quality. The thermal characteristics of the TES tank incorporating cascade‐PCMs are compared to those of a TES tank filled with a single phase change material (single‐PCM) during the charging period. The findings indicate that the cascade‐PCMs achieve complete melting, while the single‐PCM only reaches a melting fraction of 0.903 at the end of the charging process. Furthermore, the optimal configuration of the cascade‐PCMs storage tank exhibits slightly higher sensible and latent thermal energy storage capacity compared to the single‐PCM tank. The combination of the solar collector with the cascade‐PCMs storage tank results in a 3.47% higher average collection efficiency when compared to the single‐PCM tank.

Preparation, stabilization, and thermal characterization of CuO/water nanofluids applicable to domestic solar water heater

In this contribution, an experimental investigation has been carried out to analyze the stability and light absorbance characteristics of CuO/water nanofluids applicable to domestic solar water heaters. Nanofluids are prepared at 0.01–0.05 wt% by dispersing dry CuO nanopowder in water in presence of Gum Acacia (GA) stabilizer via ultrasonic agitation. The stability of the nanofluids is examined through gravity sedimentation. The samples are exposed to natural sunlight as well as LED light to examine their light absorbance potential by virtue of temperature rise. The light absorbance potential of nanofluids as compared to water is expressed as Temperature Variation Ratio (TVR). The nanofluids remain stable for six months. The sedimentation is more in higher concentration relative to their dilute counterparts. The absorbance capacities of the nanofluids augment with the nanoparticle addition to base fluid. However, 0.01 and 0.05 wt% samples show relatively lower absorbance due to a higher sedimentation rate. Maximum absorbance is observed with 0.03 wt% which shows a maximum temperature rise up to 60 °C under sunlight and 56 °C under LED light. Whereas, water shows a maximum increase up to 52 °C under sunlight and 48 °C under LED. The TVR shows the highest values of 2.3 and 1.86 with 0.03 wt% sample when kept under sunlight and LED lights respectively. Hence, nanofluids are recommended as working fluids in solar water heating applications.

Recent Advancements in Augmentation of Solar Water Heaters Using Nanocomposites with PCM: Past, Present, and Future

Energy consumption in India is massive, and even the quantity used for household tasks is substantial. The majority of the requirement is satisfied by using fossil fuels, which are the traditional methods. Heating water is the most frequent home application. Accordingly, this article examines studies from the previous ten years. The information in this article demonstrates that using renewable energy is the greatest way to cut back on both the use of fossil fuels and carbon emissions while heating water for residential use. Solar, hydroelectric, wind, and biofuels are the most significant renewable sources for improving building efficiency that can be used for an extended period of time. The solar water heater is a common example of how solar energy is being used in homes more frequently. In order to identify key issues and solutions related to employing solar water heaters as an effective water heating application in both commercial and residential buildings, this article compiles research data from earlier studies (2012–2022). The literature survey was carried out using Scopus, a specialized database. Sixty-six dedicated research publications having search keywords plus recently published articles that matched the inclusion criteria were chosen for this review study. The study’s findings show that there is a greater inclination of researchers towards research and development in the field of domestic solar water heaters. The research publications that are being presented are all from the past 10 years (2012–2022) and stress the use of solar energy in increasing building efficiency. The study highlights how flat plate solar collectors with distilled water as the heat transfer fluid and a phase-changing substance as the thermal energy storage could potentially be enhanced. The thermal conductivity of paraffin wax and distilled water was improved by 75% of the researchers by using 0.05 to 0.5% concentrations of Al and Cu oxide nanoparticles, making it useful in solar water heaters. A total of 78% of researchers are interested in domestic water heating applications since they use a lot of energy in both urban and rural settings.

Türkiye'de Ankara ili için düz plaka kollektör güneş sıcak su sisteminin TRNSYS yazılımı ile incelenmesi

A domestic solar water heating system using a flat plate collector is modeled for the domestic hot water requirement of a residential unit in Ankara, Turkey. The necessary design parameters were determined and the analysis was carried out using the TRNSYS simulation program. In the modeled system, the domestic water temperature was determined as 55 °C and water withdrawals were carried out at different flow rates during the day according to the usage intensity. The water withdrawal rates were determined as 80 kg/h between 07.00-09.00, 100 kg/h between 12.00-13.00 and 50 kg/h between 17.00-22.00. According to the results obtained, the designed system was able to meet the hot water need in summer and winter months by using solar energy through auxiliary heaters. While the collector efficiency reached its highest value with 40% in September, it reached the lowest efficiency value with 8% in December.

Design and experimentation on domestic solar water heaters using kenics twist inserts

Design and experimentation on domestic solar water heaters using kenics twist inserts

Optimization of collector area and storage volume in domestic solar water heating systems with on–off control—A thermal energy analysis based on a pre-specified system performance

Numerical simulations of solar water heating systems using on–off control were performed for four locations in the Portuguese territory, two collector types, and a wide range of parameters. Two main design parameters were considered: the collector area and the storage volume. An innovative technique was used to investigate the relationship between system performance and system parameters: a pre-specified annual solar fraction is selected and the optimal parameters needed to achieve this solar fraction are then computed. The optimum collector area is almost always higher for a double-glazed than for a single-glazed collector, suggesting that in Portugal, the single-glazed type is more effective for most solar water heating applications. This fact is more significant for lower solar fractions and warmer climates. A small increase in the optimum collector area leads to a very strong decrease in the optimum storage volume (an area increase of 1% leads to a volume decrease of 27%). Collector flow rate and storage volume increments result in lower collector areas. However, high flow rates lead to high pumping losses and lower collector efficiencies, and when the storage tank losses are significant, higher tank sizes may lead to higher collector areas. The solar fraction has a very strong impact on the collector area and storage volume (when the solar fraction increases from 0.5 to 0.99, the optimum collector area and storage volume increase about 17 and 56 times, respectively).

Low thermal conductivity solar domestic water heater

Solar domestic water heaters (SWH) with thermosyphon circulation are the most common commercial applications of solar energy in Mexico. They are also becoming popular in the rest of the world, given their simplicity, good economic returns, and sustainability. Traditionally the solar collector, the piping, and the storage tank are built of copper and steel. However, water quality in many parts of the Mexican Northwest has high mineral contents and, when heated, results in early metal pitting corrosion of SWH parts. Short-lived water heaters are bad promoters of the technology. In this work, a SWH thermoplastic Chlorinated Polyvinyl Chloride (CPVC) is built and tested under real operating conditions in La Paz, BCS, Mexico. The optimal design is detected with the aid of a suitable numerical model. Results reveal that a full SWH-CPVC can be technically and economically convenient for the weather conditions of the Northwestern states of Mexico.

Thermal energy storage properties, thermal conductivity, chemical/and thermal reliability of three different organic phase change materials doped with hexagonal boron nitride

Myristic acid (MA), Lauric Acid (LA) and Polyethylene Glycol (PEG) are promising organic Phase Change Materials (PCMs) for Thermal Energy Storage (TES). However, low thermal conductivity (TC) negatively affects their heat transfer efficiency during the heat storage/release periods in TES systems. In this regard, hexagonal Boron Nitride (h-BN) was chosen as a filler for TC enhancement. The present study targets to improve the TC of MA, LA and PEG by adding h-BN nanoparticle at different weight amounts, 0.5, 1.0, 1.5 and 2 %, along with a systematic examination of other chemical and thermal properties. Scanning electron microscopy (SEM)/Energy dispersive X-Ray spectroscopy (EDX), Fourier-transformed infrared (FTIR) and X-Ray diffraction (XRD) analysis results demonstrated that the dispersion of h-BN in the PCMs was fairly homogeneous and had no damaging influence on their chemical/crystalline structures. Differential scanning calorimetry (DSC) results indicated that the addition of h-BN (2wt%) marginally shifted their phase change temperatures and slightly decreased the LHS capacities compared to pure PCMs. The h-BN/PCM composites exhibited good chemical stability and thermal reliability after 500 heating/cooling cycles. The addition of h-BN (2 wt%) resulted in 1.40, 1.27 and 1.30 times-enhancement in TC values of MA, LA and PEG, respectively. This improvement was also displayed in the T-History curves. All findings revealed that 2 wt% h-BN addition could be enough for satisfactory TC enhancement without affecting the LHS properties of the selected PCMs significantly. Thus, h-BN enhanced PCMs could be used for thermal management of electronic equipment, solar collectors, solar PV systems and domestic water heating systems etc.

Assessing the potential and utilization of solar energy at the building-scale in Shanghai

The assessment of potential and utilization of solar energy for each building has become an essential precondition of urban sustainable development. Currently, there are two challenges, namely high computation cost for an assessment within a large city and missing rooftop information for each building. In this study, by taking the downtown area in Shanghai as sample, a grid scheme with buffer was proposed to alleviate the computational burden and successfully estimate solar radiation with an accuracy of 0.91. Also, a quadrant-based segmentation method was developed to classify rooftop types with an overall accuracy of 83.63%, which helps better calculate solar energy utilization cost. Finally, we assumed PhotoVoltaic conversion (PV) systems or Domestic Solar Water Heater (DSWH) systems are installed on all suitable rooftops and analyzed their utilization cost, as well as economic and ecological benefits. The results show that 165,529 and 52,131 buildings are suitable for PV and DSWH systems, respectively. PV system's average payback time is about five years with reducing standard coal consumption of 1.85 × 1011kg. The DSWH system requires three more years to balance the cost and benefits. The criteria of further solar energy planning are also concluded from three perspectives: building height and density, and rooftop structure.

Energy, exergy, environmental impact, and economic analyses of evacuated tube compound parabolic concentrator–powered solar thermal domestic water heating system

In the reported study, a dynamic analytical model is developed to propose the energy, exergy, environmental impact, and economic analyses of the water heating system at Jaipur (India) with an evacuated tube compound parabolic concentrator field of a total area of 81 m2. Consequently, the model is used to perform parametric studies to report the effect of operating and meteorological parameters on the productivity and performance of the system. Moreover, the system's performance, environmental impact, and economic aspects have been investigated and compared under different meteorological conditions at four different Rajasthan (India) locations using TMY2 weather data files. Results clarified that Jodhpur receives the highest solar radiation intensity from these four locations. The model results were validated with the experimental data, and a good agreement has prevailed. Consequently, the results indicate the highest annual energy and exergy gain for Jodhpur with 79.72 MWh and 9.311 MWh, respectively, followed by Jaisalmer, Barmer, and Jaipur. The economic analysis results clarified that the simple payback period ranged from 4.5 to 4.75 years and the discounted payback period ranged from 6.6 to 7 years based on a 6% discount rate. At the same time, the levelized cost of heating for the given system is around 0.023 $/kWh which is very economical closest to that of CNG as a fuel which costs around 0.059 $/kWh. The internal rate of return is reported to be 16.76, 16.82, 16.77, and 16.75% for Barmer, Jodhpur, Jaipur, and Jaisalmer, respectively, and savings of 74.4, 78.1, 75.4, and 73.8 tonnes of CO2 emission to the environment.

Effect of Nanocoating (CuO Nanoparticles) on the Performance of Solar Evacuated Tube

In domestic solar water heating solar evacuated tubes have been widely used. Enhancement of solar energy absorption is the demand of time and CuO nanoparticles on account of their potential uses mainly in the field of solar energy applications. Cost effective sol-gel method is applied to synthesize CuO nanoparticles on solar evacuated glass tube. The synthesizing initiated from Cupric Acetate with the colloidal solution in water. A thin film has been prepared at room temperature nearly at 30 to 38 °C. The synthesized thin film had been annealed at 300 °C for one hour to give uniform grain structure and good surface morphological properties. For the structural study, the film was characterized by XRD-X-Ray diffraction, SEM-Scanning Electron Microscopy & TEM- Transmission Electron Microscopy. To exhibit the optical behavior of CuO nanoparticles on solar evacuated glass tube, UV-visible spectrum has been performed. By the calculations of an effective mass model, the size of particles determined as 2.26 nm, which supported and justified the TEM analysis. Coated CuO nanoparticles on borosilicate evacuated glass tube has been installed as a domestic solar water heater and working satisfactorily to generate hot water. For solar water heating system (domestic) application of nanotechnology is a novel concept. To develop durable nanocoating on 1800 mm long solar evacuated borosilicate glass tube itself it was a challenge. In this research it is shown that coating is working satisfactorily with energy enhancement. This paper opens the door for new nanocoating developments opportunities.

Effect of simultaneous & consecutive melting/solidification of phase change material on domestic solar water heating system

The foremost challenges in heat pipe ETC are low heat transfer rate between absorber tube & heat pipe, overheating of heat pipes, and its inability to supply hot water during off-pick hours. The incorporation of latent heat storage material (LHSM) between absorber tube and heat pipe is the efficient solution to overcome these challenges. Also, along with energy and exergy analysis, economic & environmental analysis to be done to ensure whether utilization of LHSM with ETC system is viable for the commercial utility. Thereby, in this study, energy, exergy, economic & environmental analysis of stearic acid integrated ETC for two different modes (ETC/Mode-I & II) have been done and distinctly in comparison to the reference system. The daily energy efficiency of ETC/SA for ETC/Mode-I and ETC/Mode-II improved by 37–45 and 65–81% respectively, whereas, improvement in exergy efficiency was observed by 21–29 and 57–73% respectively. The positive value of NPV shows that investment in ETC/SA will be highly profitable. The ETC/SA mitigated CO2 emission in the range of 26–37 and 8–12 tCO2/lifetime based on energy and exergy approach respectively. Thus, ETC/SA working for ETC/Mode-II system was found to be more economical, highly energetic & exergetic efficient, and more environmentally friendly.

Towards Strategic Plan for Wide Spreading of Solar Water Heaters in Libya

Solar water heaters have been in use for decades in many countries in the world that have less favorable climatic conditions for solar energy as compared with Libya. However, still there is no usage of such technologies in the country. This could be attributed to many factors including, among others, lack of clear policy and/or serious plans to establish such technology, cheap prices of conventional energy, and lack of environmental awareness. The Center for Solar Energy Research and Studies (CSERS) of Libya has developed an excellent research and development program on a national scale for domestic solar water heating systems. The national program started in the early 1990’s aiming at increasing publicawareness. The program utilizes different ways such as pilot projects, studies, workshops, and reports to convince people and decision-makers of Libya about this subject and its benefits.This paper attempts to suggest a strategic plan (win-win situation between government and people) for encouraging and helping widespread (replacement) of solar water heaters nationwide based on economic and environmental pointers in favour of the replacement. Th suggested strategic plan is to provide 25% of existing houses in 2013 with solar water heating systems by 2022, with a governmental subsidy of up to 65% of the system cost. The study has shown that every L.D. paid by the government will return with at least 2 L.D. after 10 years of investment without considering the money saved from the fuel savings, powerplant installations to fulfill the demand, and the environmental benefits.

Experimental and numerical analysis of thermal performance of shape stabilized PCM in a solar thermal collector

A typical solar domestic water heating system suffers from low energy efficiency due to multiple heat transfer process among components, i.e., the solar thermal collector and the thermal energy storage. In this work, a compact design of storage-integrated solar thermal collector and its compatible phase change material (PCM) storage material were explored. The salt hydrate based composite PCM, the sodium acetate trihydrate (SAT), was used to create a shape stabilized PCM (ssPCMs) for a feasible PCM by its low leakage and high thermal conductivity. The developed ssPCMs has been tested experimentally and a numerical model has been developed to obtain the effective thermal property of the developed ssPCMs by comparing the predicted results with the measurements. Furthermore, the model has been used to study the (dis)charging behavior of PCM in a storage-integrated solar thermal collector which is composed of an evacuated tube and a double spiral coils heat exchanger. A geometrical optimization has been performed to achieve 2.6 times longer of discharging period with a minimum outlet temperature of 55 °C. Moreover, the circulating water is found useful in increasing the PCM charging rate with 9% by transferring the heat from the surface to the center of tube.

MgO-Nano Coating Consequences on the Performance of Domestic Solar Water Heating System

Nowadays, government around the world confining to usage of fossil fuels as they are emitting more harmful emissions to the nature. Thereby, some novel approaches which curbs the fossil fuel addiction and environmental degradation plays an imperative role in present days. The technologies which helps to effective utilization of solar energy is too urge. In line with this an effort is made to use solar energy effectively by doing some changes in solar water heating system. In this current study Magnesium Oxide (MgO) nano particles are prepared in house and characterized. Later, study unfolds the effect of reflective coatings on the performance of solar water heating system. From the learn, it is cleared that solar water heating system with MgO nano coated reflective plate has shown the better performance (heat flux & Reynolds no.) when compared to without reflective plate, with reflective plate and reflective plate with micro coatings.