Comparative Experimental Efficiency of Solar Water Heating Systems With Enhanced Thermal Performance: A Review

Phase change material can be used as heat transfer fluid in the solar water heating system, which is the latest way to improve thermal efficiency. In this paper, graphene composite paraffin emulsion is used as heat transfer fluid in a solar water heating-phase change material (SWH-PCM) system. By comparing with the traditional solar water heating (SWH) system, the thermal performance characteristics of SWH-PCM system have been investigated experimentally. The SWH-PCM system has higher heat storage than the SWH system. The heat storage of SWH-PCM system and SWH system all increase with the increase of solar irradiance, while the thermal efficiency has the opposite trend. The flow rate has a greater influence on the thermal efficiency of SWH-PCM system than that of the SWH system. With the flow rate of 200 L/h, the thermal efficiency of SWH-PCM system is 14.21% higher than that of the SWH system. In summary, the SWH-PCM system is a promising solar water heating system with high heat storage and thermal efficiency.

The use of solar energy source using Solar Water Heating (SWH) system for hot water supply is increasing due to environmentally friendly technology. The increase of the application of solar energy equipment is beneficial for technology development related to the issue of sustainable energy and green energy buildings. This study develops a SWH system for hot water supply with modification of absorber plate. An integrated V-shaped absorber plate with phase change material (PCM) energy storage in the SWH system has been installed and its performance has been investigated experimentally. Two SWH systems consisting of V-shape absorber plate with and without PCM storage are built. The V-shape absorber plate is constructed and integrated with PCM storage in the system. The experimental tests of the two SWH systems using V-shaped absorber plate with and without PCM storage have been carried-out in the same operation time with various flowrates. The temperature of the paraffin has increased until the melting temperature and has decreased with the decrease of solar radiation in the afternoon. Paraffin as PCM storage contributes to increase the outlet water temperature. The results show that the average efficiency of the SWH system with PCM storage using paraffin is higher than the one of the SWH system without PCM storage. It has increased significantly of 20%, 14% and 13% with flowrates of 0.5; 1 and 1.5 L/min respectively. In addition, the characteristics of the PCM storage are shown clearly from 16:00 to 20:00 local time. After 16:00 local time, the storage energy can be a source of heat energy to heat the water up to the end of the day.

Organic phase change materials (PCMs) have been utilized as latent heat energy storage medium for effective thermal management. In this work, a PCM nanocomposite, consisting of a mixture of two organic PCMs (referred to as eutectic gel PCM) and minimal amount (0.5 wt%) of nanographite (NG) as a supporting material, was prepared. Differential scanning calorimeter was used to determine the melting temperature and latent heat of pristine PCM, paraffin (61.5 °C and 161.5 J/g), eutectic gel PCM (54 °C and 158 J/g) and eutectic gel PCM nanocomposite (53.5 °C and 155 J/g). The prepared PCM nanocomposites exhibited enhanced thermal conductivity and ultrafast thermal charging characteristics. The nanocomposites were employed for two different applications: (i) providing hot water using an indigenously fabricated solar water heating (SWH) system and (ii) solar rechargeable glove that can be rapidly warmed and used. Experimental results on SWH system show that the use of PCM nanocomposites helps to increase the charging rate of PCM while reducing the discharging rate of heat by PCM to water, thus enhancing the maximum utilization of solar energy and hence improving the efficiency of the SWH system. The experimental results on solar rechargeable glove revealed that the glove has the ability to retain the temperature up to 3 hours.

Recent projections anticipate that the essential energy consumption will increase by 48% in 2040. This has prompted to a need to create proficient and sustainable techniques of storing energy. Solar thermal energy can be stored in the form of latent heat by utilizing appropriate phase change materials (PCMs), which offer high heat storage capacity. An experimental study was done in Khartoum city during summer season to investigate the thermal performance of solar water heating system integrated with PCM using flat plate collector as a heat source. The PCM used was paraffin wax whose melting point is 56 °C. An energy and exergy analysis was done to assess the thermal performance of the system and fix the thermodynamic blemish in the energy system. The outcomes showed that PCM acted as smart material which can regulate the temperature of system in the required range. The outcomes indicated that the overall energy and exergy efficiencies of the system were 85% and 76% respectively. The number of entropy generated was 0.26. The results showed that PCM acted as smart regulator to keep supplying the amount of heat to the system even after the absent of heat source. PCM also could increase the exergy output and led to reduce the exergy destruction. This indicates that the PCM could improve the exergy efficiency. The overall outcomes showed that the PCM optimized the performance of solar water heater system by improve energy and exergy efficiencies.

In this paper, hydrated salts of disodium hydrogen phosphate dodecahydrate and disodium sulfate decahydrate are employed to compose a composite hydrated salt with a ratio of 9·5:0·5. The composite hydrated salt has been used as a phase-change thermal storage material in a solar hot-water system to study the effect of phase-change material on the thermal conversion efficiency of such a system. The phase-change material is packaged in a plastic container. The experimental results show that the thermal conversion efficiency is significantly affected by the amount of thermal storage medium and solar radiation intensity. The solar thermal conversion efficiency for the 2 m2 solar panel collector could reach up to 66·4% for a thermal storage medium consisting of 38·1 kg phase-change thermal storage material and 124·7 kg water and with an averaged radiation intensity of 1243 w/m2, even at lower ambient temperatures between −7·0°C in the morning and 1·0°C at 15:00. It indicates that the use of phase-change materials in a solar water-heating system could improve the solar thermal conversion efficiency of such a system.

Using the Taguchi method and grey relational analysis to optimize the parameter design of flat-plate collectors with nanofluids, and phase change materials in an integrated solar water heating system

Applications of solar water heating system with phase change material

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

Performance analysis of phase change material (PCM) integrated conical cavity receiver in solar parabolic dish collector

The shortage in energy resources combined with the climb in greenhouse emissions is the main incentive beyond the deployment of solar energy resource in various applications. One of the most successful applications is the utilization of solar energy in the domestic water heating systems (DWHS) because 70% of the consumed energy in the residential segment is utilized for space heating and appliances in cold climates 1. However, the full deployment of solar energy in domestic water heating is only possible when an energy storage system with acceptable price is available. Recently a new tendency for deploying phase change materials (PCMs) as an energy storage system is introduced in several solar DWHS. These systems are known as integrated PCM in solar DWHS and offer several advantages including high storage capacity, low storage volume, and isothermal operation during the charging and discharging phases. The present study reviews various techniques utilized for integrating the PCM in solar water heating systems and the utilized methods for enhancing the heat transfer characteristics of the PCM through the usage of extended surfaces and high conductive additives. Copyright © 2017 John Wiley & Sons, Ltd.

Thermal performance enhancement in evacuated tube solar collector with working fluid MWCNT/Al2O3/MgO tri-hybrid nanofluid

Experimental study on the performance of a novel solar water heating system with and without PCM

Dynamic simulation and parametric study of solar water heating system with phase change materials in different climate zones

Recent development in thermal performance of solar water heating (SWH) systems

Solar energy is known as an environmentally friendly energy source with a wide range of applications. This energy can be utilized in various applications such as domestic and industrial water heating using solar water heating (SWH) systems. The thermal performance of an SWH system using a V-shaped absorber plate is presented in this study. Two SWH systems with different absorber plates, i.e. a flat-plate and a V-shaped plate, have been investigated experimentally. First, the absorptivity of the absorber plates was calculated analytically. The optimum V-shaped configuration with angle at β = 21° (V-shaped dimensions t = 4 cm and l = 4 cm) was determined from various V-shaped plate absorbers based on their absorptivity and applied in the experimental study. Two SWH systems were installed and tested at a low flowrate of 0.5 L/min and at a high flowrate of 2 L/min. The results showed that the SWH system with V-shaped plate absorber had a 3.6-4.4% better performance compared with that of the system with flat-plate absorber.