Numerical Investigation of Thermal Separators Within the Evacuated Tubes of a Water-in-Glass Solar Water Heater

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Asif Soopee ◽  
Abdel Anwar Hossen Khoodaruth ◽  
Anshu Prakash Murdan ◽  
Vishwamitra Oree
Keyword(s):  
Tilt Angle ◽  
Thermal Efficiency ◽  
Thermal Stratification ◽  
Maximum Deviation ◽  
Water Tank ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Thermal Distribution ◽  
Evacuated Tubes

The effects of thermal separators within the evacuated tubes of a water-in-glass solar water heater (SWH) were numerically investigated using the commercial computational fluid dynamics (CFD) software ANSYS fluent. To validate the three-dimensional (3D) model, an experiment was performed for the passive operation of the SWH for a fortnight period, of which 3 h of recorded data was selected. The Boussinesq's approximation was employed, and the respective solar irradiance and ambient temperature profiles were incorporated. A maximum deviation of only 2.06% was observed between the experimental and numerical results. The model was then adapted for the case where thermal separators are inserted within the evacuated tubes of the SWH and both cases were run for two tilt angles, 10 deg and 40 deg. The temperature and velocity profiles within the evacuated tubes were analyzed alongside the temperature contours, thermal stratification, and overall thermal efficiency of the SWH. At a 40 deg tilt, without thermal separators, the flow streams within the evacuated tubes are restrained, and a chaotic thermal behavior was observed, thereby restricting thermal distribution to the water stored in the SWH tank. A lower tilt angle (10 deg) provided a more desirable thermal distribution. With thermal separators, however, the tilt angle preference was reversed. A faster and more uniform thermal distribution was achieved within the water tank, with a sizeable reduction in the thermal stratification at a 40 deg tilt. The overall thermal efficiency of the SWH was improved by 4.11% and 4.14% for tilt angles of 10 deg and 40 deg, respectively.

scholarly journals Theoretical and experimental investigation of the evacuated tube solar water heater system

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 795-808 ◽  
Author(s):  
Phrut Sakulchangsatjatai ◽  
Chaiwat Wannagosit ◽  
Niti Kammuang-Lue ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Efficiency ◽  
Experimental Results ◽  
Experimental Result ◽  
Maximum Temperature ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Evacuated Tubes ◽  
Evacuated Tube ◽  
Theoretical Results

In this study, the evacuated tube solar water heater system using thermosyphon has been investigated experimentally as well as theoretically. Solar radiation and ambient temperature data from Chiang Mai province were used for the modelling system by explicit finite difference method. The effects of thermosyphon diameters and number of evacuated tubes on the net saving of solar water heater system were analyzed. The mathematical results showed that the optimal number of evacuated tubes and thermosyphon diameter occurs at eight evacuated tubes, which are 15.88 mm of evaporator diameter and 22.22 mm of condenser diameter under personal hygiene conditions. The solar water heater system at optimal parameters was constructed and tested for the system prototype. The theoretical results were validated by the experimental results. It was found that the theoretical results can be used to predict temperature, heat transfer rate, and thermal efficiency to show good agreement with the experimental results as well as previous research. The experimental and theoretical results showed that the maximum temperature for hot water was 65.25?C and 71.66?C, respectively. Moreover, the thermal efficiency of the system based on the theoretical result was 60.11%, with relative error being about 3.04% of the experimental result.

scholarly journals Thermal efficiency and cost analysis of solar water heater made in Rwanda

2018 ◽  
Vol 37 (3) ◽  
pp. 1147-1161 ◽  
Author(s):  
Esdras Nshimyumuremyi ◽  
Wang Junqi
Keyword(s):  
Cost Analysis ◽  
Thermal Efficiency ◽  
Solar Water Heater ◽  
Water Heating ◽  
Water Heater ◽  
Solar Water Heating ◽  
Solar Water ◽  
Water Heaters ◽  
Solar Water Heaters ◽  
Made In

Solar water heating is a technology of capturing the energy from the sun's radiation for the purpose of raising the temperature of water from water supply temperature to the desired higher temperature depending on the use. There are many views and discussions on the questions of thermal efficiency of solar water heaters and their associated cost, especially different customers/users want to replace their existing conventional water heating energy by solar water heating systems. In this present paper, a deep investigation has been accomplished to determine thermal efficiency and cost analysis of solar water heater made in Rwanda. During manufacturing of solar water heater, the collector was the main part to emphasize on. The high efficiency of the system was achieved by replacing galvanized iron sheet by aluminum sheet slotted and black painted as an absorber plate. The ambient temperature and average solar radiation of the three sites where solar water heaters are installed were investigated. The used materials, specifications and sizing were discussed in this paper.

The Device of the Automatic Backflow in Solar Water Heater-Temperature Control and Backflow for Pipe of Water Heater

2013 ◽  
Vol 827 ◽  
pp. 99-104
Author(s):  
Bin Li ◽  
Xi Chen ◽  
Xin Hao Li ◽  
Lu Kuan Ma ◽  
Wen Bo Lu ◽  
...  
Keyword(s):  
Water Resources ◽  
Cold Water ◽  
Hot Water ◽  
Water Tank ◽  
Solar Water Heater ◽  
Recycle Water ◽  
Delay Effect ◽  
Water Heater ◽  
Domestic Water ◽  
Solar Water

Now in general use in solar water heater, there is a long pipeline between water heater and tap, we have to empty the stored cold water before we use the hot water; and usually the water cannot meet required temperature due to the heating delay effect, thus the water also should be emptied, which leads to a waste of water resources. In order to solve this water wastage, we propose a device which can help to control the temperature and backflow of the water in water heater. The device accomplishes backflow of cold water automatically under the effect of gravity, and refluxed water will be stored in the recycle-water tank, thus ensuring the result that the water temperature satisfies the requirement. After the recycle-water tank is full, it will trigger the buoy to control the relay switch, then the water pump start to work to force the water into the water heater tank. Thus, realizing the recycling of water. This device can significantly save water resources in domestic water, and it has a broad market prospect.

Evacuated Tube Solar Collectors Integrated With Phase Change Materials and Silicone Oil

2017 ◽  
Author(s):  
Alexios Papadimitratos ◽  
Sarvenaz Sobhansarbandi ◽  
Vladimir Pozdin ◽  
Anvar Zakhidov ◽  
Fatemeh Hassanipour
Keyword(s):  
Phase Change ◽  
Solar Collector ◽  
Phase Change Materials ◽  
Silicone Oil ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Water Heaters ◽  
Evacuated Tubes ◽  
Solar Water Heaters

This paper presents a novel method of integrating Phase Change Materials (PCMs) and Silicone oil within the Evacuated solar Tube Collectors (ETCs) for application in Solar Water Heaters (SWHs). In this method, heat pipe is immersed inside the phase change material, where heat is effectively accumulated and stored for an extended period of time due to thermal insulation of evacuated tubes. The proposed solar collector utilizes two distinct phase change materials (dual-PCM), namely Tritriacontane paraffin and Erythritol, with melting temperature 72°C and 118°C respectively. The integration of Silicone oil for uniform melting of the PCMs, utilizes the convective heat transfer inside the evacuated tubes, as this liquid polymerized material is well known for its temperature-stability and an excellent heat transfer medium. The operation of solar water heater with the proposed solar collector is investigated during both normal and stagnation (on-demand) operation. The feasibility of this technology is tested via small scale and large scale commercial solar water heaters. Beyond the improved functionality for solar water heater systems, the results from this study show show efficiency improvement of 26% for the normal operation and 66% for the stagnation mode compared with standard solar water heaters that lack phase change materials and silicone oil. The benefit of this method includes improved functionality by delayed release of heat, thus providing hot water during the hours of high demand or when solar intensity is insufficient such in a cloudy day and during night time.

Analysis of the thermal efficiency of a compound parabolic Integrated Collector Storage solar water heater in Kerman, Iran

2019 ◽  
Vol 36 ◽  
pp. 100564 ◽  
Author(s):  
Rashid Panahi ◽  
Mohammad Hassan Khanjanpour ◽  
Akbar A. Javadi ◽  
Mohammad Akrami ◽  
Mohammad Rahnama ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

scholarly journals Energy Analysis of a Complementary Heating System Combining Solar Energy and Coal for a Rural Residential Building in Northwest China

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Xiaofei Zhen ◽  
Jinping Li ◽  
Yassir Idris Abdalla Osman ◽  
Rong Feng ◽  
Xuemin Zhang ◽  
...  
Keyword(s):  
Solar Energy ◽  
Thermal Efficiency ◽  
Residential Building ◽  
Heating System ◽  
Energy Utilization ◽  
Prototype Model ◽  
Dual Function ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

In order to utilize solar energy to meet the heating demands of a rural residential building during the winter in the northwestern region of China, a hybrid heating system combining solar energy and coal was built. Multiple experiments to monitor its performance were conducted during the winter in 2014 and 2015. In this paper, we analyze the efficiency of the energy utilization of the system and describe a prototype model to determine the thermal efficiency of the coal stove in use. Multiple linear regression was adopted to present the dual function of multiple factors on the daily heat-collecting capacity of the solar water heater; the heat-loss coefficient of the storage tank was detected as well. The prototype model shows that the average thermal efficiency of the stove is 38%, which means that the energy input for the building is divided between the coal and solar energy, 39.5% and 60.5% energy, respectively. Additionally, the allocation of the radiation of solar energy projecting into the collecting area of the solar water heater was obtained which showed 49% loss with optics and 23% with the dissipation of heat, with only 28% being utilized effectively.

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