scholarly journals Computational fluid dynamics analysis on solar water heater: Role of thermal stratification and mixing on dynamic mode of operation

2020 ◽  
Vol 24 (2 Part B) ◽  
pp. 1461-1472 ◽  
Author(s):  
Karuthedath Dileep ◽  
Arun Raj ◽  
Divakaran Dishnu ◽  
Ahamed Saleel ◽  
Mokkala Srinivas ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Water Temperature ◽  
Thermal Stratification ◽  
Outlet Temperature ◽  
Solar Water Heater ◽  
Water Heater ◽  
Flow Rates ◽  
Solar Water ◽  
Evacuated Tube Collector ◽  
Evacuated Tube

The present work attempts to demonstrate the competence and reliability of the proposed computational solver for real-scale modelling and analysis of a commercially available evacuated tube collector type solar water heater. A 3-D, transient numerical solver with user-defined functions is modelled using CFD program ANSYS-Fluent 15.0?. The objective is to analyse the evacuated tube collector type solar water heater in two states of operation, namely, static (stagnant charging) and dynamic (retrieval) modes. This work emphasizes the determination of the impact of thermal stratification, and fluid mixing in the storage tank on the outlet temperature profile during discharging. Volume flow rates vary from 3-15 Lpm. The reported findings suggest that with an increase of fluid-flow during discharge, the stratified layers disorient and lead to rapid mixing, which eventually results in an earlier drop in the outlet water temperature. Furthermore, at low fluid-flow rates, the stratified layers remain intact with only a gradual decay in the outlet temperature profile. The analysis reveals that based on the user?s choice, it is possible to vary discharge flow rate until 7 Lpm without a significant drop in the outlet water temperature. Furthermore, computational results have been successfully validated with experimental findings.

scholarly journals PERBANDINGAN PERFORMANSI KOLEKTOR SURYA TIPE EVACUATED TUBE MENGGUNAKAN FLUIDA KERJA ETANOL DENGAN TIPE PELAT DATAR

2020 ◽  
Vol 4 (1) ◽  
pp. 275-279
Author(s):  
Rusmana ◽  
Kurnia Chandra
Keyword(s):  
Flat Plate ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Evacuated Tube Collector ◽  
Flat Plate Collector ◽  
Evacuated Tube

Mengingat wilayah Indonesia yang letaknya berada di garis khatulistiwa, sumber energi surya yang diterima Indonesia sangat melimpah. Pemanfaatan yang paling sederhana adalah menjadikan energi surya sebagai sumber panas pada proses pemanasan air. Teknologi kolektor surya merupakan salah satu sarana untuk mengambil panas matahari. Aneka jenis kolektor surya memiliki kinerja yang bervariasi. Kemampuan penyerapan panas yang tinggi dapat diperoleh dari kolektor surya berjenis evacuated tube collector yang mempunyai waktu pemanasan air awal lebih cepat dibandingkan dengan jenis flat plate collector. Penelitian ini bertujuan untuk mengetahui perbandingan efisiensi kolektor surya tabung vakum terhadap solar water heater sederhana. Metode pengujian dilakukan dengan cara memasukan debit air yang sama pada setiap pengujian. Hasil pengujian menunjukkan bahwa solar water heater tabung vakum dengan fluida kerja etanol memberikan efisiensi tertinggi sebesar 44.5% dan efisiensi terendah sebesar 26.4%. Temperatur air output tertinggi mencapai 35,4°C.

scholarly journals Simulation of Convection Flow and Sensitivity Analysis of Model Parameters of Evacuated Glass Tube Solar Water Heater

2018 ◽  
pp. 1-14
Author(s):  
K. D. N. Kumari ◽  
J. K. Wijerathna
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Inclination Angle ◽  
Transfer Process ◽  
Weather Conditions ◽  
Heat Transfer Process ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Evacuated Tube

The water-in-glass evacuated collectors are made up of parallel circular tubes. They are installed with some inclination angle to the horizontal. The thermal performance of water-in-glass evacuated tube solar water heater heavily depends on weather conditions. The analysis of the sensitivity of the model parameter and weather conditions on heat transfer process is extremely important to install a solar water heater system in order to achieve its maximum efficiency. The evaluation of the sensitivity of the system parameters is done by considering one parameter after another while keeping the remaining fixed. Further to the analysis of the heat transfer process, the average heat transfer coefficient and the average natural circulation flow rate are calculated. The fluid flow is assumed to be unsteady, two-dimensional, laminar and incompressible. The heat and fluid flow are analyzed using the Navier-Stokes equations and temperature equation for an incompressible fluid, subject to density variation with temperature. The discretization of the governing equations is done by Finite Volume Method (FVM). The Open FOAM computational fluid dynamic software with PISO-SIMPLE algorithm is used for the simulation. The results show that the heat transfer process is improved when there is a moderate level inclination angle. Further, it is found that when the ratio of tube length to diameter is high, the heat transfer process is improved. The solar radiation input highly affects the performance of a solar water heater. The cold-water inlet temperature does not directly affect the buoyancy induced flow, but it influences the temperature gain. The angle of the solar rays vary within the daytime, however it does not affect the performance of the solar water heater since an evacuated-tube has a circular absorbing surface, it passively tracks the sun throughout the day.  These results recommend using moderate level tube inclination angle and high  ratio to improve the performance of a solar water heater.

Performance Analysis and Optimization of Fresnel Lens Concentrated Solar Water Heater

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Vinod Kumar Soni ◽  
R. L. Shrivastava ◽  
S. P. Untawale ◽  
Kshitij Shrivastava
Keyword(s):  
Life Cycle ◽  
Performance Analysis ◽  
Flat Plate ◽  
Mass Flow ◽  
Critical Parameters ◽  
Total System ◽  
Outlet Temperature ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

Concentrated solar power (CSP) is a mature and efficient technology to cater the large-scale demand of hot water. Conventional reflectors/mirrors in CSP share 50% of total system cost. High installation as well as O&M cost is the major concern in reflector-based CSP. Apart from the above, manufacturing defects and adverse service environment cause premature degradation of reflectors and substantial drop in efficiency and service life. Performance analysis of an innovative optically concentrated solar water heater (OCSWH) using plurality of Fresnel lenses of poly methyl methacrylate (PMMA) is presented in the work. Size and yield of any solar water heater (SWH) are mainly dependent on its aperture area, output temperature, and mass flow rate, which are termed herein as critical parameters. Series of experimentations is carried out by varying critical design and operating parameters viz. aperture area, outlet temperature, and rate of mass flow, and similar experimentation is also carried out on commercially available flat plate SWH to compare its performance. Loss of heat from riser and header pipes is restricted by application of effective insulation. Substantial improvement in collector efficiency, increase in rate of mass flow, and rise in discharge temperature with reference to flat plate collector are noted. Economics is also studied covering life cycle cost (LCC), life cycle saving (LCS), and energy payback period.

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.

Measurement and simulation of flow rate in a water-in-glass evacuated tube solar water heater

Solar Energy ◽  
2005 ◽  
Vol 78 (2) ◽  
pp. 257-267 ◽  
Author(s):  
G.L. Morrison ◽  
I. Budihardjo ◽  
M. Behnia
Keyword(s):  
Flow Rate ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Evacuated Tube

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.

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