Numerical Investigation of Heat Flow and Fluid Flow in a Solar Water Heater with an Evacuated-Tube Collector

2020 ◽  
pp. 95-130
Author(s):  
K.D.N. Kumari ◽  
J.K. Wijerathna
Keyword(s):  
Fluid Flow ◽  
Heat Flow ◽  
Numerical Investigation ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Evacuated Tube Collector ◽  
Evacuated Tube

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.

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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