scholarly journals Effects of Nanofluids in Improving the Efficiency of the Conical Concentrator System

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 28
Author(s):  
Alsalame Haedr Abdalha Mahmood ◽  
Muhammad Imtiaz Hussain ◽  
Gwi-Hyun Lee
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Thermal Efficiency ◽  
Fossil Fuels ◽  
Distilled Water ◽  
Flow Rates ◽  
Practical Applications ◽  
Heat Transfer Fluids ◽  
Significant Research ◽  
Collector Efficiency

Fossil fuels are being depleted, resulting in increasing environmental pollution due to greenhouse gases and, consequently, emerging detrimental environmental problems. Therefore, renewable energy is becoming more important; hence, significant research is in progress to increase efficient uses of solar energy. In this paper, the thermal performance of a conical concentrating system with different heat transfer fluids at varied flow rates was studied. The conical-shaped concentrator reflects the incoming solar radiation onto the absorber surface, which is located at the focal axis, where the collected heat is transported through heating mediums or heat transfer fluids. Distilled water and nanofluids (Al2O3, CuO) were used in this study as the heat transfer fluids and were circulated through the absorber and the heat storage tank in a closed loop by a pump to absorb the solar radiation. The efficiency of the conical concentrating system was measured during solar noon hours under a clear sky. The collector efficiency was analyzed at different flow rates of 2, 4, and 6 L/min. The thermal efficiency, calculated using different heat transfer fluids, were 72.5% for Al2O3, 65% for CuO, and 62.8% for distilled water. Comparing the thermal efficiency at different flow rates, Al2O3 at 6 L/min, CuO at 6 L/min, and distilled water at 4 L/min showed high efficiencies; these results indicate that the Al2O3 nanofluid is the better choice for use as a heating medium for practical applications.

Computational Study on Estimating the Surface Heat Transfer Coefficient of Absorber Tube in Solar Parabolic Trough Collector

2013 ◽  
Vol 446-447 ◽  
pp. 1546-1551
Author(s):  
Harshit Saxena ◽  
Arpit Santoki ◽  
Nimish Awalgaonkar ◽  
Arpan Jivani ◽  
Ganni Gowtham ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Solar Radiation ◽  
Computational Study ◽  
Surface Heat ◽  
Parabolic Trough ◽  
Flow Rates ◽  
Surface Heat Transfer Coefficient ◽  
Mass Flow Rates ◽  
The Given

Solar Parabolic Trough collectors are commonly used to harness the solar power for power generating applications involving high temperatures. In the given paper study we have made use of the SolTrace software which uses the Monte Carlo algorithm for finding out the radiation received on the absorber tube of the collector. The computational study was performed taking into account the solar radiation received at Vellore city in India (12.92oN, 79.13oE) as on 16th February 2013. Further a 3D model of the absorber tube used in the parabolic trough collector was created and meshed with the help of the Ansys Gambit software. The absorber tube which we considered for our study is made up of Stainless Steel AISI 302 material. The meshed model so created was then exported to the Ansys Fluent 6.3 software and simulations were performed for different mass flow rates of the fluid. The fluid which we used in the computational analysis study is Therminol 55. The temperature differences for different mass flow rates of the liquid passing through the absorber tube were found out and based on the temperature rise contours plots so obtained, we have plotted the surface heat transfer coefficient for the absorber tube. We also found out the static temperature contour plot for the fluid flowing through the given absorber tube taking into account the heat flux acting on the absorber tube due to the hourly and daily average solar radiation.

First and second thermodynamic law analyses applied to a solar dish collector

2014 ◽  
Vol 39 (4) ◽  
Author(s):  
Vahid Madadi ◽  
Touraj Tavakoli ◽  
Amir Rahimi
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Flow Rates ◽  
Energy And Exergy ◽  
Mass Flow Rates

AbstractThe energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The effect of receiver type, inlet temperature and mass flow rate of heat transfer fluid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the effect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal efficiency. The cylindrical receiver has greater energy and exergy efficiency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy efficiency is minimum for a specified HTF mass flow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass flow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass flow rates than the above mentioned values are recommended.

Analysis of Heat Transfer Factors for a Heat Pipe Absorber Array Connected to a Common Manifold

1986 ◽  
Vol 108 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. R. Hull
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Efficiency ◽  
Transfer Rate ◽  
Heat Pipes ◽  
Maximum Efficiency ◽  
Pipe Surface ◽  
Transfer Factors ◽  
Collector Efficiency ◽  
Flow Through

Heat transfer factors and thermal efficiency are calculated for a heat pipe absorber array connected to a common manifold. Arrays with less than ten heat pipes are shown to have significantly less efficiency than a conventional flow-through collector. Efficiency is also sensitive to the heat transfer rate per unit temperature difference from the heat pipe fluid to the manifold fluid divided by that from the heat pipe surface to the ambient, with maximum efficiency occurring for ratios greater than 100.

Comparative Study on Parabolic Trough Collector by using Different Heat Transfer Fluids

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Krishna Mounica ◽  
Y.V. Hanumantha Rao ◽  
Vinay Atgur ◽  
G. Manavendra ◽  
B. Srinivasa Rao
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Thermal Model ◽  
Heat Transfer Fluid ◽  
Parabolic Trough ◽  
Flow Rates ◽  
Parabolic Trough Collector ◽  
Heat Transfer Fluids ◽  
Mass Flow Rates ◽  
Simulation Results

In this paper the use of Syltherm-800 and Therminol-55 thermal oils in parabolic trough collector (PTC) is investigated with inlet temperatures of 375.35 K, 424.15 K, 470.65 K and 523.85 K and for mass flow rates of 4, 4.5 and 5 kg/sec. Analysis has been carried out using a thermal model and validated using the simulation results. Therminol-55 gives better heat transfer coefficient compared to Syltherm-800. Since Therminol-55 has higher specific heat and viscosity when compared to Syltherm-800, the use of Syltherm-800 as a heat transfer fluid in PTC is preferred. Better results are observed for temperature of 375.35 K and mass flow rate of 4 kg/sec.

Thermal Performance of a Receiver Tube for a High Concentration Ratio Parabolic Trough System and Potential for Improved Performance With Syltherm800-CuO Nanofluid

2015 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Zhongjie Huan ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Concentration Ratio ◽  
Low Flow ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
High Concentration ◽  
Flow Rates

In this paper, the thermal performance of a high concentration ratio parabolic trough system and the potential for improved thermal performance using Syltherm800-CuO nanofluid were investigated and presented. The parabolic trough system considered in this study has a concentration ratio of 113 compared with 82 in current commercial systems. The heat transfer fluid temperature was varied between 350 K and 650 K and volume fractions of nanoparticle were in the range 1–6%. Monte-Carlo ray tracing was used to obtain the actual heat flux on the receiver’s absorber tube. The obtained heat flux profiles were subsequently coupled with a computational fluid dynamics tool to investigate the thermal performance of the receiver. From the study, the results show that with increased concentration ratios, receiver thermal performance degrades, with both the receiver heat loss and the absorber tube circumferential temperature differences increasing, especially at low flow rates. The results further show that the use of nanofluids significantly improves receiver thermal performance. The heat transfer performance increases up to 38% while the thermal efficiency increases up to 15%. Significant improvements in receiver thermal efficiency exist at high inlet temperatures and low flow rates.

Analytical Technique for Estimating the Termophysical Properties of Hybrid Nanofluids

2017 ◽  
Vol 1143 ◽  
pp. 207-213
Author(s):  
Madalina Georgiana Moldoveanu ◽  
Tudor Mihai Simionescu ◽  
Alina Adriana Minea ◽  
Adrian Dima
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
High Performance ◽  
Solid Particles ◽  
Drilling Fluids ◽  
Distilled Water ◽  
Worst Case ◽  
Analytical Technique ◽  
Heat Transfer Fluids ◽  
High Concentrations

Over the past years, the development of functional heat transfer fluids by compounding different substances or different phases of matter (solid, liquid, or gas) has raised increasing interest in view of their potential applications in technologies. In particular, the nanofluids in which the solid particles (<100 nm or smaller) are incorporated as the dispersed phase in the suspensions, are currently focus of great attention because of their perspective potentials as high-performance heat transfer fluids. The potential advantage of utilizing the nanofluid lies mainly in its drastic increase in the thermal conductivity. This paper presents a study of the thermophysical characteristics of some nanofluids and their hybrids. General correlations for the effective thermal conductivity and viscosity of nanofluids are used for this analysis. Regarding the importance of thermophysical properties of water based drilling fluids, the effects of insertion of two oxides in an alumina-water nanofluid on the thermal conductivity, viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). As the results show, increase in the density of distilled water by adding the nanomaterials is insignificant, that in the worst case it did not exceed 0.9%. The least increase in the density of base fluid at high concentrations was for H1.

scholarly journals ANALISIS PASOKAN PANAS PADA PRODUKSI HIDROGEN PROSES STEAM REFORMING KONVENSIONAL DAN NUKLIR

2015 ◽  
Vol 17 (1) ◽  
pp. 11 ◽  
Author(s):  
Siti Alimah ◽  
Djati Hoesen Salimy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Hydrogen Production ◽  
Natural Gas ◽  
Steam Reforming ◽  
Thermal Efficiency ◽  
Energy Supply ◽  
Nuclear Energy ◽  
Fossil Fuels ◽  
Temperature And Pressure

ABSTRAK ANALISIS PASOKAN PANAS PADA PRODUKSI HIDROGEN PROSES STEAM REFORMING KONVENSIONAL DAN NUKLIR. Telah dilakukan analisis pasokan energi panas pada produksi hidrogen dengan proses steam reforming gas alam. Tujuan studi adalah untuk memahami sistem pasokan energi panas konvensional dan dengan nuklir. Metodologi yang digunakan adalah kajian literatur dan analisis berdasar perbandingan. Hasil studi menunjukkan bahwa proses dengan sumber panas bahan bakar fosil (gas alam) mampu memberikan kondisi operasi optimum temperatur 850-900oC dan tekanan 2-3 MPa, serta dengan perpindahan panas didominasi oleh perpindahan panas radiasi, sehingga fluks panas yang dapat dicapai pada tabung katalisator relatif tinggi (50-80 kW/m2) dan menghasilkan efisiensi thermal yang tinggi yaitu sekitar 85%. Sedang pada sistem dengan energi nuklir, karena tuntutan keselamatan, proses beroperasi pada kondisi yang kurang optimum temperatur 800-850oC dan tekanan 4,5 MPa, serta dengan perpindahan panas didominasi oleh perpindahan panas konveksi, sehingga fluks panas yang dapat dicapai pada tabung katalisator jauh lebih rendah (10-20 kW/m2) dan menghasilkan efisiensi thermal yang rendah sekitar 50%. Modifikasi reformer dan utilisasi panas mampu meningkatkan fluks panas sampai 40 kW/m2 sehingga efisiensi thermal dapat mencapai 78%. Meskipun demikian, aplikasi energi nuklir untuk produksi hidrogen dengan proses steam reforming mampu menghemat pembakaran bahan bakar fosil yang berimplikasi pada potensi penurunan laju emisi CO2 ke lingkungan. Kata kunci: produksi hidrogen, steam reforming, reformer, HTGR ABSTRACT HEAT SUPPLY ANALYSIS OF STEAM REFORMING HYDROGEN PRODUCTION PROCESS IN CONVENTIONAL AND NUCLEAR. The analysis of heat energy supply in the production of hydrogen by natural gas steam reforming process has been done. The aim of the study is to compare the energy supply system of conventional and nuclear heat. Methodology used in this study is an assessment of literature and analysis based on the comparisons. The study shows that the heat sources of fossil fuels (natural gas) is able to provide optimum operating conditions of temperature and pressure of 850-900oC and 2-3 MPa, as well as the heat transfer is dominated by radiation heat transfer, so that the heat flux that can be achieved on the catalyst tube relatively high (50-80 kW/m2) and provide high thermal efficiency of about 85%. While in the system with nuclear energy, due to the demands of safety, process operating at less than optimum conditions of temperature and pressure of 800-850oC and 4.5 MPa, as well as the heat transfer is dominated by convection heat transfer, so that the heat flux that can be achieved catalyst tube is relatively low (10- 20 kW/m2) and it provides a low thermal efficiency of about 50%. Modifications of reformer and heat utilization can increase the heat flux up to 40 kW/m2 so that the thermal efficiency can reach 78%. Nevertheless, the application of nuclear energy to hydrogen production with steam reforming process is able to reduce the burning of fossil fuels which has implications for the potential decrease in the rate of CO2 emissions into the environment. Keywords: hydrogen production, steam reforming, reformer, HTGR 

Heat Transfer Performance of a Parabolic Trough Receiver Using SWCNTs-Therminol®VP-1 Nanofluids

2017 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Concentration Ratio ◽  
Heat Transfer Performance ◽  
Energy System ◽  
Transfer Performance ◽  
Parabolic Trough ◽  
Flow Rates

In this paper, the potential for improved thermal performance of a high concentration ratio parabolic trough solar energy system working with high thermal conductivity single-walled carbon nanotubes (SWCNTs) and Therminol®VP-1 nanofluid is numerically investigated. In the numerical analysis, the practical heat flux profiles expected for parabolic trough receivers were obtained using Monte-Carlo ray tracing and coupled with a computational fluid dynamics tool using user defined functions to investigate the thermal performance of the parabolic trough solar energy system. A parabolic trough system with a concentration ratio of 113 was considered in this study and heat transfer fluid inlet temperatures between 400 K and 650 K were used. The volume fraction of SWCNTs in the base fluid was in the range 0% to 2.5% and the flow rates used were in the range 0.82 to 69.41 m3/h. Results show improvements in the convective heat transfer performance and receiver thermal efficiency as well as a considerable reduction of the receiver thermal losses with increasing volume fractions. The heat transfer performance increases up to 64% while the thermal efficiency increases by about 4.4%. Higher increments are observed at low flow rates and inlet temperatures. The receiver thermodynamic performance also increases significantly with the use of nanofluids. Entropy generation rates reduce by about 30% for the range of parameters considered.

scholarly journals Study and Feasibility of a Flat Collector Cooker using Vegetal Heat Transfer Fluid

2021 ◽  
pp. 216-223
Author(s):  
Palm Kalifa ◽  
Kabore Arouna ◽  
Ouedraogo Boukaré ◽  
Lankouande Roland ◽  
Sanogo Oumar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Lower Cost ◽  
Weather Conditions ◽  
Heat Transfer Fluid ◽  
Solar Systems ◽  
Heat Transfer Fluids ◽  
Collector Efficiency ◽  
The City ◽  
Better Than ◽  
Made In

Solar cookers currently produced are solar systems that use parabolic heat transfer to concentrate sun rays on a cooker. The new trend is focus on the cooker that uses a flat collector operating as a thermosiphon where the heat transfer fluid (oil) flows by natural convection. They are developed to address household needs at a lower cost, making them popular both in terms of research and use. Some of vegetable oils were previously investigated and which could be used as heat transfer fluids in such systems. A digital study using vegetable oil called "Kibi oil", an artisanal oil produced in Côte d’Ivoire, as a coolant, was conducted under poor weather conditions to calculate temperatures that could be reached in these cases. In the Sahelian zone, conditions are much better than these, and we can expect fairly excellent results. This study focused on temperature variation at different areas (1, 2, 3 and 4 specified in the diagram) of the cooker, on the mass flow of the fluid throughout the study day and to some quantities which enable to follow the performance of the solar collector of the stove. Sunlight measurements used are those of the city of Abidjan made in September, a very cloudy day with poor weather conditions. Temperature T3, very close to that of the hot plate, was around 110 °C between 10:30 am and 12:30 pm, which enables to cook certain dishes during this period. It should be noticed that at the exit of the flat panel collector, over the same period, the temperature is around 120 ° C. At that same time, the collector efficiency varies around 30%.

scholarly journals Efisiensi Kompor Surya Parabola Berreflektor Cermin Untuk Menunjang Ketahanan Energi

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Abdul Haris Subarjo ◽  
Benedictus Mardwianta ◽  
Anugrah Budi Wicaksono
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Water Temperature ◽  
Environmental Conditions ◽  
Thermal Efficiency ◽  
Research Methodology ◽  
Single Point ◽  
Data Retrieval ◽  
Time Parameters ◽  
The Subject

Radiasi matahari menghasilkan kalor sebagai sumber energi yang dapat dikumpulkan menjadi satu titik sehingga mampu untuk memasak air menggunakan alat bernama Reflektor cermin parabolic. Untuk memperbesar perpindahan kalor menyeluruh (Qm) maka dipilih bahan reflector yang mudah memantulkan sinar matahari. Tujuan yang dilakukan pada penelitian ini adalah untuk mengetahui daya dan efisiensi termal kolektor pada kompor tenaga surya. Metodologi penelitian ini dengan cara pengambilan data dengan parameter waktu yang sudah ditentukan sesuai kondisi  lingkungan untuk memanaskan air 1000 gram. Subyek penelitian ini adalah parabolic solar cooker dengan diameter 84 cm. Hasil daya kompor yang diperoleh sebesar 36,59 Watt dan efisiensi termal kompor sebesar 6,18 %. Daya kompor dipengaruhi oleh selisih temperatur air setelah dipanaskan dengan temperatur air sebelum dipanaskan. Semakin besar temperatur air setelah dipanaskan maka akan memperbesar daya kompor tersebut. Semakin besar perpindahan kalor menyeluruh Qm dan semakin kecil intensitas radiasi matahari pada reflector yang menggunakan cermin maka efisiensi termal semakin besar.Kata kunci: kompor parabola tenaga surya, daya kompor, efisiensi termalABSTRACTSolar radiation generates the heat as a source of energy that can be collected into a single point so that it is able to cook water using a tool named mirror parabolic reflector. To enlarge the whole heat transfer (QM) then selected reflector material that easily reflects the sunlight. The purpose of this study is to find out the power and efficiency of thermal collectors on solar power stoves. This research methodology by means of data retrieval with specified time parameters according to environmental conditions to heat water 1000 grams. The subject of this study is the parabolic solar cooker with a diameter of 84 cm. Results of stove Power obtained at 36.59 Watt and thermal efficiency of the stove amounted to 6.18%. The cooker's power is influenced by the water temperature difference after heated with water temperature before heated. The larger the water temperature after heated it will enlarge the stove's power. The larger the overall heat transfer of the Qm and the smaller the intensity of the solar radiation on the reflector using the mirror hence the greater the thermal efficiency.

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