scholarly journals Effect of Greenhouse Gases on the Behaviour of Parabolic Trough Collector Based on CFD Simulation

2020 ◽  
Vol 8 (5) ◽  
pp. 1950-1954
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Greenhouse Gas ◽  
Cfd Simulation ◽  
Parabolic Trough ◽  
Green Technologies ◽  
Ansys Fluent ◽  
Water Heaters ◽  
Cell Reynolds Number ◽  
Solar Water Heaters

Energy extraction by solar energy harnessing method is one of the most futuristic approach to accelerate towards green technologies. The parabolic trough solar collectors are most widely used entities in entire world for solar water heaters. The existing problem of low rate of water heating is disadvantageous for its commercial use. Hence the study focuses on observing the effect of greenhouse when the evacuated tubes are equipped with most common greenhouse gas CO_2 (Carbon dioxide). The simulations were carried out on Ansys (FLUENT) at steady state conditions. The parameters observed to compare the rate of boiling are Cell Reynolds number, Surface skin friction and the average steady state temperature. The greenhouse gas seems effective in increasing the rate of boiling due to which the Cell Reynolds number has increased in both minima and maxima.

Steady State Analysis on Efficiency Improving Methods for Series Flat Plate Solar Water Heaters

2014 ◽  
Vol 592-594 ◽  
pp. 1784-1788
Author(s):  
M. Sridharan ◽  
E. Siva Prakash ◽  
N. Prasanna
Keyword(s):  
Steady State ◽  
Theoretical Analysis ◽  
Flat Plate ◽  
Experimental Analysis ◽  
New Combination ◽  
Improve Performance ◽  
Steady State Analysis ◽  
Water Heaters ◽  
Different Types ◽  
Solar Water Heaters

Now a day’s different types of solar flat plate collectors are in use. Out of which only few type of collectors proved their performance by producing better results of expected level. In this paper a new set of collectors are combined as mean to improve performance of series SFPC collectors available in market now a days. In such new combination a collector with reduced overall loss coefficient was used to improve the efficiency of the existing system. New collector with zig-zag flow pattern gives a slight change in flow path. Thus the objective of this experimental analysis is to improve efficiency with new set of series FPC by comparing with existing series FPC. Experimental results obtained give better and higher results suggested by theoretical analysis.

scholarly journals CFD Simulation Strategy for Hypersonic Aerodynamic Heating around a Blunt Biconic

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Shutian Yu ◽  
Xinyue Ni ◽  
Fansheng Chen
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Thermal Protection ◽  
High Reliability ◽  
Aerodynamic Heating ◽  
Discretization Scheme ◽  
Wall Cell ◽  
Simulation Strategy ◽  
Cell Reynolds Number

The design of the thermal protection system requires high-precision and high-reliability CFD simulation for validation. To accurately predict the hypersonic aerodynamic heating, an overall simulation strategy based on mutual selection is proposed. Foremost, the grid criterion based on the wall cell Reynolds number is developed. Subsequently, the dependence of the turbulence model and the discretization scheme is considered. It is suggested that the appropriate value of wall cell Reynolds number is 1 through careful comparison between one another and with the available experimental data. The excessive number of cells is not recommended due to time-consuming computation. It can be seen from the results that the combination of the AUSM+ discretization scheme and the Spalart-Allmaras turbulence model has the highest accuracy. In this work, the heat flux error of the stagnation point is within 1%, and the overall average relative error is within 10%.

An analysis of the economic viability and greenhouse gas emissions reductions resulting from the use of solar water heaters in a typical Brazilian dwelling

2018 ◽  
Vol 4 (2) ◽  
pp. 1-10
Author(s):  
Leandra Altoé ◽  
Delly Oliveira Filho ◽  
Joyce Correna Carlo ◽  
Paulo Marcos Barros Monteiro ◽  
Isabella Theresa Almeida Martins
Keyword(s):  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Economic Viability ◽  
Solar Water Heater ◽  
Water Heater ◽  
Emissions Reductions ◽  
Gas Emissions ◽  
Solar Water ◽  
Water Heaters ◽  
Solar Water Heaters

Several countries have reduced their energy consumption and greenhouse gas emissions levels in buildings by promulgating laws, formulating standards and instituting certification programs. In this context, Brazil launched an energy efficiency certification for buildings in 2009. This study aimed to analyze the economic viability and potential greenhouse gas emissions reductions associated with the use of solar water heaters in a typical Brazilian dwelling. Solar thermal systems were simulated at different energy efficiency levels and shower water flow rates. It was found that the use of solar water heater, as compared with electric heater without a hot water storage, presented internal return rate of approximately 26% per year, simple payback around 4.5 years; net present value about US$ 2,194.00 and cost of conserved energy around US$ 0.12 kWh-1. This study also verified that solar water heater use in a typical Brazilian dwelling reduced emissions compared with electric and gas heating by approximately 95 and 256 kgCO2equivalentyear-1, respectively. The total reduction potential of greenhouse gas emissions by use solar water heaters for the Brazilian residential sector was substantial, around 5.75 million tCO2equivalentyear-1.

Experimental Study on the Heat Exchanger Performance of Parabolic Trough Solar Water Heater

2014 ◽  
Vol 1008-1009 ◽  
pp. 58-62
Author(s):  
Bin Yang ◽  
Wei Wang ◽  
De Gong Zuo
Keyword(s):  
Solar Water Heater ◽  
Parabolic Trough ◽  
Water Heater ◽  
Average Efficiency ◽  
Solar Water ◽  
Daily Average ◽  
Water Heaters ◽  
Solar Energy Flux ◽  
Energy Flux Density ◽  
Solar Water Heaters

This paper introduces a new type of solar water heater——Parabolic trough solar water heater,the biggest feature of the solar water heater is that the parabolic trough reflector can reflect light onto the tube with reflective principles,which may lead to lots of advantages,such as more strong solar energy flux density,fewer losses,fewer tubes used.In a word,the cost is reduced while the performance is guaranteed.On this basis,we built a collector area of about 1.54 square meters of parabolic trough solar water heaters bench and made experiments to test.Instantaneous average efficiency and daily average efficiency of the water heater can be calculated.Efficiency curve can also be generated.Meanwhile we measured the heat loss coefficient of the water heater.The results showed that the daily average efficiency of the parabolic trough concentrating solar collector is between 30% and 50%,while at higher temperatures the collector showed its good insulation properties.

scholarly journals CFD Simulation of Heat Transfer and Turbulent Fluid Flow over a Double Forward-Facing Step

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Hussein Togun ◽  
Ahmed Jassim Shkarah ◽  
S. N. Kazi ◽  
A. Badarudin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Cfd Simulation ◽  
Step Height ◽  
Ansys Fluent ◽  
Contour Maps ◽  
Before And After ◽  
Forward Facing Step ◽  
Energy Equations

Heat transfer and turbulent water flow over a double forward-facing step were investigated numerically. The finite volume method was used to solve the corresponding continuity, momentum, and energy equations using theK-εmodel. Three cases, corresponding to three different step heights, were investigated for Reynolds numbers ranging from 30,000 to 100,000 and temperatures ranging from 313 to 343 K. The bottom of the wall was heated, whereas the top was insulated. The results show that the Nusselt number increased with the Reynolds number and step height. The maximum Nusselt number was observed for case 3, with a Reynolds number of 100,000 and temperature of 343 K, occurring at the second step. The behavior of the Nusselt number was similar for all cases at a given Reynolds number and temperature. A recirculation zone was observed before and after the first and second steps in the contour maps of the velocity field. In addition, the results indicate that the coefficient pressure increased with increasing Reynolds number and step height. ANSYS FLUENT 14 (CFD) software was employed to run the simulations.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

scholarly journals Prediction of Liner Metal Temperature of an Aeroengine Combustor with Multi-Physics Scale-Resolving CFD

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 901
Author(s):  
Davide Bertini ◽  
Lorenzo Mazzei ◽  
Antonio Andreini
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Turbulence Models ◽  
Metal Temperature ◽  
Lean Burn ◽  
Turbulence Scale ◽  
Ansys Fluent ◽  
Multi Scale ◽  
Assessment Tests ◽  
Rans Turbulence Models

Computational Fluid Dynamics is a fundamental tool to simulate the flow field and the multi-physics nature of the phenomena involved in gas turbine combustors, supporting their design since the very preliminary phases. Standard steady state RANS turbulence models provide a reasonable prediction, despite some well-known limitations in reproducing the turbulent mixing in highly unsteady flows. Their affordable cost is ideal in the preliminary design steps, whereas, in the detailed phase of the design process, turbulence scale-resolving methods (such as LES or similar approaches) can be preferred to significantly improve the accuracy. Despite that, in dealing with multi-physics and multi-scale problems, as for Conjugate Heat Transfer (CHT) in presence of radiation, transient approaches are not always affordable and appropriate numerical treatments are necessary to properly account for the huge range of characteristics scales in space and time that occur when turbulence is resolved and heat conduction is simulated contextually. The present work describes an innovative methodology to perform CHT simulations accounting for multi-physics and multi-scale problems. Such methodology, named U-THERM3D, is applied for the metal temperature prediction of an annular aeroengine lean burn combustor. The theoretical formulations of the tool are described, together with its numerical implementation in the commercial CFD code ANSYS Fluent. The proposed approach is based on a time de-synchronization of the involved time dependent physics permitting to significantly speed up the calculation with respect to fully coupled strategy, preserving at the same time the effect of unsteady heat transfer on the final time averaged predicted metal temperature. The results of some preliminary assessment tests of its consistency and accuracy are reported before showing its exploitation on the real combustor. The results are compared against steady-state calculations and experimental data obtained by full annular tests at real scale conditions. The work confirms the importance of high-fidelity CFD approaches for the aerothermal prediction of liner metal temperature.

scholarly journals Settling of an asymmetric dumbbell in a quiescent fluid

2016 ◽  
Vol 802 ◽  
pp. 174-185 ◽  
Author(s):  
F. Candelier ◽  
B. Mehlig
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Size Difference ◽  
Fluid Inertia ◽  
Horizontal Orientation ◽  
Vertically Aligned ◽  
Rigid Rod ◽  
Quiescent Fluid

We compute the hydrodynamic torque on a dumbbell (two spheres linked by a massless rigid rod) settling in a quiescent fluid at small but finite Reynolds number. The spheres have the same mass densities but different sizes. When the sizes are quite different, the dumbbell settles vertically, aligned with the direction of gravity, the largest sphere first. But when the size difference is sufficiently small, then its steady-state angle is determined by a competition between the size difference and the Reynolds number. When the sizes of the spheres are exactly equal, then fluid inertia causes the dumbbell to settle in a horizontal orientation.

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