Energy
M. Bagheri; I. Mirzaee; M. Khalilian; V. Mousapour
Abstract
The present study simulates Invelox in a three-dimensional and stable way. The flow regime is turbulent flow and an unorganized grid with 350000 cells was utilized. This work has studied the modeling of invelox with conventional dimensions and four different sizes in the form of four modes for use in ...
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The present study simulates Invelox in a three-dimensional and stable way. The flow regime is turbulent flow and an unorganized grid with 350000 cells was utilized. This work has studied the modeling of invelox with conventional dimensions and four different sizes in the form of four modes for use in a residential building. The numerical data with an error of less than 6% are in good agreement with the available experimental and analytical data. The results show that considering the average velocity of mode 2 with a velocity of 6.54 m/s and a 5% difference from the other two modes, it can be operated in a residential building. It is worth noting that in this investigation, in addition, the effect of dust on the turbine performance was evaluated. The results represent that the oscillation frequency of the blades increases with the increase of the rotational speed. In the case of not considering dust particles on blades, this amount increases by 25%, while considering dust particles with an amount of 0.1%, it increases up to 300%, and this can cause irreparable damage to the turbine as well as the power generation system.
Chemical Engineering
Z. Aouissi; F. Chabane; M. S. Teguia; N. Belghar; N. Moummi; A. Brima
Abstract
This numerical and experimental work aims to improve the heat transfer inside a solar thermal collector. By incorporating rectangular baffles in the middle of the distributed air passing channel at different angles of inclination (ß= 90°, ß= 180°, ß= 180° and ß= 90°). ...
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This numerical and experimental work aims to improve the heat transfer inside a solar thermal collector. By incorporating rectangular baffles in the middle of the distributed air passing channel at different angles of inclination (ß= 90°, ß= 180°, ß= 180° and ß= 90°). That is called the model H. These experiments were carried out in the Biskra region of Algeria in good natural conditions with an average solar radiation approximately constant I= 869 W/m2 varying from 11:30 to 14:00. After the completion of the experimental investigation, a computational fluid dynamics (CFD) model was created that matches this experimental model with the same experimental boundary conditions. In the numerical study, ANSYS Fluent 18.1 was used to conduct simulations and compare the results of the thermal and hydraulic performance of the collector. It was concluded that the effectiveness of the CFD model, meaning that the theoretical and numerical data were very close to each other for all mass flow rates. As the mass flow increased the heat transfer process increased, while the absorber plate temperature inside the collector for experimental and numerical studies decreased. Addition of baffles increased heat transfer, due to the creation of turbulent flow that leads to crack the dead thermal layers near the absorber plate, which leads to an increase in heat transfer from the absorber plate to the air.
S. A. Gandjalikhan Nassab; M. Moein Addini
Abstract
In the present paper, the use of radiating gas instead of air inside the cavity of compound parabolic collectors (CPSs) is suggested and verified by numerical analysis. The collector under study has a simple cone shape with flat absorber which is filled with a participating gas such as carbon dioxide ...
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In the present paper, the use of radiating gas instead of air inside the cavity of compound parabolic collectors (CPSs) is suggested and verified by numerical analysis. The collector under study has a simple cone shape with flat absorber which is filled with a participating gas such as carbon dioxide instead of air for the purpose of increasing the thermal performance. In numerical simulation, the continuity, momentum and energy equations for the steady natural convection laminar gas flow in the CPC’s cavity and the conduction equation for glass cover and absorber plate were solved by the finite element method (FEM) using the COMSOL multi-physics. Because of the radiative term in the gas energy equation, the intensity of radiation in participating gas flow should be computed. Toward this end, the radiative transfer equation (RTE) was solved by the discrete ordinate method (DOM), considering both diffuse and collimated radiations. The approximation was employed in calculation of the diffuse part of radiation. It was observed that the gas radiation causes high temperature with more uniform distribution inside the cavity of collector. Also, numerical results reveal more than 3% increase in the rate of heat transfer from absorber surface into working fluid and hence a desired performance for the collector because of the gas radiation effect. Comparison between the present numerical results with theoretical and experimental data reported in the literature showed good consistency.
A. Kumar Thakur; S. Kumar Pathak
Abstract
Solar still is a device, used to convert brackish water into distill water but the major issue low profitability and it is imperative to outline an ideal device. Computational Fluid Dynamics (CFD) simulation can help designers to improve the execution of a sun oriented still for a given cost. In this ...
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Solar still is a device, used to convert brackish water into distill water but the major issue low profitability and it is imperative to outline an ideal device. Computational Fluid Dynamics (CFD) simulation can help designers to improve the execution of a sun oriented still for a given cost. In this study, we examine the capacity of CFD simulation in calculation of heat and mass transfer in a single basin sun powered still. Experiments were performed in month of June in Jaipur, India. In this work, single basin solar still was fabricated and then optimized using CFD based methodology for water depth of 0.01m, 0.02m and 0.03 m. CFD based results help in a designing a solar still with maximum yield productivity of distilled water. It was concluded that maximum yield was achieved when water depth has minimum value i.e. 0.01 m. Total dissolved solid (TDS) value for sample water taken at water basin was in range of 500 PPM but after distillation water at output reaches below 50 PPM. Therefore, solar still was capable of improving the quality of water and brackish water of high TDS value can be reduced and used for drinking purpose.
