scholarly journals Thermal Performance Enhancement Using Absorber Tube with Inner Helical Axial Fins in a Parabolic Trough Solar Collector

2021 ◽  
Vol 11 (16) ◽  
pp. 7423
Author(s):  
Mohammad Zaboli ◽  
Seyed Soheil Mousavi Ajarostaghi ◽  
Seyfolah Saedodin ◽  
Mohsen Saffari Pour
Keyword(s):  
Performance Improvement ◽  
Thermal Performance ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Parabolic Trough ◽  
Ansys Fluent ◽  
Swirl Generator ◽  
Previous Part ◽  
Energy Equations ◽  
Volume Method

In the present work, a parabolic trough solar (PTC) collector with inner helical axial fins as swirl generator or turbulator is considered and analyzed numerically. The three-dimensional numerical simulations have been done by finite volume method (FVM) using a commercial CFD code, ANSYS FLUENT 18.2. The spatial discretization of mass, momentum, energy equations, and turbulence kinetic energy has been obtained by a second-order upwind scheme. To compute gradients, Green-Gauss cell-based method has been employed. This work consists of two sections where, first, four various geometries are appraised, and in the following, the selected schematic of the collector from the previous part is selected, and four various pitches of inner helical fins including 250, 500, 750 and 1000 mm are studied. All the numerical results are obtained by utilizing the FVM. Results show that the thermal performance improvement by 23.1% could be achieved by using one of the proposed innovative parabolic trough solar collectors compare to the simple one. Additionally, the minimum and maximum thermal performance improvement (compare to the case without fins) belong to the case with P = 250 mm by 14.1% and, to the case with P = 1000 mm by 21.53%, respectively.

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

2014 ◽  
Vol 1082 ◽  
pp. 100-105
Author(s):  
Camila Almeida Martins ◽  
Jhon Jairo Ramirez-Behainne
Keyword(s):  
Numerical Model ◽  
Thermal Cycling ◽  
Material Properties ◽  
Three Dimensional ◽  
Fusion Line ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Simplifying Assumptions ◽  
Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

scholarly journals CONSTRUCTAL DESIGN OF A TUBULAR ARRAY SUBJECTED TO FORCED CONVECTION

2015 ◽  
Vol 14 (1) ◽  
pp. 16
Author(s):  
V. A. Pedrotti ◽  
J. A. Souza ◽  
E. D. Dos Santos ◽  
L. A. Isoldi
Keyword(s):  
Thermal Performance ◽  
Mesh Generation ◽  
Constructal Theory ◽  
Forced Flow ◽  
Constructal Design ◽  
Fluent Software ◽  
Energy Equations ◽  
Volume Method ◽  
Study Setting ◽  
Tubular Array

In this work a tubular array (four tubes) subjected to a transverse forced flow is analyzed in terms of thermal performance. Taking into account that there are two main assembles usually used in heat exchanger equipment (aligned and staggered), and that there exist an uncountable number of possible assembles for an array of tubes, present work proposes to use the Constructal Theory to build an optimized assemble. The distance between tubes (p), and the region where tubes can be positioned are the geometric constraint of the problem. Four values for p were considered: p = 1.25D (tube diameter), p = 1.5D, p = 2D, p is free (no restriction). Fluid flow is considered bi-dimensional, incompressible and laminar with ReD = 10 and Pr = 0.71. Mass, momentum and energy equations were solved by the Finite Volume Method (FVM) using FLUENT software. Geometry creation and mesh generation were performed with GMSH software while VISIT software was used for the post processing. Results have shown that imposing no restriction to tube positioning do not necessarily lead to best system thermal performance. In this particular study, setting p = 2D has resulted in best thermal performance.

Numerical Investigation of the Thermal Performance of an Axially Rotating Internally Finned Receiver Tube of Parabolic Trough Concentrator

2021 ◽  
Vol 16 ◽  
pp. 241-253
Author(s):  
Andrew S. Tanious ◽  
Ahmed A. Abdel-Rehim
Keyword(s):  
Thermal Performance ◽  
Rotation Rate ◽  
Pressure Coefficient ◽  
Axial Rotation ◽  
Finned Tube ◽  
Outlet Temperature ◽  
Parabolic Trough ◽  
Ansys Fluent ◽  
Fluid Layers ◽  
Internally Finned Tube

Enhancement of the thermal performance of the parabolic trough receiver tube is one of the approaches to energy sustainability. In the present work, the thermal performance of an axially rotating receiver tube equipped with internal flat longitudinal fins is studied. The effects of both the fin height and the rate of axial rotation are investigated at low values of axial Reynold’s number. The numerical analysis is held at various rotation rates using ANSYS Fluent. The numerical findings showed that the effect of the axial rotation on the internally finned receiver tube is not significant yet negative where a maximum reduction of 6% in the outlet temperature is reached in the 2mm height internally finned tube at rotation rate of N=21. However, the analysis showed that as the rotation rate increases, the temperature homogeneity between the fluid layers also increases and thus the liquid stratification phenomenon between the fluid layers is eliminated. The percentage of temperature difference between the fluid layers near the pipe center and the layers near the pipe wall reaches an optimum value of 58.4% at N=21 which is confirmed by an optimum increase of 110% in Nusselt number at the same rotation rate. However, a maximum loss of 81.6% in pressure coefficient is found in the case of the 2mm internally finned tube due to the increased turbulence. Thus, the integration of pipe axial rotation and internal fins can yield an enhancement in the heat transfer to the parabolic trough concentrator receiver tube and thus its thermal performance.

Fluid Flow and Heat Transfer in an Annulus With Ribs on the Rotating Inner Cylinder Surface

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
S. Gokul ◽  
M. Deepu
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Cylinder Surface ◽  
Turbulent Fluid Flow ◽  
Cylindrical Annulus ◽  
Volume Method

Abstract Numerical studies on heat transfer in Taylor-Couette-Poiseuille flow in a cylindrical annulus with ribs mounted on the rotating inner cylinder are presented. The present study focuses on two different types of ribs, namely, longitudinal ribs and helical ribs. Three-dimensional, steady, incompressible, turbulent fluid flow is solved using a semi-implicit method for pressure linked equations (SIMPLE) algorithm based finite volume method. The numerical solution method is validated using two sets of benchmark experimental data. Extensive numerical computations are carried out at various Reynolds numbers (2100 < Re < 2400) and modified Taylor numbers (30,000 < Tam < 90,000) for annulus with and without ribs. Ribs enhance the transport of heat and momentum by inducing more vorticity and turbulence in the flow. The overall performance is presented in terms of thermal performance factor (TPF), which takes in to account the heat transfer as well as pressure drop in the ribbed annulus. Helical ribs are found to offer superior thermal performance than its longitudinal counterpart.

scholarly journals Numerical assessment of brick walls` use incorporating a phase change material towards thermal performance in buildings during a passive cooling strategy

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 1909-1922
Author(s):  
Zohir Younsi ◽  
Hassan Naji
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Thermal Performance ◽  
Building Materials ◽  
Performance Enhancement ◽  
Numerical Approach ◽  
Building Envelope ◽  
Passive Cooling ◽  
Volume Method ◽  
Change Material

The integration of new building materials incorporating phase change material (PCM) into the building envelope leads to an increase of the heat storage capacity, which may have an influence on minimizing the cooling demand and heating of the building. This work addresses a thermal performance enhancement of brick walls with incorporated PCM. The improvement has been assessed through a numerical approach in dealing with a 1-D transient conduction problem with phase change, while leaning on experimental results from a transient guarded hot plates method. The simulations have been fulfilled using a hybrid method combining both the finite volume method and an enthalpy porosity technique. The results of this combined approach are in good agreement. In the light of the findings obtained, it appears that PCM incorporation into a brick masonry can both reduce peak temperatures up to 3?C and smooth out daily fluctuations. Thereby, the evaluation achieved can turns out useful in developing brick walls with an incorporated PCM for passive cooling, thus improving buildings thermal performance.

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