scholarly journals Comprehensive performance investigation and optimization of a plate fin heat exchanger with wavy fins

2021 ◽  
pp. 322-322
Author(s):  
Mengmeng Cui ◽  
Rui Song
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pump Power ◽  
Pressure Drop ◽  
Objective Function ◽  
Entropy Generation ◽  
Entropy Generation Number ◽  
Generation Number ◽  
Comprehensive Performance ◽  
Modified Entropy

As the pressure drop and pump power increase with the enhancement of heat transfer, it is of great value to investigate the comprehensive performance of the heat exchanger based on common accurate correlations of heat transfer and flow friction. This paper adopts a generalized air-side thermal-hydraulic correlation to study the comprehensive performances of the plate fin heat exchanger with wavy fins. To better understand the fin characteristics, performance indexes under the same flow rate, pressure drop and pump power are employed to estimate the comprehensive flow and heat transfer performances. The nonlinear optimization problem is established in consideration of the multiple independent variables with the maximum effectiveness or the minimum modified entropy generation number as the optimization objective function, which is solved by the genetic algorithm. Comparative analysis is conducted for results obtained from the parametric analysis and heat exchanger optimization, indicating that the objective function of the modified entropy generation number is effective for the design optimization of the comprehensive performance.

Performance evaluation and entropy generation of chevron-type plate-fin equipped with ribs and holes

2021 ◽  
pp. 095440622110127
Author(s):  
F Nejati Barzoki ◽  
M Khoshvaght-Aliabadi ◽  
GA Sheikhzadeh ◽  
AA Abbasian Arani ◽  
A Feizabadi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Entropy Generation ◽  
Geometrical Parameters ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Generation Number ◽  
Performance Indexes ◽  
The Relationship

The complexity caused by an enhanced technique may significantly enhance the heat transfer along with a penalty in the pressure drop. Thus, it is needed to assess the counteracting effects between the enhanced heat transfer and the augmented pressure drop in practical applications. In order to comprehensively evaluate the hydrothermal performance of the chevron-type plate-fin (CTPF) equipped with ribs and holes, this study focuses on the relationship between hydraulic and thermal characteristics. Firstly, the relationship between the Colburn factor and the friction factor is presented, then two performance indexes are applied using these factors to evaluate the use of ribs and holes in the CTPIt F is found that the simultaneous use of ribs and holes shows better overall performances as compared with the use of ribs or holes individually. At the same geometrical parameters, the highest values of 1.52 and 1.07 are recorded for these performance indexes. In order to further improve the overall performance of the CTPF, the effects of geometrical parameters are also investigated. With the decrease of corrugation amplitude ( a) and the increase of corrugation length ( l), rib height ( h), and rib thickness ( t), the CTPF performs better overall performances. And, for the models with different levels of hole width ( w), the better performance is seen when this parameter is at the middle level. However, in the studied models, the best overall hydrothermal performance is detected for the model with a = 2.5 mm, l = 60 mm, h = 2.5 mm, t = 10 mm, and w = 10 mm, and highest performance indexes of 2.52 and 1.15 are reported for this model. Likewise, an entropy generation analysis is carried out, and the obtained results are discussed based on the Bejan number and entropy generation number. The results show that the increase of Reynolds number can lead to decrease of Bejan number and to increase of entropy generation number. For Reynolds number ranging from 4000 to 10000, the best model, which is described above, shows 17% decrease in the entropy generation number comparing with the reference model. Finally, two correlations are developed to predict the Bejan number and entropy generation number of the current study.

scholarly journals Analytical Assessment of (Al2O3–Ag/H2O) Hybrid Nanofluid Influenced by Induced Magnetic Field for Second Law Analysis with Mixed Convection, Viscous Dissipation and Heat Generation

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 498
Author(s):  
Wasim Ullah Khan ◽  
Muhammad Awais ◽  
Nabeela Parveen ◽  
Aamir Ali ◽  
Saeed Ehsan Awan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Heat Generation ◽  
Transfer Rate ◽  
Second Law ◽  
Hybrid Nanofluid ◽  
Entropy Generation Number ◽  
Generation Number ◽  
Second Law Analysis

The current study is an attempt to analytically characterize the second law analysis and mixed convective rheology of the (Al2O3–Ag/H2O) hybrid nanofluid flow influenced by magnetic induction effects towards a stretching sheet. Viscous dissipation and internal heat generation effects are encountered in the analysis as well. The mathematical model of partial differential equations is fabricated by employing boundary-layer approximation. The transformed system of nonlinear ordinary differential equations is solved using the homotopy analysis method. The entropy generation number is formulated in terms of fluid friction, heat transfer and Joule heating. The effects of dimensionless parameters on flow variables and entropy generation number are examined using graphs and tables. Further, the convergence of HAM solutions is examined in terms of defined physical quantities up to 20th iterations, and confirmed. It is observed that large λ1 upgrades velocity, entropy generation and heat transfer rate, and drops the temperature. High values of δ enlarge velocity and temperature while reducing heat transport and entropy generation number. Viscous dissipation strongly influences an increase in flow and heat transfer rate caused by a no-slip condition on the sheet.

Thermodynamic optimization of nanofluid flow over a non-isothermal wedge with nonlinear radiation and activation energy

2021 ◽  
Author(s):  
M R Acharya ◽  
P Mishra ◽  
Satyananda Panda
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Reynolds Number ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Mathematical Formulation ◽  
Bejan Number ◽  
Nanofluid Flow ◽  
Entropy Generation Number ◽  
Generation Number

Abstract This paper analyses the augmentation entropy generation number for a viscous nanofluid flow over a non-isothermal wedge including the effects of non-linear radiation and activation energy. We discuss the influence of thermodynamically important parameters during the study, namely, the Bejan number, entropy generation number, and the augmentation entropy generation number. The mathematical formulation for thermal conductivity and viscosity of nanofluid for Al2O3 − EG mixture has been considered. The results were numerically computed using implicit Keller-Box method and depicted graphically. The important result is the change in augmentation entropy generation number with Reynolds number. We observed that adding nanoparticles (volume fraction) tend to enhance augmentation entropy generation number for Al2O3 − EG nanofluid. Further, the investigation on the thermodynamic performance of non-isothermal nanofluid flow over a wedge reveals that adding nanoparticles to the base fluid is effective only when the contribution of heat transfer irreversibility is more than fluid friction irreversibility. This work also discusses the physical interpretation of heat transfer irreversibility and pressure drop irreversibility. This dependency includes Reynolds number and volume fraction parameter. Other than these, the research looked at a variety of physical characteristics associated with the flow of fluid, heat and mass transfer.

Second law analysis of magneto-natural convection in a nanofluid filled wavy-hexagonal porous enclosure

2020 ◽  
Vol 30 (11) ◽  
pp. 4811-4836 ◽  
Author(s):  
Seyyed Masoud Seyyedi ◽  
A.S. Dogonchi ◽  
M. Hashemi-Tilehnoee ◽  
D.D. Ganji ◽  
Ali J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Entropy Generation ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Content Type ◽  
Entropy Generation Number ◽  
Maximum Value ◽  
Generation Number

Purpose Natural convection heat transfer analysis can be completed using entropy generation analysis. This study aims to accomplish both the natural convection heat transfer and entropy generation analyses for a hexagonal cavity loaded with Cu-H2O nanoliquid subjected to an oriented magnetic field. Design/methodology/approach Control volume-based finite element method is applied to solve the non-dimensional forms of governing equations and then, the entropy generation number is computed. Findings The results portray that both the average Nusselt and entropy generation numbers boost with increasing aspect ratio for each value of the undulation number, while both of them decrease with increasing the undulation number for each amplitude parameter. There is a maximum value for the entropy generation number at a specified value of Hartmann number. Also, there is a minimum value for the entropy generation number at a specified value of angle of the magnetic field. When the volume fraction of nanoparticles grows, the average Nusselt number increases and the entropy generation number declines. The entropy generation number attains to a maximum value at Ha = 14 for each value of aspect ratio. The average Nusselt number ascends 2.9 per cent and entropy generation number decreases 1.3 per cent for Ha = 0 when ϕ increases from 0 to 4 per cent. Originality/value A hexagonal enclosure (complex geometry), which has many industrial applications, is chosen in this study. Not only the characteristics of heat transfer are investigated but also entropy generation analysis is performed in this study. The ecological coefficient of performance for enclosures is calculated, too.

Parametric study of heat transfer performance including entropy generation of microchannel heat sink with fan cavity and different rib structure

2021 ◽  
pp. 095440892110434
Author(s):  
K. Bala Subrahmanyam ◽  
Aparesh Datta ◽  
Pritam Das
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Microchannel Heat Sink ◽  
Transfer Performance ◽  
Bulk Fluid ◽  
Simultaneous Application ◽  
Entropy Generation Number ◽  
Generation Number

This numerical study investigates the simultaneous application of axial wall conduction effect and entropy generation minimization as two principles to identify heat transfer performance in a microchannel heat sink with fan cavity and ribs. In this conjugate analysis, three different materials for a microchannel heat sink considered are silicon, aluminium, and copper. In addition to the fan cavity (F), effects of different rib configurations arranged symmetrically inside the fan cavity, that is, backward triangle rib (FB), rectangular rib (FR), forward triangle rib (FF), and diamond rib (FD) with Reynolds numbers ranging from 136 to 588 are studied. The comparative study between silicon and copper in terms of local wall and bulk fluid temperatures, increment in solid wall to fluid thermal conductivity ratio within the range (247.07 <  ksf < 669.44), local Nusselt number (Nu x), axial conduction number (M), and entropy generation number ( Ns, a) were furnished and examined. Structural optimization is performed on diamond rib configuration geometrical parameters to observe entropy generation number and wall conduction effects trend as thermal performance is greatly improved to 2.49, at the lowest Ns, a to 0.31 at Re 391.47, with copper in the back to back cavities case. However based on the numerical results, comparative importance of axial wall conduction effect consideration in the present design of microsink, silicon is showing best results in overcoming at Re 588.4, consistently in all optimization cases.

3-D Numerical Study on Shell-Side Comprehensive Performance of Shell-and-Tube Heat Exchanger With Combined Helical Baffles

2010 ◽  
Author(s):  
Guidong Chen ◽  
Jing Xu ◽  
Ming Zen ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Comprehensive Performance ◽  
Shell And Tube ◽  
The Heat Transfer Coefficient

In order to improve heat transfer performance of conventional segmental baffled shell-and-tube heat exchangers (STHXs), the shell-and-tube heat exchanger with combined helical baffles (CMH-STHX) were invented. In the present study, the CMH-STHX is compared with three other STHXs which were set up with continuous helical baffles (CH-STHX), discontinuous helical baffles (DCH-STHX) and segmental baffles (SG-STHX), by Computational Fluid Dynamics method. The numerical results show that, for the same mass flow rate at the shell side, the overall pressure drop of the CMH-STHX is about 50% and 40% lower than that of SG-STHX and CH-STHX. The heat transfer coefficient of the CMH-STHX is between those of CH-STHX and DCH-STHX and it is 6.3% lower than that of SG-STHX. The heat transfer coefficient under unit pressure drop h/Δp is introduced to evaluate the comprehensive performance of STHXs. The h/Δp of the CMH-STHX is 7.5%, 6.5% and 87.4% higher on average than those of the CH-SHTX, DCH-STHX and SG-STHX. Furthermore, the total heat transfer rate of CMH-STHX is about 25% higher than that of SG-STHX for the same total pressure drop of shell side. Supported by these results, the new heat exchanger (CMH-STHX) may be used to replace the conventional shell-and-tube heat exchanger in industrial applications.

A modified entropy generation number for heat exchangers

1996 ◽  
Vol 5 (4) ◽  
pp. 257-263 ◽  
Author(s):  
Z. M. Xu ◽  
S. R. Yang ◽  
Z. Q. Chen
Keyword(s):  
Entropy Generation ◽  
Heat Exchangers ◽  
Entropy Generation Number ◽  
Generation Number ◽  
Modified Entropy

scholarly journals Thermodynamical Analysis of the Flow and Heat Transfer over a Static and a Moving Wedge

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Adnan Saeed Butt ◽  
Asif Ali
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Temperature Fields ◽  
Entropy Production Rate ◽  
Physical Parameters ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Flow And Heat Transfer ◽  
Generation Number ◽  
Moving Wedge

The first and second law characteristics of fluid flow and heat transfer over a static and a moving wedge are investigated. With the help of suitable similarity transformations, the governing boundary layer equations for the velocity and temperature fields are transformed into ordinary differential equations and are solved numerically. The velocity and the temperature profiles are obtained for various parameters and are utilized to compute the entropy generation number Ns and the Bejan number Be. The effects of various physical parameters on the entropy generation number and the Bejan number are depicted through graphs and are discussed qualitatively. It is observed that the entropy production rate is less in case of wedge moving in the opposite direction to flow as compared to static wedge.

scholarly journals Entropy analysis in moving wavy surface boundary-layer

2019 ◽  
Vol 23 (1) ◽  
pp. 233-241 ◽  
Author(s):  
Ahmer Mehmood ◽  
Muhammad Iqbal ◽  
Sajid Khan ◽  
Sufian Munawar
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Wavy Surface ◽  
Bejan Number ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Entropy Generation Number ◽  
Keller Box Method ◽  
Generation Number ◽  
Group Parameter

It is a well-established fact that significant gain in the heat transfer rate can be obtained by altering that flat surface texture of the working body. The most convenient alteration, in view of mathematical handling, is the wavy one. Existing studies reveal that the convective heat transfer phenomenon is affected significantly due to the presence of a solid wavy surface. How does the phenomena of entropy generation is effected due to a wavy surface is the question investigated in this manuscript. The expressions for irreversibility distribution rate, Bejan number, and volumetric entropy generation number have been evaluated by Keller-Box method. The effect of important parameters of interest, such as wavy amplitude, Prandtl number, and group parameter on irreversibility distribution rate, Bejan number and entropy generation number, have been discussed in detail. The study reveals that entropy generation number decreases and irreversibility rate increases by increasing the amplitude of the wavy surface.

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