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Article
Publication date: 20 June 2019

Ali Akbar Abbasian Arani, Ali Arefmanesh and Hamidreza Ehteram

The purpose of this paper is to recommend a validated numerical model for simulation the flue gases heat recovery recuperators. Due to fulfill of this demand, the…

Abstract

Purpose

The purpose of this paper is to recommend a validated numerical model for simulation the flue gases heat recovery recuperators. Due to fulfill of this demand, the influences of ash fouling characteristics during the transient/steady-state simulation and optimization of a 3D complex heat exchanger equipped with inner plain fins and side plate fins are studied.

Design/methodology/approach

For the particle dispersion modeling, the discrete phase model is applied and the flow field has been solved using SIMPLE algorithm.

Findings

According to obtained results, for the recuperator equipped with combine inner plain and side plate fins, determination of ash fouling characteristics is really important, effective and determinative. It is clear that by underestimating the ash fouling characteristics, the achieved results are wrong and different with reality.

Originality/value

Finally, the configuration with inner plain fins with characteristics of: di =5 mm, do = 6 mm, dg = 2 mm, dk = 3 mm and NIPFT = 9 and side plate fins with characteristics of: TF = 3 mm, PF = 19 mm, NSPF = 17·2 = 34, WF = 10 mm, HF = 25 mm, LF = 24 mm and ß = 0° is introduced as the optimum model with the best performance among all studied configurations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 7 August 2020

Ali Akbar Abbasian Arani and Reza Moradi

Using turbulators, obstacles, ribs, corrugations, baffles and different tube geometry, and also various arrangements of these components have a noticeable effect on the…

Abstract

Purpose

Using turbulators, obstacles, ribs, corrugations, baffles and different tube geometry, and also various arrangements of these components have a noticeable effect on the shell and tube heat exchangers (STHEs) thermal-hydraulic performance. This study aims to investigate non-Newtonian fluid flow characteristics and heat transfer features of water and carboxyl methyl cellulose (H2O 99.5%:0.5% CMC)-based Al2O3 nanofluid inside the STHE equipped with corrugated tubes and baffles using two-phase mixture model.

Design/methodology/approach

Five different corrugated tubes and two baffle shapes are studied numerically using finite volume method based on SIMPLEC algorithm using ANSYS-Fluent software.

Findings

Based on the obtained results, it is shown that for low-mass flow rates, the disk baffle (DB) has more heat transfer coefficient than that of segmental baffle (SB) configuration, while for mass flow rate more than 1 kg/s, using the SB leads to more heat transfer coefficient than that of DB configuration. Using the DB leads to higher thermal-hydraulic performance evaluation criteria (THPEC) than that of SB configuration in heat exchanger. The THPEC values are between 1.32 and 1.45.

Originality/value

Using inner, outer or inner/outer corrugations (outer circular rib and inner circular rib [OCR+ICR]) tubes for all mass flow rates can increase the THPEC significantly. Based on the present study, STHE with DB and OCR+ICR tubes configuration filled with water/CMC/Al2O3 with f = 1.5% and dnp = 100 nm is the optimum configuration. The value of THPEC in referred case was 1.73, while for outer corrugations and inner smooth, this value is between 1.34 and 1.57, and for outer smooth and inner corrugations, this value is between 1.33 and 1.52.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 19 June 2019

Behrouz Mozafari, Ali Akbar Abbasian Arani, Ghanbar Ali Sheikhzadeh and Mahmoud Salimi

The purpose of this paper is to study the effects of using different Brownian models on natural and mixed convection fluid flow and heat transfer inside the square…

Abstract

Purpose

The purpose of this paper is to study the effects of using different Brownian models on natural and mixed convection fluid flow and heat transfer inside the square enclosure filled with the AlOOH–water nanofluid.

Design/methodology/approach

Due to fulfill of this demand, five different models for the effective thermal conductivity and viscosity of the nanofluid are considered. The following results are presented for the Ra=107 to 1010 and Ri=0.01 to 100, whereas the volume fraction of the nanoparticles is varied from φ = 0.01 to 0.04.

Findings

According to the obtained results, increasing of Rayleigh number and reduction of Richardson number leads to the higher values of the average Nusselt number and entropy generation. Also, it is realized that, variation trend of the average Nusselt number and entropy generation in all cases is increasing by growing the volume fraction. It is found that the obtained average Nusselt numbers and entropy generations with Koo and Kleinstreuer are the highest among all the studied cases, and it is followed by Patel, Vajjha and Das, Corcione and Maxwell–Brinkman models, respectively.

Originality/value

Based on the results of present investigation, the Nusselt number difference predicted between the Maxwell–Brinkman model (as constant-property model) and Koo and Kleinstreuer model is about 7.84 per cent at 0.01 per cent volume fraction and 5.47 per cent at 0.04 per cent volume fraction for the Rayleigh number equal to 107. The entropy generation difference predicted between the two above studied model is about 8.05 per cent at 0.01 per cent volume fraction and 5.86 per cent at 0.04 per cent volume fraction for the Rayleigh number equal to 107. It is observed that using constant-property model has a significant difference in the obtained results with the results of other variable-property models.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 25 January 2021

Faezeh Nejati Barzoki, Ghanbar Ali Sheikhzadeh, Morteza Khoshvaght Aliabadi and Ali Akbar Abbasian Arani

The purpose of this paper is to investigate thermohydraulic characteristics of turbulent flow of water (4,000 = Re = 10,000) in a rectangular channel equipped with…

Abstract

Purpose

The purpose of this paper is to investigate thermohydraulic characteristics of turbulent flow of water (4,000 = Re = 10,000) in a rectangular channel equipped with perforated chevron plat-fin (PCPF) with different vortex generators (VGs) shapes.

Design/methodology/approach

First, three general shapes of VGs including rectangular, triangular and half circle, are compared to each other. Then, the various shapes of rectangular VGs, (horizontal, vertical and square) and triangular VGs, (forward, backward and symmetric) are evaluated. To comprehensively evaluate the thermohydraulic performance of the PCPF with various VG shapes, the relationship between the Colburn factor and the friction factor (j/f) is presented, then a performance index (η) is applied using these factors.

Findings

Results show that the enhanced models of the PCPF, which are equipped with VGs, have higher values of j/f ratio and η as compared with the reference model (R). Further, the half-circle VG with the lowest pressure drop values (about 2.4% and 4.9%, averagely as compared with the S and ST vortex generators), shows the highest thermohydraulic performance among the proposed shapes. The maximum of performance index of 1.14 is found for the HC vortex generator at Re = 4,000. It is also found that the square and forward triangular VGs, have the best thermohydraulic performance among the rectangular and triangular VGs respectively and the highest performance index of 1.13 and 1.11 are reported for these VGs.

Originality/value

The thermohydraulic performance of the PCPF with different vortex generators VGs shapes have been investigated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 5 April 2021

Ali Akbar Abbasian Arani and Hamed Uosofvand

This paper aims to present a numerical investigation on laboratory-scale segmental baffles shell-and-tube heat exchanger (STHX) having various tube bundles and baffle…

Abstract

Purpose

This paper aims to present a numerical investigation on laboratory-scale segmental baffles shell-and-tube heat exchanger (STHX) having various tube bundles and baffle configuration.

Design/methodology/approach

To discover the higher performance the thermohydraulic behavior of shell-side fluid flow with circular, elliptical and twisted oval tube bundles with segmental and inclined segmental baffled is compared. Shell side turbulent flow and heat transfer are simulated by a finite volume discretization approach using SolidWorks Flow Simulation. To achieve greater configuration performance of this device, the following two approaches is considered: using the inclined baffle with 200 angles of inclination and applying the different tube bundle.

Findings

Different parameters as heat transfer rate, pressure drop (Δp), heat transfer coefficient (h) and heat transfer coefficient to pressure drop ratio (h/Δp) are presented and discussed. Besides, for considering the effect of pressure penalty and heat transfer improvement instantaneously, the efficiency evaluation coefficient (EEC) in the fluid flow and heat transfer based on the power required to provide the real heat transfer augmentation are used.

Originality/value

Obtained results displayed that, at the equal mass flow rate, the twisted oval tubes with segmental baffle decrease the pressure drop 53.6% and 35.64% rather than that the circular and elliptical tubes bundle, respectively. By comparing the (h/Δp) ratio, it can result that the STHX with twisted oval tubes bundle (both segmental and inclined baffle) has better performance than other kinds of the tube bundles. Present results showed that the values of the EEC for all provided models are higher than 1, except for elliptical tube bundles with segmental baffles. The STHX with twisted oval tube bundles and segmental baffle gives the highest EEC value equal to 1.16 in the range of investigated mass flow.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 8 January 2020

Ali Akbar Abbasian Arani and Hamed Uosofvand

This paper aims to investigate the fluid flow and heat transfer of a laboratory shell and tube heat exchanger that are analyzed using computational fluid dynamic approach…

Abstract

Purpose

This paper aims to investigate the fluid flow and heat transfer of a laboratory shell and tube heat exchanger that are analyzed using computational fluid dynamic approach by SOLIDWORKS flow simulation (ver. 2015) software.

Design/methodology/approach

In this study, several types of baffle including segmental baffle, butterfly baffle, helical baffle, combined helical-segmental baffle, combined helical-disk baffle and combined helical-butterfly baffle are examined. Two important parameters as the heat transfer and pressure drop are evaluated and analyzed. Based on obtained results, segmental baffle has the highest amount of heat transfer and pressure drop. To assess the integrative performance, performance coefficient defines as “Q/Δp” is used.

Findings

This investigation showed that among the presented baffle types, the heat exchangers equipped with disk baffle has the highest heat transfer. In addition, in the same mass flow rate, the performance coefficient of the shell and tube heat exchanger equipped with helical-butterfly baffle is the highest among the proposed models.

Originality/value

After combined helical-butterfly baffle the butterfly baffle, disk baffle, helical-segmental baffle and helical-disk baffle show their superiority of 35.12, 25, 22 and 12 per cent rather than the common segmental baffle, respectively. Furthermore, except for the combined helical-disk baffle, the other type of combined baffle have better performance compare to the basic configuration (butterfly and segmental baffle).

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

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