Experimental and numerical analysis of heat transfer in the helically coiled heat exchanger

2019 ◽  
Vol 30 (6) ◽  
pp. 2935-2951 ◽  
Author(s):  
Tomasz Sobota
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Least Squares Method ◽  
Thermal Design ◽  
Content Type ◽  
Tube Heat Exchanger

Purpose The knowledge of the heat transfer coefficient is important for the proper design of heat exchangers as well as for the determination of the working medium outlet temperatures. This paper aims to present a method of simultaneous determination of coefficients in correlation formulas for the Nusselt number on both sides of the heat transfer surface. Design/methodology/approach The idea of the developed method is based on determining such a values of the coefficients in Nusselt number correlations that fulfill the condition of equality between the measured and calculated temperature at the outlet of heat exchanger in terms of least squares method. To test the proposed method, a special experimental installation was built. The heat transfer in helically coiled tube-in-tube heat exchanger was examined for the wide range of temperature changes and volumetric flow rates of working fluid. Findings The simulation results were validated with an experimental data. The results show that the heat transfer coefficient of the counter-current is higher than the co-current flow in helically coiled heat exchanger. This phenomenon can be beneficial particularly in the laminar flow regime. Research limitations/implications The correlation for the Nusselt number as a function of the Reynolds and Prandtl numbers for hot and cold liquid was obtained with the least squares method for the experimental data. Practical implications The presented method allows for the simultaneous determination of heat transfer coefficient on both sides of the wall without the necessity of indirect calculation of the overall heat transfer coefficient. The presented method can be used in the thermal design of various type heat exchangers. Originality/value This work presents the new methodology of determination correlations for the helically coiled tube-in-tube heat exchanger for co-current and counter-current arrangement, which can be used in thermal design.

Thermal Performance Enhancement of an Industrial Shell and Tube Heat Exchanger

2015 ◽  
Author(s):  
Fadi A. Ghaith ◽  
Ahmed S. Izhar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Numerical Study ◽  
Thermal Design ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube

This paper aims to enhance the thermal performance of an industrial shell-and-tube heat exchanger utilized for the purpose of cooling raw natural gas by means of mixture of Sales gas. The main objective of this work is to provide an optimum and reliable thermal design of a single-shelled finned tubes heat exchanger to replace the existing two- shell and tube heat exchanger due to the space limitations in the plant. A comprehensive thermal model was developed using the effectiveness-NTU method. The shell-side and tube-side overall heat transfer coefficient were determined using Bell-Delaware method and Dittus-Boelter correlation, respectively. The obtained results showed that the required area to provide a thermal duty of 1.4 MW is about 1132 m2 with tube-side and shell-side heat transfer coefficients of 950 W/m2K and 495 W/m2K, respectively. In order to verify the obtained results generated from the mathematical model, a numerical study was carried out using HTRI software which showed a good match in terms of the heat transfer area and the tube-side heat transfer coefficient.

scholarly journals Transient behavior of a plate-fin-and-tube heat exchanger taking into account different heat transfer coefficients on the individual tube rows

2019 ◽  
Vol 128 ◽  
pp. 04001
Author(s):  
Dawid Taler ◽  
Jan Taler ◽  
Katarzyna Wrona
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Analytical Formula ◽  
Cfd Modeling ◽  
Tube Heat Exchanger ◽  
Individual Tube ◽  
The Heat Transfer Coefficient

Experimental studies of multi-row plate-fin heat exchangers show that the highest average heat transfer coefficient on the air side occurs in the first row of tubes when the air velocity in front ofthe exchanger is less thanapproximately 3.5 m/s. In the subsequent rows of tubes up to about the fourth row the heat transfer coefficient decreases. In the fifth and further rows, it can be assumed that the heat transfer coefficient is equal in each tube row. It is necessary to find the relationships fortheair–side Nusselt number on each tube row to design a plate–fin and tube heat exchanger(PFTHE) with the appropriate number of tube rows. The air–side Nusselt number correlations canbe determined experimentally or by CFD modeling (Computational and Fluid Dynamics). The paper presents a newmathematical model of the transient operation of PFTHE, considering that the Nusselt numbers on the air side of individual tube rows are different. The heat transfer coefficient on an analyzed tube row was determined from the equality condition of mass– average air temperature differences on agiven tube row determined using the analytical formula and CFD modeling. The results of numerical modelingwere compared with the results of the experiments.

Convective heat transfer and fluid flow characteristics in fin and oval-tube heat exchanger

2021 ◽  
Vol 15 (2) ◽  
pp. 7936-7947
Author(s):  
Yamina Abdoune ◽  
Sahel Djamel ◽  
Benzeguir Redouane ◽  
Alem Karima
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Tube Heat Exchanger ◽  
Baseline Case ◽  
Oval Tube ◽  
The Heat Transfer Coefficient

The forced convective heat transfer behavior of a turbulent air flow, steady and Newtonian over a fin and oval-tube heat exchanger has been examined numerically. Where, the effect of the tube tilt angle (α) on the heat transfer coefficient and the friction factor was tested. The inclination angle of the oval-tubes going from 0° (Baseline case) to 90° with a step of 10°. The fluid flows and heat transfer characteristics are presented for Reynolds numbers ranging from 3.000 to 12.000. All investigations are carried out with the help of the CFD ANSYS Fluent. Heat transfer coefficient results in the term of the Nusselt number are validated with the available experimental data and a maximum deviation of 9 % is observed. Reasonable agreement is found. The obtained results show that the tube's inclination angle of 20° is the best design which significantly removes the hot spots behind the tubes, thus giving an increase in the heat transfer coefficient of 13 % compared to the baseline case. In addition, useful correlations are developed to predict Nusselt number and friction factor in the fin and oval-tube heat exchanger.

Turbulent forced convection in a shell and tube heat exchanger equipped with novel design of wing baffles

2019 ◽  
Vol 29 (6) ◽  
pp. 2103-2127 ◽  
Author(s):  
Ahmed Youcef ◽  
Rachid Saim ◽  
Hakan F. Öztop ◽  
Mohamed Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Rates ◽  
Content Type ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates ◽  
Shell And Tube

Purpose This work presents a numerical study of the dynamic and thermal behavior of a turbulent flow in a shell and tube heat exchanger equipped with a new design of baffle type wing. The implementation of this type of baffle makes it possible to lengthen the path of the fluid in the shell, to increase the heat flux exchanged on the one hand and is to capture the weakness of the shell and tube heat exchanger with segmental baffles on the other hand. Design/methodology/approach This paper aims to analyze numerically the thermo-convective behavior of water using CFD technique by solving the conservation equations of mass, momentum and energy by the finite volume method based on the SIMPLE algorithm for coupling velocity-pressure. To describe the turbulence phenomenon, the Realizable k–ε model is employed. The analysis is done for different mass flow rates. The parameters studied are: the fluid outlet temperature, the average heat transfer coefficient, the pressure drop, the total heat transfer rate, the effect of the geometric shape of the baffle on the thermal behavior. The purpose of this study is to propose a new design of a shell and tube heat exchanger with a high heat transfer coefficient and a lower pressure drop compared to a shell and tube heat exchanger with transverse and segmental baffles. Findings The results showed that the use of the wing baffles enhanced the heat transfer coefficient significantly and reduced the friction coefficient. Compared with segmental baffles, the wing baffles are 11.67, 18.53 and 11.5 per cent lower in the pressure drop and 1.79, 1.9 and 2.39 per cent higher in the Nusselt number for the three mass flow rates 0.5, 1 and 2 kg/s, respectively. Originality/value The originality of this work lies in proposing a three-dimensional analysis for a novel heat exchanger.

Numerical simulation of the effect of baffle cut and baffle spacing on shell side heat exchanger performance using CFD

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Swanand Gaikwad ◽  
Ashish Parmar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Numerical Results ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Two Parameters

AbstractHeat exchangers possess a significant role in energy transmission and energy generation in most industries. In this work, a three-dimensional simulation has been carried out of a shell and tube heat exchanger (STHX) consisting of segmental baffles. The investigation involves using the commercial code of ANSYS CFX, which incorporates the modeling, meshing, and usage of the Finite Element Method to yield numerical results. Much work is available in the literature regarding the effect of baffle cut and baffle spacing as two different entities, but some uncertainty pertains when we discuss the combination of these two parameters. This study aims to find an appropriate mix of baffle cut and baffle spacing for the efficient functioning of a shell and tube heat exchanger. Two parameters are tested: the baffle cuts at 30, 35, 40% of the shell-inside diameter, and the baffle spacing’s to fit 6,8,10 baffles within the heat exchanger. The numerical results showed the role of the studied parameters on the shell side heat transfer coefficient and the pressure drop in the shell and tube heat exchanger. The investigation shows an increase in the shell side heat transfer coefficient of 13.13% when going from 6 to 8 baffle configuration and a 23.10% acclivity for the change of six baffles to 10, for a specific baffle cut. Evidence also shows a rise in the pressure drop with an increase in the baffle spacing from the ranges of 44–46.79%, which can be controlled by managing the baffle cut provided.

Experimental Investigation of Heat Transfer Enhancement of Shell and Tube Heat Exchanger Using SnO2-Water and Ag-Water Nanofluids

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
S. V. Sridhar ◽  
R. Karuppasamy ◽  
G. D. Sivakumar
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Two Phase ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Abstract In this investigation, the performance of the shell and tube heat exchanger operated with tin nanoparticles-water (SnO2-W) and silver nanoparticles-water (Ag-W) nanofluids was experimentally analyzed. SnO2-W and Ag-W nanofluids were prepared without any surface medication of nanoparticles. The effects of volume concentrations of nanoparticles on thermal conductivity, viscosity, heat transfer coefficient, fiction factor, Nusselt number, and pressure drop were analyzed. The results showed that thermal conductivity of nanofluids increased by 29% and 39% while adding 0.1 wt% of SnO2 and Ag nanoparticles, respectively, due to the unique intrinsic property of the nanoparticles. Further, the convective heat transfer coefficient was enhanced because of improvement of thermal conductivity of the two phase mixture and friction factor increased due to the increases of viscosity and density of nanofluids. Moreover, Ag nanofluid showed superior pressure drop compared to SnO2 nanofluid owing to the improvement of thermophysical properties of nanofluid.

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