Heat Transfer Model for Liquid-Liquid Taylor Flow in Mini-Scale Coiled Tubing

2018 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Transfer Model ◽  
Straight Tube ◽  
Constant Wall Temperature ◽  
Transfer Rates ◽  
Taylor Flow ◽  
Coiled Tubing ◽  
Low Viscosity ◽  
Benchmark Tests ◽  
Copper Tubing

In this paper, an experimental study on heat transfer enhancement using non-boiling liquid-liquid Taylor flow in mini scale coiled tubing for constant wall temperature conditions is conducted. Coiled copper tubing with different radii of curvature and lengths were used as test sections. Segmented slug flow with water and three low viscosity silicone oils (1 cSt, 3 cSt, 5 cSt) were used to examine the effect of Prandtl number on heat transfer rates in coiled tubing. Additionally, benchmark tests were conducted of single-phase flow in a straight tube. The experimental results are compared with models for liquid-liquid Taylor flow in straight and coiled tubing. This research provides new insights on the enhanced heat transfer rates attainable with using liquid-liquid Taylor flow in mini scale coiled tubing. This enhancement occurs due to internal circulation and secondary flow in the fluid segments.

Heat Transfer in Liquid–Liquid Taylor Flow in Miniscale Curved Tubing for Constant Wall Temperature

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Wesam Adrugi ◽  
Yuri Muzychka ◽  
Kevin Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Constant Length ◽  
Transfer Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Copper Tubing

In this paper, heat transfer enhancement using liquid–liquid Taylor flow in miniscale curved tubing for isothermal boundary conditions is examined. Copper tubing with an inner tube diameter of D = 1.65 mm and different radii of curvature and lengths is used in the experiments. Taylor flow is created using water and low-viscosity silicone oils (0.65 cS, 1 cS, and 3 cS) to examine the effect of Prandtl number on heat transfer rates in curved tubing. A series of experiments are conducted using tubing with constant length and variable curvature as well as variable length and constant curvature. The experimental results are compared with models for liquid–liquid Taylor flow in straight tubing and single-phase flow in curved tubes. The results of the research highlight the effects of liquid–liquid Taylor flow in curved tubing. This research provides new insights into the effect of curvature on heat transfer enhancement for liquid–liquid Taylor flow in miniscale curved tubing, at a constant wall temperature.

Heat Transfer in Liquid-Liquid Taylor Flow in Mini-Scale Curved Tubing for Constant Wall Temperature

2016 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Constant Length ◽  
Transfer Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Copper Tubing

In this paper, heat transfer enhancement using liquid-liquid Taylor flow in mini scale curved tubing for isothermal boundary conditions is examined. The copper tubing has an inner tube diameter of Di = 1.65 mm with different radii of curvature and lengths. Taylor flow is created using water and low viscosity silicone oils (0.65 cSt, 1 cSt, 3 cSt) to examine the effect of Prandtl number on heat transfer rates in curved tubing. A series of experiments are conducted using tubing with constant length and variable curvature, as well as variable length and constant curvature. The experimental results are compared with models for liquid-liquid Taylor flow in straight tubing and single-phase flow in curved tubes. The results of the research develop a new model for liquid-liquid Taylor flow in curved tubing. This research provides new insights into the effect of curvature on heat transfer enhancement for liquid-liquid Taylor flow in mini scale curved tubing, at a constant wall temperature.

Laminar Heat Transfer of Gas-Liquid Segmented Flows in Circular Ducts With Constant Wall Temperature

2019 ◽  
Author(s):  
K. Alrbee ◽  
Y. S. Muzychka ◽  
X. Duan
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Liquid Fraction ◽  
Horizontal Tube ◽  
Two Phase ◽  
Constant Wall Temperature ◽  
Transfer Rates ◽  
Taylor Flow

Abstract Laminar heat transfer of gas-liquid Taylor flow in circular tubes is considered. Previous studies have found that introducing a gas phase into a flow stream of a liquid phase significantly increases the heat transfer rate. Other studies considered the effect of slug length on heat transfer rates. The present study’s aim is to demonstrate heat transfer enhancement due to the shortening of liquid slug lengths in a segmented flow and to further validate a model previously developed by the second author. An experimental setup was assembled using mini scale horizontal tube in which the two phase fluid flow is heated under constant wall temperature. New experimental data for gas-liquid Taylor flow in mini scale were carefully obtained using 1 cSt silicone oil which was segmented by air. The experiments were performed with a liquid fraction maintained constant at 0.5 and Reynolds numbers from 50 to 320. In the present work, it is shown that for constant wall temperature, the dimensionless mean wall flux and Nusselt number have been increased by a factor of two at the upper limit of laminar flow which was considered with ReD = 320, when the slug aspect ratio LS/D equal to 10. On other hand the enhancement becomes three times at the same limit of flow when slug aspect ratio has reduced to 1.25 which almost approaches the tube diameter.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

Separated Phase Analysis of Heat Transfer in Liquid–Liquid Taylor Flow in a Miniscale Straight Tube

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
K. Alrbee ◽  
Y. S. Muzychka ◽  
X. Duan
Keyword(s):  
Heat Transfer ◽  
Phase Analysis ◽  
Open Loop ◽  
Heat Transfer Analysis ◽  
Straight Tube ◽  
Constant Wall Temperature ◽  
New Approach ◽  
Taylor Flow ◽  
Cell Dimensions ◽  
Good Agreement

Abstract Heat transfer analysis of liquid–liquid Taylor flow in previous studies almost never shows the effect of slug length on heat transfer. The homogenous or single-phase analysis is often the only method available to deal with flow of multicomponents. In this study, a new approach is developed to model the segmented liquid–liquid Taylor flow as two separated systems to present heat transfer enhancement for each component. The effect of internal circulation and boundary layer renewal within the two fluid components is clearly observed. An experimental setup was assembled using an open loop system at miniscale size in which liquid–liquid Taylor flow is heated under a constant wall temperature. Three silicone oils of 1, 3, and 5 cSt were segmented using distilled water at three volume fractions 0.25, 0.5, and 0.75. Finally, heat transfer data of the dimensionless mean wall heat flux shows good agreement with a predictive model proposed in an earlier work by the second author. The results show an impact of the fluid cell dimensions on the rate of heat transfer.

Measurement and Analysis of Laminar Heat Transfer Coefficients in Micro and Mini-Scale Ducts and Channels

2014 ◽  
Author(s):  
Y. S. Muzychka ◽  
M. Ghobadi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Constant Wall Temperature ◽  
Fully Developed Flow ◽  
Transfer Rates ◽  
Heat Transfer Coefficients ◽  
Advantages And Disadvantages ◽  
Nusselt Numbers

Heat transfer in micro and mini-scale ducts and channels is considered. In particular, issues of thermal performance are considered in systems with constant wall temperature at low to moderate Reynolds numbers or small dimensional scales which lead to conditions characteristic of thermally fully developed flows or within the transition region leading to thermally fully developed flows. An analysis of two approaches to representing experimental data is given. One using the traditional Nusselt number and another using the dimensionless mean wall flux. Both approaches offer a number of advantages and disadvantages. In particular, it is shown that while good data can be obtained which agree with predicted heat transfer rates, the same data can be problematic if one desires a Nusselt number. Other issues such as boundary conditions pertaining to measuring thermally developing and fully developed flow Nusselt numbers are also discussed in detail.

Heat Transfer of Turbulent Gaseous Flow in Microtubes with Constant Wall Temperature

2021 ◽  
Author(s):  
Chungpyo Hong ◽  
Yutaka Asako ◽  
Mohammad Faghri ◽  
Ichiro Ueno
Keyword(s):  
Heat Transfer ◽  
Incompressible Flow ◽  
Wall Temperature ◽  
Gas Flow ◽  
Ideal Gas ◽  
Constant Wall Temperature ◽  
Transfer Rates ◽  
Circulating Water ◽  
Enthalpy Difference ◽  
Total Temperature

Abstract Experiments were conducted with nitrogen gas flow in two microtubes with constant wall temperature, made of stainless-steel and copper with diameters of 524 and 537 micrometers, to measure the total temperature at the inlet and outlet and quantitively determine the heat transfer rates. The temperature differences between the inlet and the wall were maintained at 3, 5 and 10 K by circulating water around the inlet and the wall. The stagnation pressures were controlled such that the flow with atmospheric back pressure reached Reynolds numbers as high as 26000. To measure the total temperature, a polystyrene tube with thermally insulated exterior wall containing six plastic baffles, was attached to the outlet. Heat transfer rates were obtained from the gas enthalpy difference by using the pressures and the total temperatures measured at the inlet and outlet. Heat transfer rates were also compared with those obtained from the ideal gas enthalpy using the measured total temperatures and from the Nusselt number for incompressible flow. It was found that the measured total temperature at the microtube outlet was higher than the wall temperature. Also, the heat transfer rates calculated from the total temperature difference were higher than the values obtained from the incompressible flow theory.

Fully Developed Heat Transfer in Mini Scale Coiled Tubing for Constant Wall Temperature

2013 ◽  
Author(s):  
M. Ghobadi ◽  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Tube Length ◽  
Transfer Enhancement ◽  
Dean Number ◽  
Constant Wall Temperature ◽  
Heat Transfer Augmentation ◽  
Coiled Tubing ◽  
New Correlation ◽  
Silicone Oils

An experimental study on heat transfer enhancement in mini scale coiled tubing for isothermal conditions is conducted. Copper coils with three different radii of curvature (1 cm, 2 cm, and 4 cm), and in four lengths (1, 2, 3 and 4 coil turns) were used. The tube length is long enough to consider the flow to be hydro-dynamically fully developed. Hence, the effects of varying curvatures and lengths on heat transfer are studied. The pitch of the coil is restricted to diameter of the tube to minimize the effect of coiling. Dean number is used instead of Coiled number (modified Dean number), and hence, the results can be expanded to spiral and curved tubing. Water and two different silicone oils (0.65 cSt, 1 cSt) were used in the experiments to examine the effect of Prandtl number on coiled tubing heat transfer augmentation. Prandtl number from 5 to 15 is covered in this paper. A new correlation is proposed to calculate Nusselt number in fully developed coiled tubing based on the current results. In addition, dimensionless mean wall flux and dimensionless thermal length are also considered besides Nusselt, Reynolds, and Dean numbers.

scholarly journals A Fluidized Bed Combustion Heat Transfer Model Using Finite Elements

1982 ◽  
Author(s):  
P. E. Jenkins ◽  
T. W. Richardson
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Fluidized Bed ◽  
Three Dimensional ◽  
Polar Coordinates ◽  
Transfer Model ◽  
Fluidized Bed Combustion ◽  
Combustion Heat ◽  
Transfer Rates ◽  
Element Technique

This paper deals with the analysis of the axisymmetric heat transfer which occurs in a cylindrical combustion chamber using the finite element technique. The formulation of the equations used in the finite element method presented in this paper begins with the derivation of the heat conduction in three-dimensional polar coordinates. Through a series of transformations, the Poisson’s equation is numerically integrated to obtain the surface temperatures and overall heat transfer rates for the fluidized bed model. Several examples are given to demonstrate the application of the finite element principles to a thermal problem.

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