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.

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.

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 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.

Simulation of Laminar Stratified Flow Boiling of Liquid in a Horizontal Tube by the Coupled Map Lattice Model

2009 ◽  
Author(s):  
Indrajit Chakraborty ◽  
P. S. Ghoshdastidar ◽  
G. Biswas
Keyword(s):  
Heat Transfer ◽  
Complex Systems ◽  
Wall Temperature ◽  
Flow Boiling ◽  
Heated Surface ◽  
Horizontal Tube ◽  
Stratified Flow ◽  
Coupled Map Lattice ◽  
Transfer Model ◽  
Constant Wall Temperature

A new heat transfer model for stratified flow boiling in a horizontal tube is proposed in this present study. In recent years, the subject of nonlinear dynamics has progressed and various tools of analysis have been proposed for complex systems. Coupled Map Lattice (CML) method is one such tool which makes it possible to simulate complex systems and to capture the qualitative nature of the phenomenon. In this work, steady stratified flow boiling of water is simulated qualitatively by using the CML model for laminar, hydrodynamically and thermally developing flow and heat transfer in a horizontal tube. The liquid enters in a constant wall temperature tube (Tw*>Tsat* at Pentrance*) in a subcooled or saturated condition. The present modeling by CML is based on the assumption that the flow boiling is governed by nucleation from cavities on the heated surface, migration of vapor into the core, forced convection and phase change in the bulk. The macroscopic variable chosen is temperature. The influences of mass flow rate, inlet subcooling and wall temperature have been studied. The results of the computations provide information on the effect of aforementioned parameters on the heat transfer coefficient and void fraction. The results show that the CML has been able to model flow boiling in a realistic manner.

Experimental Study of Condensation Flow Inside Horizontal Smooth, Herringbone and Three Enhanced Surface Tubes

2017 ◽  
Author(s):  
Xiaolong Yan ◽  
Wei Li ◽  
Weiyu Tang ◽  
Hua Zhu ◽  
Zhijian Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Working Fluid ◽  
Experimental Investigations ◽  
Enhancement Effect ◽  
Two Phase ◽  
Inner Diameter ◽  
Enhanced Surface

Enhanced condensation heat transfer of two-phase flow on the horizontal tube side receives more and more concerns for its fundamentality and importance. Experimental investigations on convective condensation were performed respectively in different horizontal tubes: (i) a smooth tube (11.43 mm, inner diameter); (ii) a herringbone tube (11.43 mm, fin root diameter); and (iii) three enhanced surface (EHT) tubes (11.5 mm, equivalent inner diameter): 1EHT tube, 2EHT-1 tube and 2EHT-2 tubes. The surface of EHT tubes is enhanced by arrays of dimples with the background of petal arrays. Experiments were conducted at a saturation temperature of approximately 320 K; 0.8 inlet quality; and 0.2 outlet quality; 72–181 kg·m−2·s−1 mass flux using R22, R32 and R410A as the working fluid. The refrigerant R32 presents great heat transfer performance than R410A and R22 at low mass flux due to its higher latent heat of vaporization and larger thermal conductivity. The heat enhancement ratio of the herringbone tube is 2.72–2.82, rated number one. The primary dimples on the EHT tube increase turbulence and flow separation, and the secondary petal pattern produce boundary layer disruption to many smaller scale eddies. The 2EHT tubes are inferior to the 1EHT tube. A performance factor is used to evaluate the enhancement effect except of the contribution of area increase.

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