scholarly journals Mechanical Properties and Heat Transfer Performance of Conically Corrugated Tube

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4902
Author(s):  
Zhiwei Wu ◽  
Caifu Qian ◽  
Gang Liu ◽  
Zhisheng Liu ◽  
Ping Sheng
Keyword(s):  
Heat Transfer ◽  
High Efficiency ◽  
Axial Stress ◽  
Engineering Application ◽  
Tensile Load ◽  
Elastic Stiffness ◽  
Resistance Coefficient ◽  
Smooth Tube ◽  
Corrugated Tube ◽  
Smooth Tubes

Conically corrugated tube is a new type of high-efficiency heat exchange tube. In this paper, the mechanical and heat transfer properties of conically corrugated tubes formed by the cold rolling of smooth tubes are studied through experimental measurement and numerical simulation to lay the foundations for applying the tubes in heat exchangers. The results show that while conically corrugated tube has a lower axial elastic stiffness compared with smooth tube, conically corrugated tube has a higher yield strength and ultimate strength. Unlike smooth tubes, conically corrugated tubes develop three-dimensional stresses when an axial tensile load is applied to them. In addition, the heat transfer coefficient of conically corrugated tube is 15%, 17%, and 115% higher than that of spiral grooved tube, convergent divergent tube, and smooth tube, respectively. Finally, the correlation equations of the axial stress concentration factor, stiffness equivalent coefficient, Nusselt number, and flow resistance coefficient of conically corrugated tubes are obtained for engineering application.

Convective Heat Transfer Characteristics of Laminar Flow in Sinusoidal Corrugated Tube

2011 ◽  
Vol 236-238 ◽  
pp. 1277-1282
Author(s):  
Zheng Ming Tong ◽  
Kai Zhu ◽  
Yong Hai Hu ◽  
Li Ye ◽  
Jia Lei Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Flow Resistance ◽  
Resistance Coefficient ◽  
Smooth Tube ◽  
Great Decrease ◽  
Flow State ◽  
Field Synergy ◽  
Corrugated Tube ◽  
New Type

A new type of corrugated tube based on sine function is proposed by introducing a parameter of sine camber. The heat transfer and flow around sinusoidal corrugated tubes with different sine camber e are investigated in this paper. Computational Fluid Dynamics (CFD) was used to analysis flow state and sine camber of tube influence on the heat transfer and flow, a correlation equations of Nu (Nusselt) =f(Re) is given. At last, the theoretical comparative analysis with field synergy principle is carried out for the heat transfer and flow resistance in smooth tube and sinusoidal corrugated tube. The results show that the experiment basically tallies with the value of numerical calculation of laminar flow. In the range of 500 < Re < 1000, flow resistance coefficient has great decrease extent, while low resistance coefficient has small decrease extent of 1500 < Re < 2300. The effect of field synergy is poor in the smooth tube, which is opposite to that in sinusoidal corrugated tube, and it can improve the efficiency of around 2.7 times.

scholarly journals Heat transfer performance of R1234yf for convective boiling in horizontal micro-fin and smooth tubes

2020 ◽  
Vol 207 ◽  
pp. 01009
Author(s):  
Thanh Nhan Phan ◽  
Van Hung Tran ◽  
Nikola Kaloyanov ◽  
Momchil Vassilev
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Mass Flux ◽  
Heat Transfer Performance ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Transfer Performance ◽  
Convective Boiling ◽  
Penalty Factor ◽  
Smooth Tubes

This study analyses the performance of heat transfer process which occurs in the convective boiling of Hydro fluoro Olefin (HFO) refrigerant, R1234yf, in horizontal tube. Heat transfer and pressure drop of R1234yf are analyzed and computed at the same working conditions on the same size of outer diameter of tube do = 9.52 mm with difference of inner surface, one is a smooth surface and microfin for other. The flow pattern maps were built at 5°C saturation temperature with 8.62 kW/m2 of heat flux, it is presented that flow pattern of helix flow occurs at very low mass flux and low quality, while at that condition on smooth tube the flow is still stratified wavy flow. The comparison of heat transfer performance between microfin and smooth tube would be evaluated on enhancement factor E, penalty factor P and efficiency index I. With the mass flux on the range G = 111 -- 333 kg/m2s for 5°C boiling temperature, the results show that, average value of E is 2.18; 1.45 of P and 1.54 of I. One more impressing thing is that, at the quality “x” larger than 0.8, the dryout phenomenon takes place on smooth tubes while microfin tubes do not have this phenomenon.

3D Numerical Simulation of Fluid Flow and Heat Transfer for Asymmetric Spiral-Gear Inserts in a Tube

2011 ◽  
Vol 130-134 ◽  
pp. 1686-1690 ◽  
Author(s):  
De Qi Peng ◽  
Wei Qiang Wang ◽  
Tian Lan Yu ◽  
Biao Wei ◽  
Yu Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Tube Wall ◽  
Convection Heat Transfer ◽  
Engineering Application ◽  
Tangential Velocity ◽  
Smooth Tube ◽  
Tube Heat Exchanger ◽  
Flow And Heat Transfer

For solving cleaning fouling online for shell-and-tube heat exchanger，an asymmetric spiral-gear cleaning technology is presented. The RNGk-εturbulent model is used to simulate the fluid flow and heat transfer of the tube with the spiral-gear. Its velocity and turbulent intensity field, convection heat transfer characteristic and resistance property are analyzed. Numerical simulation results shows that radial velocity is larger in the annular area near the tube wall than that in the smooth tube. Tangential velocity in the diameter area corresponding to the width of spiral-gear insertion increases with radius，but it decreases with radius in the annular clearance between the insert and the tube wall. However, fluid tangential motion of the smooth tube is only stochastic，and its tangential velocity is lower several orders of magnitude than that for the tube with the insertions. The average surface heat transfer coefficient of the spiral-gear-inserted tube wall is increased nearly 88% than that from the smooth tube wall. In addition, the pressure drop caused by spiral-gear inserts is in the permissible range of engineering application. The inserts is applicable to the heat exchangers at a flow rate lower than 0.8 m·s-1.

Visualization of Heat Transfer Characteristics of 1EHT and Smooth Surface Tubes

2021 ◽  
Author(s):  
Humberto Santos ◽  
Ailson Alves ◽  
David Kukulka ◽  
Rick Smith ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Particle Velocity ◽  
High Speed ◽  
High Efficiency ◽  
Bubble Formation ◽  
Industrial Applications ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Average Particle ◽  
Enhanced Heat Transfer

Abstract High efficiency heat transfer tubes play a major role in industrial applications due to its benefits in recovering more energy, smaller footprint and lower operational costs. Given the importance of enhanced heat transfer tubes, an experimental investigation was carried out to compare the performance of the Vipertex 1EHT tube with an equivalent smooth tube using Particle Image Velocimetry (PIV). For the experimental setup a Dantec Dynamics PIV system was considered, and both tubes used had an outer diameter of 19.05 mm and inner diameter of 17.09 mm. Heat transfer experiments were conducted at 100% of the heater power capacity, i.e. 750 W, and observations were made in terms of boiling visualization, particle velocity vector field, and seeding particle velocity. The results obtained from the visualization showed higher density of bubble formation on the surface of 1EHT tube compared to the smooth tube, as well as a more frequent formation of bubbles. Moreover, the high-speed camera films recorded for comparison between smooth and enhanced tubes, showed that the dimples provided nucleation sites. Additionally, the average particle velocity for the 1EHT tube was 0.300 m.s−1 and for the smooth tube it was only 0.230 m.s−1, as a result of the higher heat transfer of the enhanced tube. These results suggest that the 1EHT tube performs better in boiling heat transfer application, which can be attributed to the enhanced heat transfer area produced by the series of dimples/protrusions and petals distributed over its surface.

scholarly journals Heat transfer study on a hybrid smooth and spirally corrugated tube

2018 ◽  
Vol 240 ◽  
pp. 01038
Author(s):  
Chen Yang ◽  
Min-rui Chen ◽  
Jin-yuan Qian ◽  
Zan Wu ◽  
Zhi-jiang Jin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Reynolds Numbers ◽  
Smooth Tube ◽  
Transfer Performance ◽  
Corrugated Tube ◽  
Smooth Part ◽  
Flow Part ◽  
High Reynolds ◽  
Transfer Study

Corrugated tubes are widely used in a range of applications for heat transfer enhancement. The spirally corrugated tube has a better heat transfer performance than the smooth tube. In this paper, the heat transfer performance of a hybrid smooth and six-start spirally corrugated tube is studied. With a validated numerical model, the effects of the corrugation part length on the vortex in the downstream smooth tube are studied for a range of high Reynolds numbers, where the existence of the corrugation part can turn out the secondary flow and enhance heat transfer. Meanwhile, it is found that in the smooth part, the fluid flow part with whirling can reach a maximum length, even if the length of the corrugation part continuously increases. Thus a series of critical corrugation lengths can be obtained. This work can reveal the enhanced heat transfer mechanism of the hybrid smooth and spirally corrugated tube and be of interest to researchers in heat transfer issues of corrugated tubes.

Numerical investigation of heat transfer and friction characteristics for turbulent flow in various corrugated tubes

2018 ◽  
Vol 233 (4) ◽  
pp. 457-475 ◽  
Author(s):  
A Kaood ◽  
T Abou-Deif ◽  
H Eltahan ◽  
MA Yehia ◽  
EE Khalil
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Constant Heat Flux ◽  
Turbulence Kinetic Energy ◽  
Superior Performance ◽  
Smooth Tube ◽  
Tube Length ◽  
Geometrical Parameters ◽  
Flux Boundary Condition ◽  
Corrugated Tube

Thermal and hydraulic characteristics of turbulent water flow in a transverse corrugated tube with various corrugation direction (inward/outward) and corrugation shape (triangle, curve, rectangle, and trapezoid) are numerically investigated. The axisymmetric model of corrugated tubes with 10 mm inner diameter was investigated by changing the geometrical parameters for Reynolds number ranging from 5000 to 61,000 and constant heat flux boundary condition. Structured, nonuniform grid system is applied. Momentum, continuity, and energy equations were treated by means of a finite volume method using the SIMPLE scheme with the k–ε turbulence model and enhanced wall treatment. The results reveal that corrugation direction and corrugation shape have perceptible effects upon the heat transfer in the form of Nusselt number ( Nu) and pressure drop in the form of friction factor (ƒ). The average Nu for (inward) trapezoidal, rectangular, curved, and triangular corrugation shapes are 52.61%, 50.12%, 47.82%, and 44.96%, respectively, higher than the smooth tube. The average Nu for (outward) trapezoidal, curved, triangular, and rectangular corrugation shapes are 48.31%, 45.72%, 41.23%, and 40.94%, respectively, which are higher than a smooth tube. The results reveal that both inward/outward curved and triangular roughness shape have the superior performance evaluation criterion than rectangular and trapezoidal. Turbulence kinetic energy contour shows the increase in heat transfer performance for all corrugated tubes compared with a smooth tube. Inward corrugated tube provides the highest turbulence kinetic energy along the tube length and, consequently, the highest heat transfer. In addition, inward corrugated tubes provide the highest values and homogeneity of the velocity distribution along the core of tubes.

Evaporative Heat Transfer and Pressure Drop Performance of Internally-Finned Tubes with Refrigerant 22

1979 ◽  
Vol 101 (3) ◽  
pp. 447-452 ◽  
Author(s):  
G. R. Kubanek ◽  
D. L. Miletti
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Velocity ◽  
Unit Length ◽  
Smooth Tube ◽  
Flow Area ◽  
Finned Tubes ◽  
Smooth Tubes

Heat transfer and pressure drop measurements were performed on three integral spiralled inner-fin tubes (12.7–15.9 mm OD, 30–32 fins, fin height 0.5–0.6 mm) with two-phase flow of refrigerant 22 under evaporating conditions. The data were compared with the performance of smooth tubes with and without a star-shaped insert. Based on the same length of heated test section (0.80 and 2.44 m), change in refrigerant quality (0.2 and 0.7) and mass velocity range (65,000 to 270,000 g/s · m2): (1) The enhancements in heat transfer coefficient for the internally-finned tubes over those for the smooth tubes ranged from 30 to 760 percent, and typically increased with mass velocity. Tighter fin spiralling significantly increased heat transfer. (2) The enhancements in heat transfer coefficient for the smooth tube with the star-shaped insert ranged from 40 to 370 percent, but decreased with mass velocity. (3) The increases in pressure drop for the internally-finned tubes over those for the smooth tubes ranged from 10 to 290 percent, while those for the smooth tube with the star-shaped insert were 300 to over 2000 percent. The factors enhancing the performance of the internally-finned tubes include the low fins which result in only a small reduction in cross-sectional flow area, and the tight spiral which increases the corner length per unit length of tube available for nucleation of vapor bubbles.

scholarly journals Study of PTC System with Rectangular Cavity Receiver with Different Receiver Tube Shapes Using Oil, Water and Air

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2114
Author(s):  
Alireza Rafiei ◽  
Reyhaneh Loni ◽  
Gholamhassan Najafi ◽  
Talal Yusaf
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Energy Performance ◽  
Rectangular Cavity ◽  
Smooth Tube ◽  
Heat Transfer Fluid ◽  
Outlet Temperature ◽  
Solar Heat ◽  
Corrugated Tube ◽  
Thermal Oil

Today, application of cavity receivers in solar concentrator systems is suggested as an interesting and novelty research subject for increasing thermal performance. In this research, a parabolic trough concentrator (PTC) with a rectangular cavity receiver was energetically investigated. The cavity receiver was studied with smooth and corrugated tubes. Different solar heat transfer fluids were considered, including water, air, and thermal oil. The effect of different operational parameters, as well as structural parameters, was investigated. The results showed that the linear rectangular cavity receiver with corrugated tube showed higher amounts of the absorbed heat and energy performance compared to the smooth tube as the cavity tube. Thermal performance of the rectangular cavity was improved using the application of water as the solar heat transfer fluid, which was followed by thermal oil and, finally, air, as the solar heat transfer fluid. Finally, it could be recommended that the rectangular cavity receiver with smooth tube using air as the solar heat transfer fluid is more appropriate for coupling this system with a Bryton cycle, whereas the rectangular cavity receiver with the corrugated tube using water or oil as the solar heat transfer fluid is recommended for achieving higher outlet temperature of the heat transfer fluid.

Experimental Investigation on Heat Transfer Characteristics of Thin Film Evaporation

2014 ◽  
Vol 960-961 ◽  
pp. 427-432
Author(s):  
Jing Ming Dong ◽  
Xin Xiang Pan ◽  
Zhi Tao Han ◽  
Zhi Jian Liu
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Performance ◽  
High Efficiency ◽  
Engineering Application ◽  
Heat Transfer Characteristics ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Film Evaporator

Thin film evaporation is a kind of high efficiency heat transfer. A thin film evaporator with rectangular micro groove has been designed, constructed and tested. The heat flux, superheat and thermal resistance of the thin film evaporator were investigated under different evaporating temperatures. Compared with the regular evaporator at the same condition, the thin film evaporator with rectangular micro groove has a better heat transfer performance and good temperature uniformity. The experimental investigation presented in this paper can be used as a reference to promote the engineering application and development of the thin film evaporator.

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