Current Progress in Enhanced Heat and Mass Transfer

2012 ◽  
Author(s):  
Arthur E. Bergles ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Enhancement ◽  
Heat And Mass Transfer ◽  
Transfer Enhancement ◽  
Science And Engineering ◽  
The Past ◽  
Current State ◽  
Active Enhancement

Heat transfer enhancement, which is often also referred to as augmentation or intensification, has evolved into an important component of thermal science and engineering. The accumulated literature in enhanced heat and mass transfer includes thousands of references, and it continues to grow. To give an overview of the current state of this important technology, representative developments over the past ten years in each category of enhancement techniques are cited and commented on. The discussion is divided into the literature, passive enhancement techniques, active enhancement techniques, and compound enhancement techniques.

Some Perspectives on Enhanced Heat Transfer—Second-Generation Heat Transfer Technology

1988 ◽  
Vol 110 (4b) ◽  
pp. 1082-1096 ◽  
Author(s):  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Second Generation ◽  
Historical Background ◽  
Rapid Rate ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Structured Surfaces ◽  
The Past ◽  
Microfin Tubes

During the past twenty-five years, heat transfer enhancement has grown at a rapid rate to the point where it can be regarded as a major field of endeavor, a second-generation heat transfer technology. After some historical background, mention of the driving trends, and a review of the various convective enhancement techniques, four areas of major contemporary interest are discussed: structured surfaces for shellside boiling, rough surfaces in tubes, offset strip fins, and microfin tubes for refrigerant evaporators and condensers. The review concludes with developments in the major areas of application.

scholarly journals Heat and mass transfer enhancement strategies by impinging jets: A literature review

2020 ◽  
pp. 227-227
Author(s):  
Florin Bode ◽  
Claudiu Patrascu ◽  
Ilinca Nastase
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Large Scale ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Nozzle Geometry ◽  
Small Scale ◽  
Mixing Enhancement ◽  
Transfer Enhancement

Heat and mass transfer can be greatly increased when using impinging jets, regardless the application. The reason behind this is the complex behavior of the impinging jet flow which is leading to the generation of a multitude of flow phenomena, like: large-scale structures, small scale turbulent mixing, large curvature involving strong normal stresses and strong shear, stagnation, separation and re-attachment of the wall boundary layers, increased heat transfer at the impinged plate. All these phenomena listed above have highly unsteady nature and even though a lot of scientific studies have approached this subject, the impinging jet is not fully understood due to the difficulties of carrying out detailed experimental and numerically investigations. Nevertheless, for heat transfer enhancement in impinging jet applications, both passive and active strategies are employed. The effect of nozzle geometry and the impinging surface macrostructure modification are some of the most prominent passive strategies. On the other side, the most used active strategies utilize acoustical and mechanical oscillations in the exit plane of the flow, which in certain situations favors mixing enhancement. This is favored by the intensification of some instabilities and by the onset of large scale vortices with important levels of energy.

Heat and Mass Transfer Caused by a Laminar Channel Flow Equipped With a Synthetic Jet Array

2010 ◽  
Author(s):  
Zdeneˇk Tra´vni´cˇek ◽  
Petra Dancˇova´ ◽  
Jozef Kordik ◽  
Toma´sˇ Vit ◽  
Miroslav Pavelka
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Channel Flow ◽  
Heat Mass Transfer ◽  
Low Reynolds Number ◽  
Transfer Enhancement ◽  
Laminar Channel Flow ◽  
Low Reynolds

Low-Reynolds-number laminar channel flow is used in various heat/mass transfer applications, such as cooling and mixing. A low Reynolds number implies a low intensity of heat/mass transfer processes, since they rely only on the gradient diffusion. To enhance these processes, an active flow control by means of synthetic (zero-net-mass-flux) jets is proposed. This arrangement can be promising foremost in microscale. The present study is experimental in which a Reynolds number range of 200–500 is investigated. Measurement was performed mainly in air as the working fluid by means of hot-wire anemometry and the naphthalene sublimation technique. PIV experiments in water are also discussed. The experiments were performed in macroscale at the channel cross-section (20×100)mm and (40×200)mm in air and water, respectively. The results show that the low Reynolds number channel flow can be actuated by an array of synthetic jets, operating near the resonance frequency. The control effect of actuation and the heat transfer enhancement was quantified. The stagnation Nusselt number was enhanced by 10–30 times in comparison with the non-actuated channel flow. The results indicate that the present arrangement can be a useful tool for heat transfer enhancement in various applications, e.g., cooling and mixing.

Regional Heat Transfer and Pressure Drop in Two-Pass and Three-Pass Flow Passages With 180-Degree Sharp Turns

1989 ◽  
Author(s):  
M. K. Chyu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Pressure Loss ◽  
Secondary Flows ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Pressure Loss Coefficient ◽  
Single Turn

The heat transfer distributions for flow passing through a two-pass (one-turn) and a three-pass (two-turn) passages with 180-degree sharp turns are studied by using the analogous naphthalene mass transfer technique. Both passages have square cross-section and length-to-height ratio of 8. The passage surface, including top wall, side walls and partition walls, is divided into 26 segments for the two-pass passage and 40 segments for the three-pass passage. Mass transfer results are presented for each segment along with regional and overall averages. The very non-uniform mass transfer coefficients measured around a sharp 180-degree turn exhibit the effects of flow separation, reattachment and impingement, in addition to secondary flows. Results of the three-pass passage indicate that heat transfer characteristics around the second turn is virtually the same as that around the first turn. This may imply that, in a multiple-pass passage, heat transfer at the first turn has already reached the thermally developed (periodic) condition. Over the entire two-pass passage, the heat transfer enhancement induced by the single-turn is about 45% to 65% of the fully developed values in a straight channel. Such a heat transfer enhancement decreases with an increase in Reynolds number. In addition, overall heat transfer of the three-pass passage is approximately 15% higher than that of the two-pass one. This 15% increase appears to be Reynolds number independent. The pressure loss induced by the sharp turns is found to be very significant. Within the present testing range, the pressure loss coefficient for both passages varies significantly with the Reynolds number.

Tube Transverse Pitch Effect on Heat/Mass Transfer Characteristics of Flat Tube Bank Fin Mounted With Vortex Generators

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Song Liu ◽  
Liangbi Wang ◽  
Jufang Fan ◽  
Yongheng Zhang ◽  
Yuanxin Dong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Mass Transfer ◽  
Isothermal Condition ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Tube Bank ◽  
Flat Tube ◽  
Tube Pitch

For one heat exchanger model of three-row flat tube bank fin mounted with vortex generators (VGs), the effect of transversal tube pitch on heat/mass transfer performance was investigated by the experimental method of naphthalene sublimation. For the same arrangement of VGs around the tube, it is found that the larger the transversal tube pitch, the larger the heat transfer enhancement because of less interactions of vortices generated from different VGs. Interaction of vortices decreases the heat transfer enhancement on the fin surfaces with and without VGs for the case with small transversal tube pitch. For isothermal condition, two correlated equations of average Nusselt number and friction factor considering the fin spacing, the attack angle of VG, the height of VG, the ratio of transversal tube pitch, and Reynolds number are reported.

Regional Heat Transfer in Two-Pass and Three-Pass Passages With 180-deg Sharp Turns

1991 ◽  
Vol 113 (1) ◽  
pp. 63-70 ◽  
Author(s):  
M. K. Chyu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Pressure Loss ◽  
Secondary Flows ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Pressure Loss Coefficient ◽  
Single Turn

The heat transfer distributions for flow passing through two-pass (one-turn) and three-pass (two-turn) passages with 180-deg sharp turns are studied by using the analogous naphthalene mass transfer technique. Both passages have square cross section and length-to-height ratio of 8. The passage surface, including top wall, side walls, and partition walls, is divided into 26 segments for the two-pass passage and 40 segments for the three-pass passage. Mass transfer results are presented for each segment along with regional and overall averages. The very nonuniform mass transfer coefficients measured around a sharp 180-deg turn exhibit the effects of flow separation, reattachment, and impingement, in addition to secondary flows. Results for the three-pass passage indicate that heat transfer characteristics around the second turn are virtually the same as those around the first turn. This may imply that, in a multiple-pass passage, heat transfer at the first turn has already reached the thermally developed (periodic) condition. Over the entire two-pass passage, the heat transfer enhancement induced by the single-turn is about 45 to 65 percent of the fully developed values in a straight channel. Such a heat transfer enhancement decreases with an increase in Reynolds number. In addition, overall heat transfer of the three-pass passage is approximately 15 percent higher than that of the two-pass one. This 15 percent increase appears to be Reynolds number independent. The pressure loss induced by the sharp turns is found to be very significant. Within the present testing range, the pressure loss coefficient for both passages is Reynolds number dependent.

Effect of Rib Width on the Heat Transfer Enhancement of a Rib-Turbulated Internal Cooling Channel

2009 ◽  
Author(s):  
A. P. Le ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Reynolds Numbers ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Cooling Channels ◽  
The Past ◽  
Rib Turbulators ◽  
Enhancing Heat Transfer ◽  
Straight Duct

In the quest for enhancing heat-transfer for the internal cooling channels of advanced turbo-machines, many schemes have been used and developed over the years. One such scheme is the use of rib turbulators. There have been fundamental studies in the past to understand the heat transfer enhancement phenomena caused by flow separation due to the presence of ribs. Typical ribs investigated in laboratory type experiments are square in nature i.e. the height, e, of the rib and the width, w, is the same. Although the literature deals with the effects of various rib shapes, little is known about the effect of having e/w not equal to unity. In this paper we investigate the degree of heat transfer enhancement caused by ribs with e/w not equal to unity. Experiments are carried out in a straight duct with ribs oriented normal to the main flow. The P/e ratio, P being the pitch of the ribs, is kept at a constant value of 10 while the ratio w/P is varied systematically from 0.1 to 0.5. Results are reported for Reynolds numbers ranging from 20,000 to 40,000. The aspect ratio of the channel is varied from 1:4 to 1:8 (Height : Width) and their effect is also shown. For all the cases investigated, pressure drop penalty is also presented.

Heat Transfer Enhancement in Spirally Corrugated Tube

2014 ◽  
Vol 7 (6) ◽  
pp. 970 ◽  
Author(s):  
Tholudin Mat Lazim ◽  
Zaid Sattar Kareem ◽  
M. N. Mohd Jaafar ◽  
Shahrir Abdullah ◽  
Ammar F. Abdulwahid
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Corrugated Tube
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