A REVIEW ON THE HEAT-TRANSFER PERFORMANCE AND PRESSURE-DROP CHARACTERISTICS OF VARIOUS ENHANCED TUBES

2012 ◽  
Vol 20 (04) ◽  
pp. 1230003 ◽  
Author(s):  
S. LAOHALERTDECHA ◽  
A. S. DALKILIC ◽  
S. WONGWISES
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Enhanced Tubes ◽  
Smooth Tubes ◽  
Enhanced Tube ◽  
The Common ◽  
Passive Technique

The enhanced tube is a kind of the passive technique for improving the thermal performance of the heat exchangers with a little increase of the friction penalty. They have stated to use instead of the common smooth tubes for designing of the heat exchangers. The size of these heat exchangers can be reduced considerably by using the enhanced tubes instead of smooth tubes. Normally, they are divided into four groups: the corrugated tube, ribbed tube, grooved tube, and fluted tube. Compared with the common smooth tube, many researchers reported that use of the enhanced tubes dramatically increases the heat-transfer performance, both theoretically and experimentally. Focusing on the advantages of the enhanced tubes, this article summarizes the published studies on the heat-transfer and pressure-drop characteristics of the enhanced tubes, both experimental and quantitative investigations.

Comparison of Heat Transfer Performance Between Smooth and Enhanced Heat Transfer Tubes

2019 ◽  
Author(s):  
David J. Kukulka ◽  
Wei Li ◽  
Rick Smith
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
High Performance ◽  
Heat Transfer Performance ◽  
Industrial Applications ◽  
Material Surface ◽  
Transfer Performance ◽  
Enhanced Heat Transfer ◽  
Enhanced Tubes ◽  
Smooth Tubes

Abstract Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in all heat transfer applications. A numeric study was performed that compares the performance of heat exchangers using the Vipertex enhanced heat transfer tubes (model 1EHT) to the performance of heat exchangers that use smooth surface tubes and other enhanced tubes. Surface enhancement of the 1EHT tube is accomplished through the use of the primary dimple enhancement and a secondary background pattern made up of petal arrays. Utilization of enhanced heat transfer tubes is an effective method that is utilized in the development of high performance thermal systems. Vipertex™ tubes, have been designed and produced through material surface modifications that produce flow optimized heat transfer tubes that increase heat transfer performance. Current energy demands and the desire to increase efficiencies of systems have prompted the development of optimized enhanced heat transfer surfaces. Enhanced heat transfer tubes are widely used in many areas (refrigeration, air-conditioning, process, petrochemical, chemical, etc.) in order to reduce cost, create a smaller application footprint or increase production. A new type of enhanced heat transfer tube has been created; therefore it is important to investigate relevant heat exchanger designs using the Vipertex enhanced surface tube in industrial applications and compare that performance to smooth tubes and other enhanced tubes. Results include design characteristics and performance predictions using the design simulations produced using HTRI Exchanger Suite (2016). Performance for all cases considered using the Vipertex tube predicted over design when compared to a smooth tube design. Vipertex 1EHT tubes produced enhanced heat transfer and cost efficient designs. In some of the case studies the 1EHT tubes produce an overdesign that is more than 35%, while smooth tubes produce an underdesign and other low fin tubes produce overdesign but not as large as the 1EHT tubes.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Simulation Investigation on Multi-Unit Parallel-Flow Type Condenser with Flat Tubes Distribution

2013 ◽  
Vol 423-426 ◽  
pp. 1910-1913
Author(s):  
Jian Rong Du ◽  
Zu Yi Zheng ◽  
Jun Hua Wan ◽  
Yi De Wang ◽  
Zhong Min Wan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Air Velocity ◽  
Flat Tube ◽  
Tube Arrangement ◽  
First Pass ◽  
Flat Tubes

Three heat exchangers, all of which have 38 tubes in total and 6 passes, with different tube arrangements were simulation investigated in laboratory. The effect of flat tube distribution on heat transfer performance and pressure drop characteristic was simulation investigated. The effect of different air velocity and flow on heat transfer performance and pressure drop characteristic was simulation investigated too. The results show that similar tube distribution has little effect on heat transfer but has great effect on pressure drop. It was found the tube arrangement from first pass to sixth pass is 10,9,6,5,4,4 has the best heat transfer performance and its pressure drop is small. The heat transfer and pressure drop increase with the air velocity and refrigerant flow.

Experimental Investigation on Multi-Unit Parallel-Flow Type Condenser with Flat Tubes Distribution

2014 ◽  
Vol 701-702 ◽  
pp. 1233-1236
Author(s):  
Lv Xian Zeng ◽  
Zu Yi Zheng ◽  
Jun Hua Wan ◽  
Xi Chen ◽  
Zhong Min Wan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Air Velocity ◽  
Flat Tube ◽  
The Third ◽  
Flat Tubes ◽  
Simulation Results

Three heat exchangers, all of which have 38 tubes in total and 6 passes, with different tube arrangements were manufactured to be experimental investigated in laboratory. The effect of flat tube distribution on heat transfer performance and pressure drop characteristic was experimental investigated. The effect of different air velocity and flow on heat transfer performance and pressure drop characteristic was also experimental investigated. The results show that similar tube distribution has little effect on heat transfer quality but has great effect on pressure drop. It was found the third arrangement has the best heat transfer and its pressure drop is small. Thus the third arrangement is the best solution. The heat transfer and pressure drop increase with the air velocity and refrigerant flow, so a proper value should be chosen, it was found that the simulation results were mainly agreement with the experimental results.

Air-Side Heat Transfer Performance of Louver Fin and Multitube Heat Exchanger for Direct Methanol Fuel Cell Cooling Application

2014 ◽  
Vol 11 (4) ◽  
Author(s):  
Hie Chan Kang ◽  
Hyejung Cho ◽  
Jin Ho Kim ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Direct Methanol Fuel Cell ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Side Pressure ◽  
Direct Methanol ◽  
Methanol Fuel Cell

The present work is performed to evaluate the heat transfer performance of a heat exchanger used in a direct methanol fuel cell. Because of material constraints and performance requirements, a louver fin heat exchanger is modified for use with conventional microchannel tubes and also with multiple small-diameter tubes (called multitubes). Prototype heat exchangers are tested, and the air-side heat transfer, pressure drop, and fan power are measured in a wind tunnel and simulated using a commercial code. The air-side pressure drop and heat transfer coefficient of the multitubes show similar trends to those of the flat-tube heat exchanger if the contact resistance is negligible. The tube spacing of the prototype multitube heat exchangers has a small effect on the pressure drop and heat transfer, but it has a profound effect on the air-side heat transfer performance because of the contact resistance between the tubes and louver fins. The air-side pressure drop agrees well with an empirical correlation for flat tubes.

Review: Condensation and Evaporation Characteristics of Low GWP Refrigerants in Plate Heat Exchangers

2016 ◽  
Vol 24 (02) ◽  
pp. 1630004 ◽  
Author(s):  
Byung Hoon Shon ◽  
Seung Won Jeon ◽  
Yongchan Kim ◽  
Yong Tae Kang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Saturation Temperature ◽  
Transfer Performance ◽  
Plate Heat ◽  
Frictional Pressure Drop ◽  
Evaporation Heat ◽  
Lower Heat

In this paper, condensation and evaporation characteristics of low global warming potential (GWP) refrigerants such as R-1234yf and R-1234ze series are reviewed. This review focuses on heat transfer and pressure drop in plate heat exchangers. Mass flux is considered as an important factor while saturation temperature is not for condensation and evaporation process in plate heat exchangers. The dryout phenomenon occurs occasionally and gives greatly harmful impact on evaporation heat transfer. It is found that R-1234yf and R-1234ze(E) give slightly lower heat transfer performance than R-134a for both condensation and evaporation processes. Generally, low GWP refrigerants presented in this review give lower heat transfer coefficient and higher frictional pressure drop than the conventional refrigerants. Nevertheless, R-1234ze(Z) gives superior heat transfer performance than other refrigerants in condensation. R-32 gives remarkable performance in evaporation, but it gives relatively high GWP compared to other low GWP refrigerants.

Comparison of Evaporation and Condensation Characteristics Among Three Enhanced Tubes

2018 ◽  
Author(s):  
Kunrong Shen ◽  
Zhichuan Sun ◽  
Xiaolong Yan ◽  
Wei Li ◽  
David J. Kukulka ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Heat Transfer Performance ◽  
Saturation Temperature ◽  
Transfer Performance ◽  
Vapor Quality ◽  
Enhanced Tubes

With the current ozone depletion and global warming issues, it is critical to develop systems with better heat transfer performance and nontoxic refrigerants. An experimental investigation was performed to evaluate convective condensation and evaporation heat transfer characteristics using R410A at low mass fluxes. Experiments were conducted in a 12.0-mm O.D. horizontal smooth tube, and three enhanced tubes: 2EHT1 tube, 2EHT2 tube and 1EHT1 tube (O.D. 12.7 mm), with different sizes and shapes of dimple/protrusion and petal arrays. Refrigerant inlet quality varied in this study. Single phase experiment was conducted before the two-phase flow measurement. In-tube evaporation measurements of R410A were reported for saturation temperature at 6°C with vapor quality in the range of 0.2 to 0.9, and mass flux varied from 60 to 200 kg/m2s. Condensation tests were performed at saturation temperature of 45°C, vapor quality of 0.9 to 0.2, and mass flux of 60 to 260 kg/m2s. For evaporation with mass flux less than 200 kg/m2s, heat transfer coefficient of the 2EHT2 tube, 2EHT1 tube and 1EHT1 tube were greater than the experimental HTC (heat transfer coefficient) of smooth tube results by an average factor of 1.71, 1.69 and 1.87, respectively. Pressure drop in the 2EHT2 tube was 5% higher than the 2EHT1 tube and 1EHT1 tube. For condensation, when mass flux was less than 200 kg/m2s, the 1EHT1 tube showed obvious enhancement in heat transfer coefficient, while the pressure drop in the 1EHT1 tube was slightly 3–5% higher than that of the 2EHT1 tube and the 2EHT2 tube. In conclusion, for mass flux below 200 kg/m2s, the 1EHT1 tube presented the best heat transfer performance among others with R410A as the refrigerant.

Numerical simulation of the fluid flow and heat transfer characteristics of microchannel heat exchangers with different reentrant cavities

2019 ◽  
Vol 29 (11) ◽  
pp. 4334-4348
Author(s):  
Minqiang Pan ◽  
Hongqing Wang ◽  
Yujian Zhong ◽  
Tianyu Fang ◽  
Xineng Zhong
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Content Type ◽  
Microchannel Heat Exchanger ◽  
Flow And Heat Transfer

Purpose With the increasing heat dissipation of electronic devices, the cooling demand of electronic products is increasing gradually. A water-cooled microchannel heat exchanger is an effective cooling technology for electronic equipment. The structure of a microchannel has great impact on the heat transfer performance of a microchannel heat exchanger. The purpose of this paper is to analyze and compare the fluid flow and heat transfer characteristic of a microchannel heat exchanger with different reentrant cavities. Design/methodology/approach The three-dimensional steady, laminar developing flow and conjugate heat transfer governing equations of a plate microchannel heat exchanger are solved using the finite volume method. Findings At the flow rate range studied in this paper, the microchannel heat exchangers with reentrant cavities present better heat transfer performance and smaller pressure drop. A microchannel heat exchanger with trapezoidal-shaped cavities has best heat transfer performance, and a microchannel heat exchanger with fan-shaped cavities has the smallest pressure drop. Research limitations/implications The fluid is incompressible and the inlet temperature is constant. Practical implications It is an effective way to enhance heat transfer and reduce pressure drop by adding cavities in microchannels and the data will be helpful as guidelines in the selection of reentrant cavities. Originality/value This paper provides the pressure drop and heat transfer performance analysis of microchannel heat exchangers with various reentrant cavities, which can provide reference for heat transfer augmentation of an existing microchannel heat exchanger in a thermal design.

Design Considerations and Heat Transfer Enhancement of CFB Heat Exchangers for Flue Gas Heat Recovery

2005 ◽  
Author(s):  
Yong-Du Jun ◽  
Kum-Bae Lee ◽  
Seok-Bo Ko ◽  
Sheikh Zahidul Islam
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Heat Transfer Performance ◽  
Fluid Composition ◽  
Generation Model ◽  
Transfer Performance

Now-a-day’s energy recovery process in the industry is a common practice for improving the production process while major concern goes to environment. The performance of the heat exchangers, used for the purpose of recovering energy, decreases continuously with time due to fouling depending on surface temperature, surface condition, construction material, fluid velocity, flow geometry and fluid composition. To overcome the fouling of fly ash on the heat transfer surface and erosion and periodical cleaning which are the major drawbacks in conventional heat exchangers for flue gas heat recovery, a no-distributor-circulating-fluidized-bed (NDCFB) heat exchanger with automatic particle controlling is devised. One of the main advantages of this model is the reduced pressure drop through the entire heat exchanger system, while increasing heat transfer performance. The research started with a single riser system with multiple down comers and multi-riser system is also studied. The heat transfer performance and pressure drop have been evaluated through experiments for these gas-to-water lab scale heat exchanger systems. However, due to the operational complexity, these two models are not readily applicable to real applications. As a derivation of the previous studies regarding the no-distributor CFB heat exchangers, third generation model of the heat exchanger is now under investigation.

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