Heat Transfer Performance of Finless Flat Tube Heat Exchanger With Vortex Generator

2010 ◽  
Author(s):  
Hajime Onishi ◽  
Haruka Yonekura ◽  
Yukio Tada ◽  
Akira Takimoto
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Vortex Shedding ◽  
Heat Transfer Performance ◽  
Vortex Generator ◽  
Longitudinal Vortex ◽  
Transfer Performance ◽  
Flat Tube ◽  
Longitudinal Vortices ◽  
Tube Heat Exchanger

As the longitudinal vortex is known to be effective in enhancing heat transfer, a three-dimensional unsteady numerical analysis has been made especially for the flow and thermal fields in a unit element of flat tube heat exchanger with vortex generator (VG) in so-called middle Reynolds number range. Both staggered and in-lined arrangements of the tubes with VG are considered and results obtained from the case with VG are compared with those without VG. The study was aimed at the influence of Reynolds number and some geometrical parameters on the heat transfer and the pressure drop. Moreover, as little research has been considered the interaction between transverse vortices and longitudinal vortices in the literatures, the effect is also investigated. It is found that the longitudinal vortex plays an important role in enhancing the local heat transfer by exchanging the fluid from the tube surface region to the fresh fluid of the main flow region and lasts over long distances. Moreover, the longitudinal vortices restrain unsteady transverse vortex shedding. As a result, heat transfer rate for the flat tube with VG case is larger compared to that without VG case. From the view point of pressure drop, increase in pressure drop for the case with VG is not so much larger due to the restraint of transverse vortex shedding. Finally, heat transfer performance becomes higher for the flat tube with VG case compared to that without VG case for the same pumping power.

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.

scholarly journals Experimental Study on the Heat Transfer Characteristics of the Enhanced Fin-Tube Heat Exchanger Applied a Coiled Turbulator

2017 ◽  
Author(s):  
Sun-Joon Byun ◽  
Sang-Jae Lee ◽  
Jae-Min Cha ◽  
Zhen-Huan Wang ◽  
Young-Chul Kwon
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Water Flow ◽  
Flow Rate ◽  
Heat Transfer Performance ◽  
Water Flow Rate ◽  
Transfer Performance ◽  
Tube Heat Exchanger ◽  
Fin Tube

This study presents the comparison of heat transfer capacity and pressure drop characteristics between a basic fin-tube heat exchanger and a modified heat exchanger with the structural change of branch tubes and coiled turbulators. All experiments were carried out using an air-enthalpy type calorimeter based on the method described in ASHRAE standards, under heat exchanger experimental conditions. 14 different kinds of heat exchangers were used for the experiment. Cooling and heating capacities of the turbulator heat exchanger were excellent, compared to the basic one. As the insertion ratio of the coiled turbulator and the number of row increased, the heat transfer performance increased. However, the capacity per unit area was more effective in 4 rows than 6 rows, and the cooling performance of the 6 row turbulator heat exchanger (100% turbulator insert ratio) was down to about 6% than that of 4 row one. As the water flow rate and the turbulator insertion ratio increased, the pressure drop of the water side increased. This trend was more pronounced in 6 rows. In the cooling condition, the pressure drop on the air side was slightly increased due to the generation of condensed water, but was insignificant under the heating condition. The power consumption of the pump was more affected by the water flow rate than the coiled turbulator. The equivalent hydraulic diameter of a tube by the turbulator was reduced and then the heat transfer performance was improved. Thus, the tube diameter was smaller, the heat flux was better.

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.

Heat Transfer Testing of Enhanced Finned-Tube Bundles Using the Single-Blow Technique

2003 ◽  
Author(s):  
J. E. O’Brien ◽  
M. S. Sohal ◽  
P. C. Wallstedt
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Performance Testing ◽  
Finned Tube ◽  
Test Facility ◽  
Transfer Performance ◽  
Number Range ◽  
Longitudinal Vortices ◽  
Tube Bundles

A single-blow test facility has been developed at the INEEL for pressure-drop and heat transfer performance testing of heat exchanger finned-tube bundles. Initial testing in the facility has been aimed at evaluating several enhanced heat transfer geometries to be used with individually finned tubes in which winglet vortex generators have been punched into the fin surfaces at specific locations. The winglets interact with the air flow to create longitudinal vortices that enhance fin-surface heat transfer performance with minimal increase in pressure drop. Results of two initial studies indicate heat transfer enhancement levels of 20–30% across the tested Reynolds number range (100–3000), with an increase in pressure drop of only 4–12%, over the same range.

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.

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

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