Differential mass evacuation sampling technique for measuring refrigerant charge and oil retention of round tube plate fin heat exchangers (ASHRAE RP-1785)

Experimental and numerical investigations on flow and heat transfer were conducted for louver-fin round-tube two-row heat exchangers. The airflow velocity ranged from 1 m/s to 3 m/s. A three-dimensional numerical method was developed by modeling representative cell units with fluid-solid conjugated heat transfer. Results of three-dimensional numerical simulations were in good agreement with the experimental data. A stagnant flow region exists behind the round tubes, and results in diminished local convective heat transfer. For two-row heat exchangers operating at Reynolds number, Re<300, the first row dominates the heat transfer rate. With Re increasing, the heat transfer contribution of both rows tends to be more uniform. The flow pattern shows a recirculation region downstream of the heat exchanger at higher Re flows, which may be induced by a vortex-shedding instability from the tube and louver bank.

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Numerical Controlled Process of Tube Plate and Baffles on Tubular Heat Exchangers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.462.855 ◽

2012 ◽

Vol 462 ◽

pp. 855-859

Author(s):

Shi Wei Li ◽

Zheng Fang Wang

Keyword(s):

Heat Exchangers ◽

Mathematics Model ◽

Tube Plate ◽

Shell Side ◽

Machining Center ◽

Traditional Process ◽

The Cost

Tube plate and baffles are all important parts in tubular heat exchangers, drilling holes on them is an important and difficult task for factory. The efficiency of traditional process is low and the error is big. Analyzed the holes’ distributing on six shell side routes exchangers, established mathematics model, compiled numerical controlled program with EIA code, realized numerical controlled process of tube plate and baffles on MITSUBISHI machining center. This improved the quality of equipment and lowered the cost.

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THERMAL PERFORMANCE OF SINE WAVE FIN-AND-OVAL TUBE HEAT EXCHANGERS

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132513500089 ◽

2013 ◽

Vol 21 (01) ◽

pp. 1350008 ◽

Cited By ~ 2

Author(s):

NAE-HYUN KIM ◽

KANG-JONG LEE ◽

JI-CHAO HAN ◽

BYUNG-NAM CHOI

Keyword(s):

Heat Transfer ◽

Aspect Ratio ◽

Thermal Performance ◽

Heat Exchangers ◽

Sine Wave ◽

Heat Transfer Characteristics ◽

Round Tube ◽

Flow And Heat Transfer ◽

Wave Channel ◽

Oval Tube

Experiments were conducted on sine wave fin-and-tube heat exchangers having oval tubes of 0.6 aspect ratio. Twelve samples having different fin pitches and tube rows were tested. Eight herringbone wave fin-and-tube heat exchangers having round tubes were also tested. For round tube samples, the effect of tube row on j factor is not prominent. For oval tube samples, however, the highest j factor is observed for two row configuration, whereas the lowest one is observed for one row configuration. Possible reasoning is provided considering the flow and heat transfer characteristics of sine wave channel combined with connecting oval tubes. The friction factor decreases as number of tube row increases. Comparison with round tube samples reveals that airside performance of oval fin-and-tube heat exchangers is generally superior except for one-row configuration.

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Air Flow and Heat Transfer in Louver-Fin Round-Tube Heat Exchangers

Journal of Heat Transfer ◽

10.1115/1.2402180 ◽

2006 ◽

Vol 129 (2) ◽

pp. 200-210 ◽

Cited By ~ 9

Author(s):

H. L. Wu ◽

Y. Gong ◽

X. Zhu

Keyword(s):

Heat Transfer ◽

Boundary Conditions ◽

Heat Transfer Rate ◽

Heat Exchangers ◽

Transfer Rate ◽

Air Flow ◽

Fluid Temperature ◽

Round Tube ◽

Flow And Heat Transfer ◽

Representative Unit Cell

Experimental investigations were conducted to understand the air flow and heat transfer in louver-fin round-tube two-row two-pass cross-counterflow heat exchangers. The Colburn factor j and friction factor f were obtained by using the ε-NTU approach. A three-dimensional computational fluid dynamics model was developed based on a representative unit cell with periodical and symmetric boundary conditions. Analysis of tube-side circuiting effect has been conducted and showed improvement by applying overall nonlinear tube-side fluid temperature boundary conditions. Comparison of heat transfer rate of the first and second rows showed that the first row was much more effective, achieving 68-53% of the total heat transfer rate, when air velocity changes from 1.02m∕sto2.54m∕s. A dimensionless parameter, F, was introduced to describe the louver interaction for different fin designs with various louver angles. Using j′∕f1∕3 as a criterion to evaluate the heat transfer and pressure loss performance, an optimal F was predicted around 0.62.

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