Heat transfer characterization of flat plain fins and round tube heat exchangers

Higher order femtoscopy measured to examine the heat exchanger characterization of the fluid debris produced in the collisions and investigated a remarkable suppression in the bosons interferences measurement. The analogous suppression can be analyzed to explore the coherence of boson thermal particle production sources at unprecedented energies. We illustrate the particles emissions from radiated sources with statistical coherence which induce the thermal particles interferences to probe the peculiarity of the heated sources as well as the distinctions about the heat exchangers in the collisions at higher temperature. We perspicacious that the bosons seem to the pertinent aspirant of heat exchanger, and the normalized three particles correlators evaluate the existence of such hybrid phases significantly. The key point of this research is that we analyze the three particles correlations with their normalized correlations by difference equations to determine the characteristics of heat exchanger and its applications. With such distinctive and efficient approach, we observe a significant difference in the correlation functions at higher temperature and momenta regimes.

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Aspects of Flow and Heat Transfer in Louver-Fin Round-Tube Heat Exchangers

Heat Transfer: Volume 2 ◽

10.1115/ht2005-72219 ◽

2005 ◽

Author(s):

Hailing Wu ◽

Ying Gong ◽

Xiaobo Zhu

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Three Dimensional ◽

Flow Region ◽

Recirculation Region ◽

Round Tube ◽

Flow And Heat Transfer ◽

Representative Cell ◽

Conjugated Heat Transfer ◽

Good Agreement

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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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-Side Performance Characterization of Air-to-Refrigerant Heat Exchangers Using Parallel Parameterized CFD

Volume 4: Heat and Mass Transfer Under Extreme Conditions; Environmental Heat Transfer; Computational Heat Transfer; Visualization of Heat Transfer; Heat Transfer Education and Future Directions in Heat Transfer; Nuclear Energy ◽

10.1115/ht2013-17060 ◽

2013 ◽

Author(s):

Khaled Saleh ◽

Weizhe Han ◽

Vikrant Aute ◽

Reinhard Radermacher

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Cfd Simulations ◽

Cfd Models ◽

F Factor ◽

Wide Range ◽

Different Types ◽

Computational Fluid Dynamics Cfd ◽

Friction Performance

The goal of the study presented in this paper is to use Computational Fluid Dynamics (CFD) to characterize the heat transfer and friction performance of fins used in air-to-refrigerant heat exchangers. Five different types of fins used in air-cooled heat exchangers (HXs) are studied using Parallel Parameterized CFD (PPCFD) approach described in this paper. The fin types considered in this paper are; Plain, Wavy, Slit, Super Slit, and Louver. 3-D CFD models are built and tested for these fin types. Based on the CFD results, air side heat transfer coefficient (HTC), Colburn j factor, Fanning f factor, and pressure drop are calculated. The results from CFD simulations are compared against experimental data from the literature for the different fin types and a good agreement is found between the two. In addition, the results from CFD simulations are used to evaluate the thermal and hydraulic performance for a wide range of heat exchanger parameters such as tube diameters, fin pitch, number of rows, and frontal air velocity. The results show the advantages of using PPCFD to efficiently develop correlations for different types of fins used in air-cooled HX, with significant reduction in engineering time. The PPCFD approach can be extended to efficiently optimize novel heat transfer surfaces.

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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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Compact Air-Coupled and Hydronically Coupled Microchannel Heat Pumps

10.1115/imece2001/aes-23628 ◽

2001 ◽

Author(s):

Yirong Jiang ◽

Srinivas Garimella

Keyword(s):

Heat Transfer ◽

Heat Pump ◽

Heat Exchangers ◽

Coupled System ◽

Heat Pumps ◽

Coupled Systems ◽

Transfer Coefficients ◽

Round Tube ◽

Two Phase ◽

High Heat Transfer

Abstract Novel air-coupled and hydronically coupled heat pumps using microchannel components were investigated in this study. The air-coupled system uses microchannel tube, multilouver fin heat exchangers as the evaporator and condenser. In the hydronically coupled heat pump, refrigerant in the evaporator as well as the condenser transfers heat to an intermediate fluid such as an ethyleneglycol solution. The glycol loops are connected to the indoor/outdoor air through liquid-air heat exchangers. Models to simulate cycle thermodynamics, and single- and two-phase heat transfer in the components were developed to design these systems for cooling and heating mode operation. The components were optimized to develop the most compact systems that would satisfy system performance requirements. These systems were also compared with a conventional round-tube, plate-fin heat pump, which was designed using a commercially available simulation tool. Results from this study show that indoor and outdoor units of air-coupled microchannel systems can be packaged in only one-half and one-third the space required for a conventional system. Even more compact refrigerant heat exchangers are required in the hydronically coupled system, because of the high heat transfer coefficients for these liquid-coupled heat exchangers, and the counterflow orientation. The hydronic coupling offers flexibility in system location, and is well suited for integrated space-conditioning and water heating systems. Both air-coupled and hydronically coupled systems result in significant reductions in refrigerant inventories compared to round-tube systems. The refrigerant charge of the microchannel air-coupled system is 20% less than that of the round-tube heat pump. For the hydronically coupled system, the refrigerant charge is only 10% of the charge in the round-tube heat pump.

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