The effects of longitudinal heat conduction in compact plate-fin and tube-fin heat exchangers using a finite element method

Ranganayakulu, C.; Seetharamu, K. N.; Sreevatsan, K.V.

doi:10.1016/s0017-9310(96)00182-2

Cited by 42 publications

(11 citation statements)

References 6 publications

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“…Kays and London stated that this reduction in performance is seen in heat exchangers designed for high effectiveness (~>0.9), however, they did not provide much of a quantitative analysis. Ranganayakulu et. al.…”

Section: Longitudinal Tube Conductionmentioning

confidence: 99%

Potential benefits of smart refrigerant distributors, final report

Payne¹,

Domanski²

2003

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Prepared for the Under ART1 2 1 -CR Program Contract Number 605-20050 AIR-CONDITIONING AND REFRIGERATION TECHNOLOGY INSTITUTE Use of Non-SI Units in a Non-NIST Publication It is the policy of the National Institute of Standards and Technology to use the International System of Units (metric units) in all of its publications. However, in North America in the HVAC&R industry, certain non-SI units are so widely used instead of SI units that it is more practical and less confusing to use measurement values for customary units only in figures and tables describing system performance. EXECUTIVE SUMMARYThe main goal of this study was to investigate the benefits possible for finned tube refrigerant evaporators when refrigerant distribution was precisely controlled to produce a desired equal superheat in each circuit. This goal was accomplished by examining three different finned tube evaporators; a wavy fin, wavy-lanced fin, and a wavy-lanced fin evaporator with tube sheets separated. The effects of non-uniform airflow on capacity were also examined while superheat was controlled in each evaporator circuit. In parallel with the experimental effort, a modeling program was implemented and validated with the experimental results and then used to determine the savings in evaporator core volume possible if refrigerant distribution was controlled by a smart distributor. In extreme cases, the savings in core volume could be as much as 40 YO.Within the experimental part of this study, all three evaporators could avoid significant performance degradation using the ability to control superheat within each of the three finned tube circuits. As an example, with cross-counter flow configuration, uniform airflow, and exit manifold superheat fixed at 5.6 "C (10.0 OF), the wavy fin and wavy-lanced fin evaporator's capacity dropped by as much as 41 YO and 32 %, respectively, as the superheat was allowed to vary between the circuits. Control of superheat was shown to be even more important during cross-parallel refrigerant flow due to the rapid pinching of the refrigerant and air temperatures.For the wavy and lanced finned evaporators in cross-parallel flow, capacity dropped by 85 YO and 78 YO as superheat changed from 5.6 "C (10.0 O F ) to 16.7 "C (30.0 OF). As the coil faces were blocked to produce a non-uniform airflow, pressure drop through the coils increased 1 substantially and control of superheat was shown to restore performance. The non-uniform airflow tests showed that when airflow rate was held constant, the losses in capacity due to low airflow over a portion of the coil could be recovered to within 2% of the original uniform airflow capacity by controlling superheat. The more non-uniform the airflow over the coil, the more capacity was improved by controlling superheat.

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Section: Longitudinal Tube Conductionmentioning

confidence: 99%

Potential benefits of smart refrigerant distributors, final report

Payne¹,

Domanski²

2003

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“…After the determining the average Nusselt number they got the conclusion that the rate of heat transfer is highest in the in the non-staggered geometry and the staggered geometry achieved the best volume goodness factor. Ranganayakulau et al [2] analyzed the cross flow plate fin, cross flow tube fin, parallel plate fin and the counter-flow plate fin heat exchangers by taking the effect of heat conduction in the longitudinal direction across the heat exchanger wall by using finite element method. They observed that the performance declination of cross flow type heat exchangers is higher compared to the counter-flow and parallel flow heat exchangers for all the cases.…”

Section: Development Of Experimental Analysis and Results In Platmentioning

confidence: 99%

Review of Experimental Analysis and Comparision of Results With Correlations Developed for Colburn Factor (J) and Friction Factor (F) in Plate Fin Heat Exchangers

2017

IJAERD

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“…The experimental results were 20% lower than their CFD results [4] due to deviation in the boundary conditions and LHC in the test core solid wall along the flow direction. In earlier studies [5][6][7], LHC, flow non-uniformity and temperature non-uniformity effects on the heat transfer characteristics of plate-fin heat exchangers were studied. They found that LHC in the wall had significant effects in cross-flow and counter-flow heat exchangers and the effect of LHC was negligible for the parallel-flow heat exchanger.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

Borjigin

Zeng

et al. 2018

Energies

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Abstract:Longitudinal heat conduction has a significant effect on the heat transfer performance of plate heat exchangers, but longitudinal heat conduction is usually neglected in numerical studies and the thermal design of a heat exchanger. In this paper, heat transfer models with and without longitudinal heat conduction are proposed to analyze the effect of small-scale longitudinal heat conduction in a plate heat exchanger. The performance of small-scale longitudinal heat conduction is illustrated by temperature and heat flux contours in the heat transfer models with and without longitudinal heat conduction. The results show that small-scale longitudinal heat conduction occurs in the plate and a more uniform temperature profile of the plate is obtained due to small-scale longitudinal heat conduction. In balanced flow, the contributions of longitudinal heat conduction for counter-flow, cross-flow and parallel-flow plate heat exchangers are −3.15%, −0.09% and 0, respectively, whereas, for the respective unbalanced flows they are evaluated to be −1.73%, 0.53% and 0.05%, respectively. Moreover, it is observed that small-scale longitudinal heat conduction in plates is influenced by the thermal conductivity of the plate. The higher the thermal conductivity, the larger is the reduction of thermal performance. The contribution of longitudinal heat conduction varies from −0.54% to −4.01%.

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The effects of longitudinal heat conduction in compact plate-fin and tube-fin heat exchangers using a finite element method

Cited by 42 publications

References 6 publications

Potential benefits of smart refrigerant distributors, final report

Potential benefits of smart refrigerant distributors, final report

Review of Experimental Analysis and Comparision of Results With Correlations Developed for Colburn Factor (J) and Friction Factor (F) in Plate Fin Heat Exchangers

A Numerical Study of Small-Scale Longitudinal Heat Conduction in Plate Heat Exchangers

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