The Experts below are selected from a list of 428475 Experts worldwide ranked by ideXlab platform
Jinjin Tian - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of two-phase Flow Distribution in plate-fin heat exchangers
Chemical Engineering Research & Design, 2017Co-Authors: Zhe Zhang, Sunil S Mehendale, Jinjin TianAbstract:Abstract Flow malDistribution causes declining plate-fin heat exchanger thermal-hydraulic performance. A first-of-its kind experimental facility and the related data acquisition system were constructed for studying liquid–gas Flow Distribution in a plate-fin heat exchanger. The gas Reynolds numbers ranged from 1880 to about 2600 and the inlet dryness (i.e., quality) from 12% to 41%. Two-phase Flow malDistribution among the heat exchanger passages was more widespread compared to that of single-phase Flow. More specifically, the liquid-phase Distribution was more uneven compared to the gas-phase Distribution. The inlet Flow rate and dryness were identified as the chief factors affecting the Distribution of phases in the heat exchanger. For a given inlet dryness, the two-phase Flow Distribution became increasingly non-uniform with the inlet gas Flow rate, consistent with the behavior observed for single-phase Flow. Additionally, the non-uniformity in the gas Flow Distribution decreased and that in the liquid Flow non-uniformity increased with increasing inlet dryness fraction. A novel distributor design, with a complementary fluid cavity was also built and tested. Experimental results show that improving the distributor design is very effective in improving the two-phase Flow Distribution in plate-fin heat exchangers. Based on heat transfer studies conducted at a single Reynolds number of about 1500 and a dryness of 29.2%, the heat exchanger effectiveness was also correlated as a function of the dryness Distribution non-uniformity parameter S x . The effectiveness was found to reduce as the Flow Distribution became more uneven, highlighting the importance of accounting for and controlling the Flow malDistribution through proper distributor design.
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CFD Simulation on Flow Distribution in Plate-Fin Heat Exchangers
Advanced Materials Research, 2013Co-Authors: Zhe Zhang, Jinjin Tian, Yong Gang GuoAbstract:The influences of the conventional header configuration used in industry at present on the fluid Flow Distribution in plate-fin heat exchanger were numerically investigated. The numerical results showed that the fluid Flow malDistribution is very serious in the heat exchanger. The header configuration with perforated plate was brought forward for the first time. The computational results indicated that the improved header configuration can effectively improve the performance of fluid Flow Distribution in the heat exchanger. The fluid Flow Distribution for the header configuration with curving perforated plate is more uniform than for the header configuration with plane perforated plate. The absolute degree of fluid Flow nonuniformity in plate-fin heat exchanger has reduced from 3.47 to 0.32 by changing the header configuration. The numerical results are compared with the experimental results. They are basically consistent which indicates that the mathematical model and the calculating method are reliable.
K. Naveen - One of the best experts on this subject based on the ideXlab platform.
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CFD Simulation of Flow Distribution in the Header of Plate‐Fin Heat Exchangers
Chemical Engineering & Technology, 2007Co-Authors: Kailas L. Wasewar, S. Hargunani, P. Atluri, K. NaveenAbstract:The Flow Distribution through a plate-fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The Flow Distribution through any heat exchanger affects its performance. In designing a heat exchanger, it is assumed that the fluid is uniformly distributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the Flow Distribution in the header of a conventional plate-fin heat exchanger is presented. It is found that the Flow malDistribution is very serious in the y-direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform Flow Distribution than the conventional header configuration. Hence, the efficiency of the modified heat exchanger is seen to be higher than that of the conventional heat exchanger.
Zhe Zhang - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of two-phase Flow Distribution in plate-fin heat exchangers
Chemical Engineering Research & Design, 2017Co-Authors: Zhe Zhang, Sunil S Mehendale, Jinjin TianAbstract:Abstract Flow malDistribution causes declining plate-fin heat exchanger thermal-hydraulic performance. A first-of-its kind experimental facility and the related data acquisition system were constructed for studying liquid–gas Flow Distribution in a plate-fin heat exchanger. The gas Reynolds numbers ranged from 1880 to about 2600 and the inlet dryness (i.e., quality) from 12% to 41%. Two-phase Flow malDistribution among the heat exchanger passages was more widespread compared to that of single-phase Flow. More specifically, the liquid-phase Distribution was more uneven compared to the gas-phase Distribution. The inlet Flow rate and dryness were identified as the chief factors affecting the Distribution of phases in the heat exchanger. For a given inlet dryness, the two-phase Flow Distribution became increasingly non-uniform with the inlet gas Flow rate, consistent with the behavior observed for single-phase Flow. Additionally, the non-uniformity in the gas Flow Distribution decreased and that in the liquid Flow non-uniformity increased with increasing inlet dryness fraction. A novel distributor design, with a complementary fluid cavity was also built and tested. Experimental results show that improving the distributor design is very effective in improving the two-phase Flow Distribution in plate-fin heat exchangers. Based on heat transfer studies conducted at a single Reynolds number of about 1500 and a dryness of 29.2%, the heat exchanger effectiveness was also correlated as a function of the dryness Distribution non-uniformity parameter S x . The effectiveness was found to reduce as the Flow Distribution became more uneven, highlighting the importance of accounting for and controlling the Flow malDistribution through proper distributor design.
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CFD Simulation on Flow Distribution in Plate-Fin Heat Exchangers
Advanced Materials Research, 2013Co-Authors: Zhe Zhang, Jinjin Tian, Yong Gang GuoAbstract:The influences of the conventional header configuration used in industry at present on the fluid Flow Distribution in plate-fin heat exchanger were numerically investigated. The numerical results showed that the fluid Flow malDistribution is very serious in the heat exchanger. The header configuration with perforated plate was brought forward for the first time. The computational results indicated that the improved header configuration can effectively improve the performance of fluid Flow Distribution in the heat exchanger. The fluid Flow Distribution for the header configuration with curving perforated plate is more uniform than for the header configuration with plane perforated plate. The absolute degree of fluid Flow nonuniformity in plate-fin heat exchanger has reduced from 3.47 to 0.32 by changing the header configuration. The numerical results are compared with the experimental results. They are basically consistent which indicates that the mathematical model and the calculating method are reliable.
Kailas L. Wasewar - One of the best experts on this subject based on the ideXlab platform.
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CFD Simulation of Flow Distribution in the Header of Plate‐Fin Heat Exchangers
Chemical Engineering & Technology, 2007Co-Authors: Kailas L. Wasewar, S. Hargunani, P. Atluri, K. NaveenAbstract:The Flow Distribution through a plate-fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The Flow Distribution through any heat exchanger affects its performance. In designing a heat exchanger, it is assumed that the fluid is uniformly distributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the Flow Distribution in the header of a conventional plate-fin heat exchanger is presented. It is found that the Flow malDistribution is very serious in the y-direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform Flow Distribution than the conventional header configuration. Hence, the efficiency of the modified heat exchanger is seen to be higher than that of the conventional heat exchanger.
Sunil S Mehendale - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of two-phase Flow Distribution in plate-fin heat exchangers
Chemical Engineering Research & Design, 2017Co-Authors: Zhe Zhang, Sunil S Mehendale, Jinjin TianAbstract:Abstract Flow malDistribution causes declining plate-fin heat exchanger thermal-hydraulic performance. A first-of-its kind experimental facility and the related data acquisition system were constructed for studying liquid–gas Flow Distribution in a plate-fin heat exchanger. The gas Reynolds numbers ranged from 1880 to about 2600 and the inlet dryness (i.e., quality) from 12% to 41%. Two-phase Flow malDistribution among the heat exchanger passages was more widespread compared to that of single-phase Flow. More specifically, the liquid-phase Distribution was more uneven compared to the gas-phase Distribution. The inlet Flow rate and dryness were identified as the chief factors affecting the Distribution of phases in the heat exchanger. For a given inlet dryness, the two-phase Flow Distribution became increasingly non-uniform with the inlet gas Flow rate, consistent with the behavior observed for single-phase Flow. Additionally, the non-uniformity in the gas Flow Distribution decreased and that in the liquid Flow non-uniformity increased with increasing inlet dryness fraction. A novel distributor design, with a complementary fluid cavity was also built and tested. Experimental results show that improving the distributor design is very effective in improving the two-phase Flow Distribution in plate-fin heat exchangers. Based on heat transfer studies conducted at a single Reynolds number of about 1500 and a dryness of 29.2%, the heat exchanger effectiveness was also correlated as a function of the dryness Distribution non-uniformity parameter S x . The effectiveness was found to reduce as the Flow Distribution became more uneven, highlighting the importance of accounting for and controlling the Flow malDistribution through proper distributor design.
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A Critical Assessment of Two-Phase Flow Distribution in Microchannel Heat Exchangers
2016Co-Authors: Karthik Panghat, Sunil S MehendaleAbstract:Due to the many benefits offered by Microchannel Heat Exchangers (MCHX), such as compactness, high heat transfer coefficients, reduced refrigerant charge, and energy and material cost savings, microchannel condensers and evaporators continue to be increasingly applied and investigated in the HVAC&R fields. One of the practical challenges associated with MCHX is the uniform Distribution of two-phase refrigerant in the headers and tubes of the heat exchanger. In MCHX, which typically have port sizes about 1 mm or less, to maintain the pressure drop at reasonable levels while providing fairly uniform two phase Flow Distribution, an appropriate header size and number of tubes need to be chosen. In this paper, a critical review of experimental and analytical investigations of two-phase Flow malDistribution in MCHX is presented. The influence of header and microchannel tube geometry, heat exchanger orientation, Flow and operating conditions, fluid properties and Flow patterns on the MCHX Flow Distribution is discussed. Researchers have investigated upward and/or downward two-phase Flow in MCHX with horizontal and vertical headers, for which the microchannel tubes/ports are, respectively, vertical and horizontal. Traditionally, compared to investigations in horizontal headers, the studies on vertical headers have been relatively few. However, recently, due to applications involving automotive evaporators, more studies on vertical headers are reported. In all these studies, gravity is seen to profoundly affect the two-phase Flow Distribution. Various fluids such as R410A, R134a, R245fa, CO2, air-water, etc. have been studied in published works. Fluid thermophysical properties and Flow patterns greatly influence the Flow Distribution in MCHX. Very few investigators have studied the effects of fluid properties on two-phase Flow Distribution. Zou and Hrnjak (2014) [16] speculated that fluids with high liquid to vapor density ratio would provide better Flow Distribution. However, this hypothesis needs to be experimentally confirmed. Most studies agree that in headers, compared to annular Flow, churn Flow is desirable for better Flow Distribution. Most of the experimental investigations on Flow Distribution have been conducted for adiabatic Flow. However, the applicability of such investigations to practical situations is dubious as the Flow will be accompanied by condensation or boiling heat transfer. Refrigerant mass flux (G) and inlet quality (x) are seen to have a significant impact on Flow Distribution which is discussed in detail. Tube protrusion into the headers, and tube spacing also greatly affect the Flow Distribution. Since these interacting factors make the prediction of two-phase Flow Distribution very complex, a limited number of semi-empirical models/correlations have been proposed to quantify the two-phase Flow malDistribution in MCHX. Five correlations for predicting the liquid take-off ratio in MCHX headers were assessed and among these five, Zou and Hrnjak (2013b)[15] correlation for R410A was found to perform reasonably. Based on the current study, recommendations regarding the applicability of these correlations to practical problems have been provided. Having identified and examined the key factors influencing two-phase Flow malDistribution in MCHX, recommendations for further study are made.