Single-phase Flow Thermal Performance Characteristics of a Parallel MicroChannel Heat Exchanger

Ravigururajan, T. S.; Drost, M.K.

doi:10.1615/jenhheattransf.v6.i5.50

Cited by 23 publications

(24 citation statements)

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“…Heat transfer results obtained in a number of experimental studies on microchannels have been compared in the literature [13,22,33] against the numerical results of Wibulswas [21], to assess the applicability of a conventional analysis. Simultaneously developing as well as thermally developing flows in channels of rectangular cross-section were considered in [21], both with T (constant wall temperature) and H1 (constant wall heat flux with circumferentially constant wall temperature) boundary conditions [28].…”

Section: Numerical Analysismentioning

confidence: 99%

“…Based on comparison with these conventional correlations, various conclusions have been drawn regarding their applicability to microchannel heat transfer [1,12,13,14,15,[29][30][31][32][33][34][35][36][37]. Table 4 summarizes the conditions considered in these past microchannel studies, the conventional correlations against which results were compared, the conclusions that were drawn regarding applicability of conventional correlations, and any new correlations that were proposed.…”

Section: Alternative Prediction Approachesmentioning

confidence: 99%

“…Using x *  0.05 as the thermal entrance length, all studies (except for [1], which is the only study in the table where the working fluid is a gas) are 13 seen to be in a thermally developing state. In a majority of the studies [13,29,30,33,36] in which comparisons were made to conventional laminar correlations, a good portion of the channel length is in a hydrodynamic entrance region, such that the flow in these studies is in a state of simultaneously developing laminar flow. The Sieder-Tate [25] and Stephan [26] correlations (Eqs.…”

Section: Alternative Prediction Approachesmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of heat transfer in rectangular microchannels

Lee

Garimella

Liu

2005

International Journal of Heat and Mass Transfer

722

295

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An experimental investigation was conducted to explore the validity of classical correlations based on conventional-sized channels for predicting the thermal behavior in single-phase flow through rectangular microchannels. The microchannels considered ranged in width from 194 m to 534 m, with the channel depth being nominally five times the width in each case. Each test piece was made of copper and contained ten microchannels in parallel. The experiments were conducted with deionized water, with the Reynolds number ranging from approximately 300 to 3500. Numerical predictions obtained based on a classical, continuum approach were found to be in good agreement with the experimental data (showing an average deviation of 5 percent), suggesting that a conventional analysis approach can be employed in predicting heat transfer behavior in microchannels of the dimensions considered in this study. However, the entrance and boundary conditions imposed in the experiment need to be carefully matched in the predictive approaches.

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Section: Numerical Analysismentioning

confidence: 99%

Section: Alternative Prediction Approachesmentioning

confidence: 99%

Section: Alternative Prediction Approachesmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of heat transfer in rectangular microchannels

Lee

Garimella

Liu

2005

International Journal of Heat and Mass Transfer

722

295

View full text Add to dashboard Cite

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“…However, microchannel size, flow velocity, and inlet sub-cooling temperature had no significant effect on the heat transfer coefficient in the fully nucleate boiling regime. Ravigururajan et al (1996Ravigururajan et al ( , 1998 studied the impact of size and geometry of microchannels on their heat transfer characteristics. For single-phase flow, they found that microchannels provided significantly higher heat transfer coefficients.…”

Section: Microchannels Have Almost Completely Replaced Circular Tubesmentioning

confidence: 99%

Microchannel Heat Exchangers with Carbon Dioxide

Zhao¹,

Ohadi²,

Radermacher³

2001

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The objective of the present study was to determine the performance of C02 microchannel evaporators and gas coolers in operational conditions representing those of residential heat pumps. A set of breadboard prototype microchannel evaporators and gas coolers was developed and tested. The refrigerant in the heat exchangers followed a counter cross-flow path with respect to the airflow direction. The test conditions corresponded to the typical operating conditions of residential heat pumps. In addition, a second set of commercial microchannel evaporators and gas coolers was tested for a less comprehensive range of operating conditions. The test results were reduced and a comprehensive data analysis, including comparison with the previous studies in this field, was performed. Capacity and pressure drop of the evaporator and gas cooler for the range of parameters studied were analyzed and are documented in this report. A gas cooler performance prediction model based on non-dimensional parameters was also developed and results are discussed as well.In addition, in the present study, experiments were conducted to evaluate capacities and pressure drops for sub-critical C02 flow boiling and transcritical C02 gas cooling in microchannel heat exchangers. An extensive review of the literature failed to indicate any previous systematic study in this area, suggesting a lack of fundamental understanding of the phenomena and a lack of comprehensive data that would quantify the performance potential of C02 microchannel heat exchangers for the application at hand.All experimental tests were successfully conducted with an energy balance within +3%. The only exceptions to this were experiments at very low saturation temperatures i (-23 "C), where energy balances were as high as 10%. In the case of evaporators, it was found that a lower saturation temperature (especially when moisture condensation occurs) improves the overall heat transfer coefficient significantly. However, under such conditions, air side pressure drop also increases when moisture condensation occurs. An increase in airflow rate also increases the overall heat transfer coefficient. Air side pressure drop mainly depends on airflow rate. For the gas cooler, a significant portion of the heat transfer occurred in the first heat exchanger module on the refrigerant inlet side.The temperature and pressure of C02 significantly affect the heat transfer and fluid flow characteristics due to some important properties (such as specific heat, density, and viscosity). In the transcritical region, performance of C02 strongly depends on the operating temperature and pressure.Semi-empirical models were developed for predictions of C02 evaporator and gas cooler system capacities. The evaporator model introduced two new factors to account for the effects of air-side moisture condensate and refrigerant outlet superheat. The model agreed with the experimental results within *13%. The gas cooler model, based on nondimensional parameters, successfully predicted the experimental results ...

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“…They tested with water, and their heat exchanger provided a volumetric heat transfer coefficient of nearly 45 MW m -3 K -1 . Ravigururajan et al [4] have investigated on single-phase characteristics of a parallel microchannel heat exchanger. They used Refrigerant-124 as an experimental fluid.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Heat Transfer Characteristics on a Gas-to-Gas Parallel Flow Microchannel Heat Exchanger~!2009-07-27~!2009-10-13~!2010-04-02~!

Koyama¹,

Asako²

2010

TOTPJ

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Abstract:Heat transfer characteristics of a gas-to-gas parallel flow microchannel heat exchanger have been experimentally investigated. Temperatures and pressures at inlets and outlets of the heat exchanger are measured to obtain heat transfer rates and pressure drops. The heat transfer and pressure drop characteristics are discussed. The results show that experimental pressure drop is approximately ten times as large as theoretically estimated pressure drop. Geometric configuration of the heat exchanger dominates pressure drop characteristics. The conventional log-mean temperature difference method and the constant wall temperature model proposed in our earlier work are applied to predict heat transfer rate of the parallel flow microchannel heat exchanger. Prediction accuracy of the log-mean temperature difference method is superior to that of the constant wall temperature model. Applicability of the log-mean temperature difference method depends on direction of fluid flow.

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Single-phase Flow Thermal Performance Characteristics of a Parallel MicroChannel Heat Exchanger

Cited by 23 publications

References 0 publications

Investigation of heat transfer in rectangular microchannels

Investigation of heat transfer in rectangular microchannels

Microchannel Heat Exchangers with Carbon Dioxide

Experimental Investigation of Heat Transfer Characteristics on a Gas-to-Gas Parallel Flow Microchannel Heat Exchanger~!2009-07-27~!2009-10-13~!2010-04-02~!

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