Effect of Localized Hotspot on the Thermal Performance of Two-Phase Microchannel Heat Exchanger

2005 ◽  
Author(s):  
Ravi S. Prasher ◽  
John Dirner ◽  
Je-Young Chang ◽  
Alan Myers ◽  
David Chau ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Multiple Time ◽  
Time Varying ◽  
Uniform Heating ◽  
Test Chip ◽  
Two Phase ◽  
Convective Boiling ◽  
Microchannel Heat Exchanger ◽  
Future Technologies

Microchannel heat exchangers using two-phase convective boiling is one of the most promising future technologies for the cooling of microprocessors. Heat generation on microprocessors is highly non-uniform due to the presence of multiple time-varying localized hotspots. Previous literature has primarily been focused on the performance of microchannels under uniform heating conditions. In this paper we report the performance of microchannel heat exchanger under both uniform and hotspot (non-uniform) heating conditions. We performed these experiments using a novel test setup where the test chip has multiple temperature sensors, one heater to provide uniform heating and a hotspot heater of size 400 μm × 400 μm. We report some of the preliminary results on the thermal performance of the heat exchanger. Results show that fluctuation in the wall temperature is different under hotspot heating conditions as compared to the uniform heating conditions.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

THERMAL PERFORMANCE OF GRAPHENE OXIDE NANOFLUID IN MICROCHANNEL HEAT EXCHANGER

2020 ◽  
Vol 27 (5) ◽  
pp. 439-461
Author(s):  
Yue Seong Ong ◽  
Ku Zilati Ku Shaari ◽  
Afiq Mohd Laziz ◽  
Inn Leon Lu ◽  
Mohamad Fakhrul Ridhwan Samsudin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Microchannel Heat Exchanger

scholarly journals NUMERICAL INVESTIGATION OF ROUGNESS EFFECTS ON HYDERDYNMIC AND THERMAL PERFORMANCE OF COUNTER FLOW MICROCHANNEL HEAT EXCHANGER

2019 ◽  
Vol 11 (4) ◽  
pp. 426-445
Author(s):  
Ahmed A. Ali ◽  
Mushtaq I. Hasan ◽  
Ghassan Adnan
Keyword(s):  
Surface Roughness ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Substrate Material ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Counter Flow ◽  
Roughness Effect ◽  
Microchannel Heat Exchanger ◽  
Effect Of Surface

In this paper the effect of surface roughness on the performance of counter flow microchannel heat exchanger has been numerically investigated. The studied Microchannel heat exchanger is a square shape and made of aluminum as substrate material with different values of hydraulic diameters (20, 50, 110, 150 ) μm. The working fluid used is water  at constant properties. Roughness- viscosity model has been used to study the roughness effect with 0.14 ratio of roughness to hydraulic diameter.  The results obtained indicate that pressure drop of (CFMCHX) increased with increasing surface roughness and decrease hydraulic diameter also the results showed that there is a slight increasing in thermal performance with increasing the surface roughness.

Hydrodynamic and Thermal Performance of a Vapor-Venting Microchannel Copper Heat Exchanger

2008 ◽  
Author(s):  
Milnes P. David ◽  
Amy Marconnet ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Exchanger ◽  
Carbon Fiber ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Single Phase ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Large Pressure ◽  
Dry Out

Two-phase microfluidic cooling has the potential to achieve low thermal resistances with relatively small pumping power requirements compared to single-phase heat exchanger technology. Two-phase cooling systems face practical challenges however, due to the instabilities, large pressure drop, and dry-out potential associated with the vapor phase. Our past work demonstrated that a novel vapor-venting membrane attached to a silicon microchannel heat exchanger can reduce the pressure drop for two-phase convection. This work develops two different types of vapor-venting copper heat exchangers with integrated hydrophobic PTFE membranes and attached thermocouples to quantify the thermal resistance and pressure-drop improvement over a non-venting control. The first type of heat exchanger, consisting of a PTFE phase separation membrane and a 170 micron thick carbon-fiber support membrane, shows no improvement in the thermal resistance and pressure drop. The results suggest that condensation and leakage into the carbon-fiber membrane suppresses venting and results in poor device performance. The second type of heat exchanger, which evacuates any liquid water on the vapor side of the PTFE membrane using 200 ml/min of air, reduces the thermal resistance by almost 35% in the single-phase regime in comparison. This work shows that water management, mechanical and surface properties of the membrane as well as its attachment and support within the heat exchanger are all key elements of the design of vapor-venting heat exchangers.

Cavitation-Enhanced Microchannel Heat Exchanger Demonstration and Heat Transfer Correlation Development Using R-134a

2012 ◽  
Author(s):  
Joshua D. Sole ◽  
Bradley J. Shelofsky ◽  
Robert P. Scaringe ◽  
Gregory S. Cole
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
High Heat ◽  
High Heat Flux ◽  
Heat Transfer Correlation ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Military Aviation ◽  
R 134A ◽  
Two Phase Heat Transfer

Electronics of all types, particularly those in the military aviation arena, are decreasing in size while at the same time increasing in power. As a result, newer high-heat-flux electronic components are exceeding the cooling capabilities of conventional single-phase military aviation coldplates and coolants. It is for this reason that we have been investigating new methods to cool the next generation of high-heat-flux military aviation electronics. In this work, a novel method of inducing two-phase conditions within a microchannel heat exchanger has been developed and demonstrated. Micro-orifices placed upstream of each microchannel in a microchannel heat exchanger not only cause an improvement in flow distribution, but can also induce cavitation in the incoming subcooled refrigerant and result in favorable two-phase flow regimes for enhanced heat transfer. In this study, R-134a is used as the coolant in the cavitation enhanced microchannel heat exchanger (CEMC-HX) which has been integrated into a vapor compression refrigeration system. Multiple micro-orifice geometries combined with a fixed microchannel geometry (nominally 250 μm × 250 μm) were investigated over a range of applied base heat fluxes (10–100 W/cm2) and mass fluxes (500–1000 kg/m2-s). Two-phase heat transfer coefficients exceeding 100,000 W/m2-K at refrigerant qualities of less than 5% have been demonstrated due to the achievement of preferential, cavitation-induced, flow regimes such as annular flow. To the author’s knowledge, this is the highest heat transfer coefficient ever reported in the literature for R-134a. Additionally, a four term two-phase heat transfer correlation was developed that achieved a mean absolute error (MAE) of 25.5%.

Investigation of Two Phase Heat Transfer Coefficients of Cryogenic Mixed Refrigerants

2013 ◽  
Author(s):  
Seungwhan Baek ◽  
Sangkwon Jeong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Heat Transfer Coefficients ◽  
Evaporation Heat ◽  
Two Phase Heat Transfer

Mixed Refrigerant Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multiphase and multi-component fluid in cryogenic temperature range is necessarily required in the heat exchanger design of MR-JT refrigerator, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of mixed refrigerant are measured in a microchannel heat exchanger. Printed Circuit Heat Exchanger (PCHE) has been developed as a compact microchannel heat exchanger and used in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.

Two-phase flow distribution of R410A within the vertical header of a microchannel heat exchanger

2017 ◽  
Vol 2017.27 (0) ◽  
pp. 427
Author(s):  
Mark Anthony REDO ◽  
Niccolo GIANNETTI ◽  
Jongsoo JEONG ◽  
Koji ENOKI ◽  
Ikuhide OTA ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Two Phase Flow ◽  
Flow Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Microchannel Heat Exchanger
Sign in / Sign up

Export Citation Format

Share Document