Non-identity compensation of heat transfer conditions of differential calorimeter measuring cells  during  evaporation heat  study

An experiment investigation was performed using R410A in order to determine the single-phase and evaporation heat transfer coefficients on the outside of (i) a smooth tube; (ii) herringbone tube; and (iii) the newly developed Vipertex enhanced surface 1EHT tube; all with the same external diameter (12.7 mm). The nominal evaporation temperature is 279 K, with inlet and outlet qualities of 0.1 and 0.8. Mass fluxes ranged from 10 to 40 kg m−2s−1. Results suggest that the 1EHT tube has excellent heat transfer performance but a higher pressure drop when compared to a smooth tube. Evaporation heat transfer coefficient for the 1EHT is lower than the herringbone tube and the pressure drop is almost the same.

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Experimental Study of Evaporation Heat Transfer Characteristics and Pressure Drops of R410A and R134a in a Multiport Mini-Channel

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82209 ◽

2009 ◽

Cited By ~ 1

Author(s):

Jatuporn Kaew-On ◽

Somchai Wongwises

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Pressure Drop ◽

Transfer Coefficient ◽

Transfer Coefficients ◽

Pressure Drops ◽

Heat Transfer Coefficients ◽

Evaporation Heat ◽

Evaporation Heat Transfer ◽

R 134A

The evaporation heat transfer coefficients and pressure drops of R-410A and R-134a flowing through a horizontal-aluminium rectangular multiport mini-channel having a hydraulic diameter of 3.48 mm are experimentally investigated. The test runs are done at refrigerant mass fluxes ranging between 200 and 400 kg/m2s. The heat fluxes are between 5 and 14.25 kW/m2, and refrigerant saturation temperatures are between 10 and 30 °C. The effects of the refrigerant vapour quality, mass flux, saturation temperature and imposed heat flux on the measured heat transfer coefficient and pressure drop are investigated. The experimental data show that in the same conditions, the heat transfer coefficients of R-410A are about 20–50% higher than those of R-134a, whereas the pressure drops of R-410A are around 50–100% lower than those of R-134a. The new correlations for the evaporation heat transfer coefficient and pressure drop of R-410A and R-134a in a multiport mini-channel are proposed for practical applications.

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Boiling/Evaporation Heat Transfer Augmentation Using Subchannels-Inserted Metal Porous Media

Volume 2: Heat Transfer Enhancement for Practical Applications; Heat and Mass Transfer in Fire and Combustion; Heat Transfer in Multiphase Systems; Heat and Mass Transfer in Biotechnology ◽

10.1115/ht2013-17220 ◽

2013 ◽

Cited By ~ 2

Author(s):

Kazuhisa Yuki ◽

Masahiro Uemura ◽

Koichi Suzuki ◽

Ken-ichi Sunamoto

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Heat Sink ◽

Heat Transfer Performance ◽

Electronic Devices ◽

High Heat Flux ◽

Transfer Performance ◽

Power Electronic ◽

Copper Particles ◽

Evaporation Heat

Two-phase flow loop system using a metal porous heat sink is proposed as a cooling system of the future power electronic devices with a heat load exceeding 300W/cm2. In this paper, as the first step, the heat transfer performance of the porous heat sink is evaluated under high heat flux conditions and the applicability and some engineering issues are discussed. The porous medium, which is fabricated by sintering copper particles, has a functional structure with several sub-channels inside it to enhance phase-change as well as discharge of generated vapor outside the porous medium. This porous heat sink is attached onto a heating chip and removes the heat by evaporating cooling liquid passing through the porous medium against the heat flow. Experiments using 30 kW of heating system show that the heat transfer performance of a copper-particles-sintered porous medium with the sub-channels exceeds 800W/cm2 in both high and low subcooling cases and achieves 300W/cm2 at a wall temperature of 150 °C (Tin = 70 °C) and 130 °C (Tin = 70 °C). These results prove that this porous heat sink is applicable enough for cooling 300 W/cm2 class of power electronic devices.

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