New proposed two-phase multiplier and evaporation heat transfer coefficient correlations for R134a flowing at low mass flux in a multiport minichannel

2012 ◽  
Vol 39 (6) ◽  
pp. 853-860 ◽  
Author(s):  
Jatuporn Kaew-On ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Two Phase ◽  
Evaporation Heat ◽  
Low Mass ◽  
Evaporation Heat Transfer

Experimental Study on Flow Evaporation Heat Transfer Characteristics Inside Horizontal Three-Dimensional Enhanced Tubes

2018 ◽  
Author(s):  
Wei Li ◽  
Chuancai Zhang ◽  
Zhichuan Sun ◽  
Zhichun Liu ◽  
Lianxiang Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Three Dimensional ◽  
Outer Diameter ◽  
Evaporation Heat ◽  
Enhanced Tubes ◽  
Evaporation Heat Transfer ◽  
The Heat Transfer Coefficient

Experimental investigation was performed to measure the evaporation heat transfer coefficients of R410A inside three three-dimensional enhanced tubes (1EHT-1, 1EHT-2 and 4LB). The inner and outer enhanced surface of the 4LB tube is composed by arrays of grooves and square pits, while 1EHT-1 tube and 1EHT-2 tube consist of longitudinal ripples and dimples of different depths. All these tubes have an inner diameter of 8.32 mm and an outer diameter of 9.52 mm. Experiment operational conditions are conducted as follows: the saturation temperature is 279 K, the vapor quality ranges from 0.2 to 0.8, and the mass flux varies from 160 kg/(m2·s) to 380 kg/(m2·s). With the mass flux increasing, the heat transfer coefficient increases accordingly. The heat transfer coefficient of 1EHT-2 is the highest of all three tubes, and that of 1EHT-1 is the lowest. The heat transfer coefficient of 4LB ranks between the 1EHT-1 and 1EHT-2 tube. The reason is that the heat transfer areas of the 1EHT-2 and 4LB tube are larger than that of 1EHT-1 and interfacial turbulence is enhanced in 1EHT-2.

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

2009 ◽  
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.

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.

scholarly journals Experimental Study of HFE 7000 Refrigerant Condensation in Horizontal Pipe Minichannels

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6886
Author(s):  
Małgorzata Sikora ◽  
Tadeusz Bohdal ◽  
Karolina Formela
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flux Density ◽  
Mass Flux ◽  
Internal Diameter ◽  
Two Phase ◽  
Horizontal Pipe

This article presents the results obtained from our own experimental investigations on heat exchange and pressure drop during the condensation flow of the HFE 7000 refrigerant in pipe minichannels with an internal diameter of di = 1.2–2.5 mm. The influence of vapor quality x and the mass flux density G on the two-phase flow pressure drops and heat transfer is presented. The tests were performed for the mass flux density range of G = 110–4700 kg/m2s, saturation inlet temperature of Ts = 36–43 °C and heat flux density of q = 1 ÷ 20 kW/m2. The pressure drop characteristics and heat transfer coefficient as a function of the internal diameter of minichannels are illustrated. The results of experimental research on the heat transfer coefficient and two-phase pressure drop are compared with correlations developed by other authors. The best accuracy has a comparison of experimental study with correlation of Rahman-Kariya-Miyara et al. and Mikielewicz et al.

Impact of Channel Geometry on Two-Phase Flow Heat Transfer Characteristics of Refrigerants in Microchannel Heat Exchangers

1998 ◽  
Vol 120 (2) ◽  
pp. 485-491 ◽  
Author(s):  
T. S. Ravigururajan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Heat ◽  
The Heat Transfer Coefficient

Microchannel surfaces, often machined to 20 to 1000 μm in width and depth, are employed in high-heat-flux applications. However, a large number of variables, control the two-phase flow heat transfer coefficient. The pressure, the surface heat flux, and the mass flux significantly affect the thermal transport. Experiments were conducted on a setup that was built for testing microchannel heat exchanges. The parameters considered in the study are power input: 20 to 300 W, volume flow rate: 35 to 300 ml/min, quality: 0 to 0.5, inlet subcooling: 5 to 15°C. The results indicate that the heat transfer coefficient and pressure drop are functions of the flow quality, the mass flux, and, of course, the heat flux and the related surface superheat. The heat transfer coefficient decreases from a value of 12,000 W/m2-K to 9000, W/m2-K at 80°C, when the wall superheat is increased from 10 to 80°C. The coefficient decreases by 30 percent when the exit vapor quality is increased from 0.01 to 0.65.

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