Convective boiling of R-410A in 5.0 and 7.0 mm outer diameter microfin tubes

2019 ◽  
Vol 33 (4) ◽  
pp. 355-373 ◽  
Author(s):  
Nae-Hyun Kim
Keyword(s):  
Outer Diameter ◽  
Convective Boiling ◽  
Microfin Tubes

scholarly journals Heat transfer performance of R1234yf for convective boiling in horizontal micro-fin and smooth tubes

2020 ◽  
Vol 207 ◽  
pp. 01009
Author(s):  
Thanh Nhan Phan ◽  
Van Hung Tran ◽  
Nikola Kaloyanov ◽  
Momchil Vassilev
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Mass Flux ◽  
Heat Transfer Performance ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Transfer Performance ◽  
Convective Boiling ◽  
Penalty Factor ◽  
Smooth Tubes

This study analyses the performance of heat transfer process which occurs in the convective boiling of Hydro fluoro Olefin (HFO) refrigerant, R1234yf, in horizontal tube. Heat transfer and pressure drop of R1234yf are analyzed and computed at the same working conditions on the same size of outer diameter of tube do = 9.52 mm with difference of inner surface, one is a smooth surface and microfin for other. The flow pattern maps were built at 5°C saturation temperature with 8.62 kW/m2 of heat flux, it is presented that flow pattern of helix flow occurs at very low mass flux and low quality, while at that condition on smooth tube the flow is still stratified wavy flow. The comparison of heat transfer performance between microfin and smooth tube would be evaluated on enhancement factor E, penalty factor P and efficiency index I. With the mass flux on the range G = 111 -- 333 kg/m2s for 5°C boiling temperature, the results show that, average value of E is 2.18; 1.45 of P and 1.54 of I. One more impressing thing is that, at the quality “x” larger than 0.8, the dryout phenomenon takes place on smooth tubes while microfin tubes do not have this phenomenon.

Convective boiling pressure drop of refrigerant R-134a in horizontal smooth and microfin tubes

2004 ◽  
Vol 27 (8) ◽  
pp. 895-903 ◽  
Author(s):  
Enio P.Bandarra Filho ◽  
José M.Saiz Jabardo ◽  
Paulo E.L. Barbieri
Keyword(s):  
Pressure Drop ◽  
Convective Boiling ◽  
R 134A ◽  
Microfin Tubes

scholarly journals Heat Transfer and Pressure Drop Characteristics During R22 Evaporation in an Oval Microfin Tube

2000 ◽  
Vol 123 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Man-Hoe Kim ◽  
Jeong-Seob Shin ◽  
Clark W. Bullard
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Horizontal Tube ◽  
Outer Diameter ◽  
Transfer Coefficients ◽  
Round Tube ◽  
Two Phase ◽  
Axis Ratio ◽  
Oval Tube ◽  
Microfin Tubes

An experimental study on R22 evaporating heat transfer in round and oval microfin tubes has been performed. The oval tube was an elliptic tube of axis ratio 1:1.5, which was fabricated from the round tube with an outer diameter of 9.52 mm and 18 deg helix angle counterclockwise. The test section was a straight horizontal tube of 0.6 m in length and was heated electrically by a tape heater wound on the tube surface. Heat flux of 12 kW/m2 was maintained constant and the range of refrigerant quality was 0.2–0.8. The tests were conducted for evaporation at 15 °C for 30–60 kg/h mass flow rate (mass flux based on the oval tube: 150–300 kg/m2s) and the installation angles of the oval tube were varied between 0 and 135 deg in the circumferential direction. The local and average heat transfer and pressure drop characteristics for the oval tube were compared to those for the baseline round tube. The average two-phase heat transfer coefficients for the oval tube were 2–12 percent higher than that for the round tube and pressure drops for both tubes are similar. The single heat transfer coefficient and friction factor correlations for the round and oval microfin tubes are developed within the rms errors of ±5.6 percent and ±10.0 percent, respectively.

scholarly journals A Review on Convective Boiling Heat Transfer of Refrigerants in Horizontal Microfin-Tubes: A Typical Example

2021 ◽  
Author(s):  
Thanh Nhan Phan ◽  
Van Hung Tran
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
General Concept ◽  
Transfer Performance ◽  
Convective Boiling ◽  
Microfin Tubes ◽  
The Heat Transfer Coefficient

Understanding the Heat transfer performance of refrigerant for convective boiling in horizontal microfin tube and smooth tube is place an importance role on the designing of evaporator, the main equipment on refrigeration system. Reviewing the general concept especially the theory of boiling in the tube, the formation of the flow pattern map, the calculating procedure for heat transfer coefficient and pressure drop during boiling process of refrigerant in microfin tube. Besides, a typical example will be presented more detail in step by step to define the heat transfer coefficient and pressure drop for one working condition to estimate the data results without doing experiments.

Structure of rattlesnake venom lectin determined by single particle high-resolution electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 62-63
Author(s):  
Peter D. Moisiuk ◽  
Daniel R. Beniac ◽  
Ross A. Ridsdale ◽  
Martin Young ◽  
Bhushan Nagar ◽  
...  
Keyword(s):  
High Resolution Electron Microscopy ◽  
Lipid Monolayer ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
Single Particles ◽  
Crotalus Atrox ◽  
3D Reconstructions ◽  
X Ray ◽  
Rattlesnake Venom ◽  
Covalently Linked

Venom from the rattlesnake Crotalus atrox contains a mixture of enzymes that induce a localized effect leading to hemorrhaging, necrosis and edema. As a member of the crotalid family of snake venoms, Crotalus atrox venom contains a C-type lectin that will agglutinate blood cells in a Ca2+-dependent fashion. The lectin is a hydrophilic protein, consisting of two covalently linked, 135 amino acid residues, identical subunits that are rich in aspartic acid, glutamic acid and lysine. Sequence homology with known carbohydrate recognition domains (CRDs) indicates that rattlesnake venom lectin (RSLV) contains a CRD motif that is not linked to accessory domains. Preliminary X-ray diffraction and sedimentation analysis has indicated that lectin from Crotalus atrox forms decamers composed of two five-fold symmetric pentamers. Single particles of RSVL imaged at – 171°C displayed two distinct orientations on the specimen support (Figure a) following incubation in a crystallization Teflon well, coated with a lipid monolayer consisting of phosphatidylcholine and monosialoganglioside. When lying in an end-on orientation, the lectin exhibited a “pentagonal ring” with an outer diameter of 6.7 nm and an inner hollow core of 1.7 nm. A side orientation was also seen, whereby a thickness of 5.8 nm was measured for the lectin. Image processing of 2280 single particles placed in 100 classes (Figure b) led to 3D reconstructions of RSVL (Figure c). Density limited 3D reconstructions showed the lectin to be made of two five-fold symmetrical rings covalently linked between the five subunits that constitute each ring of this homodimer. These results are consistent with sedimentation and preliminary X-ray diffraction analysis on the shape of RSVL and provide the framework for structural verification by 2D electron crystallography.

The Effect of the Diameter in Convective Boiling of Refrigerant R-134a

Equipment ◽  
2006 ◽  
Author(s):  
J. M. Saiz Jabardo ◽  
P. E. Lopes Barbieri
Keyword(s):  
Convective Boiling ◽  
R 134A
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