Boiling heat transfer at reduced pressures with water supplied to the heat-transfer surface through a capillary-porous body

1968 ◽  
Vol 14 (6) ◽  
pp. 501-504 ◽  
Author(s):  
T. A. Kolach ◽  
R. Kh. Sharipov ◽  
V. V. Yagov
Keyword(s):  
Heat Transfer ◽  
Porous Body ◽  
Boiling Heat Transfer ◽  
Heat Transfer Surface ◽  
Reduced Pressures

Evaluation of General Correlations for Heat Transfer During Boiling of Saturated Liquids in Tubes and Annuli

2005 ◽  
Author(s):  
M. Mohammed Shah
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Large Deviations ◽  
Boiling Heat Transfer ◽  
Mean Deviation ◽  
Data Sets ◽  
Vapor Quality ◽  
Dimensional Parameters ◽  
Vertical Tubes ◽  
Reduced Pressures

Six of the most verified correlations for boiling heat transfer were compared to data for horizontal and vertical tubes and annuli. The correlations evaluated were: Chen (1966), Shah (1982), Gungor and Winterton (1986), Liu & Winterton (1991), Kandlikar (1990), and Steiner and Taborek (1992). The database used to evaluate these correlations included 29 fluids: water, refrigerants, cryogens, organic and inorganic chemicals. The data cover reduced pressures from 0.005 to 0.783, mass flux from 28 to 11071 kg/m2s, vapor quality from 0 to 0.95, and boiling number from 0.000026 to 0.00742. The correlations of Shah and Gungor & Winterton gave the best agreement with data with a mean deviation of about 17.5%, only a couple of data sets showing large deviations. The paper presents and discusses the results of this study. Included are tables giving the range of dimensional and non-dimensional parameters covered by each experimental study.

Flow Behavior and Flow Boiling Heat Transfer in Thin-Rectangular Mini-Channels

2008 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Tomonari Yamada
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Pattern ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Annular Flow ◽  
Flow Channel ◽  
Heat Transfer Surface ◽  
Liquid Slug ◽  
Flux Condition

Boiling heat transfer of thin-rectangular channels of the width of 10 mm has been examined. The height of the flow channel was in a range from 0.6 mm to 0.4 mm. Experimental fluid was water. Bubbly flow, slug flow, semi annular flow and annular flow were observed. The flow pattern transition agreed well with the Baker flow pattern map for the usual sized flow path. The critical heat flux was lower than the value of the usual sized flow channel. The Koizumi and Ueda method predicted well the trend of the critical heat flux of the present experiments. At the critical heat flux condition, the heat transfer surface was covered by liquid slug, a large bubble pushed away the liquid slug, a dry area was formed on the heat transfer surface and then liquid slug came around to cover the heat transfer surface again. This process repeated rapidly. Following this observation, a heat transfer surface temperature calculation model at the critical heat flux condition was proposed. The calculated result re produced the experimental result.

Pool Boiling Characteristics of Heat Transfer Surface With Micro Structures Created by Using MEMS Technology

2010 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Takato Sato
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Small Diameter ◽  
Nucleate Boiling ◽  
Micro Electro Mechanical System ◽  
Heat Transfer Surface ◽  
Wall Superheat ◽  
Straight Line ◽  
Mems Technology ◽  
Cylindrical Cavities

Pool nucleate boiling heat transfer experiments were performed for water by using well-controlled and -defined heat transfer surfaces. The silicon wafers of 0.200 mm thickness were used as the heat transfer surfaces. Artificial-cylindrical cavities, micro-straight-line grooves or micro-crossing-straight-line grooves (square pillars) were created on the silicon plate by utilizing the Micro-Electro Mechanical System (MEMS) technology. In the case of the straight-line grooves and the crossing-straight-line grooves, the grooves were wetted after the heat transfer surface experienced subcooling. Once the grooves were wetted, only small diameter cavities which were formed during the MEMS processing at the bottom of the grooves functioned at the inception of boiling. Thus, a large overshooting of the wall superheat at the inception of boiling was observed. In this point, the micro grooves and micro pillars are not advantageous to cooling a body that periodically generates heat such as MPUs and electro devices. In the fully developed nucleate boiling region, the general trend was similar to that of the usual heat transfer surface. In the case of the artificial-cylindrical cavities, nuclei were well preserved in cavities even after the heat transfer surface experienced subcooling. Thus, no overshooting of the wall superheat at the inception of boiling was observed. As the number of the artificial-cylindrical cavities was increased, the wall superheat shifted to a low wall superheat side. The boiling heat transfer coefficient of the heat transfer surface that had the artificial-cylindrical cavities of the 1 mm pitch was better than that of a usual copper heat transfer surface. The artificial-cylindrical cavities are advantageous to get reliable and better cooling efficiency.

Film Boiling Heat Transfer From an Oscillating Sphere

1969 ◽  
Vol 91 (2) ◽  
pp. 267-271 ◽  
Author(s):  
L. G. Rhea ◽  
R. G. Nevins
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Correlation Equation ◽  
Heat Transfer Surface ◽  
Film Boiling ◽  
Maximum Deviation ◽  
Coated Surface ◽  
Good Agreement ◽  
Oscillating Sphere

An experimental investigation has been undertaken to determine the effect of oscillation of the heat transfer surface on turbulent film boiling heat transfer. A transient technique was used to calculate the heat flux from copper spheres of 1 in., 3/4 in., and 1/2 in. dia. In all tests, saturated liquid nitrogen at atmospheric pressure was used as the boiling fluid. The data obtained were found to be in good agreement with published theory at zero frequency. The range of frequencies studied was from zero to approximately 12 cps at peak-to-peak amplitudes of 2 in. and 1 in., i.e., at amplitude-to-diameter ratios of 1.00, 1.34, 2.00, 2.67, and 4.00. It was determined that oscillation of the heat transfer surface considerably increases the heat flux for a given temperature difference over that for natural convection film boiling. The results were correlated with a maximum deviation of +35, −17 percent. The correlation equation Nu=0.14gd3ρvf(ρl−ρvf)μvf2(Pr)vfhfgCpvfΔT+0.5ag+X2F2gd1/3 showed that the Nusselt number was proportional to the vibrational Fronde number to the 2/3 power. Tests were conducted with spheres having a corroded surface, a glass-bead-peened surface and a Teflon-coated surface. The results show that the turbulent film boiling from an oscillating sphere is independent of the condition of the heat transfer surface over the range of frequencies and amplitudes tested.

Study on Nucleate Boiling Heat Transfer by Measuring Detailed Surface Temperature Distribution and Variation With Infrared Radiation Camera

2014 ◽  
Author(s):  
Kazuki Takahashi ◽  
Yasuo Koizumi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Infrared Radiation ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Transfer Surface ◽  
Bubble Generation ◽  
Test Vessel

Pool boiling heat transfer experiments were performed for water at 101 kPa to examine elementary process of nucleate pool boiling. The heat transfer surface was made from a copper printed circuit board. The size of the heat transfer surface was 10 mm × 10 mm. Direct current was supplied to the heat transfer surface to heat it up. The Bakelite plate of the backside of the copper layer was taken off at the center portion of the heat transfer surface. The test vessel was a closed 200-mm cube container made of duralumin. It has transparent view windows on opposing side walls made of a Polycarbonate plate to observe a boiling state. Heat transfer surface was placed at the bottom of the test vessel. Distilled water was used for the experiments. The instantaneous variation of the backside temperature of the heat transfer surface was measured with an infrared radiation camera. Bubble behavior was recorded with a high speed video camera. The time and the space resolution of the infrared radiation cameras used in present experiments were 60 Hz and 0.1 mm × 0.1 mm, and 120 Hz and 0.315 mm × 0.315 mm, respectively. When the heat flux was increased, the instantaneous surface temperature variation explain the pattern. In the isolated bubble region, surface temperature was uniform during waiting time. When boiling bubble generation started, a large dip in the surface temperature was formed under the bubble. After the bubble left from the heat transfer surface, the surface temperature returned to former uniform temperature distribution. Surface temperature was not affected by the bubble generation beyond 1.8 mm from the center of the bubble. In the intermediate and high heat flux region, the variation of surface temperature and heat flux were small. Rather the heat flux variation range was close to that at the isolated boiling region.

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