The Influence of Coriolis Force on Boiling Crisis and Heat Transfer in a Rotating Cryostat at High Overloads

1986 ◽  
Author(s):  
M. O. Lutset ◽  
Samson Semenovich Kutateladze
Keyword(s):  
Heat Transfer ◽  
Coriolis Force ◽  
Boiling Crisis ◽  
Rotating Cryostat

Heat Transfer Enhancement at Boiling Crisis in Straight and Spiral Tubes

2004 ◽  
Vol 11 (4) ◽  
pp. 283-290 ◽  
Author(s):  
Yu. A. Kuzma-Kichta ◽  
A. S. Komendantov ◽  
Yanhua Yang ◽  
B. Kuang ◽  
R. N. Bolshakov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Boiling Crisis

Effects of Rotation on Heat Transfer for a Single Row Jet Impingement Array With Crossflow

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Justin A. Lamont ◽  
Srinath V. Ekkad ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Rotation Number ◽  
Coriolis Force ◽  
Room Temperature ◽  
Turbine Blades ◽  
Target Surface ◽  
Channel Height ◽  
Potential Core ◽  
Single Row

The effects of the Coriolis force are investigated in rotating internal serpentine coolant channels in turbine blades. For complex flow in rotating channels, detailed measurements of the heat transfer over the channel surface will greatly enhance the blade designers’ ability to predict hot spots so coolant may be distributed more effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer in a rotating, radially outward channel with impingement jets. A simple case with a single row of constant pitch impinging jets with the crossflow effect is presented to demonstrate the novel liquid crystal technique and document the baseline effects for this type of geometry. The present study examines the differences in heat transfer distributions due to variations in jet Rotation number, Roj, and jet orifice-to-target surface distance (H/dj = 1,2, and 3). Colder air, below room temperature, is passed through a room temperature test section to cause a color change in the liquid crystals. This ensures that buoyancy is acting in a similar direction as in actual turbine blades where walls are hotter than the coolant fluid. Three parameters were controlled in the testing: jet coolant-to-wall temperature ratio, average jet Reynolds number, Rej, and average jet Rotation number, Roj. Results show, such as serpentine channels, the trailing side experiences an increase in heat transfer and the leading side experiences a decrease for all jet channel height-to-jet diameter ratios (H/dj). At a jet channel height-to-jet diameter ratio of 1, the crossflow from upstream spent jets greatly affects impingement heat transfer behavior in the channel. For H/dj = 2 and 3, the effects of the crossflow are not as prevalent as H/dj = 1: however, it still plays a detrimental role. The stationary case shows that heat transfer increases with higher H/dj values, so that H/dj = 3 has the highest results of the three examined. However, during rotation the H/dj = 2 case shows the highest heat transfer values for both the leading and trailing sides. The Coriolis force may have a considerable effect on the developing length of the potential core, affecting the resulting heat transfer on the target surface.

Heat Transfer in a Radially Rotating Square-Sectioned Duct With Two Opposite Walls Roughened by 45Deg Staggered Ribs at High Rotation Numbers

2006 ◽  
Vol 129 (2) ◽  
pp. 188-199 ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Jui-Hung Hung ◽  
Wen-Hsien Yeh
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Coriolis Force ◽  
Density Ratio ◽  
Inertial Force ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Test Channel ◽  
Rib Roughened

This paper describes an experimental study of heat transfer in a radially rotating square duct with two opposite walls roughened by 45deg staggered ribs. Air coolant flows radially outward in the test channel with experiments to be undertaken that match the actual engine conditions. Laboratory-scale heat transfer measurements along centerlines of two rib-roughened surfaces are performed with Reynolds number (Re), rotation number (Ro), and density ratio (Δρ∕ρ) in the ranges of 7500–15,000, 0–1.8, and 0.076–0.294. The experimental rig permits the heat transfer study with the rotation number considerably higher than those studied in other researches to date. The rotational influences on cooling performance of the rib-roughened channel due to Coriolis forces and rotating buoyancy are studied. A selection of experimental data illustrates the individual and interactive impacts of Re, Ro, and buoyancy number on local heat transfer. A number of experimental-based observations reveal that the Coriolis force and rotating buoyancy interact to modify heat transfer even if the rib induced secondary flows persist in the rotating channel. Local heat transfer ratios between rotating and static channels along the centerlines of stable and unstable rib-roughened surfaces with Ro varying from 0.1 to 1.8 are in the ranges of 0.6–1.6 and 1–2.2, respectively. Empirical correlations for periodic flow regions are developed to permit the evaluation of interactive and individual effects of ribflows, convective inertial force, Coriolis force, and rotating buoyancy on heat transfer.

New nanofluids, based on clay minerals, as promising heat carriers for energetics

Clay Minerals ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 255-269 ◽  
Author(s):  
Vasily Moraru
Keyword(s):  
Heat Transfer ◽  
Clay Minerals ◽  
Sudden Onset ◽  
Heater Surface ◽  
Enhancement Of Heat Transfer ◽  
Nanoparticle Deposition ◽  
Boiling Crisis ◽  
Transfer Parameters ◽  
Automated Installation ◽  
Heat Carriers

ABSTRACTIn an automated installation powered by direct current (DC), the boiling curves and heat-transfer-coefficient (HTC) dependencies on the superheat values (ΔT) under free convection conditions for the water nanodispersions of clay minerals – illite, montmorillonite, palygorskite and genetic mixtures of the latter two – were obtained. The effects of some factors on pool boiling heat transfer were also studied.A significant influence of the shape and anisotropy of nanoparticles (NPs) on the heat-transfer parameters of nanofluids (NFs) was detected. A significant critical heat flux (CHF) enhancement (up to 200–300%) at boiling of the nanofluids studied was established, which is due to nanoparticle deposition on the heater surface during nanofluid boiling. The structure of the nanomaterials deposited is important in the enhancement of heat transfer at boiling of nanofluids and in avoiding boiling crises.The present study showed the effectiveness of clay-mineral nanofluids for extra emergency cooling of overheated surfaces of powerful equipment in the event of the sudden onset of a boiling crisis.

Heat Transfer in a Radially Rotating Square-Sectioned Duct With Two Opposite Walls Roughened by 45° Staggered Ribs

2006 ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Wen-Hsien Yeh ◽  
Jui-Hung Hung
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Coriolis Force ◽  
Density Ratio ◽  
Inertial Force ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Test Channel ◽  
Rib Roughened

This paper describes an experimental study of heat transfer in a radially rotating square duct with two opposite walls roughened by 45° staggered ribs. Air coolant flows radially outward in the test channel with experiments to be undertaken that match the actual engine conditions. Laboratory-scale heat transfer measurements along centerlines of two rib-roughened surfaces are performed with Reynolds number (Re), rotation number (Ro) and density ratio (Δρ/ρ) in the ranges of 7500–15000, 0–1.8 and 0.076–0.294. The experimental rig permits the heat transfer study with the rotation number considerably higher than those studied in other researches to date. The rotational influences on cooling performance of the rib-roughened channel due to Coriolis forces and rotating buoyancy are studied. A selection of experimental data illustrates the individual and interactive impacts of Re, Ro and buoyancy number on local heat transfer. A number of experimental-based observations reveal that the Coriolis force and rotating buoyancy interact to modify heat transfer even if the rib induced secondary flows persist in the rotating channel. Local heat transfer ratios between rotating and static channels along the centerlines of stable and unstable rib-roughened surfaces with Ro varying from 0.1 to 1.8 are in the ranges of 0.6–1.6 and 1–2.2 respectively. Empirical correlations for periodic flow regions are developed to permit the evaluation of interactive and individual effects of rib-flows, convective inertial force, Coriolis force and rotating buoyancy on heat transfer.

Heat Transfer and Boiling Crisis at Droplets Evaporation of Ethanol Water Solution

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
S. Y. Misyura
Keyword(s):  
Heat Transfer ◽  
Water Solution ◽  
Nucleate Boiling ◽  
Droplet Surface ◽  
Alcohol Concentration ◽  
Ethanol Solution ◽  
Temperature Zone ◽  
Boiling Crisis ◽  
Leidenfrost Temperature ◽  
The Heat Transfer Coefficient

Droplets evaporation and boiling crisis of ethanol water solution were studied experimentally. At intensive nucleate boiling within a droplet, most evaporation relates to an increase in the area of the wetting droplet surface and only 10–20% of evaporation relates to the effect of diffusion and a change in the thermal–physical coefficients. In alcohol solution with mass salt concentration C0 = 25–35%, maximal instability of the bubble microlayer is observed. The critical heat flux behaves nonmonotonously due to changes in mass alcohol concentration in the solution, and there are two extrema. The maximal value of sustainability coefficient at droplets evaporation of ethanol solution corresponds to C0 of 25–30%. The heat transfer coefficient of ethanol water solution of droplet in the suspended state decreases with a rise of wall overheating and spheroid diameter. Experimental dependence of the vapor layer height on wall overheating at boiling crisis was observed. The height of this layer at Leidenfrost temperature was many times higher than the surface microroughness value. The liquid–vapor interface oscillates, and this extends the transitional temperature zone associated with a droplet's boiling crisis.

scholarly journals Наножидкости для энергетики: механизм влияния диспергентов на тепловые параметры и кризисные явления при кипении

2020 ◽  
Vol 90 (2) ◽  
pp. 175
Author(s):  
В.Н. Морару ◽  
Б.И. Бондаренко ◽  
С.В. Сидоренко ◽  
Д.В. Комыш
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Critical Heat Flux ◽  
Direct Current ◽  
Sedimentation Stability ◽  
Boiling Crisis ◽  
Transfer Parameters ◽  
The Heat Transfer Coefficient

Abstract: The effect of dispersants organic (CTAB) and inorganic nature (sodium pyrophosphate and sodium silicate) on the critical heat flux (CHF) and heat-transfer coefficient (HTC) of boiling various aqueous nanofluids (NFs) under conditions of free convection is studied. It has been established that the addition of ionic dispersants to aluminosilicate NFs, increasing their aggregative and sedimentation stability, as a rule, worsens their heat-transfer parameters during boiling, causing a sudden pre-crisis heater burnout in a test unit powered by direct current. The mechanism of the phenomenon is revealed. On the contrary, the addition of dispersants and surfactants to carbon-containing NFs with high thermal conductivity, improving their stability, at the same time increases the heat transfer coefficient during boiling of NFs, but also cause pre-crisis heater burnout in the case of direct current heating. The effect of dispersants on crisis phenomena during boiling of water and NFs is analyzed and the causes of sudden pre-crisis heater burnout have been elucidated. Several mechanisms have been proposed for interpreting the observed effects, from which the expediency of using alternating heating current and non-ionic, non-foaming surfactants and dispersants to avoid an early onset of the boiling crisis in order to achieve higher values of the critical heat flux and the heat transfer coefficient during the NFs boiling.

Multi-Pass Serpentine Cooling Designs for Negating Coriolis Force Effect on Heat Transfer: 45-Degree Angled Rib Turbulated Channels

2018 ◽  
Author(s):  
Prashant Singh ◽  
Yongbin Ji ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Coriolis Force ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
Steady State Condition ◽  
Uniform Heat ◽  
Wide Range ◽  
Serpentine Passages ◽  
Rib Roughened

Traditional gas turbine blades are equipped with serpentine passages arranged along the height, wherein the coolant flows radially outward in 1st passage and radially inward in 2nd passage. Prior experimental studies have established that for traditional two-pass rib roughened ducts, under the influence of Coriolis and centrifugal forces, the heat transfer gets enhanced on trailing side for radially outward flow and gets reduced on the leading side for a radially outward flow. A reverse trend in heat transfer is observed for radially inward flow. Rotation induced forces result in non-uniform heat transfer coefficient distribution which results in non-uniform metal temperatures under steady state condition. Present study addresses the problem of non-uniform heat transfer distribution on leading and trailing sides due to rotation effect. Experimental investigation of two configurations has been carried out, where Coriolis effect was negated by aligning the coolant flow vector and rotation vector such that their cross product was effectively a null vector. Novel multi-passage serpentine ducts featuring 45-degree angled rib turbulators with four-passage and six-passage configurations have been studied. Transient liquid crystal thermography experiments were carried out under stationary and rotating conditions. Heat transfer experiments were carried out for Reynolds numbers ranging from 12000 to 80000 under stationary conditions and rotating heat transfer experiments were carried out at two Rotation numbers of 0.05 and 0.11. We found that the heat transfer characteristics of serpentine passages were not influenced by Coriolis force after the 2nd passage. The local heat transfer distribution on leading and trailing sides of serpentine passages were near-similar to each other and comparable with corresponding stationary cases. The contribution of multiple passages connected with 180-degree bends towards overall frictional losses has been evaluated in terms of pumping power and normalized friction factor. The configurations are ranked based on their thermal hydraulic performances over a wide range of Reynolds numbers. The heat transfer enhancement levels of four-passage rib roughened duct was higher than the six-passage configuration and the six-passage configuration had slightly higher thermal hydraulic performance compared to four-passage configuration.

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