Steam Condensation in a Vertical Passive Condenser

2006 ◽  
Author(s):  
Haijing Gao ◽  
Seungmin Oh ◽  
S. T. Revankar
Keyword(s):  
Heat Transfer ◽  
Heat Removal ◽  
Water Pool ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Comparison Result ◽  
Heat Transfer Coefficients ◽  
Removal Capacity ◽  
Test Conditions ◽  
Condensation Model

A set of steam condensation experiments is conducted to evaluate the heat removal capacity of a vertical passive condenser. A condensing tube is submerged in a water pool where condensation heat is transferred by secondary boiling heat transfer. Condensation heat transfer coefficients (HTC) are obtained under various test conditions, such as different primary pressure (150 - 450 kPa), inlet steam flow rate (1 - 5 g/s), air mass fraction (0 - 20%) and tube size (26.6 mm and 52.5 mm ID). The effects of these parameters to condensation performance are evaluated in this paper. Experimental data are compared with code predictions from RELAP5 with 2 condensation models. The comparison result shows that an improved condensation model is needed in RELAP5.

Experimental Study of Non-Condensable Effect on Passive Condenser System

2007 ◽  
Author(s):  
Wenzhong Zhou ◽  
Shripad T. Revankar
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Heat Removal ◽  
Scaling Analysis ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Specific Design ◽  
Heat Transfer Coefficients ◽  
Removal Capacity ◽  
Safety Systems

One of the engineered safety systems in the advanced boiling water reactor is a passive containment cooling system (PCCS) which is composed of a number of vertical heat exchanger. A set of steam condensation experiments is conducted to evaluate the heat removal capacity of a PCCS condenser. A condensing tube is submerged in a water pool where condensation heat is transferred by secondary boiling heat transfer. The specific design of condensing tube is based on scaling analysis from the PCCS design of ESBWR. The two condensing tubes have same height (0.9m) but different inside diameters, 26.6mm and 52.5mm, respectively. Condensation heat transfer coefficients (HTC) are obtained under various test conditions, such as different primary pressure (150 – 450 kPa), inlet steam flow rate (1 – 5 g/s), air mass fraction (0 – 20%) and tube size (26.6 mm and 52.5 mm ID). The effects of these parameters to condensation performance are evaluated.

scholarly journals Verification of Thermal Models of Internally Cooled Gas Turbine Blades

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Igor Shevchenko ◽  
Nikolay Rogalev ◽  
Andrey Rogalev ◽  
Andrey Vegera ◽  
Nikolay Bychkov
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Heat Removal ◽  
Leading Edge ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Transfer Coefficients ◽  
Single Experiment ◽  
Heat Transfer Coefficients

Numerical simulation of temperature field of cooled turbine blades is a required element of gas turbine engine design process. The verification is usually performed on the basis of results of test of full-size blade prototype on a gas-dynamic test bench. A method of calorimetric measurement in a molten metal thermostat for verification of a thermal model of cooled blade is proposed in this paper. The method allows obtaining local values of heat flux in each point of blade surface within a single experiment. The error of determination of local heat transfer coefficients using this method does not exceed 8% for blades with radial channels. An important feature of the method is that the heat load remains unchanged during the experiment and the blade outer surface temperature equals zinc melting point. The verification of thermal-hydraulic model of high-pressure turbine blade with cooling allowing asymmetrical heat removal from pressure and suction sides was carried out using the developed method. An analysis of heat transfer coefficients confirmed the high level of heat transfer in the leading edge, whose value is comparable with jet impingement heat transfer. The maximum of the heat transfer coefficients is shifted from the critical point of the leading edge to the pressure side.

Experimental and Numerical Investigation of Impingement on a Rib-Roughened Leading-Edge Wall

2003 ◽  
Vol 125 (4) ◽  
pp. 682-691 ◽  
Author(s):  
M. E. Taslim ◽  
K. Bakhtari ◽  
H. Liu
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Cross Flow ◽  
Heat Removal ◽  
Leading Edge ◽  
Target Surface ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Edge Surface ◽  
Rib Roughened

Effective cooling of the airfoil leading edge is imperative in gas turbine designs. Among several methods of cooling the leading edge, impingement cooling has been utilized in many modern designs. In this method, the cooling air enters the leading edge cavity from the adjacent cavity through a series of crossover holes on the partition wall between the two cavities. The crossover jets impinge on a smooth leading-edge wall and exit through the film holes, and, in some cases, form a cross flow in the leading-edge cavity and move toward the end of the cavity. It was the main objective of this investigation to measure the heat transfer coefficient on a smooth as well as rib-roughened leading-edge wall. Experimental data for impingement on a leading-edge surface roughened with different conical bumps and radial ribs have been reported by the same authors previously. This investigation, however, deals with impingement on different horseshoe ribs and makes a comparison between the experimental and numerical results. Three geometries representing the leading-edge cooling cavity of a modern gas turbine airfoil with crossover jets impinging on (1) a smooth wall, (2) a wall roughened with horseshoe ribs, and (3) a wall roughened with notched-horseshoe ribs were investigated. The tests were run for a range of flow arrangements and jet Reynolds numbers. The major conclusions of this study were: (a) Impingement on the smooth target surface produced the highest overall heat transfer coefficients followed by the notched-horseshoe and horseshoe geometries. (b) There is, however, a heat transfer enhancement benefit in roughening the target surface. Among the three target surface geometries, the notched-horseshoe ribs produced the highest heat removal from the target surface, which was attributed entirely to the area increase of the target surface. (c) CFD could be considered as a viable tool for the prediction of impingement heat transfer coefficients on an airfoil leading-edge wall.

An Empirical Correlation for Steam Condensing and Flowing Downward in a 50mm Diameter Inclined Tube

2013 ◽  
Vol 732-733 ◽  
pp. 67-73 ◽  
Author(s):  
Jian Guo Yang ◽  
Xiao Li Ju ◽  
Sheng Ye
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Characteristic ◽  
Horizontal Tube ◽  
Transfer Characteristic ◽  
Empirical Correlation ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Inclined Tube

The heat transfer characteristic of steam condensation in a 50mm diameter and 30° inclined tube was experimentally investigated. Based on the experiment and Akhavan-Behabadi correlation, a new correlation has been developed. It is shown that the heat transfer coefficients for the inclined tube are approximately 1.06-2.98 times higher than those for the horizontal tube. The heat transfer coefficients predicted by Shah correlation, Würfel correlation and Akhavan-Behabadi correlation deviate greatly, though Akhavan-Behabadi correlation is better. But by the developed correlation, more accurate heat transfer coefficients are predicted than Shah correlation, Würfel correlation and Akhavan-Behabadi correlation, and the deviation is less than 15%. The developed empirical correlation is a better one to predict heat transfer coefficients for steam condensation in larger diameter inclined tubes.

An Experimental Study of Impingement on Roughened Airfoil Leading-Edge Walls With Film Holes

2001 ◽  
Vol 123 (4) ◽  
pp. 766-773 ◽  
Author(s):  
M. E. Taslim ◽  
Y. Pan ◽  
S. D. Spring
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbines ◽  
Heat Removal ◽  
Leading Edge ◽  
Target Surface ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Impingement Heat Transfer

Airfoil leading-edge surfaces in state-of-the-art gas turbines, being exposed to very high gas temperatures, are often life-limiting locations and require complex cooling schemes for robust designs. A combination of convection and film cooling is used in conventional designs to maintain leading-edge metal temperatures at levels consistent with airfoil life requirements. Compatible with the external contour of the airfoil at the leading edge, the leading-edge cooling cavities often have complex cross-sectional shapes. Furthermore, to enhance the heat transfer coefficient in these cavities, they are often roughened on three walls with ribs of different geometries. The cooling flow for these geometries usually enters the cavity from the airfoil root and flows radially to the airfoil tip or, in the more advanced designs, enters the leading edge cavity from the adjacent cavity through a series of crossover holes in the wall separating the two cavities. In the latter case, the crossover jets impinge on a smooth leading-edge wall and exit through the showerhead film holes, gill film holes on the pressure and suction sides, and, in some cases, form a crossflow in the leading-edge cavity, which is ejected through the airfoil tip hole. The main objective of this investigation was to study the effects that film holes on the target surface have on the impingement heat transfer coefficient. Available data in the open literature are mostly for impingement on a flat smooth surface with no representation of the film holes. This investigation involved two new features used in airfoil leading-edge cooling, those being a curved and roughened target surface in conjunction with leading-edge row of film holes. Results of the crossover jets impinging on these leading-edge surface geometries with no film holes were reported by these authors previously. This paper reports experimental results of crossover jets impinging on those same geometries in the presence of film holes. The investigated surface geometries were smooth, roughened with large and small conical bumps as well as tapered radial ribs. A range of flow arrangements and jet Reynolds numbers were investigated, and the results were compared to those of the previous study where no film holes were present. It was concluded that the presence of leading-edge film holes along the leading edge enhances the internal impingement heat transfer coefficients significantly. The smaller conical bump geometry in this investigation produced impingement heat transfer coefficients up to 35 percent higher than those of the smooth target surface. When the contribution of the increased area in the overall heat transfer is taken into consideration, this same geometry for all flow cases as well as jet impingement distances Z/djet provides an increase in the heat removal from the target surface by as much as 95 percent when compared with the smooth target surface.

Experimental and Numerical Investigation of Impingement on a Rib-Roughened Leading-Edge Wall

2003 ◽  
Author(s):  
M. E. Taslim ◽  
K. Bakhtari ◽  
H. Liu
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Heat Removal ◽  
Leading Edge ◽  
Target Surface ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Impingement Heat Transfer ◽  
Edge Surface ◽  
Rib Roughened

Effective cooling of the airfoil leading-edge is imperative in gas turbine designs. Amongst several methods of cooling the leading edge, impingement cooling has been utilized in many modern designs. In this method, the cooling air enters the leading edge cavity from the adjacent cavity through a series of crossover holes on the partition wall between the two cavities. The crossover jets impinge on a smooth leading-edge wall and exit through the film holes, and, in some cases, form a crossflow in the leading-edge cavity and move toward the end of the cavity. It was the main objective of this investigation to measure the heat transfer coefficient on a smooth as well as rib-roughened leading-edge wall. Experimental data for impingement on a leading edge surface roughened with different conical bumps and radial ribs are reported by the same authors, previously. This investigation, however, deals with impingement on different horseshoe ribs and makes a comparison between the experimental and numerical results. Three geometries representing the leading-edge cooling cavity of a modern gas turbine airfoil with crossover jets impinging on 1) a smooth wall, 2) a wall roughened with horseshoe ribs, and 3) a wall roughened with notched-horseshoe ribs were investigated. The tests were run for a range of flow arrangements and jet Reynolds numbers. The major conclusions of this study were: a) Impingement on the smooth target surface produced the highest overall heat transfer coefficients followed by the notched-horseshoe and horseshoe geometries. b) There is, however, a heat transfer enhancement benefit in roughening the target surface. Amongst the three target surface geometries, the notched-horseshoe ribs produced the highest heat removal from the target surface which was attributed entirely to the area increase of the target surface. c) CFD could be considered as a viable tool for the prediction of impingement heat transfer coefficients on an airfoil leading-edge wall.

An Experimental Study of Impingement on Roughened Airfoil Leading-Edge Walls With Film Holes

2001 ◽  
Author(s):  
M. E. Taslim ◽  
Y. Pan ◽  
S. D. Spring
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbines ◽  
Heat Removal ◽  
Leading Edge ◽  
Target Surface ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Impingement Heat Transfer

Airfoil leading-edge surfaces in state-of-the-art gas turbines, being exposed to very high gas temperatures, are often life-limiting locations and require complex cooling schemes for robust designs. A combination of convection and film cooling is used in conventional designs to maintain leading-edge metal temperatures at levels consistent with airfoil life requirements. Compatible with the external contour of the airfoil at the leading edge, the leading-edge cooling cavities often have complex cross-sectional shapes. Furthermore, to enhance the heat transfer coefficient in these cavities, they are often roughened on three walls with ribs of different geometries. The cooling flow for these geometries usually enters the cavity from the airfoil root and flows radially to the airfoil tip or, in the more advanced designs, enters the leading edge cavity from the adjacent cavity through a series of crossover holes in the wall separating the two cavities. In the latter case, the crossover jets impinge on a smooth leading-edge wall and exit through the showerhead film holes, gill film holes on the pressure and suction sides, and, in some cases, forms a cross-flow in the leading-edge cavity and is ejected through the airfoil tip hole. The main objective of this investigation was to study the effects that film holes on the target surface have on the impingement heat transfer coefficient. Available data in the open literature are mostly for impingement on a flat smooth surface with no representation of the film holes. This investigation involved two new features used in airfoil leading-edge cooling those being a curved and roughened target surface in conjunction with leading-edge row of film holes. Results of the crossover jets impinging on these leading-edge surface geometries with no film holes were reported by these authors previously. This paper reports experimental results of crossover jets impinging on those same geometries in the presence of film holes. The investigated surface geometries were smooth, roughened with large and small conical bumps as well as tapered radial ribs. A range of flow arrangements and jet Reynolds numbers were investigated and the results were compared to those of the previous study were no film holes were present. It was concluded that the presence of leading-edge film holes along the leading edge enhances the internal impingement heat transfer coefficients significantly. The smaller conical bump geometry in this investigation produced impingement heat transfer coefficients up to 35% higher than those of the smooth target surface. When the contribution of the increased area in the overall heat transfer is taken into consideration, this same geometry for all flow cases as well as jet impingement distances (Z/djet) provides an increase in the heat removal from the target surface by as much as 95% when compared with the smooth target surface.

Microjet Impingement Cooling With Phase Change

2004 ◽  
Author(s):  
Evelyn N. Wang ◽  
Juan G. Santiago ◽  
Kenneth E. Goodson ◽  
Thomas W. Kenny
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Heated Surface ◽  
Heat Removal ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Impingement Cooling ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Wall Superheat

The large heat generation rates in contemporary microprocessors require new thermal management solutions. Two-phase microjet impingement cooling promises high heat transfer coefficients and effective cooling of hotspots. We have fabricated integrated microjet structures with heaters and temperature sensors to study local heat transfer at the impingement surface of a confined microjet. Circular jets with diameters less than 100 μm are machined in glass. Preliminary temperature measurements (for Rej = 100–500) suggest that heat transfer coefficients of 1000 W/m2C close to the jet stagnation zone can be achieved. As the flowrate of the jet is increased, a tradeoff in heat removal capability and wall superheat is observed. To aid in understanding the mechanism for wall superheat during boiling at the heated surface, the devices allow for optical access through the top of the device. However, the formation of vapor from the top reservoir makes visualization difficult. This study aids in the design of microjet heat sinks used for integration into a closed-loop cooling system.

Entrainment of Water Around a Single Rod Immersed in Water Pool with Gas Jet Impingement

2006 ◽  
Author(s):  
Kazuo Soga ◽  
Hideto Niikura ◽  
Ken-ichiro Sugiyama ◽  
Tadashi Narabayashi ◽  
Hiroyuki Ohshima ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Jet Impingement ◽  
Gas Jet ◽  
Water Pool ◽  
Transfer Coefficients ◽  
Heat Transfer Tube ◽  
Heat Transfer Coefficients ◽  
Transfer Tube ◽  
Ar Gas

In a steam generator of liquid sodium cooled fast breeder reactor, the occurrence of secondary heat transfer tube failure has been considered due to overheating in sodium-water reaction. A computer code SERAPHIM has been developed to analyze this kind of secondary heat transfer tube failure due to steam jet with heat generation and chemical reaction by Japan Atomic Energy Agency (JAEA). The detailed experimental data that verify the adequacy of SERAPHIM code and upgrade it, are now required. In ICONE13, the local and mean heat transfer coefficients around a horizontal heated rod (φ 15mm) immersed in a water pool and in a sodium pool with gas jet impingement without chemical reaction, were reported as the first step. It was confirmed in the water pool experiment that the local and mean heat transfer coefficients slowly increase with increasing the Ar jet velocity from 8.7m/s to 78m/s The local and mean Nusselt numbers almost keeps same values independent on the Ar gas velocity in the sodium pool experiment. From these results, we inferred that the ambient liquid is entrained inside and contributes to high heat transfer rates. A series of experiments that investigate the entrainment process of ambient liquid toward jet interior are carried out by using a laser-sheet visualization and a void meter in water pool in the present work. It was observed that the entrainment of water into Ar gas jet is constantly caused in two regions just above the nozzle and just below the single rod. In the region just above the nozzle, negative pressure causes the entrainment of water. In the region below the rod, the entrainment of water is caused because the preceding Ar gas jet is caught up by the succeeding gas jet. The basic behavior of Ar gas jet causing the entrainment of water was confirmed to be almost same over the Reynolds number range of Ar gas jet, 2.17×103 to 2.17×104, in the present study. In addition, the measurement of void fraction was performed to investigate the entrainment of water quantitatively and the behavior of local heat transfer coefficients around a single rod with gas jet impingement in water pool was made clear.

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