Study on the Heat Transfer in the Water Pool Type Reactor Cavity Cooling System of the Very High Temperature Gas Cooled Reactor

2005 ◽  
Author(s):  
H. K. Cho ◽  
D. U. Seo ◽  
M. O. Kim ◽  
G. C. Park
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Cooling System ◽  
Reactor Vessel ◽  
Water Pool ◽  
Cooling Pipe ◽  
Cavity Cooling ◽  
The Heat Transfer Coefficient ◽  
Pool Type ◽  
High Temperature Gas

In the HTGR (High Temperature Gas Cooled Reactor), the Reactor Cavity Cooling System (RCCS) is equipped to remove the heat transferred from the reactor vessel to the structure of the containment. The function of the RCCS is to dissipate the heat from the reactor cavity during normal operation including shutdown. The system also removes the decay heat during the loss of forced convection (LOFC) accident. A new concept of the water pool type RCCS was proposed at Seoul National University. The system mainly consists of two parts, water pool located between the containment and reactor vessel and five trains of air cooling system installed in the water pool. In normal operations, the heat loss from the reactor vessel is transferred into the water pool via cavity and it is removed by the forced convection of air flowing through the cooling pipes. During the LOFC accident, the after heat is passively removed by the water tank without the forced convection of air and the RCCS water pool is designed to provide sufficient passive cooling capacity of the after heat removal for three days. In the present study, experiments and numerical calculations using CFX5.7 for the water pool and cooling pipe were performed to investigate the heat transfer characteristics and evaluate the heat transfer coefficient model of the MARS-GCR (Multi-dimensional Analysis of Reactor Safety for Gas Cooled Reactor Analysis) which was developed for the safety analysis of the gas cooled reactor. From the results of the experiments and CFX calculations, heat transfer coefficients inside the cooling pipe were calculated and those were used for the assessment for the heat transfer coefficient model of the MARS-GCR.

Experiments on a Water Pool-Type Reactor Cavity Cooling System in a High-Temperature Gas-Cooled Reactor

2007 ◽  
Vol 159 (1) ◽  
pp. 39-58 ◽  
Author(s):  
Hyoung Kyu Cho ◽  
Yun Je Cho ◽  
Moon Oh Kim ◽  
Goon Cherl Park
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Water Pool ◽  
Type Reactor ◽  
Cavity Cooling ◽  
Pool Type ◽  
High Temperature Gas

Simulation of the Operation in Passive Mode of Reactor Cavity Cooling System of High-Temperature Gas-Cooled Reactor

2008 ◽  
Author(s):  
Alex Matev
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Fission Products ◽  
Computer Code ◽  
Reactor Vessel ◽  
Passive Mode ◽  
Axial Distribution ◽  
Air Ingress ◽  
Cavity Cooling ◽  
High Temperature Gas

The Reactor Cavity Cooling System (RCCS) of a High-Temperature Gas-Cooled Reactor (HTGR) may be required to operate in a “passive” mode when heat is removed from the reactor cavity by letting RCCS water inventory to boil off to atmosphere. Overheating of the reactor cavity concrete walls may lead to a failure of the reactor vessel support structures and its shift off the design position. Dislocation of the massive reactor vessel may cause multiple ruptures of pipes, connected to both the upper and lower vessel heads. Such breaks of the reactor pressure boundary will enable air ingress into the core, fuel oxidation and overheating, and possible release of fission products into the environment. The computer code TINTE [3] was used to simulate a “Depressurized Loss Of Flow Circulation (DLOFC) Without Reactor Scram” accident and determine from its results the magnitude, axial distribution, and time dependence of the heat flux on the RCCS cooling panels. The computer code RELAP [4] was used to model the operation in “passive” mode of one RCCS train, consisting of a tank and four standpipes. This paper describes the application of both RELAP and TINTE for the simulation of RCCS operation in passive mode. The main conclusion from this analysis is that the proposed way of using both codes is suitable to perform scoping studies and design evaluation of RCCS of a pebble-bed HTGR.

Finned Metal Foam Heat Sinks for Electronics Cooling in Forced Convection

2002 ◽  
Vol 124 (3) ◽  
pp. 155-163 ◽  
Author(s):  
A. Bhattacharya ◽  
R. L. Mahajan
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Metal Foam ◽  
Experimental Results ◽  
Heat Sinks ◽  
The Heat Transfer Coefficient

In this paper, we present recent experimental results on forced convective heat transfer in novel finned metal foam heat sinks. Experiments were conducted on aluminum foams of 90 percent porosity and pore size corresponding to 5 PPI (200 PPM) and 20 PPI (800 PPM) with one, two, four and six fins, where PPI (PPM) stands for pores per inch (pores per meter) and is a measure of the pore density of the porous medium. All of these heat sinks were fabricated in-house. The forced convection results show that heat transfer is significantly enhanced when fins are incorporated in metal foam. The heat transfer coefficient increases with increase in the number of fins until adding more fins retards heat transfer due to interference of thermal boundary layers. For the 20 PPI samples, this maximum was reached for four fins. For the 5 PPI heat sinks, the trends were found to be similar to those for the 20 PPI heat sinks. However, due to larger pore sizes, the pressure drop encountered is much lower at a particular air velocity. As a result, for a given pressure drop, the heat transfer coefficient is higher compared to the 20 PPI heat sink. For example, at a Δp of 105 Pa, the heat transfer coefficients were found to be 1169W/m2-K and 995W/m2-K for the 5 PPI and 20 PPI 4-finned heat sinks, respectively. The finned metal foam heat sinks outperform the longitudinal finned and normal metal foam heat sinks by a factor between 1.5 and 2, respectively. Finally, an analytical expression is formulated based on flow through an open channel and incorporating the effects of thermal dispersion and interfacial heat transfer between the solid and fluid phases of the porous medium. The agreement of the proposed relation with the experimental results is promising.

Applied Pulsed Flow for Single-Phase Convective Heat Transfer Enhancement in a Laminar Flow Cooling System

2008 ◽  
Author(s):  
Bolaji O. Olayiwola ◽  
Gerhard Schaldach ◽  
Peter Walzel
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Cooling System ◽  
Transfer Enhancement ◽  
Flow Rates ◽  
The Heat Transfer Coefficient

Experimental and CFD studies were performed to investigate the enhancement of convective heat transfer in a laminar cooling system using flow pulsation in a flat channel with series of regular spaced fins. Glycerol-water mixtures with dynamic viscosities in the range of 0.001 kg/ms–0.01 kg/ms were used. A steady flow Reynolds number in the laminar range of 10 < Re < 1200 was studied. The amplitudes of the applied pulsations are in the range of 0.25 < A < 0.55 mm and the frequency range is 10 < f < 60 Hz. Two different cooling devices with active length L = 450 mm and 900 mm were investigated. CFD simulations were performed on a parallel-computer (Linux-cluster) using the software suit CFX11 from ANSYS GmbH, Germany. The rate of cooling was found to be significant at moderate low net flow rates. In general, no significant heat transfer enhancement at very low and high flow rates was obtained in compliance with the experimental data. The heat transfer coefficient was found to increase with increasing Prandtl number Pr at constant oscillation Reynolds number Reosc whereas the ratio of the hydraulic diameter to the length of the channel dh/L has insignificant effect on the heat transfer coefficient. This is due to enhanced fluid mixing. CFD results allow for performance predictions of different geometries and flow conditions.

Determination of the Thermal Conductivity of Metal-Polymers

2019 ◽  
Vol 973 ◽  
pp. 9-14 ◽  
Author(s):  
Mikhail S. Chepchurov ◽  
Nikolay S. Lubimyi ◽  
Vladimir P. Voronenko ◽  
Daniel R. Adeniyi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Injection Molding ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Using Data ◽  
Measuring Tool ◽  
The Heat Transfer Coefficient

The use of metal-polymers in the manufacture of mold-forming parts allows for the significant reduction in price and time used in manufacturing of parts. Using data on the thermal conductivity of metal-polymers in calculations of the cooling system of molds allows calculating the optimal cycle of obtaining the product. The authors propose a method of determining the coefficient of heat transfer of metal-polymers based on a die matrix, filled with aluminum. The chosen equipment or measuring tool by them, allows determining the heat transfer coefficient of the material in use. The values of the coefficient of heat transfer of the material in question, obtained in the course of the research can be use in different databases of applications used for modeling production by injection molding. The described method of determining the coefficient of heat transfer may be repeated for samples of metal-polymers.

Effects of Aging on the Thermal Conductivity of the AP1000® Containment Vessel Inorganic Zinc Coating

2014 ◽  
Author(s):  
Thomas A. Kindred ◽  
Richard F. Wright
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Cooling System ◽  
Mechanistic Model ◽  
Zinc Coating ◽  
High Energy ◽  
Reactor Vessel ◽  
Transfer Coefficients ◽  
Water Storage Tank ◽  
Containment Vessel

During a loss-of-coolant accident (LOCA) event the AP1000® passive safety features actuate to provide emergency core cooling (ECC) to the reactor core using passive features that do not rely on electrical power being available. The core makeup tanks (CMTs), and accumulators (ACCs) actuate to quench the fuel rods and refill the reactor vessel. After the CMTs and ACCs empty, the in-containment refueling water storage tank (IRWST) utilizing gravity injects a large volume of sub-cooled fluid into the reactor vessel. This floods the vessel and the lower region of containment (containment sump) initiating gravity induced long-term recirculation cooling. The discharge of high energy fluid during the blowdown, re-flood, and re-fill phases is assumed to condense on the colder structures inside the containment including the containment vessel shell. Heat is transferred through the shell to the film of water from the Passive Containment Cooling System (PCS) applied to the outside of the containment vessel shell. This results in evaporative heat transfer on the outside of the containment vessel. Due to the large heat transfer coefficients on the inside and outside of the shell the heat conduction through the shell is very important to the heat rejection capability of the PCS, and plays a large part in ensuring the containment vessel pressure is not exceeded during design basis events. The AP1000® containment vessel is forged from a high strength carbon steel alloy that is coated with an inorganic zinc coating which protects the containment vessel from corrosion during its design life. The coating acts as a sacrificial anodic layer which corrodes in lieu of corrosion of the substrate beneath it. The corrosion of the coating can potentially lead to degradation in thermal conductivity of the coating due to metallic oxides typically having a lower thermal conductivity than that of the non-oxidized state. A reduction in thermal conductivity of the protective coating will impact the overall heat transfer through the containment vessel during PCS operation. The purpose of this work is to develop a mechanistic model demonstrated against empirical validation for assessing the effects of oxidation on the thermal conductivity of the protective inorganic zinc coating (IOZ) on the AP1000® containment vessel.

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