Heat Transfer and Fluid Flow Characteristic of One Side Heated Vertical Rectangular Channel That Inserted Thin Metallic Wire

2020 ◽  
Author(s):  
Gota Suga ◽  
Tetsuaki Takeda
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
High Temperature ◽  
Natural Convection ◽  
Cooling System ◽  
Copper Wire ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Experimental Apparatus ◽  
High Temperature Reactor

Abstract A Very High Temperature Reactor (VHTR) is one of the next generation nuclear systems. From a view point of safety characteristics, a passive cooling system should be designed as the best way of a reactor vessel cooling system (VCS) in the VHTR. Therefore, the gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. Japan Atomic Energy Agency (JAEA) is advancing the technology development of the VHTR and is now pursuing design and development of commercial systems such as the 300MWe gas turbine high temperature reactor GTHTR300C (Gas Turbine High Temperature Reactor 300 for Cogeneration). In the VCS of the GTHTR300C, many rectangular flow channels are formed around the reactor pressure vessel (RPV), and a cooling panel utilizing natural convection of air has been proposed. In order to apply the proposed panel to the VCS of the GTHTR300C, it is necessary to clarify the heat transfer and flow characteristics of the proposed channel in the cooling panel. Thus, we carried out an experiment to investigate heat transfer and fluid flow characteristics by natural convection in a vertical rectangular channel heated on one side. Experiments were also carried out to investigate the heat transfer and fluid flow characteristics by natural convection when a porous material with high porosity is inserted into the channel. An experimental apparatus is a vertical rectangular flow channel with a square cross section in which one surface is heated by a rubber heater. Dimensions of the experimental apparatus is 600 mm in height and 50 mm on one side of the square cross section. Air was used as a working fluid and fine copper wire (diameter: 0.5 mm) was used as a porous material. The temperature of the wall surface and gas in the channel were measured by K type thermocouples. We measured the outlet flow rate by hot-wire anemometer which is an omnidirectional spherical probe of diameter 2.5mm. The experiment has been carried out under the condition that a copper wire with a scourer model and a cubic lattice model were inserting into the channel.

Heat Transfer and Fluid Flow Characteristics of One Side Heated Vertical Rectangular Channel Applied As Vessel Cooling System of VHTR

2018 ◽  
Author(s):  
Kenta Fujikami ◽  
Tetsuaki Takeda ◽  
Shumpei Funatani
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
High Temperature ◽  
Natural Convection ◽  
Porous Material ◽  
Cooling System ◽  
Flow Characteristics ◽  
High Porosity ◽  
High Temperature Reactor ◽  
Fluid Flow Characteristics

A Very High Temperature Reactor (VHTR) is one of the next generation nuclear reactor systems. From a view point of safety characteristics, a passive cooling system should be designed as the best way of a reactor vessel cooling system (VCS) in the VHTR. Therefore, the gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. Japan Atomic Energy Agency (JAEA) is advancing the technology development of the VHTR and is now pursuing design and development of commercial systems such as the 300MWe gas turbine high temperature reactor GTHTR300C (Gas Turbine High Temperature Reactor 300 for Cogeneration). In the VCS of the GTHTR300C, many rectangular flow channels are formed around the reactor pressure vessel (RPV), and a cooling panel utilizing natural convection of air has been proposed. In order to apply the proposed panel to the VCS of the GTHTR300C, it is necessary to clarify the heat transfer and flow characteristics of the proposed channel in the cooling panel. Thus, we carried out an experiment to investigate heat transfer and fluid flow characteristics by natural convection in a vertical rectangular channel heated on one side. Experiments were also carried out to investigate the heat transfer and fluid flow characteristics by natural convection when a porous material with high porosity is inserted into the channel. An experimental apparatus is a vertical rectangular flow channel with a square cross section in which one surface is heated by a rubber heater. Dimensions of the experimental apparatus is 600 mm in height and 50 mm on one side of the square cross section. Air was used as a working fluid and fine copper wire (diameter: 0.5 mm) was used as a porous material. The temperature of the wall surface and gas in the channel were measured by K type thermocouples. The flow velocity distribution was obtained by a PIV method. In this paper, we discuss the heat transfer and fluid flow characteristics of the proposed channel. From the results obtained in the experiment, it was found that the amount of removed heat decreased with increasing of temperature of gas when a copper wire was inserted into the channel with high porosity. This is because the mass flow rate decreased with increasing of viscosity of gas. Since it is expected that the porosity of a porous material will have an optimum value, further studies will be needed.

Heat Transfer and Fluid Flow Characteristic of U-Shaped Flow Channel for Applications of VHTR

2021 ◽  
Author(s):  
Yasuaki Takayama ◽  
Tetsuaki Takeda
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
High Temperature ◽  
Natural Convection ◽  
Pressure Vessel ◽  
Cooling System ◽  
Flow Channel ◽  
Working Fluid ◽  
Experimental Apparatus ◽  
High Temperature Reactor

Abstract A very high-temperature reactor (VHTR) is a next-generation nuclear reactor systems. A gas cooling system with natural circulation is considered as a candidate for the pressure vessel cooling system (VCS) of the VHTR. The Japan Atomic Energy Agency is pursuing the design and development of commercial systems such as the 300 MWe gas turbine high-temperature reactor 300 for cogeneration (GTHTR300C). In the VCS of the GTHTR300C, many rectangular flow channels are formed around the reactor pressure vessel (RPV). A cooling panel utilizing the natural convection of air has been proposed. However, the amount of removed heat is inferior to that of cooling by forced convection. In this study, we use an experimental apparatus to simulate the cooling panel of a VCS. The experimental apparatus is a U-shaped flow channel, and the heating surface side is a vertical rectangular flow channel. Air is used as the working fluid. A fine copper wire is used as the porous material. The porosity is varied from 0.996 to 0.999. We perform an experiment to investigate the heat transfer and fluid flow characteristics by natural convection in a vertical rectangular channel heated on one side. Additionally, we perform an experiment on a smooth surface for comparison.

Heat Transfer Characteristics of One Side Heated Vertical Rectangular Channel Inserting Porous Material

2012 ◽  
Author(s):  
Tetsuaki Takeda ◽  
Akihiro Sato ◽  
Shumpei Funatani
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Porous Material ◽  
Cooling System ◽  
Copper Wire ◽  
Rectangular Channel ◽  
Vertical Channel ◽  
High Porosity ◽  
The One ◽  
Passive Cooling System

The objective of this study is to not only investigate heat transfer characteristics of natural convection of a one-side heated vertical channel inserting the porous materials with high porosity but also develop the passive cooling system for the Very-High-Temperature Reactor (VHTR). An experiment and analysis was carried out using the one-side heated vertical rectangular channel. From the results obtained in the experiment and analysis, it was found that an amount of removed heat by forced convection using the copper wire (porosity>0.996) was about 15% higher than that without the wire. It was also found that the amount of transferred heat from the heated wall will be increased even if the heat removed by natural convection. Furthermore, the ratio between the amounts of heat removed of the rectangular channel with the porous material and without the porous material increases with increasing temperature of the channel wall. In order to obtain the heat transfer and fluid flow characteristics of the vertical channel inserting porous material, we have also carried out a numerical analysis using a commercial CFD code. This paper describes thermal performances of the one-side heated vertical rectangular channel inserting copper wire with high porosity. From a view point of economical and safety characteristics, the passive cooling system should be designed for the VHTR as the best way of the system. Therefore, the gas cooling system by natural convection is the one of candidate system.

Mixing Process of Two Component Gases by Natural Convection and Molecular Diffusion

2021 ◽  
Author(s):  
Takeaki Ube ◽  
Tetsuaki Takeda
Keyword(s):  
High Temperature ◽  
Natural Convection ◽  
Molecular Diffusion ◽  
Natural Circulation ◽  
Mixing Process ◽  
Circulation Flow ◽  
Experimental Apparatus ◽  
Two Component ◽  
High Temperature Reactor ◽  
Air Ingress

Abstract A depressurization accident involving the rupture of the primary cooling pipe of the Gas Turbine High Temperature Reactor 300 cogeneration (GTHTR300C), which is a very-high-temperature reactor, is a design-based accident. When the primary pipe connected horizontally to the side of the reactor pressure vessel of GTHTR300C ruptures, molecular diffusion and local natural convection facilitate gas mixing, in addition to air ingress by counter flow. Furthermore, it is expected that a natural circulation flow around the furnace will suddenly occur. To improve the safety of GTHTR300C, an experiment was conducted using an experimental apparatus simulating the flow path configuration of GTHTR300C to investigate the mixing process of a two-component gas of helium and air. The experimental apparatus consisted of a coaxial double cylinder and a coaxial horizontal double pipe. Ball valves were connected to a horizontal inner pipe and outer pipe, and the valves were opened to simulate damage to the main pipe. As a result, it was confirmed that a stable air and helium density stratification formed in the experimental apparatus, and then a natural circulation flow was generated around the inside of the reactor.

Fluid flow and heat transfer of natural convection accompanied with reverse flow in a vertical rectangular channel.

2004 ◽  
Vol 2004 (0) ◽  
pp. 89-90
Author(s):  
Satoshi ANMA ◽  
Isao ISHIHARA ◽  
Ryosuke MATSUMOTO ◽  
Tomomasa UEMURA ◽  
Yasuhumi YAMAMOTO
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Reverse Flow ◽  
Rectangular Channel ◽  
Flow And Heat Transfer

Heat Transfer and Fluid Flow Characteristics of One Side Heated Vertical Rectangular Channel Inserting Porous Material

2016 ◽  
Author(s):  
Takumi Shigematsu ◽  
Tetsuaki Takeda ◽  
Shumpei Funatani
Keyword(s):  
Heat Transfer ◽  
Porous Material ◽  
Cooling System ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Vertical Channel ◽  
Passive Cooling ◽  
Fluid Flow Characteristics ◽  
Passive Cooling System

The Very High Temperature Reactor (VHTR) is a next generation nuclear reactor system. The passive cooling system should be designed for the VHTR as the best way of reactor vessel cooling system (VCS). Therefore, the gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. Furthermore, we examined the heat transfer of rectangular vertical channel using “Spandrel” panel. “Spandrel” is the metallic plate having grooved patterns. The reason is that we can set it at low cost to the VCS because it is a kind of general construction materials. The objective of this study is to examine heat transfer characteristics of one side heated vertical rectangular channel with natural circulation and application of spandrel panel to the VCS of VHTR in order to construct the passive cooling system of the VHTR. We have performed an experiment and a numerical analysis. On experiment, we set the panel to adiabatic wall and supplied 100–400W/m2 heat flux to the panel. In order to obtain the heat transfer and fluid flow characteristics of a vertical channel inserting porous material, we have also carried out a numerical analysis using the commercial CFD code as the first step. From the results obtained in the analysis, it was found that the amount of heat removal was increased for 1–21% by inserting copper wires as porous material. This paper describes a thermal performance of the one-side heated vertical rectangular channel inserting copper wire with high porosity. From the view point of the economical and safety characteristic, the passive cooling system should be designed for the VTHR as the best way of the system. So, the gas cooling system by natural convection is the one of candidate system.

Effects of Upstream Geometry on Natural Convection of a Darcian Fluid About a Semi-Infinite Inclined Heated Surface

1985 ◽  
Vol 107 (2) ◽  
pp. 283-292 ◽  
Author(s):  
C. T. Hsu ◽  
P. Cheng
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Heated Surface ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Fluid Flow Characteristics ◽  
Inclined Surface

The method of matched asymptotic expansions is applied to the problem of steady natural convection of a Darcian fluid about a semi-infinite inclined heated surface with a power law variation of wall temperature, i.e., Tˆwaxˆλ for xˆ≥0 where 0≤λ<1. The leading edge of the inclined surface intercepts at an angle, Λ0, with another impermeable unheated surface extending upstream. The effects of the inclination angle α0 (0 ≤ α0 < < π/2) of the heated surface as well as the upstream geometry at xˆ<0 (as specified by Λ0) on heat transfer and fluid flow characteristics near the heated surface are investigated. At a given inclination angle α0, it is found that heat transfer from an upward-facing heated inclined surface is larger than that of a downward-facing heated surface, and that decreasing the intercepting angle (Λ0) tends to lower the heat transfer rate. These effects become increasingly pronounced as the Rayleigh number is decreased.

Sign in / Sign up

Export Citation Format

Share Document