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JAERI-Research95-056

JAERI-Research—95-056

JP9511193

BENCHMARK PROBLEMFOR IAEA COORDINATED RESEARCH PROGRAM (CRP-3)

ON GCRAFTERHEAT REMOVAL (I)

August 1995

Shoji TAKADA, Yasuaki SHIINA, Yoshiyuki INAGAKIMakoto HISHIDA and Yukio SUDO

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This report is issued irregularly.

Inquir ies about avai labi l i ty of the reports should be addressed to Informat ion Division.

Department of Technical Information, Japan Atomic Energy Research Ins t i tu te , Tokai-

mura, Naka-gun, Iburaki-ken 3 I 9 - 1 I , Japan.

©Japan Atomic Energy Research Institute, 1995

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JAERI-Research 95-056

Benchmark Problem

for IAEA Coordinated Research Program (CRP-3)

on GCR Afterheat Removal( I )

Shoji TAKADA, Yasuaki SHIINA, Yoshiyuki INAGAKI

Makoto HISHIDA and Yukio SUDO

Department of High Temperature Engineering

Tokai Research Establishment

Japan Atomic Energy Research Institute

Tokai-mura, Naka-gun, Ibaraki-ken

(Received July 26, 1995)

In this report, detailed data which arc necessary for the benchmark analysis

of International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP-

3) on "Heat Transport and Afterheat Removal for Gas-cooled Reactors under

Accident Conditions" are described concerning about the configuration and sizes

of the cooling panel test apparatus, experimental data and thermal properties.

The test section of the test apparatus is composed of pressure vessel (max.

450°C) containing an electric heater (max. 100kW, 600°C)and cooling panels

surrounding the pressure vessel. Gas pressure is varied from vacuum to I.OMPa

in the pressure vessel.

Two experimental cases are selected as benchmark problems about afterheat

removal of HTGR, described as follows,

The experimental conditions are vacuum inside the pressure vessel and heater

output 13.14kW, and helium gas pressure 0.73MPa inside the pressure vessel and

heater output 28.79kW. Benchmark problems are to calculate temperature

distrbutions on the outer surface of pressure vessel and heat transferred to the

cooling panel using the experimental data.

The analytical result of temperature distribution on the pressure vessel was

estimated +38°C, -29 °C compared with the experimental data, and analytical

result of heat transferred from the surface of pressure vessel to the cooling

panel was estimated max. -11.U5& compared with the experimental result by using

i

JAERI- Research 95-056

the computational code -THANPACST2- of JAERI.

Keywords: IAEA, Benchmark Problem, Afterheat Removal, HTGR, Passive Cooling

System, Heat Transfer, Radiation, Natural Convection, Accident,

Reactor Cavity Cooling System, Coolling Panel System, Surface

Cooler System

JAER1- Research 95-056

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600°C,

( In te rna t iona l Atomic Energy Agency : IAEA)©i§&#;*fr'¥iSfel${:::fctf 3

Research Program : CRP-SKjE

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Contents

1. Introduction 1

2. Experimental Apparatus 3

2.1 Test Apparatus of Cooling Panel System 3

2.2 Thermophysical Properties 5

3. Benchmark Problem 6

3.1 Experimental Data 6

3.1.1 Vacuum Condition 6

3.1.2 Helium Gas Condition 7

3.2 Benchmark Problems 7

4. Analytical Method 8

4.1 Computational Code 8

4.2 Analytical Model 8

4.3 Analytical Conditions 10

5. Comparison between Experimental and Analytical Results 11

5.1 Benchmark Problem (1) 11

5.1.1 Vacuum Condition inside the Pressure Vessel 11

5.1.2 Helium Gas Condition inside the Pressure Vessel ----' 11

5.2 Benchmark Problem (2) 12

6. Conclusion 13

Acknowledgement 14

Reference 14

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1.

5.

6.

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35

6

6

6

7

7

1011

11

11

11

12

13

14

14

VI

JAEH1-Research 95-056

1. INTRODUCTION

International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on "Heat

Transport and Afterheat Removal for Gas-cooled Reactors under Accident Conditions" started at

November, 1993. In this program, benchmark tasks were proposed for the analysis of passive afterheat

removal from gas-cooled reactors (OCR) under accident conditions.

Specific objective of the benchmark program is to capture the essential heat transfer features of

reactor-to-reactor vessel cooling system (VCS) and provide useful information applicable to a wide variety

of designs, operating conditions and model parameters. The exercise would result in partial validation and

verification of the analytical tools used for OCR applications. Sensitivity studies would be used to determine

the relative importance of selected design features and to investigate the effects of changing various

modeling options and parameters.

The comparisons of various analytical techniques and approximation methods with each other and

with the experimental data should prove to be useful. Hence, verification and validation (V&V) of both

the VCS design features and the analytical methods used to predict behavior should be derivable from the

fact that an international variety of analytical approaches used by the participants and that the corroborating

experimental data are in agreement.

Other objectives should include: 1) evidence of the advantages of some design choices over others;

and 2) indications of how the reactor vessel and VCS can be monitored during normal operation so that

problems potentially affecting performance during an accident condition can be detected.

Specific benefits expected through the exercises of this program are described as follows,

(1) Determination of the relative accuracy and cost effectiveness of using 1- or 2- vs 3-dimensional analysis

for various aspects and conditions of the accident scenarios (for radiant and convective heat transfer). The

combination of the analytical and experimental validation exercises should help to determine the degree

of complexity required to analyze passive decay heat removal phenomena with a given accuracy.

(2) Accuracy, applicability, and importance of candidate correlations for various elements of the analysis.

(Example: the correlation for convective heat transfer in the reactor vessel-to-VCS cavity for various vessel

and VCS temperature distribution scenarios.)

(3) Predictability of VCS heat rejection, vessel temperature distributions, hot spots for VCS asymmetries,

and performance degradation (e.g., due to reduced emissivity or panel partial failures, and top head

penetrations - such as control rod drive tubes might be crucial and difficult to predict.

(4) Effects of participating media (e.g., steam) in the vessel-to-VCS on radiant heat transfer.

(5) Some practical aspects of VCS design and operation would probably become apparent to CRP

participants from their involvement in the experimental validation work.

An important point in formulation of the benchmark problem is the fact that time response of the

reactor internals during conduction cooldown accidents (one of the limiting accident conditions is referred

to as a "conduction cooldown" accident) is much slower than that for the heat removal process of the VCS.

Hence, if the temperature profiles are established for the reactor vessel, the calculation of cooling

performance of the passive cooling system can be treated as a steady state problem. Therefore, experimental

JAER1-Research 95-056

data of cooling performance of the cooling panel test apparatus (Japan Atomic Energy Research Institute:

JAERI, JAPAN) investigating heat transfer performance of the cooling panel system was selected as the

benchmark problem between computational codes and experimental data.

The computational code -THANPACST2- (l) , \vhich can calculate the flow and temperature

distribution with thermal conduction, radiation and natural convection, was applied to the benchmark

problem.

This report describes detailed data which are necessary for the benchmark analysis: configuration

and sizes of the experimental apparatus, experimental data and thermal properties. And the analytical results

using the computational code -THANPACST2- were compared with the experimental results to verify the

analytical method and model.


2. EXPERIMENTAL APPARATUS

2.1 Test apparatus of cooling panel system

Schematic diagrams of the apparatus and detailed configurations of the components are shown in

Figs. 2.1~2.18. Materials and thermophysical properties of the components are shown in Tables 2.2 and

2.3.

A flowsheet of the test apparatus of cooling panel is shown in Fig. 2.1. The test apparatus consists

of a test section and systems for water supply, helium gas supply and for vacuum. The test section is

composed of a pressure vessel containing a heater and cooling panels surrounding the pressure vessel as

shown in Fig. 2.2.

The pressure vessel is divided into upper head, shell, lower head, legs and skirt. Main specifications

of the pressure vessel are described as follows,

Height of the pressure vessel : 3000mm,

Inner diameter of the shell : 1000mm,

Thickness : 12mm,

Radius of the upper head : 500mm,

Configuration of the lower head : 2 : 1 half ellipsoid,

Longer radius of the lower head : 500mm,

Shorter radius of the lower head : 250mm,

Working fluid : Helium and Nitrogen gas,

Pressure : 1.3Pa~1.0MPa.

The upper head is connected with the shell of the pressure vessel by a flange as shown in Fig. 2.3. Detailed

sizes and configuration of the flange is shown in Fig. 2.4. The pressure vessel is supported by four legs,

and four boards attached between the legs to simulate the skirt type support as shown in Fig. 2.5 ~2.7. The

pressure of working fluid is varied from vacuum (1.3Pa) to l.OMPa to investigate the effects of gas pressure

which affects the natural convection in the pressure vessel. Helium and nitrogen gas are used as working

fluids in the pressure vessel.

The heater in the pressure vessel simulates reactor core as shown in Fig. 2.S. Main specifications of

the electric heater are described as follows,

Height : 2000mm,

Diameter : 600mm,

Maximum temperature : 600°C,

Maximum total power : lOOkW,

Maximum output power of heater segment No. 1 : 7kW,

Maximum output power of heater segments No. 2-No. 5 : 21kW,

- 3 -


Maximum output power of heater segment No. 6 : 7kW,

Heat transfer area of heater segment No. 1 : 0.283m2,

Heat transfer area of heater segments No. 2-No. 5 : O.S4Sm2,

Heat transfer area of heater segment No. 6 : 0.135m3.

The heater is divided into 6 segments. Each heater segment consists of an annular type ceramic block filled

with thermal insulator and nichrome helical coils wound around the block. The heater is supported by a

heater support composed of 8 legs and an annular plate as shown in Fig. 2.9.

The cooling panels which consist of cooling tubes are installed around the pressure vessel to remove

the heat from the pressure vessel. The cooling panel is composed of three parts: the upper, side and lower

cooling panels. Each cooling panel has 25, 88 and 12 cooling tubes, respectively. Figure 2.10 shows the

upper, side and lower cooling panels. Main specifications of the cooling panels are described as follows,

Outer diameter of the cooling tube : 31.8mm,

Pitch of the cooling tubes : 60mm,

(the length between the center lines of cooling tubes),

Maximum flow rate of water : 10m3/h.

The cooling tubes are connected with two ring type headers. Cooling water is supplied from two water

supply systems. In order to unify the emissivity, black paint is coated on the outer surfaces of cooling tubes

and the pressure vessel.

Thermal insulator made of KAOWOOL (ceramic fiber insulator) surrounds outside of the cooling

panels. Main specifications of the insulator are described as follows,

Outer diameter : 2210mm,

Height : 4000mm,

Thickness : 100mm.

In the test section, the cooling panel removes the heat from the heater with thermal radiation and

natural convection of helium gas (inside the pressure vessel) and the air(outside).

Temperatures of the surfaces of the pressure vessel, the heater, the cooling tubes and the insulator

are measured by sheathed chromel-alumel thermocouples.

Outer surface temperature of the pressure vessel was measured on four different angles at

90° intervals around the surface as shown in Fig. 2.11. All thermocouples are divided into 7 groups from

A to K and the thermocouples in each groups are numbered by tag number. Attached positions, groups and

tag numbers of the thermocouples are shown in Table 2,1 and Figs. 2.12~2.18. Detailed positions of the

measuring points of temperatures on the shell, upper head and lower head of the pressure vessel are shown

in Figs. 2.12, 2.13 and 2.14, respectively.

Figure 2.15 shows the measuring points of the temperatures on the heater, of working fluid in the

- 4 -


pressure vessel, and on the inner surface of the pressure vessel.

Detailed positions of the measuring points of temperatures on the middle 4 heater segments are shown

in Fig. 2.16. Thermocouples are attached on the thermocouple holders which are vertically connected

between the heater support plate and upper plate of the heater.

Detailed positions of the measuring points of temperatures on the top and bottom heater segments

are shown in Fig. 2.17. Thermocouples are attached on the holders which'are horizontally connected with

the top and bottom annular plates.

Temperatures of helium gas are measured by sheathed chromel-alumel thermocouples. Detailed

positions of the measuring points of gas temperatures inside the pressure vessel are shown in Fig. 2.18.

Thermocouples are held by thermocouple holders connected to the upper plate of the heater. Radiation

preventing plates are installed between the tips of the thermocouples and the heater.

In addition, temperatures of cooling water are measured by platinum resistance bulbs and the flow

rate of the water in cooling tubes are measured by magnetic flowmeters as shown in Fig. 2.1. Electric

powers of heater segments are measured by power transducers. Heat removed by the cooling panel is

calculated from the enthalpy rise of cooling water.

Table 2.1 shows the correspondence of the tag numbers to measuring items in the experimental

apparatus.

2. 2 Thermophysical properties

Tables 2.2 and 2.3 show thermophysical properties of the materials used in the test apparatus. Table

2.2 shows thermal conductivities®. Table 2.3 shows emissivities of the heater (nichrome coil and ceramic

blocks) and pressure vessel taken ftom reference .

In the vacuum experiments, emissivities of the components were measured to compare with the

values given in the reference. Heat transferred by thermal radiation from the heater surface to the pressure

vessel are expressed as follows by assuming infinite concentric cylinders,

^.•e-o-aV-r,') [2.1]

1e = -

1 A\,\ ..—+—•(—1)6, A, £2

q : Output power of the heater,

A; : area of the surface of the heater,

A, : area of the surface of the pressure vessel,

£ , : emissivity of the surface of the heater,

- 5 -


£ , : emissivity of the surface of the pressure vessel,

a : Stefan-Boltzmann constant,

T! : surface temperature of the heater,

T2 : surface temperature of the pressure vessel.

Emissivities are calculated by using temperatures and heat flux as shown in Table 2.4. Emissivity of the

surface of the pressure vessel is assumed to be constant: E ,=0.79. Emissivities of the heater depend on

temperature and are distributed be^/veen the values of polished and oxidized nichrome in the reference.

Therefore, experimental values of emissivities are considered to be reasonable.

The outer surfaces of pressure vessel, cooling tubes and inner surface of insulator are uniformly

coated by black paint to unify the emissivities. Emissivities of the outer surface of the pressure vessel are

assumed to be 0.95.

3. BENCHiMARK PROBLEM

Two experiments are selected as benchmark problems. The first is the case of vacuum condition to

eliminate the effect of natural convection in the pressure vessel. The second is the case of helium gas

condition to investigate heat transfer performance with natural convection in the pressure vessel.

3. 1 Experimental data

3. I. I Vacuum condition

Experimental, data are shown in Table 3.1. Output power of the heater and pressure in the pressure

vessel are described as follows,

Pressure in the pressure vessel

Total heater output power

Output power (Heat flux) of heater segment No. 1





Output power (Heat flux) of heater segment No, 6

1.3Pa,

13.14kW,

l.OlOkW (3

2.306kW (2

2.636kW (3

2.460kW (2

3.763kW (4

0.964kW (7

.569kW/m2),

.719kW/m2),

.lOSkW/m2),

90lkW/m2),

438kW/m2),

141kW/m2),

- 6 -


3. 1. 2 Helium gas condition

Experimental data are shown in Table 3.2. Output power of the henter and pressure in the pressure

vessel are described as follows,

Pressure in the pressure vessel

Total heater output power







0.73MPa,

2S.79kW,

Ll57kW(4.0SSkW/m2),

3.l06k\V(3.663kW/m2),

3.5",4kW(4.156kW/m2),

5.0%kW (6.009kW/m2),

10.42kW (!2.29kW/m2),

5.492kW (40.68kW/m2),

3.2 Benchmark problems

The benchmark problems are,

(1) to calculate the temperature distributions on the outer surface of the pressure vessel and to calculate

the heat transferred from the pressure vessel to the cooling panels under the boundary conditions of the

output power of the heater and the pressure in the pressure vessel given in 3.1.1. and 3.1.2., and the cooling

panel temperatures, FOl to F12, given in Tables 3.1 and 3.2.

(2) to calculate the heat transferred from the pressure vessel to the cooling panels under boundary conditions

of the temperature distribution on the outer surface of the pressure vessel, A01~A50, B01~B23,

C01~C29 and D01~D33, given in Tables 3.1 and 3.2, and the cooling panel temperatures, F01~F12,

given in Tables 3.1 and 3.2.

We propose all the participants solve the problem (1). We provided the problem (2) for checking

the results of the problem (1).

- 7


4. ANALYTICAL METHOD

4.1 Computational code

The analytical code -THANPACST2- is a two-dimensional time dependent flow and heat transfer

code and it is able to calculate both the flow and the temperature distribution of the components with

thermal radiation, conduction and natural convection. The staggered grid system is used to describe the

field variables such as temperature and pressure at the center of a cell and the flow variables (velocities)

at the surface.

A heat transfer coefficient between the surface of a component cell and fluid is given as a constant

local Nusselt number Nuc for each surface of component cell. And each Nusselt number Nuc is calculated

from mean Nusselt number Nura which is acquired from an empirical equation of natural convection

corresponding to the configuration of component cell and fluid.

For the flow calculation, the upwind scheme and the pressure correction method are used to

determine the variables on the finite-volume faces and nodes. The buoyancy force is calculated by

Boussinesq's approximation. The properties of the fluid, such as density, viscosity, thermal conductivity

and Plandtl number, are obtained as the function of temperature and pressure. Thermal conductivities of

components are assumed to be constant.

The surface temperatures of nodes are acquired by considering the balance of the heat transferred

with thermal radiation from surface 1 to surface 2, and the emissivity E applied to concentric cylinders

and spheres are defined as follows,

Qn=V £-a-F1 2-aV-T2T- [4.1]

£=!/(!/ e^A/A,- (II £,-!)), [4.2]

Aj : area of surface 1

(inner cylinder or sphere),

A, : area of surface 2

(outer cylinder or sphere),

E j, £ , : emissivities of surfaces 1,2,

a : Stefan-Boltzmann constant,

T,, T, : Surface temperatures of surfaces 1, 2.

Geometric factor F12 for each surface is obtained by using the unit-sphere method131. It is possible in the

code to consider heat transferred with thermal radiation between a face and maximum 30 faces.

4. 2 Analytical model

Figure 4.1 shows the differential scheme which simulates the experimental model. The two-

dimensional cylindrical geometry (a 23 X 39 grid system) is used in consideration of the arrangement of

the heater, pressure vessel and cooling panel supported by skirt type support.

There are air flow channels between the cavity which is surrounded by lower head of the pressure


vessel and skirt type support and the cavity outside of the pressure vessel. The cavities are connected with

clearances between the ground and skirt type support, and flow paths in H-type legs. The air channels are

expressed by porous body cells which have properties of bofh solid and fluid cells at the upper and lower

edges of skirt type support in the analytical model.

Outside of the cooling panel is assumed to be insulated and all the heat is transferred from pressure

vessel to cooling tubes, and heat loss from the insulator to the outside is assumed to be zero.

Thermal radiation is assumed to be exchanged between pressure vessel and surfaces of electric heater,

cooling panel and skirt type support, and also between cooling panel and skirt type support.

Natural convection heat transfer coefficients between the outer surface of shell of pressure vessel

and side cooling panel (region © in Fig. 2.2) and between the side surface of heater and the inner surface

of pressure vessel((2)) are calculated from the empirical correlation,

Num=0.2S6- Raa2S8- Pr0'006- U^s- K0'442, [4.3]

H: Aspect ratio,

K: Ratio of outer and inner radii of cylinders,

Pr: Prantdl number,

Ra: Rayleigh number (=Gr Pr),

Gr: Grashof number,

for the case of a concentric cylinder (inner surface heated, and outer surface cooled) by Thomas and de

Vahl Davis(5). Natural convection heat transfer coefficients for the top surface of heater (CD), upper cooling

panel (©) and outer surface of upper head of pressure vessel (©) are calculated from the empirical

correlation,

Num=0.54 • Raa25 (1 X !05<Ra<2 X 107), [4.4]

Nun=0.14- Ra0'33 (2X !0?<Ra<3 X 1010),

for the cases of horizontal surfaces heating above or cooling below by Fishenden and Saunders16'. Natural

convection heat transfer coefficients for the inner surface of upper head of pressure vessel (©) is calculated

from the empirical correlations by Shiina'7',

Num=0.l974-Raa2S (1.0 X 105<Ra<1.0X 109), [4.5]

Num=0.312-Raa33 (1.0 X 109<Ra<5.5X 1010).

Natural convection heat transfer coefficients for the bottom surface of heater (©), inner surface of lower

head of pressure vessel (®) and lower.cooling panel ((§)) are calculated from the empirical correlation,

Num=0.27-Raa25, [4.6]

for the cases of horizontal surfaces heating below and cooling above by Fishenden and Saunders'5). Natural

convection heat transfer coefficient for the outer surface of lower head of pressure vessel (®) is obtained

from Nuc=45 which is calculated from experimental results of vacuum condition inside the pressure vessel,

because the configuration of the lower head of the pressure vessel is half-ellipsoid and there is no empirical

correlation for this configuration. Mean Nusselt numbers used for each regions are summarized in Table

4.1.

- 9 -


4.3 Analytical conditions

In the analysis, the temperature distributions on the outer surface of pressure vessel and the heat

transferred from the pressure vessel to the cooling panels are calculated under the boundary conditions

described in 3-2 (1). Emissivity of heater is varied from 0.40 to 0.80 as a parameter. Emissivities of surfaces

of cooling panel, inner and outer surfaces of pressure vessel and skirt type support are adopted as 0.95, 0.79,

0.95 and 0.95, respectively.

The heat transferred from the pressure vessel to the cooling panels is calculated under boundary

conditions described in 3-2 (2). Emissivities of surfaces of cooling panel, outer surfaces of pressure vessel

and skirt type support are varied from 0 to 1.00 to investigate the emissivity dependence of thermal radiation

heat transfer.

-10-


5. COMPARISON BETWEEN EXPERIMENTAL AND ANALYTICAL RESULTS

5.1 Benchmark problem (1)

5. 1. 1 Vacuum condition inside the pressure vessel

Experimental and analytical results of temperature distribution of the components and heat flux

distribution of the heater are shown in Fig. 5.1. Analytical results of temperatures on the pressure vessel

don't depend on emissivity of the heater. Experimental results show that temperatures around the flange

and the connecting regions between legs and shell of pressure vessel show lower values. Temperatures are

almost uniform on the shell of pressure vessel. Analytical results of temperature distribution on the pressure

vessel agree with experimental results except the middle part of upper head and the connecting regions

between legs and shell of pressure vessel.

Analytical results of temperature at the middle part of upper head is about 17°C lower than experimental

one. Since the area of the upper head in the analytical model is about 1.2 times larger than experimental

apparatus, it is considered that the heat transferred from the upper head is over estimated and temperatures

on the upper head show lower values.

Temperature on the connecting region between legs and shell of pressure vessel is 3S=C higher than

experimental one. The reasons would be that the heat transfer area around the connecting region of the shell

of pressure vessel and legs are estimated smaller than the ones of experimental apparatus, and that there

are air channels between inside and outside of skirt through H-type legs.

On the other hand, analytical results of temperature on heater increases as emissivity of heater

decreases, and the analytical results in the case of emissivity £ =0.66 agree with experimental results except

temperatures on heater segment No. 5. Temperature on the heater segment No. 5 is 103=C higher than

experimental one. The reason would be that heat removed from segment No. 5 is small because the segment

is faced to the high temperature connecting regions.

Analytical results of temperature contour and velocity vector map are shown in Fig. 5.2. Temperature

gradient is steep around the pressure vessel as shown in the figure. Air flowing up on the shell of pressure

vessel is partially disturbed by the flange. Air heated by the pressure vessel flows upward and is cooled

and turns at the upper cooling panel. And the air is cooled and flows downward along the side cooling

panel. The air heated up below the lower head of pressure vessel flows up through the channels between

H-type beam legs and pressure vessel, and the legs and connecting regions of pressure vessel are cooled

by the air flow. Its effect on the temperature distribution around the area is not negligible as mentioned

above.

5. 1. 2 Helium gas condition inside the pressure vessel

Experimental and analytical results of temperature distribution of the components and heat flux

distribution of the heater are shown in Fig. 5.3. Temperatures around the flange and connecting regions

-11-


between legs and shell of pressure vessel show lower values. Temperatures are almost uniform on the shell

of pressure vessel. Analytical results of pressure vessel agree with experimental results except the top of

upper head and the connecting regions between legs and shell of pressure vessel. Analytical result of

temperature on the top of upper head of pressure vessel is 29=C lower than experimental one. Analytical

results of temperature and velocity vector map are shown in Fig. 5.4. Analytical result of helium gas

temperature is 7CTC lower than experimental one at measuring point of E26. High temperature gas flow

along the side wall of the heater would be prevented in the analysis by the stepwise wall which simulates

the inner wall of upper head of pressure vessel. This would be one reason of the low temperature in the

analysis. One more reason would be that the area of the upper head in the analytical model is 1.2 times

larger than experimental apparatus.

On the other hand, analytical results of temperatures on heater agree with experimental ones except

the ones on heater segments No.5 and 6. Temperatures on the heater segments No. 5 and 6 are max. 22CTC

higher than experimental ones. And temperatures on the connecting regions are max. 37°C higher than

experimental ones. This would yield high temperature of heater segment No. 5 described in previous section.

And it is also considered that temperature of heater is higher than measured value because thermocouples

which measure temperatures of heater don't contact with heater segments. Thermo-couples of No. 5 and

6 heater segments are set in low temperature helium gas flow.

Analytical result of heat transferred with thermal radiation is 60.1% of the total heat transferred from

heater.

5. 2 Benchmark problem (2)

Total heat transferred from the pressure vessel to the cooling panel are investigated van-ing emissivity

of the outer surface of pressure vessel from 0 to 1.00. Results are shown in Fig. 5.5. Analytical results

employing the emissivity of outer surface of pressure vessel E v=0.95 lies between the two values which

are total heat input and heat transferred to the cooling panel. Hence, the differences between total heat input

and heat transferred to the cooling panel in vacuum and helium gas conditions are 14.6 and 13.4% of total

heat input, respectively, and they are considered to be heat loss from the insulator.

The analytical results of relationship between emissivity and ratio of thermal radiation to total heat

transferred to the cooling panel is shown.in Fig. 5.6. The ratios of thermal radiation to total heat transferred

to the cooling panel in the case of £ v=0.95 are 71.0 and 74.4% for vacuum and helium gas conditions,

respectively.

-12-


6. CONCLUSION

International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on "Heat Transport

and Afterheat Removal for Gas-cooled Reactors under Accident Conditions" started at November, 1993.

In this program, benchmark tasks were proposed for the analysis of passive afterheat removal from gas-

cooled reactors (OCR) under accident conditions. The experimental data of cooling performance of the

cooling panel test apparatus (Japan Atomic Energy Research Institute: JAERI, JAPAN) investigating heat

transfer performance of the cooling panel system was selected as the benchmark problem between

computational codes and experimental data. This report describes detailed data which are necessary for

the benchmark analysis: configuration and sizes of the experimental apparatus, experimental data and

thermal properties. And the analytical results using the computational code -THANPACST2- of JAERI were

compared with the experimental results to verify the analytical method and model. Conclusions are

summarized as follows,

(1) Analytical results of temperature distribution on the pressure vessel are independent of emissivity of

heater under the given boundary conditions of heat input and cooling panel temperature.

(2) Analytical results of temperature distribution of the shell of pressure vessel agree with experimental

results.

(3) Analytical results of temperatures on the upper head of pressure vessel show lower values than

experimental results. This would be caused by the reasons that in the analysis the area of upper head of

pressure vessel is set 1.2 times larger than the actual area and the surface of upper head is a stepwise wall

and not smooth which prevents the hot helium gas flow inside the upper head of pressure vessel.

(4) Analytical results of temperatures around the connecting region between legs and shell of pressure vessel

in the analysis show higher value than experimental results. This would be caused by the reasons that in

the analysis the heat transfer areas around the connecting regions of the shell of pressure vessel and legs

are set smaller than the actual areas, and there is air flow through the channels between inside and outside

of skirt.

(5) Analytical results in case of the emissivity E p.tf=0.95 for outer surface of pressure vessel is between

the total heat input and heat transferred to the cooling panel in the vacuum and helium gas conditions.

(6) The analytical results of ratios of thermal radiation to total heat transferred to the cooling panel in case

of £ p.v=0.95 are 71.0 and 74.4% for vacuum and helium gas conditions, respectively.

For the benchmark problems of IAEA CRP-3 on GCR afterheat removal in 1995, the experimental

data of the case of high temperature condition of pressure vessel (max. 420=C) and of the case of the pressure

vessel with stand pipes were selected. And the experimental data of the air cooling panel and the heat pipe

cooling panel are also required for the benchmark problems. The further studys of cooling panel tests and

development of analytical code will be developed under the international corporation of IAEA CRP-3 on

GCR after removal.

-13-


ACKNOWLEDGEMENT

The authors would like to thank to Mr. Y. Miyamoto for his helpful suggestions and comments.

REFERENCE

(1) S. Takada, et. al.,"Thermal Analysis Code for Test of Passive Cooling System by Helium Engineering

Demonstration Loop (HENDEL) In-core Structure Test Section (TJ -THANPACST2-", JAERI-Data/Code

95-005(1995).

(2) ASME SECTION E, DIVISION 1-APPENDICES, Table I -4.0, 112(1989).

(3) A. Goldsmith, et. al . : Handbook of Thermophysical Properties of Solid, Vol.l~5(196l), Pergamon

Press.

(4) Siegel-Howell, "Thermal radiation heat transfer", McGraw-Hill Kogakusha, Ltd., 219-282 (1972).

(5) M. Keyhani et. al, Trans. ASME, 105, 454(1983).

(6) M. Fishenden and 0. A. Saunders, "Introduction to Heat Transfer", Clarendon Press, 180(1950).

(7) Y. Shiina, et. al, Trans. JSME, 55, 518 (1989).

-14-

Table 2.1 Correspondence of tag numbers to measuring items (No.1)

Tag

AlA31

Number

~A30~A41

A42-A46A47BlB15B21B23ClC20C27C29DlD21D29D33El •E4 •E20E23£24E25E26'

~A50~B14~B20~B22

~C19~C26~C28

~D20~D28~D32

~E3~E19~E22

~E28

Measuring Items

Temperatures on the outer surface of the shell of the pressure vessel (angle 30 )Temperatures on the outer surface of the upper head of the pressure vessel (30* )Temperatures on the outer surface of the lower head of the pressure vessel (30* )Temperatures on the surface of the leg (0* )Temperatures on the outer surface of the shell of the pressure vessel (120* )Temperatures on the outer surface of the upper head of the pressure vessel (120* )Temperatures on the outer surface of the lower head of the pressure vessel (120* )Temperature on the surface of the leg (90* )Temperatures on the outer surface of the shell of the pressure vessel (210* )Temperatures on the outer surface of the upper head of the pressure vessel (210* )Temperatures on the outer surface of the lower head of the pressure vessel (210* )Temperature on the surface of the leg (180* )Temperatures on the outer surface of the shell of the pressure vessel (300* )Temperatures on the outer surface of the upper head of the pressure vessel (300* )Temperatures on the outer surface of the lower head of the pressure vessel (300* )Temperature on the surface of the leg (270* )Temperatures on the surface of the top heater segment (No.l)Temperatures on the surfaces of the middle heater segments (No.2~No.5)Temperatures on the surface of the bottom heater segment (No.6)Temperatures on the inner surface of the pressure vessel (30* )Temperatures on the inner surface of Ihe pressure vessel (210* )Temperatures on the inner surface of the pressure vessel (300* )Temperatures of helium gas in the pressure vessel

PC]FC]FC][°C]FC]pC]FCIFC]FCJ[*C]FCJFC]FC]FC]FC]FC]PC]FCIpC]["ClPC]PC)FC]

W

CDCJl

OUl


Tag Number

Fl ~F8F9 ~F10F11-F12F13-F22F23F24F25-F27F28F29Kl ~K9K10Wl\V2W3W4W5W6W7

Diameter of thermocouples:

Diameter of resistance bulbs:

Measuring Items

Temperatures on the surfaces of the cooling tubes of the side cooling panelTemperatures on the surfaces of the cooling tubes of the upper cooling panelTemperatures on the surfaces of the cooling tubes of the lower cooling panelTemperatures on the inner surface of the side wall of the 'insulatorTemperature on the inner surface of the upper wall of the insulatorTemperature on the inner surface of the lower wall of the insulatorTemperatures on the outer surface of the side wall of the insulatorTemperature on the outer surface of the upper wall of the insulatorTemperature on the outer surface of the lower wall of the insulatorTemperatures on the outer surface of the shell of the pressure vesselTemperature on the surface of the upper head of the pressure vesselInlet temperature of cooling waterOutlet temperature of cooling water (Lower cooling panel No.l)Outlet temperature of cooling water (Lower cooling panel No.2)Outlet temperature of cooling water (Side cooling panel No.l)Outlet temperature of cooling water (Side cooling panel No.2)Outlet temperature of cooling water (Upper cooling panel No.l)Outlet temperature of cooling water (Upper cooling panel No.2)

A, B, C, D, F ; 01.0mmE ; 0 1.6mmK ; 00.5mm\V ; <63.2mm

rare][<C]m["€]rcjfC]fC)[•C]re]fC)[*]raRrcjPC]PC]re

ST


Tag Number

PD1FD1FD2FD3FD4FD5FD6PW1PW2PW3PW4PW5PW6WP1WP2WP3WP4WPSWP6THPTWPHLSTFL

Measuring Items

Working fluid gas pressure in the pressure vesselFlowrate of cooling water (Lower cooling panel No.l)Flowrate of cooling water (Lower cooling panel No.2)Flowrate of cooling water (Side cooling panel No.l)Flowrate of cooling water (Side cooling panel No.2)Flowrate of cooling water (Upper cooling panel No.l)Flowratc of cooling water (Upper cooling panel No.2)Output power of the heater segment No.lOutput power of the heater segment No.2Output power of the heater segment No.3Output power of the heater segment No.4Output power of the heater segment No.5Output power of the heater segment No.6Enthalpy difference of water in the lower cooling panel No.lEnthalpy difference of water in the lower cooling panel No.2Enthalpy difference of water in the side cooling panel No.lEnthalpy difference of water in the side cooling panel No.2Enthalpy difference of water in the upper cooling panel No.lEnthalpy difference of water in the upper cooling panel No.2Total output power of the heaterTotal enthalpy difference of the cooling waterTotal heat loss (THP-TWP)Total flowraie of cooling water

[kgf/cm'G]

P/h][1/h]P/h][Mi][1/h][1/h][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW][kW]

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-20-


Table 3.1 Experimental data of the vacuum condition

(A01)(A02)(A03)(A04)(A05)(A06)(A07)(A08)(A09)(A10)(All)(A12)(A13)(A14)(A15)(A16)(A17)(A18)(A19)(A20)(A21)(A22)(A23)(A24)(A25)(A26)(A27)(A28)(A29)(A30)(A31)(A32)(ASS)(A34)(A35)(A36)(A37)(A38)(A39)(A40)(A41)(A42)(A43)(A44)(A45)(A46)(A47)(A48)(A49)(A50)

-e*104105106122127130134131136130138144-a*14514313814114214114114314014514613813512511910311611511611911911611311010710092-B+13013412711952433834

i*.7.3,2.8.2.5.9.4.0.8.4.8Tft

.8

.2

.8

.2

.1

.5

.9

.4

.0

.2

.3

.7

.3

.8

.9

.8

.8

.9

.0

.5

.8

.9

.5

.0

.8

. 1

.2T&

.3

.7

. 1

.1

.8

.8

. 1

.0

(B01)(B02)(BOS)(B04)(B05)(B06)(B07)(BOS)(B09)(BIO)(Bll)(B12)(BIS)(B14)(B15)(B16)(B17)(B18)(B19)(B20)(B21)(B22)(B23)

(C01)(C02)(COS)(C04)(COS)(C06)(C07)(COS)(C09)(CIO)(cii)(C12)(CIS)(C14)(C15)(C16)(C17)(C18)(C19J(C20)(C2D(C22)(C23)(C24)(C25)(C26)(C27)(C28)(C29)

9310610510612512713113013113513913814213511711711911210899132108369310610510512212613112812913714014314514514814613611995

11611611611811711310212910836

.4

.4

.0

.4

.0

.7

.8

.5

.8

.8

.0

.7

.6

.5

.0

.0

.1

.0

.6

.8

.8

.9

.1

.9

.5

.3

.5

.5

.0

.6

.7

.0

.5

.4

.6

.5

.6

.8

.9

.8

.8

.3'

. 7

.3

. 1

.4

.3

.3

.0

.4

.8

.9

(D01)(D02)(DOS)(D04)(D05)(D06)(D07)(DOS)(D09)(DID)(DID(D12)-(D13)-(D14)(D15)(D16)(D17)(D18)(D19)(D20)(D21)(D22)(D23)(D24)(D25)(D26)(D27)(D28)(D29)(D30)(D31)(D32)(D33)(W01)(W02)(W03)(W04)(W05)(W06 j(W07)(WP1 )(WP2)( WP3 )(WP4)(WP5)(WP6)(TWP)(THP)(HLS)(TFL)

94.0104.4105.3105.6

• 122.2128.9131.5131.8129.9136.0143.4

or* n -r r.

r\r\r\r\ .-L

142.5142.7145.0144.8135.9118.898.3

115.5114.9117.7115.4112.6109.4108.3102.0125.3131.9126.4112.235.4

2 i . '1 1 622.05U22.29i22.83822.85521 .82721.995

.068

.0824.9075.018.482.669

11.22413.1401 .916

8138.9

(E01)(E02)(EOS)(E04)(E05)(E06)(E07)(EOS)(E09)(E10)(Ell)(E12)(E13)(E14)(E15)(E16)(E17)(E18)(E19)(E20)(E21)(E22)(E23)(E24)(E25)(E26)(E27)(E28)(KOI)(K02)(K03)(K04)(K05)(K06)(K07)(K08)(K09)(K10)(PDD(FDD(FD2)(FD3)(FD4)(FD5)(FD6)(PW1)(PW2)(PW3)(PW4)(PW5)(PW6)

298.4294.8270.6294.9298.4289.310 . 0

298.6296.9296.9297.6296.5301.0298.7282.0293.8293.3293.7297.9296.8293.1272.1150.6157.8154.3244.0233.0264.9141 .1147.7145.8144.4Dl .G

145.8143.5143.2144. 1113.2-.93790.880. 1

2967.72998.71008.0993.61.0102.3062.6362.4603.763.964

(F01)(F02)(F03)(F04)(F05)(F06)(F07)(F08)(F09)(F10)(Fll)(F12)(F13)(F14)(F15)(F16)(F17)(F18)(F19)(F20)(F21)(F22)(F23)(F24)(F25)(F26)(F27)(F28)(F29)

25.224.824.224,323.423.624.223.826.224.724.225.030.845.148.244.445.548.345.045.650.346.352.735.522.225 .722.124 .523.7

Deletion lines mean the measurement values by broken thermo-couples.

-21-

JAER1-Research 95-056

Table 3.2 Experimental data of the tvjlium gas condition

(A01)(A02)(A03)(A04)(A05)(A06)(A07)(A08)(A09)(A10).(All)(A12)(A13)(A14)(A15)(A16)(A17)(A18)(A19)(A20)(A21J(A22)(A23)(A24)(A25)(A26)(A27)(A28)(A29)(A30)(A31)(A32)(A33)(A34)(A35)(A36)(A37)(ASS)(A39)(A40)(A41)(A42)(A43)(A44)(A45)(A46J(A47.)(A48)(A49)(A50)

176177176187190189195191196190191195-*&•196194189192193192192194188194197190191182180156209207207208205201198193190181159«M *l

18017616515868514134

"J"

.6

.6

.8

.5

.8

.1

.7.

.3

.6

.6

.5

.5T*

.7

.6

.3

.0

.6

.6

.9

.0

.9

.8

.4

.8

.1

.8

.0

.0

.7

.3

. 1

.0

.8

.6

.0

.6

.8

.6

.01-9

.4

.6

.4

.9

.6

.3

.4

.7

(B01)(B02)(BOS)(B04)(BOS)(B06)(B07)(BOS)(B09)(BIO)(BID(B12)(B13)(B14)(B15)(B16)(B17)(B18)(B19)(B20)(B21)(B22)(B23)(C01)(C02)(C03)(C04)(COS)(C06)(C07J(COS)(C09)(CIO)(Cll)(C12)(C13)(C14)(C15)(C16)(C17)(CIS)(C19)(C20)(C21)(C22)(C23)(C24)(C25)(C26)(C27)(C28)(C29)

15617817717819119018919019019419419219319220920821120219818217014738

15617917817618918819019019019519519619619619819819218015020820720520219819418217015040

.1

.0

.4

.6

.3

.2

.9

.6

.2

.1

.3

.2

.6

.8

.3

.3

.2

.0

.9

.3

.0

.4

.9

.8

.5

. 1

.8

.7

.9

.2

.0

. 1

.7

. 3

.8

.8

.3

.7

.6

.9

.4

.7

.5

.1

.5

.4

.8

.3

.6

.4

.6

.0

(DOD(D02)(DOS)(D04)(D05)(D06)(D07)(DOS)(D09)(DID)(DID(D12)-(D13)-(D14)(D15)(D16)(D17)(D18)(D19)(D20)(D21)(D22)(D23)(D24)(D25)(D26)(D27)(D28)(D29)(D30)(D31)(D32)(D33)(W01)(W02)(W03)(W04)(W05)(W06)(W07)(WP1)(WP2)(WPS)(WP4)(WPS)(WP6)(TWP)(THP)(HLS)(TFL)

157,4176.8178.9178.0188.7.191.6190.1192.5190.4191.0196.2

n Q"Q~r i n194.4194.0196.1197.1192.3178.5152.1206.5203.0201.2198.5196.7195.0192.8183.6173.9170.1154.6149.8•,38.1

14.84815.84516.35917.81517.79316. 10716.229

.147

.18010.74910.6441.5031.694

24.91928.7913.873

8533.8

(E01)(E02)(EOS)(E04)(E05J(E06)(E07)(EOS)(E09)•(E10)(Ell)(B12)(E13)(E14)(E15)(E16)(E17)(E18)(E19)(E20)(E21)(E22)(E23)(E24)(E25)(E26J(E27)(E28)(KOI)(K02)(K03)(K04)(K05)(K06)(K07)(K08)(K09)(K10)(PD1)(FD1)(FD2)(FD3)(FD4)(FD5)(FD6)(PW1)(PW2)(PW3)(PW4)(PW5)(PW6)

301.1298.4291.4301.3302.8299.010. D

303.8297.8300.1302.3305.1312.2303.9272.3292.9292.5294.1279.5301.0296.7275.9197 .1201 .0199.7290.4286.8277 .3195.6198.3197.4195.1cc.o

196 .9196.5194 .9195.6197.26.255127.0102.6

3115.03108.21026.31054.61.1573. 1063.5245.096

10.4155.492

(FOD(F02)(F03)(F04)(F05)(F06)(F07)(F08)(F09)(F10)(Fll)(F12)(F13)(F14)(F15)(F16)(F17)(F18)(F19)(F20)(F21)(F22)(F23)(F24)(F25)(F26 j(F27)(F28)(F29)

22.922.522.021.219.720.020.620.126.822.619.419.232.164.064.457.564 .864.458.765.367.761. 180.338.520.522.916.821.218.5

Deletion lines mean the measurement values by broken thermo-couples.

-22-


Table U.1 Heat transfer coefficients on components

Region No. Ra Nu Equation No.

® 4.35 X 10 '© 5.65 X 10 *CD 9.43 X 10 7

© 2.12 X 10 ' °(D 2.66 X 10 'CD 8.92 X 10 7

© 9.43 X 10 7

® 4.37 X 10 '® 2.66 X 10 '

38.011.463.738719319.226.639.061.3

[4.3][4.3][4.4][4.4][4.4][4.5][4.6][4.6][4.6]

Side Cooling Panel

—^—(p

r-Pressure Vessel

WaterSupply

Flowmeter

Fig.2.1 Flowsheet of test apparatus

-23-


a

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-24-

Pressure Vessel

COen

Pressure Vessel Flange

O.D. 1021

2(!)0

\

Pressure/ Vessel

Air flow

• Air outlet

Air channel •44\

Skirt

20

=U3

CDf»

Insulator

Fig.2.4 Pressure vessel flange Fig.2.5 Schematic diagrams of leg and skirt

IIS3

- Air flow,

Air outlet

20 Air channel

Fig.2.6 Detailed sizes of a leg

c_>K

P

I

Fig.2.7 Size and detailed configuration of skirt

Pressure Vessel

ICO

Power Coble

Nichrome Helical Coil

Ceramic Block

-Thermal Insulation

Iross View A-A'

<*> 680

Heater Support

H

o

CDO1

Fig.2.8 Schematic diagram of heater in the pressurevessel

Fig.2.9 Size and detailed configuration ofheater support


Lower cooling panelUpper coolling panel

OJCOto

o I ?/?-

1Ring type header Co\ jng tube

^— tt700

J

950ih—

700

Side cooling panel

Ring type header

/

Ring type header

205

1883

Cooling tube

Cooling tube

1940

60

o

ro

205

Fig.2.10 Schematic diagrams of lower, upper and side cooling panels

-28-

toco

Insulotor *. Cooling Panel.90°

5T

COUl

I

180*120

Fig.2.11 Thermocouple positions on the cooling panels,outer surface of the pressure vessel andthe thermal insulation surface

Fig.2.12 Thermocouple positions on the outer surfaceof the pressure vessel-upper head


Fig.2.13 Thermocouple positions on the outer surface of thepressure vessel-shell

-30-

ICO

E23 E24E25

gto

CD01

IOCn

Fig.2.14 Thermocouple positions on the outer surfaceof the pressure vessel-lower head

Fig.2.15 Measuring postions of the inner surface temperatureof the pressure vessel, gas temperature andheater surface temperature


13 TL , Nichrome Coi» Thermocouple

Fig.2.16 Detailed structure of the heater and thermocouple positionson the heater surface

-32-

GO00

r 1Thermocouple

Holder

180°;Bottom of Heoter Block ^-^

<G

Nichrome Coil

J o o O o o

*I

41 j

O O O O (

\\

100 ,

)

U.s ,_

\\ \

c_>tfl

CDP

CDcn

I

Cross view A-A (E20rE2() (E22

Fig.2.17 Top and bottom of the heater and thermocouple positions on them


940

RadiationPreventingPlate

ThermocoupleHolder _

RadiationPreventingPlate.

Thermocouple-Holder

r*fr

iI Therm o-j couple

A

Fig.2.18 Positions of the thermocouples E26, E27 and E28

-34-


e>CT5ro

ooo«o-

o0in

roID

Oro

ooin

TTTTTir

5 2

8C

1000 (23 Grids)

•Upper Cooling Panel

•Side Cooling Panel

• Pressure Vessel

• Electric Heater

•Skirt type Support

• Lower Cooling Panel

-Air channel between H-type legs

"and shell of pressure vessel

Fig.U.I Differential scheme of numerical analysis

-35-

ooen

Upper Cooling Panel c., „ ,. n ,1 p J Side Cooling Panel

HealerPressure VesselInside the InsulolorCooling Panel

ExperimentoA

V

a

£H«oi«r

O A r\. H U

O K R

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Analysis

Pressure^.-Vessel

— ..

ElectricHeater

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ttl

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W|

1

Lower Cooling Panel o 100 200 300 400 500 0 5.0 10.0 15.0 20.0

(a) Modelo

Temperature [C]

(b) Temperature distribution on components

Heat Flux q(c) Heat flux distribution on heater

Fig.5.1 Experimental and analytical results(Vacuum condition )

Upper cooling panel

CO—a

Pressure vessel *~~

Side cooling panel

Flange

Temperature [°C]

Air channels

Upper cooling panel

Pressure vessel

Side cooling panel

Flange

Reference? velocity

1.00[m/sec]

Air channels

C-.

>

CDOl

Lower cooling panel Lower cooling panel

Fig.5.2(a) Analytical results of temperature contour(Vacuum condition inside the pressure vessel)

Fig.5.2(b) Analytical results of velocity vector(Vacuum condition inside the pressure vessel)

GOOO

Upper Cooling Panel Sjde Pane,

Pressure..Vessel

Elec t r i cHeoler

Lower Cooling Panel

(a) Model

HeolerPressure VesselInside Ihe InsulolorCooling Ponel

ExperimentoA

V

b

1.0

3.0

£ 2.0en

1.0

D V

a v

Okr0

4.0

3.0

2.0

a>a:

1.0

0100 200 300 400 500

Temperature [°C](b) Temperature distribution on components

600 0

Fig.5.3 Experimental and analytical results(Helium gas condition )

: Heater segment number

I tt I

tt3

tt4

1f6

10 20 30 4

Heat Flux q [kW/m?J

(c) Heat flux distribution on heater

50

CDcnI

Oon

Upper cooling panel Upper cooling panel

290°C (exp. E26)

220°C (Analysis)

GOCD

Pressure vessel

Side cooling panel

Temperature [°C]

Air channels

Pressure vessel

Side cooling panel

Flange

Reference velocity

1.00[m/sec]

Air channels

S3to

CDcn

oon

Lower cooling panel Lower cooling panel

Fig.5.U(a) Analytical results of temperature contour(Helium gas condition inside the pressure vessel)

Fig.5.4(b) Analytical results of velocity vector(Helium gas condition inside the pressure vessel)

50.0

CPI

O

cuoQ.

40.0

30.0

ooo

2 20.0

03

o

oCD

10.0

VUVAlUll l U U U U l n U l v

Hpl inm nns condition

Experimental results

0 0.5

Emissivity on outer surfaceof pressure vessel 6p. v

100.0

i.O

CDtotoCD

totoCDQ.

CDoo

to

1—CD

O

c:o

o"oO~

50.0 -

Emissivity on outer surfaceof pressure vessel 6p.v

COenI

O01en

Fig.5.5 Relationship between emissivity and totalheat transferred to cooling panel

Fig.5.6 Relationship between eraissivity and ratioof thermal radiation to total heattransferred to cooling panel

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jaeri-research 95-056

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