1. Cryogenic cavern in Asian site
Conceptual design of the cryogenic system
Layout of the cryogenic plant (old & new version)
Storage of helium inventory
Cooling water for cryogenic system
Summary & Future Plan
Oct.12,2011
KEK
K. Hosoyama

2. Conceptual Design of Cryogenic System 1
He Gas Tank Cluster
200 m3 x 24
Liq. He Dewar
He Gas Tank
50,000 L
200 m3 x 2
SC Cavities
2.5 km
2 K Ref.
Cold Box
4 K Ref.
Cold Box
Helium Gas
Compressor
Cooling Tower
CIB
2.5 km
SC Cavities
2 K Ref.
Cold Box
4 K Ref.
Cold Box
Helium Gas
Compressor
Cooling Tower
Helium Gas
Accept Station 2K
Liq. He Dewar
He Gas Tank
50,000 L
200 m3 x 2
He Gas Network 2K
Multi-transfer Line 4K
Multi-transfer Line
Cooling Water Piping
Helium Gas Piping
Note
CIB: Cryogenic Interconnection Box
Cooling Tower
He Gas Tank Cluster
He Gas Tank
Cooling Tower
Small Shaft
for Cooling & He gas storage
Cryogenic Cavern
Helium Gas
Accept Station
2 K and 4 K Ref.
Cold Box
Access Tunnel
Helium Gas
Compressor
L < 1km
SC Cavities
in Main Tunnel
~ 5 MW x 2 units

3. Conceptual Design of Cryogenic System 2
Cooling Tower
Cooling Tower
Access Tunnel
Access Tunnel
He Compressor
x 2 units
He Compressor x 2 units
2K He Ref. x 2 units
~ 5 MW x 2
~ 5 MW x 2
4 K He Ref.
2K He Ref. x 2 units
Cryomodule
Cryomodule
Cryomodule
Cryomodule
2.5 km
2.5 km
5 km
5 km
Multi-transfer Line
4K cold boxes will be installed in the large caverns at the end of access tunnel.
Two 2K cold boxes must be installed in the caverns at 5 km intervals
and each 2K cold box supports cooling of ~2.5 km long cryogenic unit.
Long multi-transfer line must be installed in the main tunnel
to connect 2K and 4K refrigerators.
2K cold box must install in the main tunnel.

4. Layout of Cryogenic Plants for Mountain Site-B
2K cold boxes and distribution boxes will be installed in the cavern in the main tunnel
4 K cold boxes & compressor units will be installed at the end of access tunnel 　
2.5 km
2.5 km
5 km
5 km
2.5 km
2.5 km
5 km
5 km
1.1 km
2.2 km
1.9 km
2.6 km
2 km
1.3 km
2K Ref.#6
2K Ref.#5
2K Ref.#4
2K Ref.#3
2K Ref.#2
2K Ref.#1
Zone 6
3.8 km
Zone 5
4.8 km
Zone 4
5.8 km
Zone 3
5.1 km
Zone 2
4.7 km
Zone 1
5.4 km
2K Ref. cold box ( + cold compressor)
4 K Ref. cold box
Comments :
Long multi-transfer line must be installed in the main tunnel
In the caverns build at the end of access tunnel so called cryogenic cavern, two 4.4 K cold boxes will be installed.
Compressor unit will be installed far away from main tunnel in the cavern near by access tunnel.
He Compressor
Access Tunnel

5. Cryogenic Cavern The 4K ref. cold box will be installed in
cavern at the end of access tunnel,
so called “cryogenic cavern.”
The size of the cold box will be limited
by transportation on road from factory to
the site
Sub tunnel
18kW Helium ref. cold box
/ CERN LHC
Main tunnel
Access tunnel
4 K ref. cold box
Transportation of the cold box
Cavern at the end of access tunnel will be used
for installation of cryogenic plants.

6. Installation of Main Cryogenic Components
4K cold box will be carried through the access tunnel to the cavern at the end of access tunnel.
-- Enough cross section for transportation of 4K cold box and compressor unit!
Problems:
2K cold box must be carried in and out through the main tunnel.
2K caverns must be constructed for installation of 2K and distribution boxes.
Multi-transfer line must be installed in the crowded main tunnel.
Multi-transfer Line
(between 4K and 2K cold boxes)
Cryo-module
Cold box for LHC
18 kW at 4.5K Ref.
7.2 m
D 3.9 m
10.2 m
D 4.1 m
D 5.2 m
Sub tunnel
Main tunnel
Access tunnel

7. New Layout of Cryogenic Plant
To solve following problems:
a) 2K cold box must be installed through the main tunnel
b) Need the 2K cryogenic cavern and the long multi-transfer line.
Need new access tunnel plan:
Cryogenic caverns will be constructed at the end of the access tunnels
at every 5 km intervals in the tunnel.
Main components of two cryogenic plants:
compressor units, 4K refrigerator cold boxes, 2K cold boxes,
distribution boxes, and multi-channel transfer line,
will be installed in the cryogenic cavern.

8. Concept of New Cryogenic Cavern
Access tunnel
2K cold box
Compressor
4K cold box
Main tunnel
Sub tunnel
Access tunnel
30 m
8 m
56 m
20 m
20 m

9. Detailed Structure of Cryogenic Cavern
Temporary size of the cryogenic cavern is given here as for starting point.
To decide the shape and size of cavern, we need the detailed design study of the main components and these layout in the cavern.
In designing the cryogenic system we must care about the safety and maintenance.
compressor unit x 2
4K cold box x 2
2K cold box x 2
2K distribution box
2 liquid helium Dewar（50,000 L）

10. Helium Compressor Unit
The helium compressor is installed in far end of the cryogenic cavern
Location of the cavern is ~ 60 m away from the main tunnel to avoid the vibration
26 m
Compressor + Motor
5 m x 1.9 m x 2 m H
6 m
12.5 m
Helium compressor
for18kW Helium Ref
/ CERN LHC

11. Helium Compressor Unit for LHC
The helium compressor unit consists of several main components.
There are many option for layout of these components.
We can optimize the lay out.

12. 4K Ref. Cold Box for LHC Size of 4K cold box Linde 18kW@ 4.5K
D4m x L18 m

13. Storage of Helium Inventory
ILC Cryogenic Systems Reference Design
T.J. Peterson et al.
CEC Vol. 53
Required Total Liquid Helium ~ 650,000 L
If all helium is stored as gas:
200 m3 x 10 x 2 x 6 cryo. stations units
Storage as gas and liquid :
Liquid helium
50,000 L x 2 x 6 cryo. stations units
Gas helium (Near helium compressor unit)
200 m3 x 2 x 6 cryo. stations units
Gas helium (He tank cluster: at He gas accept station)
200 m3 x units
Helium gas network ( Gas pipe line connecting 6 cryo. plants)
Comment:
Gas helium tank D 4 m x 15 m x 20 bar
Liq. Helium Dewar D3 m x 15 m
Vaporization loss:
50,000 L x 0.5%/day = 250 L / day ~10 L/hr
Small refrigerator can be used as “Baby-Sitter”

14. Conceptual Design of Water Cooling System
Option
Cooling Tower A
Cooling Tower Cluster
Small shaft
Cryogenic Cavern
~ 100 m
Access Tunnel
Compressor
4K cold box
1 ~ 2 km
Cooling tower at the entrance of access tunnel can support cooling of underground 2 cryogenic plants.
Cooling tower cluster can support cooling of ~ 8km long distributed heat load. The cooling water circulate in 900 mm in diameter pipe.
By installation of the cooling tower in the tunnel, we can eliminate heat exchanger which need to cut the head pressure. But we need large bore shaft.
By using the “thermo-siphon” of refrigerant we can reduce the pipe size.

15. Extraction of heat from the tunnel (1/2)
Plan A
Plan A’
Circulation of cooling water
1) Use the specific heat Cp of water
2) Need large mass flow
3) Large in size and long piping
4) Heat exchanger to intercept pressure
Underground Cooling Tower
Eliminate the heat exchanger
Need large dia. shaft
Latent Heat of Water
37oC
Cooling
Tower
Air out
Air in
Air in
Supply Water
~ 8 m3 / hr
Latent Heat
of Water
32oC
Access
tunnel
DH = 100 ~ 150 m DT
Large Shaft
DH = 100 ~150 m
Pump
Heat
Exchanger
Specific Heat Cp of Water
37oC
37oC
Pump
37oC
37oC
Helium
compressor
Latent Heat
of Water
42oC
32oC
10 MW
Cooling
Tower
Helium compressor
42oC
32oC
Pump

16. Extraction of heat from the tunnel (1/2)
Plan B
Plan C
Circulation of refrigerant
1) Use the vaporization heat
2) Small amount of mass flow
3) Small size piping
4) Eliminate
the intercept heat exchanger
Compressor is cooled
by refrigerant directly !
NH3, R410A, R32
Tc =32oC
Cooling
Tower
Cooling
Tower
Latent Heat
of Water
Condenser
Condenser h1
Small shaft
Vapor
Liquid
Vapor
Liquid
Pump
Pump
Cooling water h3 h2
Te = 35oC
Helium
compressor
Evaporator
Helium
compressor
Evaporator
Pump
Latent heat of refrigerant

17. Cooling Power by Water vs. Refrigerant
Cooling by water DT = 5 oC
Cooing power Pc [ kW ] Specific Heat Cp [kcal / kg]
Mass flow rate mw [ kg/sec]
Pc [kJ / sec] = 4.2 [kJ / kcal] x Cp [kcal / kg] x mw [kg/sec]
Required water mass flow rate mw for cooling 1MW;
mw = 1000 / 4.2 / 5 = 48 [L/s] [ m3 /min.] [ m3 / hr.]
i.e.
For cooling Pc = 10 MW
Cooling water = 1710 m3 / hr.
Cooling by refrigerant R134a
Vaporization Heat Hv. [kcal/kg] kcal / kg
Mass flow rate mR [ kg/sec]
Pc [kJ / sec] = 4.2 [kJ / kcal] x Hv. [kcal / kg] x mR [kg/sec]
mR = 1000 / 4.2 / 40 = 6 [L/s] [ m3 /min.] [ m3 / hr.]
Cooling Refrigerant = 220 m3 / hr.

18. Heat transfer capacity of refrigerants
WATER
AIR
NH3
R410A
R32
Liquid
Gas Te 37 35 ℃ Pe
---
1350.8
2139.9
kPaA Tc 32
1238.2
1975.6
Density 1
0.0012
0.587
0.0105
1.008
0.0883
0.912
0.0652
t/m3
Specific Heat
0.24
Mcal/t･℃ DT 5
Latent Heat
268
40.5
59.0
Mcal/t
Velocity
m/s
Cooling Power
0.0072
157.3
14.1
40.8
17.9
53.8
19.2
Mcal/m2･s
Note: Cooling Power is defined by
Heat Transfer Capacity [Mcal/s] of 1m2 cross-section pipe;

19. Motor power for circulation of water and refrigerants
30 MW Heat Load (including other heat load)
WATER
AIR
NH3
R410A
R32
Liquid
Gas
Mass Flow Rate
5160
21500
96.3
637.0
437.3
t/h
Velocity
1.0
5.0
m/s
Pipe Size
1.35
35.60
0.24
0.81
0.47
0.71
0.41
0.69 m 5
1.3
0.2
ｋPa
1.00
1.82
5.00
16.7
Pipe Length
4000
2000
100
500 ⊿P
666.1 ⊿H
0 *
Water Head
587
10.5
1008
88.3
912
65.2
⊿P at H.X. 50
Total ⊿P
766
588.3
61.8
1008.2
138.5
Pe-Pc
112.6
164.3
Pump Efficency
60% %
Motor Power
1318
No Need ｋW
Moter Power
4.4%
0.0%
/ Cooling Power
Ideal case: larger pipe size
for water
Water pipe size: 1m in dia.
Note:
In the case of water ,
head of flow and return cancelled.

20. Summary & Future Plan
Cryogenic caverns should be constructed at the end of the access tunnels at every 5 km intervals of the main tunnel.
The 4K and 2K cold boxes and distribution boxes should be installed in cryogenic caverns.
The compressors will be installed in the far end of cryogenic cavern.
The helium inventory should be stored as liquid for long shutdown of the cryogenic system.
Extraction of heat from the deep tunnel economically is key issue.
We need more study including new idea.
Detailed engineering design study for the cryogenic system is needed, including topography of the site.