Development of small scale cooling systems at AT-ECR (Compact - - PowerPoint PPT Presentation

Development of small scale cooling systems at AT-ECR

(Compact Cooling System, developments at CERN Cryolab) (Compact Cooling System, developments at CERN Cryolab)

Friedrich Haug and Jihao WU Friedrich Haug and Jihao WU

Contributions by Contributions by Hugo Pereira and Phillip Santos

Context: TOTEM Roman Pots Cooling

Demand in 2004 by TOTEM collaboration to develop and

provide a system for the Silicon-Detectors cooling at 120 K.

Specific conditions:

Remote (Large distance from CMS intersection up to 220 m) Radiation environment (Radiation hard equipment) High intensity and high luminosity beams Reliability system Close to maintenance free

Our Approach

Innovative system largely based on 1) Passive heat transfer (Heat pipes) 2) Highly reliable cryo-coolers (Pulse tube refrigerator) g )

Technology

Development of Cryo-coolers (pulse tube

type) yp )

Development of Cryogenic Heat Pipes

Development of Cryogenic Loop Heat

Development of Cryogenic Loop Heat

Pipes

Thermal Models for TOTEM Roman Pots Thermo-mechanical Simulations Peltier Elements

Location of Totem Roman Pot Stations

Cooling system principle for a RP station Cooling system principle for a RP station

Cooling Principle

• The dissipated heat load in

6 R P t i t t d

H t Pi C t l C t t ith P l

6 Roman Pots is extracted by two-phase flow in heat pipes and transferred to a central cryostat.

• A Pulse Tube Refrigerator

Heat Pipes Central Cryostat with Pulse Tube Refrigerator (PTR)

g provides the cooling power Characteristics:

• In large part passive system
• Small amounts of working

Small amounts of working fluids in hermetically closed pipes (Safety for beam vacuum)

• Radiation hard

QRL Transfer Line for LHC collider magnets Helium compressor to drive the Pulse Tube Refrigerator (will be placed at non-radiation area)

Lay-out of CMS area, TOTEM Compressor location CMS detector hall

CMS Helium refrigerator Technical side cavern Location of compressor Pi t t P l T b Pipe runs to remote Pulse Tube Refrigerators in LHC tunnel at up to 220 m.

Laboratory prototypes Laboratory prototypes y p yp y p yp

Design, fabrication and testing and of Pulse tube refrigerators Heat pipes development Development of thermal-mechanical RP model

Configurations of single-stage PTRs

inline U coaxial Features of pulse tube refrigerator –No vibration –Long life Long life –Close to maintenance free –Eco-friendly (an ideal gas (helium) as the working fluid) working fluid) –Oscillating pressure wave –Thermodynamic cycle (compression/expansion) without (compression/expansion) without mechanical expander (no piston)

Stirling type GM type

Pulse tube refrigerators (PTRs) were becoming the most actively investigated area of small scale cryogenic refrigeration.

Development, fabrication and testing of PTR Development, fabrication and testing of PTR

Coaxial Type Coaxial Type U Type Coaxial Type

PTR on permanent loan from KEK Cryogenics Dep.

80 90 100 60 80 100 120 140 160 180 80 90 100

90W@165K New U type PTR 64K, 90W@165K (Japanese PTR)

40 50 60 70

g power(W)

40 50 60 70

@ ( p ) Actual performance (Japanese PTR)

Comp 1.83MPa@3kW.

10 20 30

Cooling

10 20 30

64K 63.09K

60 80 100 120 140 160 180

• 10

Temperature(K)

• 10

83.77K 64K

Highly compact, lowest T 30K

Development of heat pipes Development of heat pipes

Grooved type wick structure SInerted type wick structure Mesh type wick structure j6

Slide 11 j6 A heat pipe is a heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between the hotter and colder interfaces. Inside a heat pipe, at the hot interface a fluid turns to vapour and the gas naturally flows and condenses on the cold interface. The liquid falls

• r is moved by capillary action back to the hot interface to evaporate again and repeat the cycle.

jwu, 9/13/2007

Development of heat pipes Development of heat pipes

PTR Miniature heat pipe

Purpose of test station Purpose of test station

Optimal charging mass of working fluid Maximum heat transfer rate

Development of heat pipes Development of heat pipes— p p p p p p integration in thermal model

• ”Big” heat pipe
• Thermal connecter
• Two “miniature” heat pipes

charged with Xenon

• Copper piece welding to

“miniature” heat pipe

Development of a RP thermal model Development of a RP thermal model

Thermal model

Designed for investigation on g g thermo-mechanics analysis The model use heat pipes to conduct the dissipated heat load p to a pulse tube refrigerator

Thermal model details

03 02 01

This model uses 12 copper frames as mechanical t f th 10 PCB d d f h t d ti support for the 10 PCB cards and for heat conduction On frames and cards, they are equipped with temperature sensors, strain gauges and heaters

Test facility for a RP Thermal Model Test facility for a RP Thermal Model

• Pulse Tube Refrigerator (PTR)
• Heat Pipes heat transfer system
• Thermal Model

At this condition, the thermal model The facility integrated in vacuum envelope simulates an horizontal RP

Conclusions

Design principle validated Design principle validated Development of pulse tube refrigerator to the

stage of laboratory application stage of laboratory application

Development of cryogenic heat pipes to the

stage of laboratory application stage of laboratory application

Development of cryogenic loop heat pipes in

progress progress

Investigations with Peltier elements in

progress

Circuit of the Evaporative Cooling System

In the initial operation phase In the initial operation phase with low beam intensity, the cooling of the detectors is done with an adapted evaporative system at 250 K

Main components

system at 250 K.

Compressor, Condenser Pump of the cooling plant, The liquid inlet and the vapour back pressure regulators

Functionality

Superheated coolant vapor compressed by compressor The fluid is delivered in liquid phase at room temperature from the condenser The fluid expands through the capillaries and then remains in saturation conditions (boiling) in the detector structure p g Capillary Cold load (e.g. the detector structures ) The fluid expands through the capillaries and then remains in saturation conditions (boiling) in the detector structure The residual liquid is evaporated by means of an heater which also raises the temperature of the vapor Reaches the compressor in superheated vapor state

Loop heat pipe

Liquid Line Condenser Compensation Chamber

Q Q

Evaporator

Q

Main advantage of loop heat pipes

Vapor Line

Main advantage of loop heat pipes

• Being able to provide reliable operation
• ver long distance

Evaporator: ∅ 16mm x 30mm. g

• The ability to operate against gravity.

Improved design for higher performance, much highly compact structure in progress

BACK

Peltier elements investigation

BACK

285 295 between (K) 245 255 265 275 285 Temperature gradient hot and cold side

One stage Peltier element P lti ff t

0.14 0.56 24.8 40 57.6 78.4 97.7 DC power (W) T

Peltier effect Two stage Peltier elements Peltier element plus heat pipe (heat sink ambient water) Peltier element plus PTR (heat sink cryocooler) j5

Slide 20 j5

jwu, 9/13/2007