phase change materials for missile electronics vi/vi-3.pdf · phase change materials for missile...

Phase Change Materials for Missile Electronics

David MANTEIGAS – 2 Feb 2012

7th European Advanced Technology WorkshopMi k i d Th l t

This document and the information contained herein is proprietary information of MBDA and shall not be disclosed or reproduced without the prior authorization of MBDA. © MBDA 2011.

on Micropackaging and Thermal management

Summary

• MBDA short presentation

• Phase change materials presentation

• Phase change materials selection

• Results of the simulations and trials

• Example of prototype of electronics system using PCM as heat storage


Ref. : - -

What is MBDA?

• Created in 2001, MBDA is an industry leader and a global player in the missile and missile systems sector

• With a product portfolio covering the whole range of requirements

• Presence on more than 45 missile systems and countermeasures programmes in operational service

• Extensive experience of international programmes e.g. Storm Shadow/SCALP, Taurus, Aster, Meteor, MEADS, Milan,

• Supported by three major shareholders: BAE SYSTEMS, EADS, Finmeccanica


Ref. : - -MBDA Corporate Presentation 2011 - Page 3

MBDA • European centres of excellence

10,000 people worldwide, 60% in Technical/Engineering functions

LostockProduction

UK 2,700StevenageManagement

UlmR&D

BrusselsRepresentation Office

UK 2,700Management R&D/Integration

LondonManagement GE 1,300

SchrobenhausenManagement/R&D/Production/ Integration

USA 100

FR 4 600

BristolSoftware & Systems

AschauR&D/Production

UnterschleißheimManagement/R&D

FR 4,600La SpeziaR&D/Integration

R&D/Production

Rome

CompiègneElectronic

IT 1,300RomeManagement/R&D

FusaroProduction/Integration/R&DRégion Centre

R&D/Production/Integration

Le Plessis-RobinsonManagement/R&D



R&D/Production/Integration

Multinational programmes: MBDA's strength

• Three great Multinational Programme families have allowed MBDA entry into three key market sectors:y• Long range air-to-air missiles

with the METEOR Programme • Medium range surface-to-airMedium range surface-to-air

systems with the ASTER family • Deep strike missiles with the

Storm Shadow / SCALP andStorm Shadow / SCALP and Taurus

• These three families of th fprogrammes are the core of

MBDA’s activity now and in the future.



The context

• Traditionally thermal management of electronics in missilesystems is a significant issue• Increasing volumetric power densities• Harsh environments in which the equipment is deployedHarsh environments in which the equipment is deployed.

• Nowadays new challenges appear because electronics marketis now mainly civilian-based market with commercial-off-the-h lf (COTS) tshelf (COTS) components.• This situation is leading to a conflict between

- The low temperature range of the COTSand- The capacity of existing thermal management solutions to dissipate

the heat.• The electronics are more and more compact

• Therefore new concept needs to be identified.


Ref. : - -

A way of managing thermally electronics : PCM

• MBDA is developing solution based on incorporation of a heatstorage capability by Phase change materials (PCM) in thetemperature control system of an electronic module.

• The main benefit to be expected from this solution is to dealwith the transient period where environment does not allow

i h t ith l i l th dmanaging heat with classical method.

• The principle is to encapsulate a phase change material (PCM)The principle is to encapsulate a phase change material (PCM)very closely to main dissipating electronic components.


Ref. : - -

What is Phase Change Material?

• A phase-change material (PCM) is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy. gy

• Heat is absorbed or released when the material changes from lid t li id d isolid to liquid and vice versa.

• Thus PCM are classified as latent storage (LHS) unitsThus, PCM are classified as latent storage (LHS) units.


Ref. : - -

Choice criteria

• A large latent heat of fusion per mass unit, so that little amount of material stores a significant amount of energy.

• A specific heat (solid phase and liquid) is also important because it provides additional thermal storage and also prevent the secondary cooling.

• A high thermal conductivity so that the temperature gradient in the PCM is low

• A high density to reduce the volume of PCM with equal performance.• A melting temperature in the desired range of operating temperature.• A PCM non-toxic non-flammable and non-explosiveA PCM non-toxic, non-flammable and non-explosive.• No chemical decomposition in order to keep the lifetime of the system • No corrosive effect on the encapsulation material• No effect of supercooling


Ref. : - -

Choice of PCM

• A wide variety of Phase Change materials are available on the market mainly for building applicationsg pp

• For missile electronics, choice h b f d 3 thas been focused on 3 types :

• Paraffina a

• Hydrated salts

• Solid-solid


Ref. : - -

Parrafin

• Paraffin is the most commercial organic PCM used,

• Advantages• Chemically stable (no oxidation) and therefore well suited for aChemically stable (no oxidation) and therefore well suited for a

large number of cycles without degradation. • The phenomenon of supercooling is limited and they are

compatible with all containers of metal.• Disadvantages

• Special attention is to be taken with the plastic containers for paraffin tends to seep in and soften some plastics. p p p

• Low thermal conductivity which presents a problem when heat fluxes are high. The use of a metal fins can solve this problem.

• Paraffins undergo a strong change in volume between the solid g g gand liquid phases, which poses many problems in the design of container.


Ref. : - -

Hydrated salts

• Hydrated salts are the oldest and most studied. • They consist of a salt and water, which combine in a crystalline matrix

when the material solidifies.

Ad• Adavantages• Low cost and large supply • Precise melting point and high thermal conductivity compared to the

paraffinsparaffins.• Change in volume between the solid and liquid phases, lower than other

PCM.

• Disadvanatges• Sensitive to segregation (transformation into other hydrates of salts which

tend to precipitate and reduce the active volume for the thermal storage), • S iti t i id ti• Sensitive to air oxidation.• Sensitive to the phenomenon of supercooling (The liquid continues to cool

without solidifying).


Ref. : - -

Solid/Solid PCM

• Undergoes a transition between two solid phases, for example between two crystalline phases or meso-crystalline.

• Does not become liquid during use• Does not become liquid during use.

• Generally polymeric compounds.y p y p

• Typically, the solid-solid latent heats are less efficient (slow transformation) but more convenient to use because not withintransformation) but more convenient to use because not within a liquid phase.

• The cost of the most important manufacturing makes them attractive for applications in small volumes.


Ref. : - -

Criteria of choice for Missile Electronics

• Our choice for the melting temperature of PCM to assess was based on two findings:

• The first is that the maximum temperatures generally achieved byThe first is that the maximum temperatures generally achieved by the structure of on-board equipment are around 80°C in the air

• Above 80°C, traditionnal cooling system are no more efficient.• The initial temperature of the structure can be around 50°C due to• The initial temperature of the structure can be around 50 C, due to

solar radiation.

• We therefore chose the PCM ith melting temperat re close to• We therefore chose the PCM with melting temperature close to 80°C.


Ref. : - -

PCM chosen

• Many worldwide PCM providers have been identified

• For MBDA purposes, 3 type of products have been purchased on the same European sourcep

• Technical characteristics :

Phase change Heat Latent Specific thermal

PCM type Temperature (°C)

Density (Kg/m3)

capacity (KJ/Kg)

heat (MJ/m3)

heat (KJ/Kg°C)

conductivity (W/mK)

Salthydrate 83 1600 152 243 2.31 0.62Paraffine 82 850 170 182 2.21 0.22Solid/Solid 80 1120 192 215 2.3 0.335


Ref. : - -

Test vehicle

• As the PCM have low thermal conductivities the test vehicle must leaveconductivities, the test vehicle must leave the best heat flux on the PCM. This is why it was chosen to use a container with metal fins.s

• A heating resistor in the size of the piece is stuck under the vehicle test to distribute temperature.

• To optimize the distribution of heat this test vehicle is made of copper, and isolated from the installation. A Plexiglas cover completes the package.

• A thermocouple is located inside the PCM, a second level of the heating resistor.


Ref. : - -

Implementation of PCM

• Paraffin : 47.4g

• Salt hydrated : 44 6gSalt hydrated : 44.6g

• Solid/solid : 53.44g


Ref. : - -

Theoretical and 2D simulation hypothesis

• Theoretical calculation :• Hypothesis that the flow is uniformly distributed in the PCM, and

there is no convection.• Storage duration = (latent heat * density * volume)/(Dissipated

power)

• 2D simulation :H th i i t l ti d i h h i t t k• Hypothesis : internal convection during phase change is not taken into account. Overheating is not taken into account also.

Zone de symétrie Résultat 2D Expansion visuelle

• 3D simulationZone de symétrie Résultat 3D


Ref. : - -

Overall results

• Experimentation has been performed on the 3 PCM and compared to theoretical values and simulation results :

• For 20W input :

Analytical model 2D model 3D model Measurement Paraffin 12 min

7 min

5 min

12 min @ 79°C

Hydrated salt 17 min 16 min 18 min 23 min @ 80°C y

@

Solid Solid 21 min

21 min

26 min

23min @ 82°C


Ref. : - -

Hydrated salt results example

• 2D and 3D simulation 100

110

120

130

(°C

)

results :

50

60

70

80

90

Tem

péra

ture

• Experiment results 40

0 500 1000 1500 2000 2500 3000 3500

Temps (s)

modele 2D S83 modele 3D S83Block with PCM S83

140

100

120

110

60

80

100

mpé

ratu

re (°

C) Côté Bloc

Centre1Centre2Centre3

84,7

75,5°C 72,1°C76

20

40

60

Tem Centre4

19 min23 min


Ref. : - -0

20

0 2000 4000 6000 8000 10000 12000 14000 16000

Time (s)

25 min 48 min 86 min103 min

122 min

Application on missile electronics

• Mechanical architecture : split components

PSU Board

M h i l S t

CPU Board

Mechanical Supports& PCM Heat Sinks

Th l Shi ldThermal Shield

FPGA Board

I/O Board


Ref. : - -


• Mechanical architecture has been optimized by implementing PCM on the mechanics as close as possible to the hot points

t d b th l t igenerated by the electronics• PCM used was hydrated salt @58°C • Total PCM mass is 32 6gTotal PCM mass is 32.6g


Ref. : - -


• Thermal management with external body heating and 80W total components heating (initial temp @50°C)

• The temperature is 120°C at the end of the test (575s) without PCM• The temperature is 85°C at the end of the test (575s) with PCM.


Ref. : - -

Conclusion

• PCM thermal performance is suitable for electronic missile applications.

• It enables to use high dissipation components into small• It enables to use high dissipation components into small mechanical shapes for small time missions

• Some points must be assessed• Management of PCM liquid phase into the mechanics• Aging of PCM during missile lifetime• Aging of PCM during missile lifetime• PCM vs container regarding oxidation


Ref. : - -

phase change materials for missile electronics vi/vi-3.pdf · phase change materials for missile...

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