microclimate cooling for military vehicle crews
TRANSCRIPT
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Microclimate Cooling for Military Vehicle Crews
SAFE Europe – March 31st 2010Stephen Hunter – Product Specialist
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Established 1958Operations worldwideFamous GORE-TEX® andWINDSTOPPER® products4 divisions– Electronics– Medical– Industrial– Fabrics
Technically Oriented FabricsGore specializes in the development of highperformance protective apparel for the harshand demanding environments routinelyencountered by military forces, fire servicesand outdoor workers throughout the world.
W. L. Gore & Associates
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Heat Stress – A Hot Topic
• Numerous countries havetroops operating in very hotclimates.
• Risk of disablement and evendeath due to heat stress is veryreal.
• Politically high profile.• Recognised need for an
effective personal coolingsolution for foot mounted troops.
• Vehicles represent a particularlysevere problem.
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Heat Stress and Core Temperature
As exercise and exposure to heat increases, heart rate increases, blood flow toskin increases, skin temperature increases, body core temperature goes up.
Hypothermia HyperthermiaNormalHeat
Stress
34 C 36-37 C 39 C
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Heat Stress Habitability and Performance
Def Std 0035
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Testing to quantify the Effects of Heat Stress
• Goalunderstand the influence of thermal stress onvigilance
• Conductionauditory signal detection while walking on atreadmill in different temperature conditions
• FindingIncreasing body temperature impairs attentionand vigilance
Heat Stress Diminishes Vigilance
–Source: From et al, J. o. Occ. Med., Vol. 35, No 7, 1993, p 271 ff
0
10
20
30
40
50
37 38 39 40
Core Body Temperature [ C]
Missed signals [%]
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Heat Stress Affects Performance
Study• Goal
Find out why there are many morecrashes in summer
• Investigation of temperaturedistribution of days with and withoutaccidents and near miss occurrences
• FindingHigher heat stress on hot dayssignificantly increases the chance ofsevere pilot errors.
0
1
2
3
4
5
6
7
24°Candlower
25 to29°C
30 to34°C
35°Candhigher
Source: Froom et al, J. o. Occ. Med., Vol. 35, No 7, 1993, p 271 ff
Heat stressed helicopter pilots are more likely to crash
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Conditions inside an Armoured Vehicle
Crew-spaceTemperature
Outside air temperature(environmental conduction)
Vehicle Engine
SolarRadiated Heating
Vehicle ElectronicSystems
Crew
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Interior Temperatures in AFVsVehicle Type Location Ambient temp ( C) Interior Temperature
Degrees above ambient(Average) (Max)
M114 ARV Driver 33 - 45 7.2 16Crew 7.8 16.7
M113 APC Crew 40 - 42 5.5 11LVTPX 12 Driver 35 - 43 3.3 7.8
Commander 5.5 11Cargo 6.6 8.3
M109 SPH Crew 37 – 44 6.1 8.9Driver 7.8 11
M60 tank Turret 32 – 45 5.0 11
Average temperature range 32 – 45.5Average temperature above ambient +7.3 +13.2
Potential temperatures in vehicle 39.3 C – 58.7 CData taken from “Medical Aspects of Harsh Environments” Vol. 1 (2001) Ralf GoldmanChapter 1 “Introduction to Heat-Related Problems in Military Operations”
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
The Cost of Traditional Cooling
• Goal is to avoid crew core temperature going above 37.5 C• Traditional approach is to cool the whole crew space with an
Environmental Control System.• This has a direct impact on vehicle design and performance.
Powerrequired tocool crewspace
Environmental temperature
Weight,spaceand costfor ECS
Range, speed &manoeuvrability ofvehicle.
Hatches open or closed ???
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Cooling Strategy Efficiency Trade-off
Efficiency
PowerRequired
MACRO-CLIMATE MICRO-CLIMATE
Def Std 0035Ambient temp
of 21 C
(Individual Cooling Vest)Spot CoolingDirected Air
Crew Core TemperatureMaintained below 37.5C
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Individual Cooling Solutions
Evaporativeor
Forced Air
LiquidCirculation
Phase ChangeICE / GELL
Wicking Materials
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Depends onambience
conditions andclothing
Ideal Set point 37°C
Basicmetabolic heat
production
Dry / Conductive /Convective heat
loss
Activity increases set point
Metabolic heatproduction due toactivity
~30°C
~41°C
Core BodyTemperature
Depends onbody weight
~80W for75kg
Body Thermal Control Process
Evaporative heat loss.Sweating mechanismdrives missing heat loss
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Skin Surface
Evaporating sweat
Heatloss
Heat loss through Sweating
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Advantages of a forced air system
• Facilitates the Body’s natural thermal control process –Sweat evaporation
• Utilises systems already present in the vehicle – ECS• If not, the power, weight, space impact is least• Practical in tethered and untethered format• Very low logistic burden
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
The Gore Active Cooling Concept
EFFICIENT COMFORTABLE SAFE
• Active Cooling Vest worn under body armourclose to skin (typically over UBACS).
• The vest provides an efficient way ofintroducing air to the skin surface
• Cooling is achieved by removing saturatedair, and enhancing the rate of sweatevaporation, at skin level.
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
• Garment is a 2 layer construction.– Both layers have ‘Bump’ spacers to
create air paths.– Outer layer is impermeable.– Inner layer is controlled
permeability.• Air, pumped between the layers passes
through inner permeable layer towearers torso.
• Sweat evaporation facilitated byremoving saturated air.
• Blood cooled at skin level circulatesand helps regulate core temperature.
CoolSkin
Saturated Air out
Dry Air in
Structure and Operating Principle
HotSkin
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Cooling Air Supply
Untethered SystemSelf contained rechargeable Blowers
Tethered System – Air from vehicle ECS
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Designed for fixed crew positions.(Predominantly in vehicle).
Operates with air from vehicle ECS.
Tethered Variant
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Cooling Performance – Vehicle Crew Version
This performance information was derived from independentlyconducted habitability testing for the Titan and Trojan (UKMOD armoured engineering vehicles).
The habitability requirement was considered failed in two crewpositions even without IPE.With the Gore Active Cooling Vest worn, all crew positionspassed, with full IPE being worn in both A1 and B2 conditions.A test with full IPE and no cooling vest was not conducted asthe risk to participants was deemed too high.
No cooling vest, no IPE
With cooling vest and full IPE
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Untethered Variant.
For dismounted troops or non-fixed crew positions.Self contained for out of vehicle use.
Can charge in vehicle.
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
• Based on Def std 0035– 45 C (10% RH), UK BDU + CBA + 19kg
load, 5km/hr on treadmill• Demonstrated stabilisation of core temperature
and doubling of work-time (reduction in restperiods) @ 6hrs in conditions
• Cooling Power and distribution maintainedunder compressive loading
• Excellent distribution of cooling effect
Cooling Performance - Foot Mounted Version
Skin temperature in different body zones comparedwith non cooled
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Longer Work Periods – Shorter Rest Periods
61
38.5
36.0
37.0
38.0
60 120 180 240 300
71
38.5
36.0
37.0
38.0
60 120 180 240 300
No Vest
With Vest
22
16
40
2336
14
19
30
3640
17
25
20
25
Work 120 mins
Rest 134 mins
Work 161 mins
Rest 80 mins
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Main Garment Features
Integrated Dual Blowers• Convenient side location• Low profile• Dust Filtration• 6 hour duration• Very quiet in operation
Soft, Light Materials
One Size Fits All
Left Hand/ Right HandConfiguration
Easy connection to vehicle ECSSnap in and easy release hose connectors
Comfortable to wear
Non burn or meltAir transport layers
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
• Tethered– Habitation Trials by Qinetiq (2007)– A1 A2 A3 and B2 conditions– System met the requirements– Failure with no vest
• Untethered– Portsmouth University dept of Sports
Physiology (July 2007)– Met concept of doubling workload @ 6hrs
in conditions– Qinetiq March 2010
• Field trials conducted in Turkey,Morocco and Iraq.
• Extensive in house laboratorytesting.
Validation and Testing
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Role Compatibility
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
The Challenges of System Evaluation
• Physiological effectiveness is proven• Several trials have now demonstrated core temperature control
under body armour using ambient air temperatures up to 46 C• User perceptions are more challenging
– It’s an extra layer– Does it add more thermal burden when off?– Cooling “sensation” can be subjective
• Body reacts to change• Normalisation is unremarkable once achieved
– Side by side comparison not easy to make• Education, expectation and briefing is key.
© 2008 W L Gore & Associates GORE® and designs are registered trade marks of W L Gore & Associates
Cool The Man Directly – With Air !!
Vehicle Benefits• Save power• Save weight• Save space• Gain range• Gain manoeuvrability
Crew Benefits• Control core temp• Better performance
– Situational awareness– Reaction Time– Cognitive ability
• More comfortable