Passive and Active Soldier Armor cooling enhance soldier performance in extreme environments

Rajesh Uppal July 31, 2022 Energy & Propulsion, Soldier Comments Off on Passive and Active Soldier Armor cooling enhance soldier performance in extreme environments 207 Views

The wearing of body armour provide troops an unparalleled advantage on the battlefield, improving survivability and reducing casualtiesis. It has also been very effective in reducing injuries and fatalities within the police force and correctional services.

This protection comes at a price, however. U.S. ground troops today carry an average of 27 pounds of personal protective equipment (body armor and helmet). This weight comes on top of an already heavy burden consisting of a weapon, ammunition, water, batteries, and other gear. Surveys from recent wars have found dismounted ground combat troops carrying 90 to 140 pounds or more in combat. Heavy loads reduce mobility, increase fatigue, and reduce mission performance.

Additionally, over the course of a mission, the weight has a cumulative effect of increasing soldier fatigue, further reducing physical and cognitive performance. In hot climates, the increased thermal load that comes from body armor trapping heat on the torso can also severely negatively affect soldier performance and risk heat injury.

Soldiers can work in extreme conditions, where different negative influences from the surrounding area act on them. Besides high temperatures above 30°C, there is also the possibility of fire, water, dust, and mechanical loads.

One of the greatest problems occurs during thermal overload as the consequence of exposure to the weight of the equipment and the hours of activity. This means that when performing work in a warm environment, the temperature range of the human core (between 36°C and 38°C), as well as the temperature on the skin surface (between 20°C and 35°C), can change very quickly.

Slight deviations from the normal condition are acceptable for short periods of time, however, long-term exposure to heat can have a negative impact. Dangerous situations, injuries and perhaps even death are possible, the reasons for which have often been studied.

The military has been trying to solve the problem of cooling soldiers efficiently for several decades. The insulating properties of protective body armor increase the risk of dehydration, heat stroke, and performance loss for those who wear it, as their bodies cannot offload the heat trapped by the armor.

Typical cooling mechanisms require power or add significant weight to operator kit, making them ineffective and impractical. Thus the US military spends hundreds of millions of dollars in hydration bladders and bottled water to replenish and rehydrate operators in the field after they have already begun to experience dehydration.

However, coupled with the extreme temperatures of modern conflict areas, rehydration is insufficient. Operators working at even moderate levels produce 2L/hour of sweat as their bodies work to keep core temperature from elevating, while exercise research has shown water intake rates of greater than 0.5L/hour are unsustainable. As dehydration of even 2% of body weight substantially reduces performance, operators are required to reduce their work output to compensate.

Quartermaster guidelines show that moving from hot to temperate conditions lowers recommended soldier water requirements by up to 50%. Thus cooling, if effectively and efficiently applied, can significantly reduce water requirements and better balance soldier sweat versus water intake rate, substantially improving hydration and, in turn, performance.

Mostly, the soldiers’ uniforms do not ensure the optimal thermal balance which could prevent overheating. This area is still the subject of numerous researches. Progress continues towards passive (zero-energy) and active cooling systems, optimising the user-friendly and functional use in order to abolish the deficiencies, such as the reactivation of the cooling effect, unfriendly handling, difficult maintenance and use with other layers of the clothing system

Passive Systems for Cooling

The passive systems for cooling down soldiers, developed in cooperation with the army and the police at Prevent & Deloza especially for wearing under ballistic protection, are suitable for use in any weather and any climate zone, reported in 2017.

The Prevent & Deloza system is composed of knitwear, that efficiently extracts heat and moisture from underneath the ballistic protection. Additional functional material provides the quickest evaporation of excess moisture and ensures an adequate extraction and storage of excessive heat. Already, the system manufactured in this way, substantially reduces the heat load on a person. By adding the evaporative part of the system, we ensure cooling of the person wearing ballistic protection, namely by an additional 3°C already after thirty minutes of activity.

From a functional perspective, in extremely hot environmental conditions, the simplest and the most efficient products are recommended, regarding handling, maintenance, mobility and reactivation of cooling. An example of such products are systems of material combinations, integrated into cooling shirts, under-helmet hoods, trouser legs and elbow pads. The cooling effect lasts for more than 12 hours of active use, then the cooling pads are simply soaked in water, and the effect of cooling is reactivated. This means that only cold water is required to use the product.Such products not only help to maintain normal body temperature but also protect the user from possible burn injuries.

Active cooling Systems

Soldiers can wear the Light-Weight Environmental Control System, or LWECS, directly against their bodies. A small battery that fits inside body armor powers the system, according to the U.S. Defense Department (DoD), reported in 2014.

“It’s the same technology that’s in your air conditioner or in your refrigerator, except instead of conditioning air, it chills a fluid. And then it pumps that fluid through a tube-lined cooling vest,” Brad Laprise, a mechanical engineer at the Natick Soldier Research, Development and Engineering Center (NSRDEC) in Natick, Massachusetts, told Armed with Science, the DoD’s science blog. [7 Technologies That Transformed Warfare]

The cooled fluid travels through approximately 110 feet (34 meters) of tubing coiled inside the vest, which is worn against the skin. Though the unit that cools the fluid is small, measuring only 3.5 inches (9 centimeters) across, it provides 120 watts of cooling power, about the same as a small refrigerator, according to Laprise.

Helicopter pilots and their crews already use aircraft-mounted cooling systems to beat the heat. But while these systems have been shown to improve endurance and performance levels in hot climates, many crewmembers avoid using them because they tend to be inconvenient.

Such onboard cooling devices are equipped with tethers that soldiers need to attach themselves to in order to cool down. But moving around the back of a cramped helicopter on a tether is no easy feat, the researchers said. The new, tether-free system is expected to resolve this and other issues associated with staying cool mid-flight.

Air Force advancing body armor cooling system

Justin O’Brien, a security forces airman, has invented the new system that can help eliminate this problem. It is a cooling system for body armor, made up of a water bladder carefully connected to a battery-powered pump.

“Anybody that’s worn a vest in any sort of hot conditions can relate to the situations that the warfighter, anybody that has to wear ballistic armor, have to face,” O’Brien said. “But security forces have a very specific role as having to wear it for eight to 10 hours every single day.”

After promoting his personal cooling system at a Spark Tank event in 2020, 1LT Justin O’Brien is getting new R&D support from the Air Force Research Laboratory and a new prototype was constructed in December. In 2020, the Air Force filed for a 20-year U.S. utility patent, listing O’Brien as the inventor.

And the Air Force wants to out-license the patent to companies that will commercialize the technology.

IcePlate Curve, reported in Dec 2021

It is a reusable water bottle shaped like a Medium ESAPI armor plate that when frozen provides 140+ watts of cooling using the 100 ounces of water already carried by warfighters to maximize hydration efficiency beyond simple consumption when worn front and back. The IcePlate Curve helps body armor users stay safer, lighter, more hydrated, with cooler core body temperatures while wearing their protective armor. IcePlate solves the issues of warfighter cooling, heating, hydration, endurance and heat injury prevention while dramatically enhancing military-wide logistical efficiency through decreased water demand and improved volumetric storage. IcePlate is made from ultra-durable, food-grade, BPA-free, FDA-approved High Density Polyethylene (HDPE); it can be refilled and reused if need be, but it is cheap enough to be expendable.

It contains no moving parts or batteries, and is without sanitary risk associated with ROWPU water. Highlights:

140+ watts of cooling when frozen (front and back IcePlates)
50+ ounce capacity per IcePlate
<12 oz. empty bottle weight
30%+ greater storage density vs. bottled water
Optimized for Pelican Coolers
Fits any body armor or plate carrier configuration
Can be worn with or without armor using Side Release Armor Straps
TotalDrain Technology ensures total consumption, reduced contamination risk
Screw top for easy refill and addition of electrolyte tablets
Recessed fill port minimizes injury risk to neck/throat area in blast events
Recyclable
BPA-free, FDA-certified HDPE construction
Made in USA from US Materials

IcePlate Curve can be worn between a Combat Shirt (or any base layer shirt) and a plate carrier. It is designed to be secured using any number of options. Drawing on the existing practice of war-fighters freezing bottled water before going out on patrol, IcePlate is worn and stored in a frozen state. Once deployed, body heat melts the ice; cooling the user and creating cool, clean drinking water simultaneously.

The tremendous cooling power of IcePlate has the potential to dramatically reduce the amount of water required by warfighters in the field. When comparing US Military bottled water consumption in hot versus temperate climates, water consumption drops by 50%. IcePlate could potentially simulate this effect by creating a temperate microclimate for the operator when wearing IcePlate during a hot season.