Improving the Thermal Conductivity (TC) of Enhanced Performance Coolants (EPC) with inorganic additive nanotechnology

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Biotechnology OBJECTIVE: A compatible Organic Acid Technology (OAT) coolant with a 50% increase the thermal efficiency over traditional coolants that allows for improved performance of Future Vertical Lift, Unmanned, and ground vehicles. DESCRIPTION: Develop an advanced Nitrate Free Organic Acid Technology (OAT) based coolant with improved thermal efficiency of at least 50% to reduce coolant needed or improve heat rejection/reliability of affected systems. In May of 2022 DEVCOM Ground Vehicle Systems Center released a technical report in support of the Army converting to modern OAT based coolants. Heavy Duty OAT based coolants are very attractive with up to a five (5) year lifespan versus traditional Supplemental Coolant Additives (SCA) based coolant which have annual service requirements. However, this OAT chemistry only improves the thermal efficiency on average of 2% under laboratory conditions. The reference report by DEVCOM and conducted by SWRL showed OAT coolants at a 60/40 mixture with a thermal conductivity average of 0.4046 (W/mk) versus traditional SCA coolants with a thermal conductivity average of 0.3892 (W/mk). If inorganic additive nanotechnology were added to OAT coolants, a thermal conductivity of approximately 0.60 (W/mk) could be realized while maintaining all legacy performance requirements of the fluids. The new coolant (OAT plus inorganic nano additives) must perform across a wide temperature range between -60 C and 60 C ambient and be compatible to all liquid cooled Army platforms. Thermal efficiency increases of 50% would allow armored vehicles with little airflow to operate more efficiently, UAVs with liquid coolant to reduce operating weights and allow the ARMY to have a single, universal coolant for all vehicles for the next generation of warfighter. PHASE I: Identify and baseline current OAT coolants. Building upon the previous research conducted by DEVCOM, investigate various inorganic additive materials technology to optimize the thermal efficiency by 25-50% on the two final candidates for OAT/EPC coolants. Demonstrate thermal efficiency while having minimal impact on viscosity, foaming, cavitation, corrosion and without precipitation over an extended service life; begin laboratory benchtop testing on materials candidates. Testing to include by not be limited to: 1. Glycol Content (%) via Refractometer 2. ASTM D1287-11 Standard Test Method for pH of Engine Coolants and Antirusts 3. ASTM D5931-20 Standard Test Method for Density and Relative Density of Engine Coolant Concentrates and Aqueous Engine Coolants by Digital Density Meter [10] 4. Thermal Conductivity and Specific Heat using C-Therm TCi Thermal Conductivity Analyzer PHASE II: Refine and optimize the materials selected in Phase I and develop and deliver prototype OAT plus nano additive coolant for additional benchtop ASTM laboratory testing as needed. Begin long term field trials on selected ground and air warfare systems. Request OEM participation where available. PHASE III DUAL USE APPLICATIONS: Transition technology to the U.S. Army for adoption and use by specific platforms. Continue long term field trials with monitoring teams. Finalize packaging requirements Integrate this technology where current SCA technology is being utilized. Investigate where cooling systems can be made more efficient due to new EPC cooling technologies. REFERENCES: 1. https://apps.dtic.mil/sti/citations/AD1170629 2. https://www.sciencedirect.com/science/article/pii/S0142727X99000673 3. https://www.ijert.org/a-review-on-nanofluids-the-next-super-coolant-for-radiator KEYWORDS: Enhanced Performance Coolants (EPC), Organic Acid Technology (OAT), GVSC's Ground Systems Fluids and Fuels (GSFF), UAS, Future Vertical Lift (FVL), Nanotechnology, Nanofluids, Nanocoolant