Modern battery electric vehicles (BEVs) require high mileage capabilities and fast charging speeds to meet consumer demands. The 800V architecture facilitates rapid charing at rates exceeding 4C, generating significant heat that must be effectively managed. Current cooling methods such as cold plate cooling or indirect cooling with air are insufficient for efficient heat removal. Immersion cooling emerges as a viable solution.
Immersion cooling is the most effective method to achieve shorter charging times. In this process, the battery is completely immerged in a cooling liquid. The fluid can efficiently dissipate excess heat from the battery cells during the charging process. This allows the coolant to absorb much more heat in a short time than other cooling approaches.
To be suitable as an immersion coolant, a fluid must exhibit specific properties and meet certain requirements.
Reotherm® Fluids for Immersion Cooling of EV Batteries
LANXESS has developed a range of cooling fluids that can flow diretly around the battery cells. They do not conduct electricity, do not react with the various metals, plastics or rubbers that surround them, and they are able to flow well, no matter the temperature inside the battery pack. All these properties add to the requirements of high flame retardancy, high heat capacity an environmental compatibility.
Reotherm® E-Series
Reotherm® E-Series offer ultimate fire protection. Based on phosphate esters, these coolants are nonhazardous, non-conductive and highly flame-resistant.
Reotherm® HXL-Series
Reotherm® HXL-Series offer good fire protection and very low viscosity. There are biodegradable options available.
| Characteristics | Units | E-565 | E-577 | E-567 | HXL-9119 | HXL-9099 |
| Thermophysical Properties (20°C) | ||||||
| Density | kg/m3 | 918 | 943 | 1064 | 830 | 941 |
| Specific Heat Capacity | J/kg-K | 1948 | 1672 | 1489 | 2240 | 1971 |
| Thermal Conductivity | W/m-K | 0.133 | 0.136 | 0.131 | 0.138 | 0.138 |
| Visometrics + Low Temperature Behavior |
||||||
| Viscosity 100°C | cSt | 2.0 | 2.4 | 3.2 | 1.4 | 2.7 |
| Viscosity 40°C | cSt | 8.0 | 8.6 | 15 | 4.7 | 9.1 |
| Viscosity 0°C | cSt | 36 | 46 | 120 | 22 | 45 |
| Viscosity -40°C | cSt | 343 | 8500 | 225 | 650 | |
| Pour point | °C | -90 | -72 | -50 | <-65 | -68 |
| Chemical and Physical Properties | ||||||
| Water Content | ppm | <2000 | <2000 | <1000 | 20 | 300 |
| Acidity | mgKOH/g | <0.05 | <0.05 | <0.05 | <0.05 | 0.04 |
| Fire Safety | ||||||
| Flash Point | °C | 190 | 235 | 224 | 161 | 213 |
| Fire Point | °C | 240 | >300 | 176 | 235 | |
| Auto-Ignition Temperature | °C | 375 | >450 | >450 | 236 | 378 |
| Electrical Properties | ||||||
| Breakdown Voltage (rt) | kV | 228 | 70 | 65 | 52 | 48 |
| DC Resistivity (25°C) | GOhm-m | 1.2 | 0.7 | 0.4 | 3860 | 17 |
| DC Resistivity (25°C) | GOhm-m | 0.09 | 0.02 | 618 | 1 | |
These items are provided as general information only. They are approximate values and are not considered part of the product specifications.
Technical data sheet available upon request
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