Specialized chiller systems are used when equipment, electronics, or industrial processes need precise temperature control. In these systems, the selection of coolant fluids for chillers is crucial, as the coolant is not just a fluid that moves heat. It becomes part of the system’s performance, safety, and reliability.
Standard coolants such as water, glycol, or oil work well in many industrial applications. However, they may not be suitable when the cooling loop is used near electronics, sensitive components, low-temperature processes, or equipment originally designed around 3M™ Novec™ or Fluorinert™ fluids. For these applications, BestSolv® fluids include exact molecule replacement options designed to help support continuity in systems that previously relied on discontinued 3M™ fluids.
BestSolv® Engineered Fluids support these specialized coolant applications by providing dielectric, non-flammable, low-residue heat-transfer fluids for demanding thermal management systems.
How a Chiller System Uses the Coolant Fluid
A chiller system controls temperature by circulating coolant through a closed loop. The fluid leaves the chiller at a controlled temperature, travels through the process or equipment, absorbs heat, and returns to the chiller to be cooled again.
In many specialized chiller systems, a BestSolv® heat-transfer fluid circulates through the equipment, absorbs heat, and carries that heat back to the chiller, where it is removed before the fluid is recirculated.
Single-Phase vs Two-Phase Cooling
Single-phase and two-phase cooling describe two different ways a heat-transfer fluid can remove heat from electronic equipment, processors, machinery, or other heat-generating components.
Single-Phase Cooling
In a single-phase cooling system, the coolant remains a liquid throughout the heat-transfer cycle. The fluid circulates through a cold plate, heat exchanger, cooling loop, or immersion system and absorbs heat as its temperature increases. It then carries that heat away from the equipment and releases it through a heat exchanger or chiller before circulating back through the system.
Single-phase cooling is commonly used because the system architecture can be relatively straightforward. Pumps circulate the coolant through the loop, and there is no intentional boiling or condensation of the heat-transfer fluid.
In data centers, single-phase liquid cooling may be used in direct-to-chip systems, where coolant flows through cold plates attached to CPUs, GPUs, or other high-heat components. Single-phase immersion systems may instead submerge electronics directly in a dielectric heat-transfer fluid that remains liquid during normal operation.
Two-Phase Cooling
Two-phase cooling intentionally uses both the liquid and vapor phases of the coolant. Rather than relying only on an increase in fluid temperature, heat from the electronic component causes the coolant to boil. The resulting vapor moves away from the heat source and is condensed back into liquid so the cycle can repeat.
Because the liquid-to-vapor phase change absorbs a significant amount of heat, two-phase cooling can provide high heat-transfer capability while limiting the temperature rise of the coolant at the heat source. This makes the technology particularly relevant as data centers evaluate ways to manage concentrated heat loads from AI, high-performance computing, GPUs, and other high-density electronics.
Two-phase cooling systems require equipment specifically designed to accommodate fluid boiling and condensation. Important considerations include the coolant’s boiling point, operating pressure, dielectric characteristics, material compatibility, vapor containment, condensation system, and fluid recovery.
Choosing Between Single-Phase and Two-Phase Cooling
Neither method is automatically better. The right choice depends on the amount of heat being generated, the desired operating temperature, the cooling-system design, maintenance requirements, and the properties of the coolant.
Single-phase cooling is often the better choice when circulating liquid can keep the equipment within its required operating-temperature range without needing the coolant to boil. Because the fluid remains liquid, the system is generally simpler to design, operate, and maintain. Single-phase immersion systems have been demonstrated with coolant inlet temperatures around 30°C to 50°C (86°F to 122°F), although the correct operating range depends on the hardware and fluid. In practical terms, if the equipment can stay safely within its target temperature while the coolant remains below its boiling point, single-phase cooling may provide the required performance with less system complexity.
The boiling point of the coolant still matters in single-phase cooling because the fluid must remain liquid during normal operation. BestSolv® 7100 boils at approximately 61°C (142°F), BestSolv® 7200 at 76°C (169°F), BestSolv® 7300 at 98°C (208°F), and BestSolv® 3283 at approximately 130°C (266°F). In a single-phase system, the normal operating temperature should stay safely below the fluid’s boiling point. System pressure can also affect boiling temperature, so operating temperature, pressure, and fluid selection should be considered together when designing the cooling loop.
Two-phase cooling is useful when the system is designed to take advantage of boiling for greater heat-transfer capability. In this approach, the coolant is intentionally allowed to boil as it absorbs heat from components such as CPUs and GPUs. The vapor is then condensed back into liquid so the cycle can repeat. This can be especially useful for high-density computing, but it requires equipment designed for vapor containment, condensation, pressure control, and fluid recovery.
For two-phase cooling, the boiling point helps determine the temperature at which phase-change cooling begins. A system designed to begin boiling at a relatively low temperature may use a lower-boiling fluid such as BestSolv® 7100 at approximately 61°C (142°F). Systems designed around higher operating temperatures may instead consider BestSolv® 7200 at 76°C (169°F) or BestSolv® 7300 at 98°C (208°F). BestSolv® 3283, with a boiling point of approximately 130°C (266°F), may be used in compatible single-phase or two-phase liquid-cooling applications where a Fluorinert™ FC-3283 replacement is needed.
There is no single ideal operating temperature or boiling point for every system. Single-phase cooling is generally attractive when liquid circulation alone can maintain the required equipment temperature and simpler equipment is preferred. Two-phase cooling becomes attractive when higher or more concentrated heat loads justify the added heat-transfer capability of controlled boiling and condensation.
Fluid selection must be matched to the equipment, desired operating temperature, system pressure, materials compatibility, and overall cooling-system design. For additional guidance, see our Thermal Management / Heat Transfer information.
A typical system may include a reservoir, pump, tubing or manifolds, a cold plate, chamber, bath, coil, heat exchanger, and controls for temperature, flow, and operating conditions.
In either approach, the system must be designed around the selected fluid.
Why Specialized Systems May Need More Than Water or Glycol
Water and glycol are common because they are effective and economical. The limitation is that they are not always compatible with sensitive thermal management requirements.
In electronics cooling, water-based fluids can create electrical and corrosion risk. In low-temperature systems, glycol mixtures may become too viscous or may not provide enough freeze protection for the full operating range. In direct-contact cooling, water or glycol may not be acceptable because the coolant could touch components that cannot tolerate conductive fluids.
Oil-based coolants can solve some electrical concerns, but they may introduce others. Higher viscosity can increase pump load and reduce flow through small passages. Oils may also leave residue, complicate cleanup, or create compatibility concerns with seals, plastics, or other materials in the loop.
BestSolv® fluids are used where the system requires a cleaner, dielectric, non-flammable coolant option with stable performance across the required temperature range.
What Makes BestSolv® Fluids Useful in Chiller Applications
For a coolant to work well in a specialized chiller system, it must do more than absorb heat. It must circulate efficiently, remain stable, avoid damaging system materials, and support the safety requirements of the equipment.
BestSolv® fluids are useful in these applications because of several combined properties:
| Fluid Property | Why It Matters in the Chiller System |
|---|---|
| Dielectric strength | Allows the fluid to be used near electronics or sensitive electrical components. |
| Low viscosity | Helps the fluid move through pumps, tubing, cold plates, and small channels with less flow resistance. |
| Thermal stability | Supports repeated heating and cooling cycles without rapid fluid breakdown. |
| Non-flammable performance | Helps reduce fire risk in enclosed, high-value, or sensitive equipment. |
| Low residue | Helps keep the cooling loop and equipment cleaner. |
| Material compatibility | Supports use with many common metals and hard plastics found in thermal systems. |
| Low-temperature flow | Helps maintain circulation in systems operating below the range of standard coolants. |
The value comes from the combination of these properties. A fluid may transfer heat, but if it creates electrical risk, freezes, thickens, leaks, or attacks system materials, it may not be suitable for the application.
Where BestSolv® Coolant Fluids May Be Used
BestSolv® fluids may be considered where standard coolant options create process risk or do not meet the system’s operating requirements.
Common specialized coolant applications include:
- Semiconductor tool temperature control
- Electronics cooling
- Power electronics cooling
- High-performance computing
- Data center immersion cooling
- Aerospace and defense electronics
- Environmental chambers
- Thermal shock and reliability testing
- Low-temperature process chillers
- Sealed heat-transfer systems
- Specialized machinery with precise temperature requirements
- Systems replacing 3M™ Novec™ or Fluorinert™ fluids
Each application should be reviewed individually. The right fluid depends on the temperature range, heat load, cooling method, system materials, dielectric requirements, and current or legacy fluid being replaced.
Important System Factors Before Selecting a Fluid
Temperature Range
The fluid must remain usable at the lowest and highest temperatures in the system. This includes startup conditions, normal operation, peak heat load, and any low-temperature hold points.
For low-temperature chillers, viscosity is especially important. If a fluid becomes too thick, the pump may struggle to maintain flow, which can reduce cooling performance.
Heat Load and Flow
The fluid, pump, tubing, and heat exchanger must be sized to remove the required amount of heat. Low-viscosity fluids can help maintain flow, but the total system design still determines how well the chiller performs.
A system with narrow tubing, small channels, or long fluid paths may need closer review because pressure drop can affect circulation.
Single-Phase or Two-Phase Design
Most process chillers use single-phase cooling, where the fluid stays liquid. This is simpler and common in closed-loop systems.
Two-phase cooling uses boiling and condensation to move heat. It can be effective, but it requires different equipment design and cannot be assumed for a standard chiller loop.
Dielectric Requirements
If the coolant may be used near energized electronics or sensitive electrical components, dielectric performance becomes a major selection factor. The fluid must help remove heat without creating an electrical path.
Materials in the System
BestSolv® fluids are compatible with most common metals, hard plastics, elastomers, seals, gaskets, tubing, adhesives, and pump components used in specialized cooling systems.
Material compatibility should still be reviewed for the specific system design, especially when unusual materials, custom components, or critical operating conditions are involved.
BestSolv® Fluid Options for Thermal Management
Best Technology offers several BestSolv® fluids for thermal management, heat transfer, immersion cooling, and specialized coolant applications. Some applications may require an exact replacement for a discontinued 3M™ Novec™ or Fluorinert™ fluid. In other cases, a different BestSolv® fluid may be suitable if the operating temperature range, boiling point, dielectric requirements, material compatibility, and system design align with the application.
BestSolv® Zulu may be considered for electronics cooling, immersion cooling, and heat-transfer applications where dielectric performance, non-flammability, and a lower boiling point fluid option are needed, as well as systems originally designed around Novec™ 649.
BestSolv® 7100 may be evaluated for thermal heat transfer, immersion cooling, and thermal management applications, including systems originally designed around Novec™ 7100.
BestSolv® 7200 may be considered for heat management, semiconductor applications, data center immersion cooling, and electronic or electrical applications, including systems replacing Novec™ 7200.
BestSolv® 7300 may be evaluated for heat-transfer and dielectric cooling applications, including systems that need continuity from Novec™ 7300 or a higher-boiling option than 7100 or 7200.
BestSolv® 3283 may be used in single-phase or two-phase liquid cooling applications where a Fluorinert™ FC-3283 replacement is needed. It may also be considered for other Fluorinert™ replacement applications when the operating requirements overlap.
BestSolv® 40 is designed for high-performance heat transfer in electronics, power systems, semiconductor fabrication cooling systems, aerospace electronics, and sensitive industrial equipment. It may be evaluated when replacing Fluorinert™ FC-40 or other thermal fluids with overlapping operating requirements.
Replacing 3M™ Novec™ and Fluorinert™ Coolants
Many specialized chiller and thermal management systems were originally designed around 3M™ Novec™ or Fluorinert™ fluids. These fluids were often selected because they provided a specific balance of boiling point, viscosity, dielectric performance, chemical stability, and material compatibility.
When replacing a discontinued 3M™ Novec™fluid, the goal is not simply to choose a product with similar general use. The replacement fluid should be reviewed against the original system requirements.
Important comparison points include:
- Original fluid used in the system
- Operating temperature range
- Boiling point or pour point requirements
- Viscosity at operating temperature
- Dielectric requirements
- Heat-transfer method
- Material compatibility
- Validation or qualification requirements
- Long-term supply needs
In some systems, a same-molecule replacement may help reduce disruption. In others, a similar-molecule or alternative BestSolv® fluid may be the better long-term option.
Talk With Best Technology About BestSolv® Coolant Fluid Options
BestSolv® fluids are available for specialized coolant and thermal management applications where standard fluids may not meet the system requirements.
Contact Best Technology to discuss your current fluid, replacement goals, and available BestSolv® options.
612.392.2414
