075582814553
Traditional air cooling can still work for normal server loads, but it often struggles when many high-power CPUs, GPUs, and accelerators are placed close together. Single-phase liquid immersion cooling offers a different solution by placing electronic hardware directly into a non-conductive dielectric fluid. This article explains how single-phase immersion cooling works, what problems it solves, and more.
Single-phase liquid immersion cooling is a cooling method where servers, processors, GPUs, and other electronic components are placed inside a tank filled with dielectric fluid. This fluid is non-conductive, so it can safely touch electrical parts without causing short circuits. Its main role is to absorb heat directly from the hardware and move that heat away from the equipment.
It is called single-phase because the coolant remains in liquid form during normal operation. It does not boil, evaporate, or change into vapor. This makes it different from two-phase immersion cooling, where the fluid changes from liquid to vapor and then condenses back into liquid.
This cooling method is mainly used in high-density computing environments where air cooling may no longer be enough. It is useful for data centers, AI servers, high-performance computing systems, and other applications that produce high heat in a small space. By removing heat directly from the components, it can improve temperature control, reduce the need for fans, lower noise, and support higher power density.
In a single-phase immersion cooling system, the server rack or electronic hardware is submerged in dielectric coolant. As the components operate, they release heat into the surrounding liquid. The coolant absorbs this heat more directly than air, which helps keep the hardware at a more stable operating temperature.
As shown in the diagram, the warmed coolant leaves the top of the server rack and flows toward the coolant distribution unit. This unit manages the movement of the liquid and sends it through the cooling path. A pump keeps the coolant circulating so heat can be continuously removed from the system.
The heated coolant then passes through a coolant-to-water heat exchanger. In this part of the system, heat from the dielectric fluid is transferred to another cooling loop, such as a water loop. Once the coolant has released its heat, it returns to the immersion tank at the required temperature.
The remaining heat is removed through a final heat rejection system, such as an evaporative cooling tower, dry cooler, or existing chilled water loop. After this process, the same liquid continues circulating through the system. Since the coolant stays liquid throughout the cycle, the system is simpler than two-phase immersion cooling while still providing effective cooling for high-density data center equipment.
Immersion cooling helps solve the problem of high heat produced by modern servers, GPUs, CPUs, and power components. As data centers use more powerful hardware for AI, cloud computing, and high-performance computing, more heat is generated in a smaller space. Traditional air cooling can struggle to remove this heat evenly, especially when many high-power components are placed close together. Immersion cooling improves heat removal by allowing the coolant to touch the components directly and absorb heat more efficiently.
Air cooling depends on fans, airflow paths, heat sinks, and room-level cooling systems. This can become less effective when rack power density increases. If airflow is blocked or uneven, some areas may become hotter than others. Immersion cooling reduces this problem because heat is transferred into the liquid instead of relying only on moving air. This makes it easier to cool high-density equipment without needing larger fans or more complex airflow designs.
Hot spots are areas where certain components become much hotter than the rest of the system. They often happen around CPUs, GPUs, memory modules, and power delivery parts. These hot spots can reduce performance, shorten hardware life, or cause thermal throttling. Immersion cooling helps by surrounding the hardware with coolant, which spreads and removes heat more evenly from critical components.
In air-cooled systems, fans must work harder as heat output increases. This uses more power and creates more noise. In large data centers, fan energy can become a major part of total power use. Immersion cooling can reduce or remove the need for server fans because the liquid handles most of the heat transfer. This can lower noise levels and reduce the power used for internal cooling.
As computing demand grows, data centers often need to fit more power and performance into the same physical space. Air cooling can limit how much hardware can be placed in one rack because too much heat becomes difficult to manage. Immersion cooling supports higher power density by removing heat more directly from the hardware. This allows more computing capacity in a smaller area when the system is designed properly.
Rapid changes in workload can cause server temperatures to rise and fall quickly. This is common in AI training, cloud computing, rendering, and high-performance computing tasks. Unstable temperatures can affect performance and reliability. Immersion cooling helps keep temperatures more stable because the liquid can absorb and carry heat away continuously during operation.
Traditional cooling systems may require strong airflow, large air-conditioning units, and careful room temperature control. This can waste energy, especially in facilities with high heat loads. Immersion cooling can reduce cooling energy demand by transferring heat more efficiently from the hardware to the cooling loop. This can help improve overall data center efficiency, especially in high-density environments.
New processors, GPUs, and AI accelerators continue to increase in power consumption. Some future hardware may be difficult to cool with air alone. Immersion cooling helps prepare data centers for higher-performance equipment by offering a stronger cooling path. It gives operators more flexibility when planning for next-generation servers and high-power computing systems.
• Immersion tank – Holds the servers and dielectric coolant.
• OEM servers – The electronic equipment placed inside the cooling tank.
• Dielectric coolant – A non-conductive liquid that safely surrounds the hardware and absorbs heat.
• Warm coolant output – The heated coolant leaving the server area after absorbing heat.
• Cold coolant input – The cooled dielectric fluid returning to the tank to absorb more heat.
• Coolant circulation path – The flow route that moves coolant between the tank and the cooling unit.
• Heat exchanger – Transfers heat from the warm dielectric coolant to a separate water loop.
• Cold water input – The cool water entering the heat exchanger to absorb heat from the coolant.
• Warm water output – The heated water leaving the heat exchanger after collecting heat.
• Pump or coolant distribution unit – Moves the coolant through the system and keeps circulation steady.
Dielectric fluids are non-conductive liquids used in immersion cooling systems. They allow servers, processors, GPUs, and circuit boards to be placed directly in the fluid without causing electrical short circuits. Their main job is to absorb heat from the hardware and carry it away from the system.
In single-phase immersion cooling, the fluid stays in liquid form. It does not boil or turn into vapor. The warm fluid moves to a heat exchanger, releases heat, and then returns to the tank as cooler fluid.
Common dielectric fluids include mineral oil-based fluids, synthetic hydrocarbon fluids, and ester-based fluids. Each type has different costs, cooling performance, viscosity, safety, and material compatibility. The fluid must work well with cables, plastics, seals, connectors, and other server materials.
Choosing the right dielectric fluid is important because it affects cooling efficiency, maintenance, hardware life, and system reliability. A good fluid should transfer heat well, remain stable over time, and be easy to monitor and maintain.
As mentioned above, single-phase immersion cooling uses dielectric fluid that stays in liquid form throughout the cooling process. The liquid absorbs heat from the hardware, moves through a heat exchanger, and returns to the tank after cooling. This makes the system easier to understand, operate, and maintain because it does not depend on boiling or vapor control.
Two-phase immersion cooling works differently. In this system, the dielectric fluid boils when it contacts hot components. The liquid changes into vapor, rises inside the tank, and then condenses back into liquid through a condenser. This phase-change process can remove heat very effectively, especially in extremely high-power systems, but it usually requires a more controlled and complex design.
| Feature | Single-Phase Immersion Cooling | Two-Phase Immersion Cooling |
| Coolant behavior | Stays liquid | Changes from liquid to vapor |
| Heat transfer method | Circulating liquid and heat exchanger | Boiling and condensation |
| System complexity | Simpler | More complex |
| Maintenance | Easier to service | Requires tighter control |
| Cooling strength | Good for high-density servers | Better for extreme heat loads |
| Cost | Usually more practical | Often higher |
| Best use | Data centers, AI servers, HPC, and general high-density cooling | Advanced systems with very high thermal demand |
Air cooling is the traditional method used in most data centers. It removes heat by moving air across heat sinks, fans, and server racks. This setup is familiar, easy to service, and suitable for standard workloads. However, as servers become more powerful, air cooling can struggle to manage heat evenly, especially in racks with high-power CPUs, GPUs, or AI accelerators.
Single-phase immersion cooling uses a different approach. Instead of depending on airflow, the hardware is placed in dielectric liquid that absorbs heat directly from the components. This gives the system stronger thermal contact and helps reduce hot spots in dense computing environments. It is useful when air cooling can no longer keep temperatures stable without using more fan power or larger cooling systems.
Most facilities already support air cooling, and technicians are familiar with its maintenance process. The main advantage of single-phase immersion cooling is higher cooling capacity in a smaller space. It can support denser hardware layouts, reduce fan noise, and improve thermal control, but it also requires special tanks, coolant handling, and compatible hardware.
| Factor | Air Cooling | Single-Phase Immersion Cooling |
| Best for | Standard server rooms and normal rack loads | High-density racks, AI servers, and HPC systems |
| Setup | Uses existing airflow-based infrastructure | Needs immersion tanks and coolant circulation |
| Heat control | Can be limited by airflow paths | Provides direct liquid contact with components |
| Noise | Fan noise is usually present | Fan use can be reduced or removed |
| Maintenance | Easier for most technicians | Requires coolant handling and different service steps |
| Space use | Needs airflow clearance around equipment | Allows more compact high-density designs |
| Cost | Lower initial cost | Higher setup cost but useful for heavy workloads |
Immersion cooling and direct-to-chip cooling are both used to manage heat in high-power servers, AI systems, and data centers. The main difference is how they remove heat from the hardware.
In single-phase immersion cooling, the server or electronic components are placed inside a tank filled with dielectric fluid. The liquid surrounds the hardware and absorbs heat from many components at once. In direct-to-chip cooling, liquid flows through cold plates attached only to high-heat parts such as CPUs, GPUs, and accelerators. It keeps a more traditional rack design, but it still needs pumps, tubes, fittings, and careful leak control.
| Factor | Single-Phase Immersion Cooling | Direct-to-Chip Cooling |
| Cooling method | Hardware is submerged in dielectric fluid | Cold plates are attached to hot chips |
| Cooling coverage | Cools many components at once | Mainly cools CPUs, GPUs, and accelerators |
| Server design | Needs immersion-ready setup | Keeps a more standard rack format |
| Fluid type | Non-conductive dielectric fluid | Usually water-based coolant loop |
| Maintenance | Requires tank access and fluid handling | Requires checking tubes, fittings, and cold plates |
| Best use | Very dense systems and full-server cooling | High-power chips in rack-based data centers |
| Main challenge | Hardware compatibility and coolant handling | Leak control and cold plate coverage |
• AI data centers – Used to cool high-power GPUs and AI accelerators that generate heavy heat during training and inference.
• High-performance computing – Helps manage heat in systems used for simulations, research, engineering, and complex calculations.
• Cloud and enterprise data centers – Supports higher rack density and better cooling when traditional air cooling becomes less efficient.
• Cryptocurrency mining – Reduces heat and fan noise in mining machines that run continuously.
• Edge data centers – Useful for compact sites where space is limited and efficient cooling is needed.
• Industrial computing systems – Helps protect and cool hardware used in dusty, hot, or airflow-limited environments.
• Power electronics – Used for converters, inverters, and power modules that need stable thermal control.
Single-phase immersion cooling is generally safe for electronics because it uses dielectric fluid, which does not conduct electricity. However, the fluid must still be handled properly. Data centers need clear safety procedures for filling tanks, removing servers, cleaning components, and preventing spills. Workers should also follow the coolant manufacturer’s handling guidelines.
Some dielectric fluids have higher flash points than others, so the chosen fluid should match the safety requirements of the facility. The system should also include proper monitoring, leak control, ventilation, and emergency procedures.
Environmental impact depends on the type of coolant used. Some fluids are designed to last a long time and may reduce cooling energy use, but they still need proper storage, filtering, and disposal. A coolant should not be released into drains or the environment. Used fluid must be handled according to local waste and environmental regulations.
Single-phase immersion cooling can help reduce fan power, noise, and sometimes water use, depending on the system design. However, it should not be called automatically “green” unless the fluid type, energy savings, maintenance process, and disposal method are properly considered.
Catalogue
FPGA / CPLD
Memory
MOS 
MCU 
DSP
OCEP
Secondary 
Other