Two Phase Cooling Factory

With the rapid development of electronic information technology and manufacturing techniques, the application of high-power electronic components and devices has become increasingly widespread, leading to more prominent heat dissipation issues. Liquid cooling technology, as an efficient cooling method, is widely used across various industries due to its excellent energy-saving properties, cooling performance, and low noise. Liquid cooling technology involves using a liquid instead of air as the coolant to exchange heat with heat-generating components and carry away the heat. According to whether the cooling fluid undergoes a phase change during the heat exchange process, it is classified into single-phase liquid cooling and two-phase liquid cooling.

Single-phase liquid cooling refers to the process where the coolant remains in a liquid state throughout the heat exchange with the heat-generating component, without undergoing a phase change. In contrast, two-phase liquid cooling involves the coolant undergoing a phase change—specifically, vaporization—while absorbing heat from the heat-generating component. Clearly, in terms of heat dissipation efficiency, two-phase liquid cooling is superior to single-phase liquid cooling.

Heat pipes and vapor chambers are efficient heat transfer devices due to their high thermal conductivity resulting from phase changes during the cooling process, while the latest immersion liquid cooling represents a further innovation in two-phase liquid cooling technology. This article will introduce the applications of heat pipes, vapor chambers, and immersion liquid cooling in the thermal management industry to help you find a suitable thermal management solution.

Key Components of Two-Phase Cooling Devices: Heat Pipes and Vapor Chambers

Although heat pipes and vapor chambers have different names, their components and manufacturing processes are fundamentally similar. However, there are significant differences between immersion liquid cooling components and heat pipes and vapor chambers. Here, we will first introduce the key components of heat pipes and vapor chambers.

Outer Shell

The outer shell of heat pipes and vapor chambers is mostly made from seamless metal tubes. Depending on the specific requirements, different materials can be used, such as copper, aluminum, carbon steel, stainless steel, and alloy steel. The tubes can be standard circular shapes or special shapes, such as elliptical, square, rectangular, flat, or corrugated. The diameters can range from 2 mm to 200 mm, or even larger. The lengths can range from a few millimeters to over 100 meters.

Inner Core

To enable the vaporized liquid to condense and return, heat pipes and vapor chambers typically have a wick structure inside, which is a capillary structure. The main types of capillary structures currently used include grooves, mesh, sintered powder, fibers, and composite structures.

Working Fluid

Heat pipes use a variety of working fluids. Common ones include water (suitable for small devices like computer coolers), glycol and other organic compounds (commonly used in industrial heat pipes, suitable for a wide temperature range), and ammonia (high thermal conductivity but requires attention due to toxicity and corrosiveness). Vapor chambers focus more on efficient heat transfer, commonly using pure water as the working fluid, though other liquids may be used to meet specific needs. When selecting a working fluid, various factors must be considered.

Working Process of Two-Phase Cooling Heat sink

Before the heat pipe is in operation, the liquid level of the working fluid is flush with the core. When the heating element contacts the evaporating section, it transfers heat to the wall, core, and working fluid; the working fluid absorbs heat and vaporizes by taking in latent heat of vaporization. The vapor pressure in the evaporating section is higher than that in the condensing section, creating a pressure difference between the two ends. This pressure difference drives the vapor from the evaporating section to the condensing section. As the vapor condenses in the condensing section, it releases latent heat of vaporization, which is then transferred through the core and wall to the heat pipe's heat sink. Due to evaporation, the liquid level of the working fluid in the evaporating section forms a meniscus in the capillary pores of the core, creating capillary pumping force that pulls the condensed liquid back to the evaporating section, completing a working cycle. As long as the flow of the working fluid is uninterrupted and sufficient capillary pumping force is maintained, the heat pipe can operate continuously for a long time.

Heat Pipes

Heat pipes are common heat transfer devices typically made from copper or stainless steel. They have a wide range of uses. Depending on the need, they can serve merely as heat conductors or as heat dissipation components. For example, copper heat pipes are commonly used in CPU tower coolers to transfer heat to aluminum fins for dissipation. In cooling systems for high-power devices, water-cooling plates often embed heat pipes, which contain a coolant to efficiently absorb heat and undergo phase changes. Heat pipes utilizing two-phase cooling technology are evacuated to a negative pressure state and filled with an appropriate liquid with a low boiling point, which easily vaporizes. The inner walls of heat pipes have a wick structure made up of various types, including grooves, mesh, sintered powder, and fibers. To learn more about heat pipes, please refer to the heat pipe overview.

Vapor Chambers

Vapor chambers, also known as heat spreaders, are another important application of two-phase cooling technology. They utilize the principles of liquid evaporation and vapor condensation to achieve efficient heat transfer and uniform distribution in a very compact space. Vapor chambers are typically made from a thin plate and contain liquid, a wick structure, and vapor channels. Due to their material, internal structure, and manufacturing processes similar to heat pipes, vapor chambers are sometimes referred to as a less common type of heat pipe or a flat heat pipe with a very small aspect ratio.

The advantages of vapor chambers include extremely low thermal resistance and efficient heat distribution, making them increasingly popular in high-power electronic components (such as CPUs, GPUs, IGBT modules, etc.) and complex thermal management systems. Especially in situations requiring high-efficiency cooling with space constraints, vapor chambers can provide outstanding solutions. For more details on vapor chambers, please refer to the vapor chamber overview.

Immersion Cooling

Immersion cooling is another efficient liquid cooling technology that involves directly immersing heat-generating components in a cooling liquid, achieving high-efficiency heat transfer through direct contact. This technology typically uses low-boiling-point fluorinated liquids or other dielectric fluids to ensure safety in electrically charged environments. Immersion cooling not only offers extremely high thermal efficiency but also effectively reduces noise and vibration, while avoiding dust accumulation and cleaning issues associated with air cooling.

In data centers, high-performance computing clusters, supercomputers, and certain industrial applications, immersion cooling technology has become the preferred solution for addressing high-density, high-power device cooling challenges. By optimizing the flow and circulation system of the cooling liquid, further improvements in cooling efficiency and overall energy consumption can be achieved. Additionally, immersion cooling can provide more compact design spaces, enhancing device integration and reliability.

Professional High Power Cooling Solution Service Provider And Heat Sink Manufacturer

Two-phase Cooling