How Does Vapor Cooling Work? Principles and Applications

1. What Is Vapor Cooling?

1. Vapor cooling relies on evaporation and condensation to move heat.
2. Vapor cooling systems typically use one of several technology types.
3. Vapor cooling relies on latent heat principles to absorb significant heat.

What Is Vapor Cooling?

1. How Vapor Cooling Moves Heat

Vapor cooling moves heat using phase changes from liquid-to-vapor and vapor-to-liquid. These processes occur inside a closed device or controlled circulation loop. First, the coolant inside the device absorbs enough heat to evaporate. Next, vapor moves away from the heat source to a cooler region of the device. The vapor releases heat and condenses back into liquid before returning toward the heat source.

The cycle continues as long as the device operates within its design limitations. In essence, vapor cooling creates a continuous heat pumping loop. Since vaporization takes advantage of latent heat principles, vapor cooling does not rely on traditional solid conduction methods. As a result, vapor cooling can transport large amounts of thermal energy using minimal temperature differences.

Ultimately, the thermal performance of a vapor cooling device depends on its design and operating conditions. Examples of vapor cooling technology include:

1. Heat pipes
2. Vapor chambers
3. Loop heat pipes
4. Thermosyphons
5. Two-phase cooling loops
6. Two-phase immersion cooling

Each of these devices uses evaporation and condensation in slightly different ways. For instance, heat pipes use capillary wicks to assist liquid return. On the other hand, thermosyphons typically rely on gravity rather than capillary forces.

See 【 What Is a Heat Pipe 】 and 【 What Is Vapor Chamber 】 for more information.

2. How Does Vapor Cooling Work?

The five main stages of vapor cooling are heat absorption, evaporation, vapor transport, condensation, and liquid return.

1. Heat Absorption
2. Evaporation
3. Vapor Transport
4. Condensation
5. Liquid Return

How Does Vapor Cooling Work?

Stage 1: Heat Absorption

An electronic component produces heat that the evaporator must remove.

Stage 2: Liquid Evaporation

The working fluid evaporates by absorbing latent heat from the heat source.

Stage 3: Vapor Movement

Pressure differences cause vapor to move towards the condenser.

Stage 4: Vapor Condensation

The vapor releases heat and condenses back into liquid near the condenser.

Stage 5: Liquid Return

Finally, capillary action, gravity, or some other method return the condensed liquid to the evaporator.

Step 1: Heat Absorption

To understand how vapor cooling works, consider a simple electronic device that generates heat. For example, a computer processor produces heat as it operates. The cooling device contacts the electronic component and absorbs this thermal energy. As a result, heat transfers to the working fluid near the evaporator.

Step 2: Liquid Evaporation

When the working fluid near the evaporator absorbs enough heat, it evaporates. Since a phase change is required, the fluid absorbs latent heat. Latent heat allows the working fluid to absorb a large amount of thermal energy. Moreover, vaporization occurs when the fluid reaches its saturation conditions.

Keep in mind that a sealed device does not operate at standard atmospheric pressure. Instead, vaporizers use various technologies to achieve specific saturation conditions.

Step 3: Vapor Movement

Evaporation creates a pressure difference between vapor and liquid. Therefore, vapor will tend to move toward the condenser. Since the vapor transports heat, thermal energy effectively moves away from the heat source.

Step 4: Vapor Condensation

As the vapor reaches the condenser, it condenses by releasing latent heat. During condensation, the vapor contacts cooler surfaces within the device. Meanwhile, the condenser sends heat toward an external cooling structure. In many cases, this includes a finned heatsink that releases heat to the air.

Step 5: Liquid Return

The final step of the vapor cooling cycle forces liquid to return to the evaporator. Capillary action commonly accomplishes this in wicked heat pipes. In contrast, gravity assists liquid return in other devices.

At this point, the vapor cooling cycle repeats. Vapor cooling does not require a mechanical pump inside traditional heat pipes.

3. The Science Behind Vapor Cooling

Vapor cooling uses two main scientific principles to absorb and dissipate heat. These principles include latent heat transfer, vapor pressure differences, and capillary action in wicks. Let’s examine each one to better understand vapor cooling performance.

3.1 Latent Heat Transfer

Latent heat is the energy associated with a phase change of a material. During evaporation, the fluid soaks up energy without dramatically increasing in temperature. Once the fluid condenses, it releases the latent heat. The approximate heat transfer rate can be determined using the following equation:

In other words, higher vapor flow rates can absorb more heat. However, vaporizers experience flow resistance and other limits during normal operation.

3.2 Vapor Pressure Difference

Since vaporization and condensation occur inside the device, pressure differences happen as well. Vapor pressure differences are what cause vapor to flow through the device. Therefore, this phase change allows energy to move from hot regions toward the condenser.

3.3 Capillary Action

Wicks are common in many heat pipes and vapor chambers. A wick consists of a porous structure that creates capillary pressure. Capillary pressure is what ultimately returns liquid to the device evaporator. However, capillary pressure must counteract the flow losses of liquid and vapor.

As a result, wick design is crucial to any vapor cooling device’s maximum heat transport capabilities.

4. Main Components of a Vapor Cooling System

Let’s discuss the primary components of vapor cooling devices. This knowledge can provide a better idea of how vapor cooling works.

Evaporator

The evaporator section absorbs heat from heat sources such as electronics.

Condenser

The condenser section rejects heat toward an external heat transfer structure.

Working Fluid

Vaporizers contain a working fluid that cycles through evaporation and condensation.

Sealed Casing

Heat pipes and vapor chambers contain a sealed internal casing.

Wick Structure

Heat pipes and vapor chambers use wicks to help return liquid to the evaporator.

Heat Dissipation Structure

Since vaporizers only move heat, they require external heat dissipation mechanisms.

5. How Does a Vapor Chamber Cooling System Work?

Image via alibaba.com

A vapor chamber can spread heat from a concentrated heat source. It does this by using internal evaporation and condensation to fill the chamber with vapor. Vapor chambers usually connect to external cooling structures like heatsinks or cold plates.

How Does Vapor Chamber Cooling Work?

1. Heat from the source warms the evaporator.
2. The working fluid evaporates after absorbing heat.
3. Vapor fills the chamber and condenses on cool surfaces.
4. Capillary action returns liquid toward the evaporator.

Essentially, a vapor chamber allows for two-dimensional heat spreading. As a result, vapor chambers can help spread out hot spots on a cooling interface. Here are some common applications that use vapor chambers:

1. GPU cooling modules
2. High-performance CPUs
3. Gaming laptops
4. Server processors
5. Compact electronic systems
6. Power electronics

See 【 Vapor Chamber Working Principle 】 for related information.

6. How Does Heat Pipe Cooling Work?

Image via Alibaba.com

Heat pipes use a sealed container with a working fluid and often wick. When one end of the heat pipe absorbs heat, the fluid evaporates. The vapor then travels toward the cold end where it condenses. The capillary wick then returns liquid to the hot end of the heat pipe.

How Does Heat Pipe Cooling Work?

1. Heat enters the heat pipe and is absorbed by the evaporator.
2. A working fluid then evaporates after absorbing heat from the heat source.
3. Vapor moves toward the cooler condenser section of the pipe.
4. The vapor releases heat and condenses back into liquid form.
5. A wick structure returns liquid to the evaporator section.

Heat pipes are effective at transporting heat between two separated points. For example, they connect computer processors to heatsinks. Laptop cooling systems use flattened heat pipes made of copper to transport heat. Many desktop CPU coolers contain multiple heat pipes that transport heat to aluminum fins.

See 【Heat Pipe Production Line 】 for related manufacturing information.

7. Types of Vapor Cooling Technologies

There are many different vapor cooling technologies. However, they can all be sorted into several general categories.

Heat Pipe Cooling

Heat pipes use sealed tubes to transport heat through evaporation and condensation.

Vapor Chamber Cooling

Vapor chambers absorb heat and spread it across a larger surface area.

Thermosyphon Cooling

Thermosyphons transfer heat using vaporization and condensation.

Loop Heat Pipe Cooling

Loop heat pipes use separate liquid and vapor paths through a heat exchanger.

Two-Phase Liquid Cooling

Two-phase liquid cooling relies on vaporization in a controlled fluid circuit.

Two-Phase Immersion Cooling

Two-phase immersion cooling involves submerging components in dielectric coolant.

8. Vapor Cooling vs Traditional Air Cooling

Vapor cooling and air cooling have many differences, but can work well together. Here’s a chart that compares both technologies.

Feature Vapor Cooling Air Cooling

Main principle Evaporation and condensation Convection

Working medium Internal working fluid Air

Heat spreading Effective when designed correctly Depends on the heatsink

Moving parts Does not require moving parts inside the pipe Fans are required for forced convection

Heat source management Handles concentrated heat well Depends on the heatsink design

Manufacturing complexity More complex due to sealed design Simpler

Typical applications Heat pipes and vapor chambers Fans and heatsinks

Take computer CPU coolers for example. Heat pipes can help transport heat away from the processor die. Fans then help remove heat from the heat pipes’ condenser fins by forced convection. In short, vapor cooling and air cooling technologies can work together.

9. Vapor Cooling vs Liquid Cooling

Single-phase liquid cooling uses a circulating fluid to transport sensible heat.

Meanwhile, vapor cooling relies on evaporation and condensation.

Neither technology always provides superior performance.

Therefore, engineers should evaluate thermal load, available space, cost, and reliability.

For further comparison, see 【Vapor Chamber vs Liquid Cooling】.

10. Benefits of Vapor Cooling

High Thermal Load Capacity

Phase-change can transport large amounts of heat energy.

As a result, proper designs can handle high heat loads.

Compact Sizes

Heat pipes and vapor chambers enable small form factor heat spreads.

As a result, users can design smaller products.

Heat Spreading Capability

Vapor chambers are effective heat spreaders.

As a result, they help minimize hot spots.

Passive

Traditional heat pipes don’t require pumps.

This eliminates active parts inside the heat spreading device.

Flexible Design Options

Users can pair vapor cooling with heatsinks, fans, and liquid cooling devices.

Integration Possibilities

Vapor cooling can be used for computers, electronics, and industrial applications.

11. Vapor Cooling Uses

CPU Cooling

CPUs produce high amounts of heat from a small area.

As a result, vapor chambers and heat pipes allow for better cooling designs.

GPU Cooling

GPUs also produce a lot of heat energy.

Vapor chambers allow heat to spread toward heatsink fins.

Laptop Cooling

Laptops need small cooling solutions.

As a result, many use flattened heat pipes to move heat to heatsinks.

Server Cooling

Servers require reliable cooling under high heat loads.

Heat pipes and vapor chambers work with certain server cooling designs.

Telecommunications Cooling

Telecom equipment needs to operate reliably.

As a result, vapor chambers can be used for better heat management.

LED Lighting

High-power LEDs also produce high heat flux.

Heat pipes are effective at transporting heat away from LEDs.

Industrial Cooling

Power electronics like converters, inverters, and drives need cooling.

As a result, vapor chambers work with some industrial cooling solutions.

12. Vapor Cooling Limitations

Working Fluid

The working fluid should suit the operating temperature range.

Additionally, it should not react with other internals.

Wick Structure

Smaller pores provide higher capillary pressure.

However, they also lower permeability.

So there is a balance that must be met.

Internal Pressure

Changes to internal pressure will change the saturation temperature of the fluid.

So manufacturers need to account for and control internal pressure.

Heat Input

All devices have limits.

Too much heat will cause performance to drop.

Orientation

Heat pipes and vapor chambers can be affected by gravity.

Orientation can affect liquid return in some devices.

Condenser Temperature

The condenser end must be able to reject heat.

If the device can’t reject enough heat, temperatures will rise.

Manufacturing Defects

Leaks, improper filling, and contamination can reduce performance.

So quality control is important during manufacturing.

13. Vapor Cooling Problems

Dry-Out

When liquid return cannot keep up with the rate of evaporation, dry-out occurs.

The evaporator temperature will rise significantly.

Insufficient Amount of Working Fluid

Too little working fluid can cause poor performance.

Manufacturers should fill to manufacturer specifications.

Too Much Working Fluid

Counterintuitively, too much fluid can cause an issue as well.

Again, manufacturers should fill to specifications.

Internal Gas Contamination

Gas that does not condense in the condenser can take up space.

Reducing space for the working fluid will lead to poor performance.

Typically, this means performing a good vacuum process and cleaning parts before assembly.

Poor Wick Structure

If the wick structure is inconsistent, liquid return can be compromised.

Powder filling and wick sintering processes should be tightly controlled.

Leaks

Leaks can change the conditions inside a heat pipe.

Ensuring proper seals and testing for leaks is critical.

14. Vapor Cooling Production Processes

The production process will differ slightly depending on the device.

However, most sintered heat pipes go through several stages of production.

Step 1: Cutting Copper Tubes

To start production on heat pipes, you need copper casings.

You can cut your tubes to size with an Automatic Casing Cutter.

Step 2: Cleaning

After cutting your tubes, clean the internals to remove any debris.

Step 3: Filling With Powder

You will need a Heat Pipe Powder Filling Machine to add copper powder.

The copper powder is used to create your wick structure.

Step 4: Sintering

Next, a Vacuum Sintering Furnace will create your porous wick.

Step 5: Necking

With a Heat Pipe Necking Machine, you can create the end of the tube for sealing.

Step 6: Degassing

Next, you will want to connect your vacuum degassing machine to remove any unwanted gases.

Step 7: Fluid Filling

Finally, you will need to fill your heat pipe with your desired working fluid.

A Heat Pipe Filling & Welding Machine makes the process simple.

Step 8: Sealing

The machine will then seal your heat pipe.

This creates a sealed environment inside your heat pipe.

Step 9: Cutting Extra Material

If needed, you can use a Heat Pipe Automatic Tail Cutting machine to cleanup any extra material.

Step 10: Testing

You can now use a Multi-Station Thermal Performance Tester to test your heat pipes.

Different heat pipe designs will have different production steps.

15. Vapor Cooling Manufacturing Equipment

Manufacturers need specialized equipment to produce reliable vapor cooling components.

Therefore, integrated equipment can support consistent manufacturing processes.

Furthermore, automation can reduce manual handling between production stages.

For related information, see 【Heat Pipe Manufacturing Line】 and 【Vapor Chamber Production Line】.

16. Vapor Cooling Selection Guide

Estimate Heat Load

Calculate Expected Thermal Power

The vapor cooling solution must adequately support the desired operating conditions.

Understand Heat Source Geometry

Heat sources with high thermal density may require vapor chambers .

Heat pipes are useful for transporting heat to distant cooling solutions.

Take Note Of Available Space

Small form factor devices need carefully designed heat transport structures.

Check Expected Operating Temperature

Matching the working fluid to the intended temperature range is crucial.

Keep Orientation In Mind

Orientation can impact performance on some devices.

As a result, changes in orientation can be included in product testing.

Determine Heat Rejection Method

Heat reject solutions can include air coolers, liquid cooling, or other methods.

Plan For Reliability

Reliable products require consideration of material compatibility, seal quality, and operating limits.

Understand Manufacturing Capability

High volume manufacturing needs equipment that can support production demand.

As a result, manufacturers should consider thermal design factors and manufacturing capabilities.

17. Why Choose Bangwow Machine?

Bangwin Machine stocks manufacturing equipment and custom production solutions for thermal management products. Our core focus includes heat pipes, vapor chambers, heatsinks, and associated production equipment. Learn more about our thermal production equipment at Bangwin Machine.

Heat Pipe Manufacturing Equipment

Our services and equipment cover tube cutting machines, powder filling machines, sintering furnaces, vacuum processing equipment, filling machines, welding machines, and thermal test systems.

Vapor Chamber Production Solutions

Precision vapor chamber forming equipment, internal structure processing, filling machines, sealing equipment, and inspection tools are all vital to production. Because of this, manufacturers can benefit from comprehensive production solution consulting.

Customized Manufacturing Equipment

Heat pipes and vapor chambers have different manufacturing process steps. As a result, customers can consult with our engineers about customized fixtures, control systems, and automation.

Automated Thermal Testing Solutions

Industrial testers allow manufacturers to validate thermal performance. Additionally, multi-station systems allow users to improve testing throughput.

Integrated Heat Pipe Production Lines

An all-in-one Heat Pipe Production Line effectively integrates multiple stages of production into a cohesive system. Because of this, manufacturers can reduce excess material handling and improve production consistency.

18. FAQ

How does vapor chamber work in laptop?

Vapor cooling works by absorbing heat through evaporation. Heat pipes or vapor chambers then conduct heat to adjacent cooling fins.

What does vapor chamber do in laptop?

A vapor chamber spread heats over a larger area. This increased surface area improves heat transfer to a heatsink.

Does vapor chamber use water?

Water is common in copper heat pipes and vapor chambers.

Can you drink water from vapor chamber?

Do not drink the water from your vapor chamber. This water is distilled and used only for cooling.

Is vapor chamber water cooled?

Heat pipes and vapor chambers use water as the working fluid.

Is heat pipe better than vapor chamber?

Heat pipes are ideal for transferring heat over a distance. Vapor chambers are better at spreading heat.

Does vapor chamber cool CPU?

Passive vapor chambers can greatly improve CPU and GPU cooling.

Can laptop without fan use vapor chamber?

While vapor chambers can be used without fans, the cooling performance will be nowhere near as effective.

Does vapor chamber help cooling?

Heat pipes and Vapor chambers wick heat away from high heatflux sources and help cool these areas.

Does vapor chamber work like heat pipe?

Heat pipes are typically used to transport heat. Vapor chambers transport and spread heat.

Do heat pipes need gravity?

Heat pipes can transfer heat against gravity with the help of a wick structure. These are referred to as wicked heat pipes.

Can vapor chamber explode?

Explore heat pipe manufacturing equipment and vapor chamber automation at Bangwin Machine.

19. Conclusion

Vapor cooling works by evaporating a liquid at the heat source. Vapor then transports thermal energy to a cooler area. There, condensation releases heat, and liquid returns to the heat source by gravity or capillary action.

This process allows vapor to effectively transfer heat between two surfaces. Heat pipes utilize this concept to transfer heat between one surface and another. Vapor chambers can also spread heat across a larger area.

In either case, thermal management engineers use these technologies to cool electronic devices. From CPUs and GPUs to laptops, servers, telecom, and industrial electronics – vapor cooling can play a valuable role.

Not only does vapor cooling technology matter but also the equipment used to produce these components. Bangwin Machine offers customized heat pipe production lines that include tube cutting machines, powder filling machines, sintering furnaces, vacuum processing equipment, filling machines, welding machines, and thermal test systems.

When developing advanced heat pipes or vapor chambers, the proper equipment can allow for increased production efficiency and consistency. Visit Bangwin Machine for thermal machinery and automation – thermalmachinery.com.