Isobar® Heat Pipes (sometimes called heat tubes) are super-thermal conductors that have the capacity to transfer large amounts of energy at high speeds in both heating and cooling applications. Isobar® uses two-phase liquid-vapor heat transfer technology (boiling/evaporation and condensation) that is able to move thermal energy up to 250+ times faster than standard copper material. Acrolab has been manufacturing our trademark product Isobar® heat pipe since 1978.

Isobar® Heat Pipe Component Basics


Isobars In Composite Tooling

Standard (Straight) Isobar® Heat Pipes

Acrolab’s standard Isobar® come in a variety of diameters and sizes. Standard straight Isobars are used in heating, cooling, and isothermal applications. Acrolab can assist you with the design and size of Isobar that is right for your application.

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Baffle Isobar® Heat Pipes

Acrolab’s Baffle Isobar are best used in applications where water blockage and pressure drops occur in difficult to reach areas. These Baffle Isobars can replace your current standard baffles with minimal if any modification(s) to tooling.

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Stepped Isobar® Heat Pipes

Acrolab’s Stepped Isobar® allow for maximum surface area contact utilizing a multi-diameter design. They are typically used in core pins to delivery optimal cooling where a typical water channel cannot.

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Hollow Isobar® Heat Pipes

Acrolab’s Hollow Isobar® have a through-hole down the center for multiple functions. They are typically applied in blow molding applications or around a nozzle or component where heating or cooling can be applied from remote location(s) if required.

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Core Pin Isobar® Heat Pipes

Core pins can sometimes be the bottle neck for a tool cycle time. Acrolab manufactures Core Pin Isobar® heat pipes that allow the core pin the capability of cooling at very high speeds. By incorporating a cooling tail, the core pin has the ability to cool and/or heat the entire core pin quickly and uniformly. Acrolab can supply and install to suit your requirements.

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Custom Isobar® Heat Pipes

Acrolab manufactures custom Isobar® heat pipes of all shapes and sizes. We can assist your team with designing for applications ranging from plastics to agricultural, to extreme temperature conditions.  Designs can range from circular, to finned, to multi-geometry with bends. Our application engineers can work with your team to develop a solution that will work best for your application.

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Isobar® Heat Pipes Transfer Large Amounts of Energy at High Speeds

The Isobar® Heat Pipe achieves thermal conductivity by incorporating a sophisticated solid-state passive pump inside a contained copper unit. This pump takes the form of a fine metallic wick placed tight to the inner wall of a sealed Isobar.

In an Isobar® a small quantity of working fluid is placed in an evacuated tube. Heat is applied to the base of the tube, causing the temperature of the working fluid to rise — as this fluid heats, it vaporizes. This vapor then migrates to the colder end of the tube where it condenses and is absorbed by the wick. This wick, through its capillary action, returns the working fluid to the evaporator section, regardless of orientation.

Works in Both Heating & Cooling Applications

Isobar® technology works equally well with process tooling drawing their energy from heated platens and with integrally heated molds. Energy sources such as oil, steam, or electric heaters may be used. Since the latent heat transfer of evaporation is large, considerable quantities of energy can be transferred and significantly increase the thermal recovery rate under isothermal conditions.

Commonly used Isobars are: straight, baffled, finned, and stepped. For these types of Isobars, temperatures can range from 50°F to 500°F. Acrolab also engineers low-temperature Isobars that operate at temperatures from -103°F to 50°F. These special Isobars are application dependent and are available upon request.


Think Outside the Box

Acrolab application engineers have a vast knowledge of thermal dynamics and design and integration.

We will consider maintenance, value-add, design, integration, performance, feasibility, and timing for client solutions.

Our “outside the box” style of thinking allows Acrolab to deliver unique and even multiple solutions for client requirements.

Acrolab Isobars are a 3 in 1 solution. They can provide cooling, heating and/or thermal uniformity management in your application.

Acrolab has constructed heat pipes from a variety of materials such as; copper, monel, stainless steel, inconel and some additive powder alloys. Copper is most common for what we consider as ‘standard applications’. However, choosing a containment material ultimately depends on the working fluid.

Near-Isothermal Conditions

Acrolab’s Isobar® Heat Transfer system delivers near-isothermal conditions to all mold surfaces. Our custom-engineered Heat Transfer System uses the Isobar® Heat Pipe in order to provide thermal uniformity to molding applications.

Used in Core Pin Technology

Acrolab’s Heat Transfer System is used in core pin technology for thermoset and rubber injection molders; cold runner molds; thermal plastic molding and any application where thermal uniformity is critical.

Headlight Housing Specified

Acrolab’s Isobar® Heat Transfer Systems are specified by over 90% of the headlight housing manufacturers in North America and have been installed in hundreds of injection thermoset headlamp housing molds.

Since the Isobar® Heat Transfer System resides entirely within the mold there is no need to change your existing mold control system. Acrolab can provide all the components, engineering services, and field installation necessary to construct a complete Isobar® Heat Transfer System. All engineering drawings, electrical schematics, heating elements, Isobar® Heat Pipes, thermocouples, wiring, terminal boxes, electrical connectors, control cables, and a certified installer are provided.

Acrolab Isobar® Heat Pipe Details

Heat pipes offer thermal conductivity that can range from 5,000 W/m•K to 100,000 W/m•K, making them far superior to solid aluminum, copper and graphite conductors.

Typical Arcolab Isobar Heat Pipes have 3 sections;

  1. Evaporator Section
  2. Adiabatic Section
  3. Condenser Section

Acrolab heat pipes or, vessels, are constructed with a tight vacuum seal that contain a working fluid and a wick structure acting as a capillary. They utilize the vaporization of an inner fluid to transfer heat to the heat sink [3) Condenser Section] from the heat source [1) Evaporator Section] over the distance of the 2) Adiabatic Section.

Acrolab Isobar® Heat Pipes Transfer Heat Efficiently & Evenly

Heat transfer is achieved by the Wick Structure and Working Fluid inside the Isobar Heat Pipe. The inner surface of the Heat Pipe is lined with the ‘wick’ that provides the capillary action for liquid moving from the condenser to evaporator, inside the vacuum Isobar Heat Pipe structure. Given that the liquid will, under a vacuum, accept heat well below the boiling point in atmospheric pressure, it will be effective at transferring latent heat at low temperatures.

Working Fluids for Isobar Heat Pipes

Selecting the working liquid for a heat pipe depends on the application temperature range, but water is the most common liquid for a temperature range of 1°C to 325°C. When dealing with low temperatures, ammonia and methanol are commonly used. Whereas potassium and sodium are often utilized for high temperature applications. Best to consult with the Acrolab professionals for these types of unique Isobar Heat Pipe applications.

Wick Structures for Isobar® Heat Pipes

Here capillary action is defendant on the structure of the Isobar Heat Pipe wick and the liquid moves from the evaporator section back to the condenser. Acrolab manufactures a full variety of wick structures, depending on the exact application.