Industrial processes often require reliable heat transfer at temperatures where conventional water-based systems would need to operate at high pressure. Thermal oil offers an alternative for transferring industrial process heat at high temperatures while maintaining comparatively low system pressures.
Depending on the selected heat transfer oil and its thermal properties, heat can be transferred at temperatures of approximately 350°C at nearly atmospheric pressure. Suitable high-temperature thermal fluids can also be used at temperatures approaching 450°C, subject to the properties of the fluid and the operating conditions.
This combination of high operating temperatures, comparatively low pressure and precise temperature control makes thermal oil an established heat transfer medium for demanding industrial processes.
AURA has extensive experience in the engineering and application of thermal oil technology for industrial process heat. Understanding the properties of the heat transfer fluid is essential for selecting and designing a safe, reliable and efficient heat transfer concept.
Pressureless or low-pressure heat transfer describes the transfer of thermal energy at elevated temperatures without the high saturation pressures associated with water and steam.
The underlying principle is closely related to the physical properties of the heat transfer medium.
Water reaches its boiling point at 100°C under atmospheric pressure. To keep water liquid at significantly higher temperatures, the system pressure must increase accordingly.
Thermal oil behaves differently: Suitable thermal oils remain liquid over a much wider temperature range and have a comparatively low vapor pressure at their intended operating temperatures. This allows thermal energy to be transported at high temperatures without requiring the pressure levels associated with comparable water or steam systems.
This is the fundamental principle behind low-pressure heat transfer with thermal oil.
Thermal oil, also known as heat transfer oil or heat transfer fluid, is a liquid medium used to transport thermal energy in industrial heating and cooling processes.
Depending on the application, mineral-based, synthetic or silicone-based heat transfer fluids can be used.
The thermal oil absorbs energy from a heat generator and transports it through a closed circulation system to the connected process consumers.
After transferring its heat to the production process, the cooled thermal oil returns to the heater and is reheated.
This closed-loop system allows multiple industrial consumers to be supplied by a central heat source.
Both thermal oil and steam are established technologies for transferring industrial process heat.
Neither medium is inherently better for every application. The appropriate solution depends on the required temperature, pressure, heat transfer characteristics and production process.
| Criteria | Thermal Oil | Steam |
|---|---|---|
| High operating temperatures | Well suited | Requires increasing pressure for saturated steam |
| System pressure | Comparatively low | Increases with saturation temperature |
| Heat transfer medium | Liquid | Vapor |
| Condensate return | Not required | Typically required in closed steam systems |
| Temperature control | Precise | Precise |
| Multiple heat consumers | Well suited | Well suited |
| Typical applications | High-temperature process heating | Direct and indirect steam processes |
Thermal oil itself is the heat transfer medium, not the heat source.
The thermal energy can be supplied in different ways – for example electrically, fired, from steam or by utilizing industrial waste heat.
The thermal oil absorbs this energy and transports it to the process consumers. The equipment used to heat and circulate the thermal oil must be designed according to the required heating capacity, operating temperature, flow rate and process conditions.
AURA develops different technologies for this purpose. Learn more about the operating principle, design and different types of thermal oil heaters.
Thermal oil is used in industrial applications requiring reliable heat transfer and precise temperature control.
Typical applications include:
Thermal oil systems are used in industries such as chemical processing, food production, wood processing, paper manufacturing, plastics production and mechanical engineering.
The service life of thermal oil depends on the selected fluid, operating temperature, thermal stress, contamination and system operation.
Regular oil analysis helps assess the condition of the heat transfer fluid and determine when replacement is necessary.
With suitable system design and proper operation, thermal oil can remain in service for many years.
A thermal oil heating system typically consists of a heat generator, circulation pumps, piping, control and safety equipment, and connected heat consumers.
The heater raises the temperature of the thermal oil to the required operating level.
Circulation pumps transport the heated fluid through the piping system to the process consumers.
After transferring its thermal energy, the cooled thermal oil returns to the heater.
Depending on the application, thermal oil can be heated electrically, fired or by recovering industrial waste heat.
No. The term “pressureless” primarily refers to the low vapor pressure required to keep the heat transfer fluid in the liquid phase.
Circulation pumps still generate hydraulic pressure to transport the thermal oil through the system. Additional pressure may also be required depending on the fluid and operating temperature.
Certain heat transfer fluids can be used for both heating and cooling processes, provided their temperature range and physical properties are suitable for the application.
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