Laser-welded Finned Tube Heat Exchangers in Thermal Oil Heating/cooling Systems

Laser-welded finned tube heat exchangers are high-efficiency heat exchange elements that use a high-energy laser beam to directly metallurgically bond the fins to the base tube. Their core advantages include extremely low thermal resistance, strong welds, minimal deformation, and high-temperature resistance, making them particularly suitable for harsh operating conditions such as those involving heat transfer oil, steam, and high-temperature flue gas.

Applicable Operating Conditions

1. Medium Parameters

Inner Medium: High-temperature heat transfer oil (mineral-based/synthetic heat transfer oil)

Normal Temperature: 180～350℃ (laser welding can withstand short-term high temperatures of 400℃)

Operating Pressure: Atmospheric pressure～1.6MPa (mainstream industrial operating conditions)

Medium Characteristics: High temperature, slight tendency to coking, system experiences pipeline vibration

2. Heat Exchange Method

Heat Transfer Oil Heater: High-temperature heat transfer oil flows inside the pipe, while air/process air flows outside. Hot air circulation utilizes the heat from the heat transfer oil for drying, heating, and process air supply.

Heat Transfer Oil Cooler: High-temperature heat transfer oil inside the pipe is cooled by forced air cooling outside, reducing the temperature of the overheated heat transfer oil, protecting the oil circuit system, and preventing oil cracking and coking.

Core Advantages of Laser Welding Technology in Heat Transfer Oil Systems

Extremely low contact thermal resistance, resulting in higher heat exchange efficiency.

Precise laser beam fusion, with a heat-affected zone of only 0.1~0.5mm, ensuring complete metallurgical bonding between the fins and the base tube, without gaps or loosening. Compared to traditional high-frequency welding, the overall heat exchange efficiency is improved by 15%~22%, and the equipment size is smaller for the same heat exchange capacity.

High temperature resistance and creep resistance, suitable for long-term high-temperature operation. The weld structure is uniform, preventing fin loosening or detachment at high temperatures. It can operate stably in a 350℃ heat transfer oil environment for extended periods, solving the problem of long-term high-temperature failure of ordinary welded tubes.

Excellent vibration resistance. With continuous vibration of the heat transfer oil system's circulating pump and fan, the laser weld strength is close to that of the base material, making fins less prone to detachment. The equipment's service life is extended by more than 30% compared to high-frequency welded finned tubes.

Minimally small thermal deformation, less prone to pipeline deformation and leakage. Localized heating during welding results in almost no bending or deformation of the entire base tube, ensuring the coaxiality and sealing of the heat transfer oil pipeline, significantly reducing the risk of high-temperature oil leakage.

Less prone to exacerbating heat transfer oil coking. The smooth weld is free of burrs and weld slag protrusions, allowing for smooth airflow outside the tube; the smooth inner tube wall eliminates localized overheating dead zones, reducing localized high-temperature cracking and coking of the heat transfer oil.

Wide temperature range, adaptable to fluctuating operating conditions.

Can withstand sudden temperature changes caused by system start-up and shutdown, and load fluctuations; exhibits superior thermal fatigue resistance compared to conventional welding processes.

Heat Transfer Oil → Air Heater (Hot Air System)

Workflow: High-temperature heat transfer oil circulates within the base tube → Heat is transferred to the outside air through the tube wall and laser-welded fins → Forced airflow from the fan forms high-temperature hot air, which is then delivered to drying lines, drying rooms, workshop heating, and reactor heating, etc.

Suitable Industries: Printing and dyeing, wood drying, food processing, chemical powder drying, coating production lines.

Design Considerations: Increase fin spacing (7~10mm) to allow space for dust removal; select a high-temperature axial flow fan.

Air → Heat Transfer Oil Cooler (Oil Circuit Cooling)

Workflow: Overheated heat transfer oil flows into the finned tube base tube → External cold air forcibly removes heat → Cooled heat transfer oil returns to the system, controlling the oil temperature within a safe range.

Function: To prevent heat transfer oil from oxidation, cracking, and carbonization due to overheating, extending the oil's service life and ensuring the safety of the entire heat transfer oil furnace system.

Design Considerations: Densified tube bundles and high-heat-density fins; equipped with a variable frequency fan to automatically adjust airflow based on oil temperature, achieving energy-saving temperature control.