The laser circulating water cooler is a core auxiliary equipment in the laser system. Its working principle is based on heat exchange and fluid circulation, which continuously removes the heat generated by the laser to ensure that the equipment operates at a stable temperature. The following is a detailed analysis of its working principle:
Core working principle
The laser circulating water cooler uses a closed circulation system to transport cooling water to the laser heat source to absorb heat, and then introduces the heated cooling water into a heat exchanger (such as a plate heat exchanger or a shell and tube heat exchanger). Through heat exchange with an external cold source (such as air or refrigerant), the temperature of the cooling water is reduced and re circulated to the laser, forming a continuous heat dissipation loop.
System composition and workflow
circulation pump
Function: Provide power to drive the circulation of cooling water in the system.
Working mode: The pump extracts low-temperature cooling water from the storage tank (or buffer tank), pressurizes it, and delivers it to the laser cooling components (such as laser crystals, electrodes, or fiber optic cladding).
Key parameters: flow rate (L/min), head (m), power (W), need to be selected based on laser thermal load and pipeline resistance.
Laser heat exchange
Heat transfer pathway:
When the laser is working, the loss of electro-optical conversion efficiency (such as fiber laser efficiency of about 40% -50%) generates waste heat.
Heat is transferred through thermal conduction to the cooling water channel in contact with the laser, such as a water-cooled plate or microchannel cooling plate.
The temperature of the cooling water increases after absorbing heat (Δ T is usually designed to be 5-10 ° C).
Design points:
The cooling water channel needs to be closely attached to the heat source to reduce contact thermal resistance.
Using high thermal conductivity materials such as copper or aluminum to manufacture cold plates, optimizing channel layout (such as turbulent flow design) to enhance convective heat transfer.
Heat exchanger (secondary heat exchange)
Function: Exchange heat between the heated cooling water and an external cold source to lower the water temperature.
Common types:
Plate heat exchanger: composed of multiple layers of metal plates, cooling water and cold source (such as air or refrigerant) flow in reverse or cross flow between the plates, with high heat transfer efficiency (U value can reach 2000-5000W/(m ² ·° C)).
Shell and tube heat exchanger: Cooling water flows inside the tube, while the cold source is flushed outside the tube, suitable for high-pressure or high flow scenarios.
Work example:
If an air-cooled heat exchanger is used, the cooling water passes through the finned tube bundle, and the fan forces air to flow through the fins, taking away heat.
If a water-cooled heat exchanger is used, the cooling water exchanges heat indirectly with another low-temperature circulating water (or refrigerant) through the heat exchanger.
Temperature control and regulation
Sensor monitoring: Install temperature sensors (such as PT100 or thermocouples) at the laser outlet and heat exchanger outlet to monitor water temperature in real time.
PID control: The controller adjusts the pump speed or heat exchanger fan/refrigerant flow rate based on the deviation between the set temperature and the actual water temperature, achieving precise temperature control (with an accuracy of ± 0.1 ° C).
Bypass valve: By adjusting the opening of the bypass valve during partial load, the flow rate of cooling water entering the heat exchanger is controlled to avoid excessive cooling.
Water storage tank and filtration system
Water storage tank: buffers fluctuations in cooling water volume, stabilizes system pressure, and accommodates additional water generated by thermal expansion.
Filter: Install filter screens (such as 50-100 μ m aperture) at the pump inlet and heat exchanger inlet to intercept particulate impurities, prevent pipeline blockage or heat exchanger scaling.
Deionization device: For systems with high water quality requirements (such as high-power lasers), a deionization resin tank is required to reduce conductivity (<10 μ S/cm) and prevent electrochemical corrosion.
Typical application scenarios
Industrial laser cutting/welding
High power CO ₂ or fiber laser (1kW-20kW) requires continuous heat dissipation, and the cooler needs to have high flow rate (>50L/min) and fast temperature control capability.
Medical laser equipment
Laser beauty devices (such as picosecond lasers) require high temperature stability (± 0.5 ° C) and require high-precision PID control.
Research laser system
For titanium sapphire lasers, ultra-low vibration design is required (to avoid affecting the stability of the optical path), and magnetic drive pumps or isolation brackets are often used.
Maintenance and troubleshooting
Regular inspection:
Clean the fins/tube bundles of the heat exchanger to prevent dust accumulation and reduce heat transfer efficiency.
Replace the filter element to avoid blockage that may cause a decrease in flow rate.
Common faults:
High water temperature: Check if the pump is malfunctioning, if the heat exchanger is scaling, or if the cold source (such as the fan) is stopped.
Leakage: Check if the sealing ring or weld seam at the pipeline connection is damaged.
Temperature control fluctuations: calibrate temperature sensors or adjust PID parameters.