When a vacuum pump operates under high-temperature conditions, the core issue causing performance degradation lies in the thermal expansion of components due to internal heat accumulation, lubrication failure, and changes in gas properties. The core objective of cooling design is to control the pump body temperature within the material deformation threshold through multi-dimensional thermal management methods, while maintaining the stability of the vacuum environment.
The cooling system architecture needs to be customized according to the type of vacuum pump and operating conditions. For dry screw vacuum pumps, cooling typically employs a combined air-cooling and water-cooling mode: dense heat sinks and a forced air-cooling system accelerate air convection on the pump body surface to remove surface heat; internally, circulating cooling water flows in the rotor jacket or casing channels to directly absorb the heat generated during compression. For water-ring vacuum pumps, the cooling focus is on the temperature control of the working fluid. A separate chiller unit is needed for closed-loop cooling of the working fluid to prevent cavitation caused by increased water temperature, which in turn leads to a decrease in vacuum and increased energy consumption. Roots vacuum pumps require specific design to address the temperature difference between the rotor and the casing, using a cooler at the exhaust port or an oil circulation cooling system to balance the thermal expansion under high pressure differentials. The choice of cooling medium directly affects heat exchange efficiency and system reliability. Water-cooled media need high specific heat capacity and low viscosity to reduce pumping resistance and increase heat transfer rate, while corrosion inhibitors should be added to extend flow channel life. Oil-cooled media need to balance lubrication and cooling properties, with synthetic oils with low saturated vapor pressure preferred to avoid oil vapor contamination of the vacuum system at high temperatures. In extreme high-temperature or corrosive conditions, phase-change cooling media such as Freon can be used, achieving efficient cooling through liquid evaporation and heat absorption, but a sealing design is required to prevent media leakage.
Optimizing flow channel design is key to improving cooling uniformity. Internal pump cooling channels should employ spiral or biomimetic fractal structures to increase medium turbulence and enhance convective heat transfer, while avoiding localized dead zones that lead to heat accumulation. Rotor cooling channels require CFD simulation to determine the optimal pore size and distribution density to ensure uniform cooling medium coverage of the heat source area. For water-ring vacuum pumps, the working fluid flow channel should be designed with a gradually narrowing structure to enhance cavitation suppression through flow velocity variations and improve intake efficiency through the Venturi effect.
The application of auxiliary cooling technology can further extend performance limits. Introducing dry nitrogen or inert gas at the exhaust end can reduce rotor temperature through gas expansion and heat absorption, while preventing particulate matter deposition that could cause jamming. For high-temperature, heavy-load conditions, heat pipe technology can be used to transfer heat from the pump core area to a remote radiator, achieving physical isolation between the heat source and the heat dissipation module. An intelligent temperature control system monitors the temperature of key components in real time using temperature sensors, automatically adjusting the cooling medium flow rate or fan speed to maintain the pump body temperature within a safe range.
Maintenance strategies must consider both short-term emergency response and long-term prevention. Regularly cleaning impurities and scale from the cooling channels can prevent localized overheating caused by channel blockage; replacing aged seals can prevent performance degradation caused by cooling medium leakage; and calibrating temperature monitoring devices can ensure the timely response of the cooling system. Before the arrival of the high-temperature season, a comprehensive pressure test and thermal balance verification of the cooling system are necessary to identify potential risks in advance.
The cooling design of vacuum pumps under high-temperature conditions requires system architecture optimization, precise medium matching, innovative flow channel design, integration of auxiliary technologies, and upgrades to maintenance strategies to achieve stable performance. This process not only needs to consider the principles of thermodynamics and fluid mechanics but also needs to combine knowledge from multiple disciplines such as materials science, sealing technology, and automation control to ultimately build a closed-loop thermal management system covering the entire chain of "heat generation-heat conduction-heat dissipation."
