Vacuum heating tubes are primarily used in the field of solar water heaters, achieving efficient heat transfer through a vacuum environment. Their core structures include two types: all-glass vacuum tubes and heat pipe vacuum tubes.
Structure and Principle
The all-glass vacuum tube consists of an inner glass tube, a selective absorption coating, a vacuum interlayer, and an outer glass tube. Through magnetron sputtering technology, a high-absorption coating is applied to the glass surface to convert sunlight into thermal energy. The heat pipe vacuum tube uses a copper-aluminum composite strip to connect the absorber plate and the water tank, utilizing the latent heat of vaporization of the working fluid to transfer heat.
Features
Efficient Thermal Insulation: The vacuum interlayer reduces heat loss, similar to the principle of a thermos flask, maintaining stable water temperature.
Modular Design: Supports separate installation of the water tank, adapting to different building scenarios.
High Pressure and Frost Resistance: Employs glass-metal sealing technology, offering strong pressure resistance, making it suitable for cold northern regions.
Applications
Mainly used in household solar water heaters, which operate through natural gravity-fed water supply without additional pumping equipment. Since the 1990s, heat pipe technology has advanced solar water heating into medium-to-high temperature applications, becoming a mainstream product.