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. Using magnetron sputtering technology, a high-absorption coating is applied to the glass surface to convert sunlight into thermal energy. Heat pipe vacuum tubes employ copper-aluminum composite strips to connect the absorber plate to the water tank, utilizing the latent heat of vaporization of the working fluid to transfer heat.
Features
Efficient Thermal Insulation: The vacuum interlayer minimizes 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 various building scenarios.
High Pressure and Frost Resistance: Utilizes glass-metal sealing technology, offering strong pressure-bearing capacity, making it suitable for cold northern regions.
Applications
Mainly used in household solar water heaters, which operate via natural gravity-fed water supply without the need for additional pumping equipment. Since the 1990s, heat pipe technology has advanced solar water heating into medium and high-temperature applications, becoming a mainstream product.