Self-Powered Intelligent Water Meter for Electrostatic Scale Preventing, Rust Protection, and Flow Sensor in a Solar Heater System.

Triboelectric nanogenerators (TENGs) have been investigated for mechanical energy harvesting because of their high-energy conversion efficiency, low cost, ease of manufacturing, and so on. This paper deals with designing a kind of water-fluid-driven rotating TENG (WR-TENG) inspired by the structure of a water meter. The designed WR-TENG is effectively integrated into a self-powered electrostatic scale-preventing and rust protection system. The WR-TENG can generate a constant DC voltage up to about 7.6 kV by using a voltage-doubling rectifier circuit (VDRC) to establish a high-voltage electrostatic field in the water tank. A WR-TENG, a VDRC, and an electric water heating tank are the components of the whole system. The system is convenient to be installed in any waterway system, effectively preventing the rusting of stainless steel and restraining the formation of scale when the water is heated to 65 ± 5 °C. Moreover, the approximately linear relationship between the short-circuit current and the rotation rate of the WR-TENG makes employing it as a self-powered water flow sensor possible. This work enables a facile, safe, and effective approach for electrostatic scale prevention, rust protection, and flow sensing in solar heaters, which will enrich the high-voltage applications of TENGs.