Analysis of Crystallization Fouling Durability of Novel Heating Elements for Electric Water Heating

New materials and technologies offer the means to develop novel electrical heating systems with improved durability against crystallization fouling. In this study, an analysis of both conventional and novel heating elements under the influence of crystallization fouling is presented. The novel heating elements are based on two different coating technologies, namely, thermal spraying and thin film sputtering. The novel heating elements reach heat fluxes exceeding 15 W/cm(2) and an electrical power of approximately 1000 W. All presented heating elements operate under clean surface conditions for approximately 1000 h without any difficulties. Different properties of the presented heating elements result in different types of fouling behavior. The duration tests also demonstrate different fouling durability, which results in different lifetimes. Furthermore, it is shown that the electrical resistance of the heating conductor is adversely affected by the fouling. A comparison shows that all novel electric heating elements exhibit longer lifetimes than tubular heating elements.