Commercial low-emissivity glass-based transparent heater for effective defogging in glazed window refrigerator

Abstract

Transparent heaters have attracted significant attention in applications that require both visibility and thermal control, such as automotive defogging and energy-efficient architectural glazing. In this study, a transparent heater was developed by selectively removing the surface buffer layer of commercial Low-Emissivity (Low-E) glass using laser etching, thereby exposing the internal Ag layer to the external busbar to establish electric contact. This simple process enables low-voltage operation while utilizing the existing structure of commercial materials. When applied to a prototype refrigerator door, the heater achieved surface temperatures exceeding 70 °C within 1 min at 12 V DC supply, effectively preventing condensation and fog under cold and humid conditions. Thermal imaging confirmed rapid and uniform heating without additional protective coatings. Furthermore, a thermal-fluid numerical simulation accurately reproduced airflow and temperature distributions consistent with experimental results, which validate the large-area full-size refrigerator applicability For full-size designs maintaining an outer-surface temperature of 35 °C, the simulations estimated a heat generation of 12.04 W and a cooling load of 6.21 W for double glazing, and a heat generation of 9.60 W and a cooling load of 3.79 W for triple glazing. This study presents a scalable and energy-efficient transparent heater solution by combining commercially available materials with a simple fabrication process and predictive modeling, with potential applications in commercial refrigeration, architectural glazing, and automotive defogging systems.