Design of a printed IR modulating structure for smart windows

• Main Author: Chen, Siyuan
• Other Authors: Long Yi
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/76755
• Institution: Nanyang Technological University

Smart Window is a developing technology which can alter the solar transmittance over a large range of wavelength including ultra-violet (UV), visible light and infrared (IR), into the building “smartly” due the external thermo-, electro- or photo-stimulation. For thermochromic smart window applications, vanadium dioxide (VO2) is a promising candidate due to its attractive properties in energy conservation relying on the reversible phase transition at 68℃. Apart from simply using VO2, this project also introduces the usage of 3D printing technique, a newly developed manufacturing method which can form precise tiny parts with high aspect ratio by additive method according to the 3D model designed. This project focus on designing a thin film with special 3D pattern, in specific, strips with tilting angle and designed gaps, which is coated on the surface of the normal window. VO2 nanoparticles (NP) is composited with light-sensitive liquid monomers are used as the ink for 3D printing. This smart window system can be achieved because the Zenith angle of Sunlight is different during the summer and winter. The 3D printed strips can cut off the amount of solar radiation in summer as all solar radiation will passthrough the strip structures, which absorbs IR light in high temperature, with longer path; while the system can maintain a high transmittance during winter as the light path in the structure is the shortest and since the direction of incident light is parallel to the strip structure, a large portion of sunlight will pass through the gaps between the strips and directly enter the room. Different contents of the ink and the thickness of the printed film have been fine-tuned to achieve the highest △Tsol while maintaining acceptable Tlum. Through the experiment, this project achieved Tlum of 75.77% and TIR of 80.02% in winter; and 69.50% for Tlum and 64.7% for TIR in summer. The over △Tsol across summer and winter is 10.42%.