Numerical study of chilled ceiling air-conditioning system

• Main Author: Toh, Siang Hui
• Other Authors: Wan Man Pun
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/60049
• Institution: Nanyang Technological University

Chilled ceiling air-conditioning system utilises radiant cooling method to meet occupants’ thermal comfort and the room’s indoor air quality efficiently. It has valuable advantages such as a reduced in the consumed energy, maintenance cost and space used. However, in a hot and humid Singapore, a condensation problem is prevalent. Hence, this project aimed to provide a simulated study on increasing the heat transfer efficiency of the system through the alterations of the panel designs. Also, it would support the claims of the advantages of radiant cooling through the simulations. A comprehensive guide on the setup parameters of ANSYS Fluent would allow for future or continuation of this study. The approach in setting up the simulation case of a 2D chamber involves achieving the most efficient, accurate and repeatable methods. Circular blackbodies were simulated in the chambers and it showed that the location of it had minimal effect on the air flow. However, the smaller the blackbody, the lesser the impact it had on the air flow. It also proved that radiant cooling is more effective than conventional system as the surface temperature of the blackbody was 1 Kelvin cooler than the average room temperature. Finally, 5 types of chilled ceiling panel designs of varying number of panels, panel angles and ceiling air gaps were simulated in the chamber. The results were viewed in two approaches, one being how fast the chamber is cooled and other being at what temperature it is cooled to. It concluded with the Chamber5-Angled design having the shortest cooling time. The design of 64.04% radiant cooling obtained end temperature of 293.838K with cooling time of 9 minutes. However, if the priority of the design is to achieve the lowest temperature, the PerforatedII design of 42.65% radiant cooling was capable of producing 292.632K but at a much longer time of 20 minutes.