Author: Xiong, Tingting
Title: Chilled ceiling (condensation performance assessment of different Nano-engineered superhydrophobic materials surface in outdoor condition)
Advisors: Niu, Jian-lei (BSE)
Degree: M.Eng.
Year: 2021
Subject: Air conditioning
Heat -- Transmission
Heat -- Radiation and absorption
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Services Engineering
Pages: 2, 69 pages : color illustrations
Language: English
Abstract: Compared with the traditional air conditioning form mainly based on convection heat transfer, the radiation cooling system has great advantages in thermal comfort, sanitary conditions, and energy consumption [1], which has attracted widespread attention in recent years. However, the surface condensation of the radiation panel restricts its engineering application [2]. For this reason, many researchers have carried out research work on the surface condensation of the radiant panel, which can be divided into three categories: one is the surface temperature control of the radiant panel; The second is the dew point temperature control; Third, the application of new technologies and new materials [3]. The surface temperature of the radiant panel is controlled mainly by controlling the chilled water temperature and flow in the pipe, which controls the surface temperature of the radiant panel higher than the air dew point temperature to prevent condensation [4]. In past research, the dew point temperature control is mainly through the dehumidification equipment (traditional fan coil, dehumidifier, etc.) to undertake all the indoor moisture load, to reach the purpose of preventing condensation in the radiation panel. In this method, when the surface temperature of the radiation panel is lower than the air dew point temperature, the chilled water supply of the panel is stopped, which will cause the fluctuation of indoor air parameters. The use of new materials and technologies to restrain the condensation on the surface of radiation panels and slow down the condensation speed has attracted increasing attention of researchers, among which the use of the hydrophobic surface of radiation panel can delay the condensation. However, the current research on the influence rule of hydrophobic surface on condensation is not perfect, and it is impossible to rationally use the change law of condensation to achieve the goal of prevention of condensation [5-6].
Through the experiment, under the condition that the thermal environment is not changed, there is a risk of condensation between different materials, and when the temperature and humidity are adjusted, the change rule of the condensation water on the surface of the radiation panel with time is studied. At the same temperature and different humidity, the lower the relative humidity is, the dew-condensation can be effectively delayed. Based on the experimental data, the comprehensive influence of various influencing factors on the surface temperature of the radiant panel is analyzed numerically. In this paper, the influence of water supply parameters and thermal environment parameters on the surface temperature of the radiation panel is analyzed by combining experiment and simulation, and the dynamic change rule of the surface temperature of the radiation panel is obtained, which lays a foundation for the proposal of the reasonable and effective anti-condensation predictive control method.
Rights: All rights reserved
Access: restricted access

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