Cfd Simulation And Study On The Combined System Of Displacement Ventilation And Radiant Cooling

Health and energy conservation are two subjects that air-conditioning is towards to nowadays. The air flow in confined space is key for human's health and energy conservation. Health requires a frequent displacement of air, whereas energy conservation requires a less amount of air to be displaced. Therefore, a ventilation system which both meets the human's health demand and consumes less energy is the topic for the research. As a relatively new ventilation system developed and trialled recent years, displacement ventilation (DV) has its characteristic airflow distribution which guaranties a high quality of air distribution and less energy consumption induced by layered airflow distribution. The displacement ventilation has a good potential for a broad application in China as it offers a high efficient and more comfortable environment. Nevertheless, current displacement ventilation system is struggling to cover a large living area. The load is from 30W/m~2 to 40W/m~2. In the most area in China, as the cooling load inside the house is higher and pure displacement ventilation could not cope with, the additional radiation cooling system is required to remedy the shortcoming.On the basis of research and analysis into the efficiency of displacement ventilation, this thesis studies the temperature fields, air flow distribution, and contamination distribution using the commercial CFD software package Airpak. The characteristics of ventilation were examined in detail. By comparison of the numerical analysis results and experiment results, application of Zero equation model to accurately describe the room temperature fields, airflow velocity distribution and contamination concentration distribution is validated.On top of numerical analysis performed on temperature, velocity and contamination distribution, a system of displacement ventilation and cooling roof, and a system displacement ventilation and floor cooling were also analyzed. Finally, two system were evaluated and the application condition and limitations are pointed out. All of the above are valuable for ventilation system design, evaluation and optimization and are useful for application research into the displacement ventilation and radiation cooling system in China.