Design Of Active Chilled Beam Control System

With the development of science and technology, there are more increasing concerns on the quality of working and living environment. As an effective means of adjusting air quality, the air-conditioning systems are becoming increasingly popular all over the world. When bringing comfortable environment to people, the air-conditioning systems waste a lot of energy. It is a well-known fact that the problem of saving energy has become more and more fundamental and it is under discussion since the last decades. So how to deal with the contradiction between the quality of people’s living environment and energy savings has become one of the urgent problems to be solved.There are many advantages of chilled beam, such as energy saving, small size, easy installation and comfort, which make chilled beam become one of potential emerging air-conditioning technologies. However, presently domestic study of chilled beams is in its infancy and further exploration is still on the way. This paper analyses active chilled beam air-conditioning system configuration and operation principle and its control method, based on the project of central air-conditioning energy-saving control theory and application lab.Firstly, the active chilled beam air-conditioning system is designed. According to the actual situation of the lab and design requirements, the indoor cold moisture load is calculated to determine active chilled beam, air handing unit (AHU) and other equipment. And the waterway and air duct are designed base on the principle of the system.Secondly, the system controller is designed. The ARM micro-controller is chosen as the CPU in hardware. And the temperature and pressure are gathered in the branch and waterway, which are used to control the fan speed and to set the opening of air valve and water valve. In software, the system is divided into communication task, data acquisition task, data processing task and LCD display task, based on the uC/OS-H operating system. The function of the controller consists of the signal acquisition, processing, analysis and communication with the computer. Thirdly, the active chilled beam air-conditioning control algorithm is designed to realize the system to run with low power consumption. The control algorithm consists of AHU control algorithm, the freezing station system control algorithm and active chilled beam control algorithm. In the AHU part, carbon dioxide concentration method is selected to adjust fresh air volume, and the static pressure method is used to control supply volume. The strategy of controlling supply air temperature and humidity varies from seasons. Differential temperature method is adopted to regulate the circulating water pump in the freezing station system part. The opening of the bypass valve is controlled through differential pressure method. The volume of the heat exchanger circulating water is adjusted by differential temperature of active chilled beam. The condensation can be voided through the dewing controller.Finally, the performance of active chilled beam air-conditioning system is tested, comparing to Variable air volume air-conditioning system in the same environment. Experimental results show that active chilled beams air-conditioning system has obvious energy-saving advantages and the system can save energy up to30%.