The Study On The Fan-Coil Unit With Fresh Air System On Dry Condition

In traditional air-condition system, the wet surface of the air handing equip-ment is the ideal environment to indoor microbial propagation. So it cause great harm to the indoor air quality. Meanwhile, it is uncomfortable and unsafe for the air-conditioning system with return air system. So the Dedicated Outdoor Air Sys-tem (DOAS) which control the temperature and humidity of the building inde-pendently through handling the sensible heat load and latent load separately. In DOAS, it makes the outdoor air undertake all the indoor latent load and parts of indoor sensible heat load, then the indoor air handling units deal with the remain-ing sensible heat load. In consequence, there is no condensed water in the room and the indoor air quality is assured. According to the current situation in our country, it is most common to use the fan coil unit as the terminal air handing equipment. So domestic scholars have purposed dry coil system namely make the fan coil unit operate in the dry condition. The concept of dry coils is not strange, but many subjects about dry coils system need to be researched.First, the key parameters of the dry coil system design are analyzed and de-termined, containing Outdoor and indoor design parameters, the smallest air vol-ume for the system, the appropriate temperature for the inlet water of the fun coil unit, etc. Take a office building as an example, this paper introduce the design of the dry coil system step by step. The forming process of condensed water of the fun coil unit is analyzed, and two key questions were put forward, that is the ap-plication scope of the system and how to prevent the condensed water forming, also in the paper. And in the last, the way of the control was given for the fun coil unit maintaining dry. There are two main ways of water system serve for dry coil system, series and parallel. In the paper, the advantages and disadvantages for the two water systems was discussed separately. For the selected building, the build-ing heat load was calculated by DeST software, and then the heat load of dry coil undertaken was calculated according this, providing the basis for selecting air handing equipments. In the end, setting up the mathematical model of the key parts of the dry coil system with the platform of Matlab, the two ways of hydration System were simulated, and came to the conclusion that the series system more saving for energy, based on the same level of comfortableness in the room. Fur-thermore, the energy consumption and Initial investment for the dry coil system was compared with the common fun coil unit system.