R22 and R410A multi-line piping length theoretical analysis / pre> , residential and other widely used. But in the course of the characteristics of the multi air conditioning unit,hollister belgie, if the lack of consideration would result in increased energy consumption, the phenomenon of cold (hot) reduced serious will cause the unit can not safely run. This paper argues that fully consider the adverse effects of too long piping will bring multi air conditioning unit can be used in the construction of larger monomer,abercrombie hamburg, shall be paid. Can partition or hierarchical placement to avoid unnecessary trouble, in order to better implement the norms of national and local energy-saving requirements. References: [l] Ma too, Wang Hongli. The air conditioning system and its energy efficiency standards for progress [J] _ Machinery Industry Standardization and Quality, 2008,hollister, (2) :21-23. I21 Gao Tao,hollister wien, Wu Zhaolin, Zhigang. High-rise building hierarchical set of multi-online outdoor unit refrigeration system influencing factors [J]. HVAC,mulberry, 2008 38 (3): ll4 l17. [The 3J Huanghu Leach HE, Zhang Zhongbin. Digital Scroll multi-line performance evaluation [J]. Nanjing Normal University (Engineering and Technology),hollister donauzentrum, 2008,8 (2) :23-25. [4] HE WORKS China. R410A refrigerant in the advantages and disadvantages of multi-line applications [J]. Refrigeration, 2006,25 (1) :72-74. (81) analysis of Figure 6 and Figure 7 shows that the decline in the attached layer of air temperature along the height direction, close to the roof at the lowest temperature, it is mainly the roof cold radiation and convection. Attached layer of air relative humidity increased along the vertical direction, relative humidity and the work area to the opposite distribution. Indoor hot burning air new wind uplift to the room the upper part, the temperature rising. When you reach the attached layer, cooling the roof strengthened, temperature, water vapor upward uplift the lower part of the high temperature air, forming an inverted relative humidity layer. Adhesion layer and the dew point temperature is calculated as follows [3,4]: tl = a 35.28896-2.032221npq +1.17025 (1npq) (1) where t1 a dew point temperature of the region. ° C: p in the state of moist air water vapor partial pressure, pa. pq and = q, b (2) the state where the air relative humidity; Pq,abercrombie düsseldorf, the corresponding temperature of saturated water vapor partial pressure, pa. Calculation of summary adhesion layer and the work area of ​​the dew point temperature is shown in Figure 8: Figure 8 adhesion layer and workspace dew point temperature map analysis of Figure 8, the air dew point temperature of the workspace attached layer of dew point temperature of about 0. 8 ℃, and at the same temperature, dew point temperature with the decrease of the air relative humidity decreases. Contrast conditions, working conditions and working conditions 7 shows that changes in relative humidity of the air relative humidity conditions, temperature, dew point temperature of less than 0.2 ℃, less than the same temperature air dew point temperature impact. Workspace calculation of dew point temperature is higher than the dew point temperature of the adhesion layer, so the precision control requirements do not strictly the case, by calculating the dew point temperature of the work area to adjust the cooling roof temperature is feasible. Indoor air dew point temperature, there are strict requirements on the basis of the workspace air dew point temperature minus 0.8 ° C to get the attached layer of the roof near the dew point temperature. 3 Conclusion Numerical Simulation of displacement ventilation and cooling ceiling system, the paper the following conclusions: (1) displacement ventilation and indoor temperature of the cooling ceiling system showed an increasing trend along the vertical direction, relative humidity along the height is decreasing. The work area smaller temperature changes,hollister köln, temperature changes concentrated in the work area above. (2) in the attached layer of the roof near the air temperature along the height is decreasing relative humidity along the height showed an increasing trend. (3) under different conditions the work area and the adhesion layer air dew point temperature by calculating the size and trends. The air relative humidity the dew point temperature is greater than the temperature in the same circumstances. When the indoor dew point accuracy control requirements are relatively low, you can use the dew point temperature of the work area approximation instead of the adhesion layer, the air dew point temperature, then controlled cooling roof temperature,mulberry outlet, to prevent the generation of roof condensation. References: [l] Lu Yajun, the horse the most good, Ping-Hua Zou, et al. HVAC [M]. Beijing: China Building Industry Press, 2002:20. [2] CLVIL Zhao Cleveland,ralph lauren sverige, Liu Jing, et al. Indoor air environment [M]. Beijing: Chemical Industry Press, 2006:148149. 【3】 the cloth wenfengzhen,abercrombie online shop, Wang Shihong. Dew-point temperature calculation of the empirical correction [J1. Beijing University of Technology, 2001,9:369.370. [4] Zhang Lizhi. Dehumidification technology [M]. Beijing: Chemistry I, lk ~ Press ,2005:34 -42. 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