Research On The Cold Source Of Capillary Tube Air-conditioning System Based On Closed Cooling Tower

Building energy efficiency is one of the most effective measures to ease the energy shortage, and resolve the conflict between social and economic development and energy supply shortage. The capillary tube air-conditioning system, as a new energy efficient and comfortable air-conditioning system, has a bright future in the HVAC field.Based on the status analysis of home and abroad research of radiation air-conditioning system and closed cooling tower, simulated the cooling process of capillary tube air-conditioning system in summer, analyzed the distribution of temperature and velocity field and the thermal comfort indoor by different supply and return water temperatures, determined the economic and appropriate temperature of chilled water of capillary tube air-conditioning system. Then, based on the mathematical model of closed cooling tower, analyzed the relationship between the temperature of outlet chilled water and wet-bulb temperature. According to standard meteorological date, analyzed the theory hours that the cooling water could be directly sent to capillary tube air-conditioning system for cooling of typical areas in China.Firstly, based on elaborating the composition and characteristics of capillary tube air-conditioning system, established the three-dimensional steady-state heat transfer model. By using Airpak software, analyzed the distribution of indoor temperature and velocity when the temperatures of supply chilled water were respectively 18,19 and 20℃. The simulation results showed that, the distributions of indoor velocity are all comfortable in three different conditions, the flow velocity are all below 0.2m/s and people in the room has no hair feeling; the vertical temperature gradient is small and the indoor temperature distribution is uniform. When the temperature of supply water is 18℃, temperatures of most indoor regional are between 25.1 and 26.4℃, people in the room feel a bit cool; when the temperature of supply water is 19℃, people in the room feel comfortable; When the temperature of supply water is 20℃, temperatures of most indoor regional are between 26.3 and 28.7℃, the indoor temperature distribution almost meet the comfort requirements and people in the room feel slightly hot. In view of capillary tube air-conditioning system dominated by radiation heat transfer, as to save energy and make better use of natural cold source, the chilled water temperature of capillary tube air-conditioning system is better taken about 20℃.Secondly, based on heat and mass transfer theory, the mathematical model was established and then solved by adopting reasonable assumptions. The simulation program of closed cooling tower was programmed by using Matlab software, and the calculation results were compared with the experiment data that validated the correctness of the calculation program. The calculation results showed that, it's almost a linear relationship between the chilled water approach temperature of closed cooling tower and the wet-bulb temperature, and the function equation was determined by using Origin software.Finally, the maximum wet-bulb temperature was determined when the chilled water could be directly sent to capillary tube air-conditioning system for cooling. Then, according to standard meteorological date, the theory hours were analyzed that the cooling water could be used for cooling of typical areas in China. The results showed that, in northwest and north China, the theory hours that the chilled water could be directly used for cooling in building requires cooling all year round take more than 60 percent of the annual cooling time, the rest area decreases relatively, by using chilled water of closed cooling tower for cooling can save a lot of air-conditioning energy consumption. This topic research will provide the searching of cold source of capillary tube air-conditioning system a new pathway.