| The mild area represented by Kunming is rich in solar energy resources,and the cooling load in summer is not large.In recent years,with the continuous improvement of people’s living standards,higher requirements for indoor comfort have been put forward.In this paper,a single building with an indoor space of about 60m3 in western rural areas as a model,a photovoltaic DC air conditioning system was built in a single building in Kunming area,and experimental tests and Computational Fluid Dynamics(CFD)combined methods were used on sunny days in summer to test and analyze the characteristic of natural ventilation and indoor temperature changes,wind speed distribution,electrical parameters of air conditioning operation and the influence of different set cooling temperature.It provides reference significance for indoor cooling in sunny days in summer in mild areas.The main experimental research results are as follows:(1)When the ambient temperature is below 28℃,the test results show that opening the south window for natural ventilation can meet the human body’s demand for indoor thermal comfort temperature.When the ambient temperature is higher than 28℃,the indoor temperature is still 28℃ or above for a long period of time when only the south window is opened and the doors and Windows are fully opened.(2)Compare and test the characteristic of indoor temperature and its influence on the electric quantity of air conditioning under different air conditioning cooling temperatures and window covered and uncovered conditions.It was found that the indoor temperature can meet the requirements of human thermal comfort temperature when the indoor cooling temperature is set at 26 ~ 28℃,and the temperature at 28℃ can make the thermal balance stage faster,with good temperature uniformity.The intermittent air conditioning operation saves energy significantly.The power consumption is obviously smaller under the window covered condition,and the indoor temperature is lower at the same time.(3)The experimental results from 11:00 to 19:00 in fine weather show that: when the cooling temperature is set at 24℃ and 26℃,the temperature is lower than 22℃ at end stage;when the refrigeration temperature is set at 28℃,the temperature after 16:00 is moderate and the uniformity is good,and the minimum temperature of the whole process is 23℃,the main reason is that the cooling load is not large.The main numerical simulation results are as follows:(1)When the wind angle is 45 degree,the wind speed is 4m/s,and the cooling temperature is set at 20℃,24℃ and 28℃ respectively,the air temperature at the same height of the human body activity area is generally lower than 28℃ when the cooling temperature is set at 28℃,which meets the indoor temperature standard in summer.Mainly because the photovoltaic DC air conditioning in the low refrigeration power state can adjust the indoor temperature to the temperature of the comfort zone.(2)At the set cooling temperature of 28°C,compared with the three different air speed of 4m/s,3.5m/s and 3m/s respectively,the results show that the temperature distribution is the most comfortable under 4m/s,while the thermal comfort temperature of the other two working conditions is poor.(3)When the air speed is 4m/s,the results of the unevenness coefficient analysis can be obtained: the temperature uniformity is the best when the cooling temperature is set to 28 °C,and the speed uniformity is the best when the cooling temperature is set to 20 °C.By the Air Diffusion Performance Index(ADPI)and Draft Rate(DR),it is believed that when the cooling temperature is 28 °C,the room can have a good thermal comfort and the lowest air blowing feeling. |
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