| In 1970 s, energy crisis were obtained increasing attention, and building energy conservation has been the main target. A lot of measures were adopted to reduce building energy consumption, such as strengthening the construction closure and reducing the supply of fresh air. Thus it caused a decline in indoor air quality, and people would emerge many adverse reactions under the condition of staying in the bad air environment for a long time, such as suffering from architectural diseases. With the development of society and the improvement of living standards, people gradually began to pursue a healthy life, and the awareness of the importance of indoor air quality has been gradually deepened. In recent years, in order to realize energy conservation and good indoor air quality, how to optimize the design of air conditioning system has been aroused wide attention and research in academic circles. The personalized ventilation with personalized adjustment and energy-saving advantages has been placed in an important position. In this thesis, The desktop personalized ventilation was minutely researched. The effects of personalized supply air terminal types and supply air parameters on the micro environment of occupied zone were explored by the combination of numerical simulation and experimental study.In the process of research, ANSYS CFX was selected as the numerical simulation software. The geometric model was established according to the actual size of artificial environment chamber comprehensive test bench. In the process of preparation, the grids were divided; the control equations and turbulence model were selected; the initial and boundary conditions were set. Then the numerical model was solved. Temperature and velocity distribution of the occupied zone under different conditions were calculated to explore the influence of personalized supply air terminal types and supply air parameters on the thermal comfort and air quality of occupied zone. In the process of experimental study,the test bench was designed and built; the experimental schemes were arranged; the temperature and velocity data was measured by data acquisition unit and anemometer. Then the experimental data was collected to explore the influence of personalized supply air terminal types and supply air parameters on the thermal environment of occupied zone. The correctness and feasibility of numerical simulation results was validated by using experimental results. The main research results were as follows:(1) The velocity in the thoracic and abdominal position of occupied zone was greater than other regions in the PEM air terminal type, which was at 0.2m/s~0.3m/s. Then the velocity would be decayed and be small in head and ankle position, which was at about0.05m/s~0.1m/s. However, the velocity of the face position in occupied zone was greaterunder the other air terminal types. In the type of VDG and HDG, the velocity around the face position was at 0.15m/s~0.2m/s. And in the type of MP and CMP, the velocity around the face position was at 0.2m/s~0.4m/s.(2) Through the analysis of the thermal comfort of the occupied zone, it can be concluded that when the personalized supply air temperature was increasing, the PMV value was increasing, and the draught rate caused by air sensation decreased. With the increase of background temperature, the PMV value of occupied zone increased. With the increase of air velocity, the draught rate caused by air sensation also increased. Thus better thermal comfort of occupied zone could be obtained with the conditions of air temperature in 21℃~22℃, background temperature less than 29℃, supply air volume greater than30m3/h( the velocity greater than 0.21m/s).(3) The advantage of personalized ventilation was that better air quality could be quickly obtained in human breathing zone. The CO2 concentration of MP and CMP air terminal types were lower than the other three air terminal types, and the personal exposure effectiveness was highest, which meant that the inhaled air quality was the best. Under the desktop personalized ventilation, the effectiveness of energy utilization was improved in the conditions of the air temperature in 21℃~23℃, the background temperature in 27℃~28℃,supply air volume greater than 30m3/h( the velocity greater than 0.21m/s).(4) Found by experimental study, the temperature distribution was similar in the five air terminal types. The temperature distribution was on the rise with the height from the ankle position to the head position, and the temperature of the measuring points near human body was higher than the temperature of the measuring points distant from human body.The temperature difference of the measuring points on the face position of VDG and HDG types was smaller than that of PEM type, and temperature distribution was more uniform.The average temperature of the measuring points on the head position of MP and CMP types was lower than the other types.(5) It could be concluded from the experimental results that the average temperature around the body would increase with the increase of the background temperature as well as the height of position. Analyzing P3, P6 to P10 conditions, it could be found that when the background temperature was between 28℃ to 29℃, the temperature difference of head and foot was less. The influence of supply air volume on temperature distribution was small.The temperature showed a trend of weak diminution with the increase of the supply air volume. Analyzing P3, P10 to P14 conditions, it could be found that when the supply air volume was greater than or equal to 60m3/h, the temperature difference of head and foot was less.(6) Comparative the simulation results and experimental data, it could be found thatthere is a smaller error between the simulation results and the experimental data, and the variation trend was almost consistent. Thus the feasibility of numerical simulation method was verified in this thesis.(7) Analyzing the conditions in this study, it could be seen that the thermal comfort of occupied zone was better, the draught rate was less and the effectiveness of energy utilization was greater when the personalized supply air temperature was between 21℃ to22℃, supply air volume was between 30m3/h to 90m3/h(the velocity was between 0.21m/s to 0.63m/s), the background temperature was between 27℃ to 28℃. The the personal exposure effectiveness of MP and CMP air terminal types was greater, and the draught rate of PEM, VDG and HDG was less. |
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