| With the rapid development of HVAC technology,people put forward higher requirements for energy saving and comfort of air conditioning system.At present,in public buildings,the design of large spaces such as meeting rooms and large laboratories has gradually become a popular trend.Although most air conditioning systems are adhering to the concept of on-demand regulation and energy conservation and emission reduction,they still create an approximate uniform indoor environment,which inevitably leads to energy waste.This dissertation proposes to adopt the air conditioning operation mode of "partial space and partial time" in office buildings with large space.This mode adjusts the air supply according to the distribution of indoor personnel.According to the different thermal environment characteristics of each area of the room,the local optimization of the room is targeted to achieve the maximum improvement of the thermal comfort of indoor personnel with the minimum energy consumption of air conditioning,so as to achieve the purpose of energy saving and emission reduction.Through numerical simulation,experimental measurement and questionnaire survey,this study selects a large office of a university in Jinan as the research object to analyze the distribution of indoor air temperature,velocity and energy-saving effect when the air conditioning operation mode of "partial space and partial time" is adopted in the large space building.First,Airpak software is used to build a physical model consistent with the actual building.After the modeling is completed,three air conditioning modes of full space air supply,conference area air supply and working area air supply are designed to simulate different loads in winter and summer,and the temperature and average air velocity of different indoor areas are explored with different air volume and the air supply diffusion angle.Based on the simulation results,air flow evaluation indexes such as temperature and velocity nonuniformity coefficients and air distribution characteristic index ADPI,are analyzed.The final result is: In the case of the full-space air supply mode,the average temperature of the indoor air in both winter and summer can reach the design value of the air temperature.In the winter condition,the nonuniformity coefficient of the indoor air temperature and velocity are0.224 and 0.013,respectively,and the ADPI value is 93.1%.In the summer condition,the nonuniformity coefficient of the air temperature and velocity are 0.208 and 0.025,respectively.When the ADPI value is 100%,the thermal environment of the room tends to be consistent in this mode.In the case of the air supply mode only in the meeting area,the average air temperature of the meeting area can reach the set value,and the ADPI value is 100%.At this time,the average air temperature of the whole room is 18.7℃ in winter and 26.2℃ in summer,and the ADPI value drops to 40.7% and 83.3%,respectively.The average air temperature of the room in the work-only air supply mode decreases to 15.5℃ in winter and 29.5℃ in summer,and the ADPI value drops to 12.5% and 19.4%,respectively.The results show that the partial space air supply can only ensure that the air distribution in the air conditioning area where personnel are located is more uniform,meet the demand for thermal comfort,and thus achieve the goal of energy saving.Secondly,the experimental platform of air conditioning system with variable air volume was designed and constructed,the equipment selection of air conditioning system,the software design and development of networked detection system were completed.The human-computer interaction interface was developed to realize data display,parameter regulation and other functions,providing a supporting platform for the subsequent experimental research of partial space air supply.Based on the above experimental platform,under the heating condition in winter,the experimental research on air supply in the whole space,air supply in the meeting area and air supply in the work area was carried out,and the experimental verification was made with the numerical simulation results.During the experiment,the air supply temperature,air velocity and air supply angle were consistent with the simulated setting conditions.Indoor parameters were measured by temperature and humidity sensors,anemometer and air volume hood.The experimental results show that the ADPI value of the room at 1.1m above the ground is 91.7% under the traditional full-space air supply mode.By changing the air supply angle to the meeting area and closing supply air outlet to the working area,the air temperature of the area where personnel are located can be maintained above the design value of 20℃,while the average air temperature of other areas is less than 20℃.The ADPI values of the room under the two air supply modes are 50% and29.2%,respectively.At the same time,the comparison between the experimental results and the simulation results shows a good agreement.Finally,the thermal comfort questionnaire was conducted to explore the indoor thermal environment created by different air supply modes.The results showed that the full space air supply of the air conditioning could take into account the thermal comfort of the whole space.Under this air supply mode,the vast majority of respondents in the working and meeting areas of the room thought that the thermal environment was satisfactory.But in the case of the only air supply to the meeting area,most respondents in this area felt comfortable,while those in the non-air conditioning area felt cool and 90% of respondents were not satisfied with the air temperature.The thermal sensation of the respondents in the air conditioning working area was better than that of the respondents in the non-air conditioning area.By calculating the energy consumption of the air conditioning system under different working conditions,it is found that the partial air supply mode of "only meeting area operation" and "only working area operation" can reduce the annual heat consumption by about 16.4% and the power consumption of the air conditioning unit by about 50%.It can be concluded that,for the area where personnel are located,the comfort environment created by the full-space air conditioning operation mode is not much different from that created by the partial air supply mode.Therefore,energy waste and electricity consumption of the air conditioning will be caused to a certain extent.The partial space air supply scheme proposed in this dissertation can provide a basis for the air conditioning operation of office buildings with large space. |
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