An experiment and numerical study of resuspension of fungal spore particles from HVAC ducts

Numerical and Experimental Study on Thermal Comfort of Human Body by Split-Fiber Air Conditioner

The thermal comfort of an enclosed room with air conditioner and air-distribution duct coupling can be studied, and the parameters of a split-fiber air conditioner can be optimized on the basis of studying the thermal comfort of various parts of the human body. In this paper, a room model with a distributed air conditioner was proposed. First, the rationality of the three thermal comfort characterization models of predict mean vote (PMV), predicted percentage of dissatisfied (PPD), and percentage of dissatisfied (PD) were verified through experiments and simulations. Then, the temperature and thermal comfort of various parts of the human body were explored when the air-distribution duct had different openings and different positions of the air outlet. The simulation results showed that compared with other situations, when the split-fiber air conditioner had three rows of holes (5-o’clock, 6-o’clock, 7-o’clock) and the air outlet was located in the middle of the right wall of the human body, the PMV, PPD, and PD of the measuring points around the human body fluctuated less, the indoor temperature field distribution fluctuated less, and there was no wind feeling around the human body, which can better meet the needs of human thermal comfort.

PM2.5 mass concentration variation in urban residential buildings during heating season in severe cold region of China: A case study in Harbin

Recent years, people pay great attention to fine particle matter (PM_2.5) in indoor environment due to its negative impacts on health. Household cooking and severe air pollutant aggravate indoor PM_2.5 level, especially during heating season in severe cold region of China. To find the variation of actual household PM_2.5 influenced by both cooking activities and penetration from outdoor environment, a field measurement of PM_2.5 concentrations in living room of residential buildings was conducted in Harbin, China. Firstly, six households in urban residence were selected to monitor the indoor PM_2.5 mass concentration sequentially. Simultaneously, outdoor PM_2.5 concentrations, temperature and indoor occupants' behavior were collected. Secondly, indoor to outdoor (I/O) ratios of PM_2.5 in each household during monitoring campaigns were calculated. Influence of cooking activities and outdoor penetration on indoor PM_2.5 concentrations in living room were also analyzed. Thirdly, some discussions were done for explanation of variation of PM_2.5 in urban residential buildings. Results showed that the average PM_2.5 mass concentrations varied from 11.7 to 48.6 μg/m³ indoor, while average I/O ratio value ranged from 0.33 to 1.23. Cooking in kitchen had significant impact on PM_2.5 mass concentrations in living room, especially when frying, which could lead to peak value of 456.8 μg/m³ within 10 min from background level. Penetration led to the indoor PM_2.5 level approximately 2 h behind with outdoor PM_2.5 concentrations in general residences.

The Effect of Air leakage through the Air Cavities of Building Walls on Mold Growth Risks

Mold growth poses a high risk to a large number of existing buildings and their users. Air leakage through the air cavities of the building walls, herein gaps between walls and air conditioner pipes penetrating the walls, may increase the risks of interstitial condensation, mold growth and other moisture-related problems. In order to quantify the mold growth risks due to air leakage through air cavity, an office room in a historical masonry building in Nanjing, China, was selected, and its indoor environment has been studied. Fungi colonization can be seen on the surface of air conditioner pipes in the interior side near air cavity of the wall. Hygrothermometers and thermocouples logged interior and exterior temperature and relative humidity from June 2018 to January 2020. The measured data show that in summer the outdoor humidity remained much higher than that of the room, while the temperature near the air cavity stays lower than those of the other parts in the room. Hot and humid outdoor air may condense on the cold wall surface near an air cavity. A two-dimensional hygrothermal simulation was made. Air leakage through the air cavities of walls proved to be a crucial factor for mold growth.