A Review on Effects of Personalized Ventilation Systems on Air Quality and Thermal Comfort in Aircraft Cabin Mini-Environments

This study conducts an evaluation of air quality,dispersion of airborne expiratory pollutants and thermal comfort in aircraft cabin mini-environments using a critical examination of significant studies conducted over the last20 years.The research methods employed in these studies are also explained in detail.Based on the current literature,standard procedures for airplane personal ventilation and air quality investigations are defined for each study approach.Present study gaps are examined,and prospective study subjects for various research approaches are suggested.

Prediction of Perceived Air Quality for Personalized Ventilation Systems

The characteristics of the air jet from the outlet of a personalized ventilation system were related to the perceived air quality and ventilation rate. The perceived air quality was expressed as percentage of dissatisfied people for a system supplying isothermal fresh air. The relationship was verified using a thermal manikin with a breathing function in a climate chamber sitting by a desk equipped with a personalized venti- lation system. A trace gas was introduced into the climate chamber and fully mixed. The personal exposure effectiveness (εp) is based on concentrations of trace gas in the chamber and in the manikin nose which is affected more by the distance between the movable outlet and the occupant’s breathing zone than by the personalized air flowrate and does not change much for the personalized air flowrate higher than 10 L/s when the distance is fixed. Some predicted dissatisfied values for a personalized ventilation system com- pared with those acquired in human subject experiments have an absolute difference of less than 3%.

Experimental study on indoor environment improvement in toll booth by personalized ventilation technology

The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the analysis results,a set of equipment for controlling the indoor air quality（IAQ）of the toll booth is devised.Then,a full-scale model of the toll booth is set up in the laboratory.The airflow organization,the optimum operation parameters,and the restraint effects of the PV system on pollution are also experimentally studied.The experimental results on the air supply characteristics show that the PV system can effectively reduce the air age,improve the ventilation efficiency,and enhance the comfort and acceptability of human beings.In addition,this system plays a significant role in preventing pollution.

Performance of personalized ventilation in mitigating short-range airborne transmission under the influence of multiple factors

The effectiveness of using personalized ventilation(PV)in mitigating airborne transmission risk was found to be easily affected by multiple factors.The aim of this study was hereby to evaluate the impacts of several important factors on the performance of PV in airborne disease control for closely ranged occupants.Orthogonal experiments were designed for CFD simulations under different levels of four selected factors.Results indicated that the order of significance of these four factors affecting the intake fraction(IF)of the exposed occupant was as follows:mode of PV use>relative distance between occupants>PV airflow volume>background ventilation.The best combination of the four tested factors was PV of 15 L/s for both the infected source and the exposed occupant,with a relative distance of 2 m between them and mixing ventilation,which would yield an IF of merely 0.0246%.The worst combination was PV of 6 L/s for the exposed occupant only,with a relative distance of 0.86 m under displacement ventilation,indicating an elevated IF of 0.2919%.The increase of PV air volume and relative separation distance both contributed to lower exposure risk,but they were not as influential as the mode of PV use.PV integrated with mixing ventilation and utilized for both infected and susceptible occupants were recommended.The findings in this study will be helpful to provide guidance for the implementation of PV in indoor environment for airborne infection control.

Model-based adaptive controller for personalized ventilation and thermal comfort in naturally ventilated spaces

This work develops a standalone autonomously controlled personalized ventilation(PV)unit in a naturally ventilated(NV)office space to maintain acceptable thermal comfort{TQ under steady and transient indoor conditions and activity levels.The NV-PV proportional integral derivative(PID)controller adjusts the PV supply temperature(7spv)at the occupant set flow rate(Qspv)based on predicted TC using a regression model.The target TC level that the controller attains at all times is between 0(neutral)and 1(slightly comfortable).Process transfer functions were developed and then used to find the adaptive PID tuning coefficients using the Internal Model Control(IMC)method.The controller was tested in a case study at indoor temperature range of 25 to 33℃ with relative humidity range of 55%and 80%.It was shown that the NV-PV controller adjusted Tspv to maintain acceptable TC under transients of indoor conditions and metabolic rates.