Numerical Study Of Office Environment Under Stratum Ventilation In Lanzhou

In order to reduce carbon emission and building energy consumption, thegovernments of many countries recently required adopting higher indoor temperaturesstandard in summer. Based on this background, the fresh air of air-conditioningsystem is decreased. Such a reduction of fresh wind supply causes an increase ofconcentration of indoor pollutants and generates a non-uniform distribution of airtemperature for occupants, and this also makes the indoor air quality declined.Adopting the mixture ventilation, it is difficult to improve the indoor air quality dueto the limit of the fresh air rate and ventilation mode. Therefore, how to solve theindoor air quality and thermal comfort problems under high-temperatureair-conditioner is a very challenging subject. Stratum ventilation is proposed based onthis background. As a new high-temperature air-conditioning mode, stratumventilation provides high quality air for occupants and will not sacrifice thermalcomfort with low energy consumption.In order to have profound understanding of office environment under the newventilation mode in Lanzhou, in this dissertation, the physical and mathematicalmodels for an office with stratum ventilation system in Lanzhou is established.Distribution of velocity, temperature, local air age and CO₂concentration, theventilation efficiency and thermal comfort are studied numerically with a validatedRNG k-εturbulence model combined with UDF （user defined function）. Theresults are compared with the corresponding results obtained by displacement modeand mixture mode. Meanwhile, the effects of the supply air temperature and outletlocation of the office on the indoor air quality are discussed.The numerical results in the present study show that the newly proposed stratumventilation does not only meet international standards on indoor air quality withhigher temperature of the air supply and thermal comfort, but also has the potentialapplication in high temperature air-conditioning system to decrease building energyconsumption and carbon emission. The results in this study can provide theory basisand designing reference for the application of stratum ventilation system in Lanzhouarea.