The Research On The Airflow Characteristics Of ADPV Method

As to the study of personalized ventilation in recent years, many forms of personalized ventilation system, terminal device form and arrangement of air supply outlet arises at the historic moment. Compared with the traditional entire room ventilation, personalized ventilation can be achieved to provide fresh air for human respiratory area, satisfy the human body thermal comfort and energy saving purpose.However, most of the literature research of the personalized ventilation mode is only on the local microenvironment of the human body control, for example, head, or breathing zone, not to control the microenvironment of the entire human body. Therefore, in view of the shortage of the existing personalized ventilation way, from the perspective of all-round to improve local micro environment, put forward a more advanced way of personalized ventilation is very necessary and urgent.For all-round improving local microenvironment of the human body, this paper puts forward a new kind of Personalized Ventilation way, under the effect of this new type of Personalized Ventilation way of supply Air flow can use Coanda effect and attached to the body surface, in the human body surface to form a layer of clean and comfortable Air layer, like to put on an Air of coat, we named this method of Air supply Air Dress Personalized Ventilation, ADPV for short.This paper first through the smoke and experimental wind speed measurements were qualitatively and quantitatively analyzed under the condition of constant temperature air supply, air speed, air supply outlet and the body of the horizontal distance and vertical distance air diffuser and the head of the human body of the three factors of ADPV way under the action of the influence of the flow field characteristics. Studies have shown that under the condition of constant temperature air supply ADPV way under the action of flow field is made up of the plume and supply air jet, formed by the action of the at the same time introduced the critical air velocity concept, when the supply air speed isgreater than the critical air velocity, air supply airflow plays a leading role in the flow field, the supply air flow can be attached to the body surface. As a result, the greater the supply air velocity, the easier attached with a form. At the same time, the critical air velocity is increased with the increase of the horizontal distance L increases, and when L = 0.3 m, no matter how big supply air velocity, attached with a cannot be formed.Attached with difficulty, therefore, is along with the increase with the increase of the horizontal distance. The critical air velocity is decreases with the increase of vertical distance H, namely the difficulty of attached with is reduced with the increase of vertical distance. Considering area breathing fresh air and human comfort requirements,finally found that isothermal condition, L = 0.1 m, H = 0.25 m, argument = 0.4 m/s for the recommended design parameters.Supply air speed, air supply temperature are studied by using numerical simulation method with respect to the manner of ADPV air distribution performance and the influence of the workspace environment. The study found that for certain supply air speed, there exists a critical supply air temperature, only when the supply air temperature is lower than the critical supply air temperature, supply air flow can be attached to the body surface. At the same time, the human body on the surface of the DR value is to reduce with the increase of height increase before, each supply scheme under the maximum of the human body on the surface of the DR value of around 1.6 m height. When the background area temperature 28 ℃, the human body surface blowing a maximum of DR and the feeling of not satisfied with the maximum percentage of PPD is along with the increase with the increase of the supply air velocity, and decreased with the increase of supply air temperature. Consider percentage dissatisfied with PPD and blowing DR, non-isothermal air supply conditions recommended by the way of ADPV air supply parameters.In order to further explore the way of ADPV supply performance, verify its in improving air quality and other advantages, to ensure human thermal comfort simulation ADPV method, three kinds of traditional way of personalized ventilation(ceiling personalized ventilation of personalized ventilation, floor, desktop personalized ventilation) as well as the entire room air distribution mode of supply air flow formed in the activity of the human body temperature field, velocity field and blowing the DR,breathing fresh air ratio, and are not satisfied with the percentage distribution of PPD.Eventually found that human breathing the fresh air than the sequence from high to low is ADPV way, ceiling air supply and desktop air supply, the whole room, floor air supply air supply, respectively, 81.2%, 73.9%, 30.7%, 17%, 30.7%.At the same time,again confirm when the background area temperature for 28 ℃, blowing feeling DR percentage distribution and expectations are not satisfied with PPD have good fit,comfort evaluation is unified to the human body. Considering area breathing fresh air than and found that after the human body comfort, only ADPV way not only can provide enough fresh air for people breathing zone, at the same time of staff can get satisfying comfort.