Mapping of turbulence intensity and discomfort caused by different supply air diffusers
Research has shown that the experience of drought is determined by three main parameters: (i) local air temperature, (ii) local air velocity, and (iii) turbulence intensity, which is the standard deviation of variations of time-averaged air velocity. These three parameters used in the established equation of "draft rating" (Percentage Dissatisfied, PD%) . In Sweden, the requirements for thermal indoor climate given in standard EN 15251 , which specifies PD ≤ 20% Regulatory buildings. Unfortunately choose suppliers of supply air to not document PD, but instead documents the throw lengths, usually with a limit of 0.2 m / s. The problem is that if the air is cold or turbulence intensity is high, a rate of 0.2 m / s not satisfy the fundamental requirement of PD ≤ 20%. This problem is exacerbated by the valve suppliers most not documenting turbulence intensity for side vents, which prevents counselors from being able to assess DR yourself.
To answer the above problem positions proposed a project where the student does the following:
• Using speed sensors, the student will measure a range of supply air diffusers mounted on indoor environment laboratories. The instruments logger three parameters simultaneously (temperature, mean air velocity and turbulence intensity). The sensors installed on a column in three heights ( 1.1m,1,4, 1.7m) and measurements performed at different horizontal distances from the valve. The measurements can be performed under substantially isothermal conditions, but it is recommended to perform initial measurements at various fixed air temperatures (both upper and lower temperature). In addition, performing measurements at different airflows and different degrees valve throttling.
• The same measurement rig used to measure the turbulence intensity in selected rooms in or around the college. The purpose is to determine whether the conditions in real space is similar to that obtained in the laboratory.
1. Literature study of existing research literature on turbulence intensity of supply air and ventilated rooms in general.
2. Analysis of measurement and parameter analysis
3. Make a Discussion and Conclusions