The perimeter space near windows usually has some problems with the thermal environment which is easily affected by heat transfer and radiation from windows. Compared to interior space of the room, the airflow in this area usually has different characteristics due to the effect of buoyancy, thus it may reduce thermal comfort of perimeter space. To improve the thermal environment in perimeters, breeze line diffusers are widely used in Japan as the terminal equipment of air conditioning and ventilation systems. This diffuser is the same as so-called ceiling slot diffuser. In this research, the authors analysed the performance of breeze line diffuser for heating usage by experiment. The airflow rate and temperature around the breeze line diffuser was also obtained to define boundary conditions of CFD (Computational Fluid Dynamics) model of breeze line diffuser, which will be simulated in our future work.
For the full-scale experiment, the breeze line diffuser is set up in a free field. The air supply temperature under isothermal and non-isothermal conditions, and the length of the outlet of the diffuser are adjusted as parameters. Temperature and wind velocity distribution not only around the diffuser but also the other part of the free field were measured by hot wire anemometer, ultrasonic anemometer, and thermocouple in this study.
The results of the experiment are compared. The breeze line diffuser has a limited heating effect in the occupant zone (height below 1.7m) due to the effect of buoyancy, but heating effect can be decreased if the outlet velocity is fast enough. Install some deflection plane inside the breeze line diffuser to adjust the outlet area can help to enhance diffuser’s heating effect. And the authors will use these data to decide the location of P.V. Method’s boundary. The airflow rate and temperature distribution will also be used as comparison data to examine the accuracy of the CFD model in further study.