Displacement ventilation system Displacement ventilation system

The present study presents the experimental study of performance of the displacement ventilation . The experimental study included the effect of different internal loads of (1600,1300and 1000)W , different supplied air temperatures of ( 18,20,22and 24)?C and different supplied air velocities (0.75,1,1.25 and 1.45)m/s on the performance of displacement ventilation . The experimental results show that the cooling capacity of air increases as the temperature of supplied air decreases. At a increases in temperature of supplied air by (33.33)%,the cooling capacity of air decreases by (23.52, 24.05 and 20.63)% for internal load of (1600,1300 and 1000 )W respectively .While as supplied air velocity increases ,the cooling capacity of air increases .At supplied air increases by (93.33)% ,the cooling capacity increase by (33.61, 39.23 and 36.8 )% for internal load of (1600, 1300 and 1000)W respectively.

Center for the Built Environment, 2006

Displacement ventilation has been successfully applied for more than twenty years in Europe and it represents an opportunity for China. Displacement ventilation (DV) is based on vertical stratification of temperature in the occupied zone of rooms. Buoyancy flows generated by heat sources govern the air distribution in rooms with DV. If properly designed DV has potential to provide higher ventilation effectiveness, i.e. better inhaled air quality for occupants and lower energy consumption than mixing ventilation. In order to avoid thermal discomfort due to draughts and vertical temperature difference, the temperature distribution should be carefully predicted in the design stage. The REHVA and ASHRAE methods to design displacement ventilation systems for thermal comfort are introduced in this paper and critically reviewed.

JAPAN ARCHITECTURAL REVIEW, 2021

This study aims to acquire an understanding of the fundamental feature of IJV and DV under heating operation. Full‐scale experiments were conducted under these two different systems and supply air conditions along with temperature distribution and ventilation effectiveness. A wall surface of the test room was cooled as a heating load, and heating elements simulating occupants were located as internal heat load and contaminant emission source. Three cases of supply temperature were tested and the flow rate was also varied correspondingly. The position of the supply terminal was also changed to see its effect on heating performance, that is, mounted on the interior/exterior wall. For DV, the temperature/contaminant distribution differed significantly depending on the supply conditions, while that of IJV remained almost the same as a perfect mixing condition. Generally, IJV can achieve better temperature distribution compared to DV; however, the ventilation effectiveness of DV was supe...

Energy and Buildings, 2002

The purpose of this study is to clarify the usefulness of a displacement ventilation airconditioning system introduced into a multipurpose hall after CFD simulation and measurement. In the multipurpose hall of Kurume City, a displacement ventilation airconditioning system equipped with a floor outlet had been adopted. A CFD simulation for the purpose of selecting an air condition system indicated the floor outlet system would be more effective for the design plan of the hall than a ceiling outlet system. Measurements for the purpose of determining the effectiveness and thermal performance of a displacement ventilation system were conducted after construction of the hall, and the obtained results for thermal performance and airflow distribution in the hall were consistent with the CFD simulation. INTRODUCTION The adoption of the displacement airconditioning system, one of many airconditioning systems, was for the purpose of controlling indoor wind velocity and improvement in IAQ or increasing energy-saving performance (ASHRAE, 1997). Air conditioning in large spaces like gymnasiums must consider not only temperature control, but also games affected by wind velocity, such as table tennis and badminton. Although displacement ventilation systems appear to be useful as a cooling system for gymnasiums, and controllability and reduction of wind velocity is possible, there are few application examples in Japan.

2004

1.2 Principle of function The principle involves air supply and distribution in a room by upwards displacement, i.e. as direct as possible throughflow in the occupied zone in order to achieve high ventilation efficiency. In addition, air distribution by displacement generally makes it possible to supply a larger quantity of air than for conventional mixing ventilation, which requires concentrated supply at high velocity.

2015

International Journal of Ventilation

Mixing and displacement ventilation are common systems in commercial buildings, while mixing ventilation is used in residential buildings. Displacement ventilation provides fresh air to the occupied zone in a more efficient way than mixing ventilation but it is important to know how well it works with a floor system for heating or cooling. Can, for example, a floor heating system warm up the supply air too fast and destroy the displacement effect? Will floor cooling, combined with displacement ventilation, result in too high a vertical temperature difference and too low a temperature at feet level? The required amount of ventilation depends on the ventilation effectiveness. In standards, the recommended values for ventilation effectiveness depend on the position of the supply and exhaust device and on the difference between supply and room air temperature. Among others, for warm air heating the ventilation effectiveness is always less than 1 and can be as low as 0.4. This would then...