Applicability of displacement ventilation and impinging jet ventilation system to heating operation

The current paper reports the analysis and design of air quality and human thermal comfort in rooms using impinging jet ventilation system at different occupant distribution. Theoretical and experimental studies at different situations of occupant distribution used the square cross sectional supply air duct with height from the foot level end (0.1h). This work presents a numerical study for predicting the indoor airflow and temperature distribution by adopting impinging jet ventilation system in office room. The emergence of the three zones flow field of an impinging jet is mostly divided into three distinguished zones: impingement zone, wall jet zone and free jet zone which produce excessive kinetic energy at the stagnation zone and distribute approximately in the longitudinal and lateral directions over the floor. Acceptable Air Distribution Performance Index (ADPI), effective temperature and ventilation efficiency were found at situations of occupant distribution (when the occupant located at the center of the room one sitting in front of the other gives optimum human thermal comfort if compared with the other situations of occupant distributions).

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On-site measurement and numerical investigation of thermal environment with different air distribution systems in ice arenas

Journal of Physics Conference Series ◽

10.1088/1742-6596/2069/1/012096 ◽

2021 ◽

Vol 2069 (1) ◽

pp. 012096

Author(s):

Wenyu Lin ◽

Tao Zhang ◽

Xiaohua Liu ◽

Lingshan Li

Keyword(s):

Thermal Environment ◽

Ventilation System ◽

Simulation Method ◽

Extreme Condition ◽

Air Distribution ◽

Jet Ventilation ◽

Displacement Ventilation ◽

Air Supply ◽

Temperature And Humidity ◽

Ice Field

Abstract It is important to strictly maintain the indoor thermal environment in ice arenas which have very different features to other commercial buildings. Separated air distribution system is widely used to create a dry and cold environment near the ice and a comfortable environment in the view stand. The warm and humid air from the view stand may lead to uneven temperature and humidity distribution in the rink, leading to extra energy consumption, even fog and frost on the ice. Unreasonable air supply in the ice rink zone will also make the spectators feel too cold and uncomfortable. Jet ventilation system is the most extensively used system in the ice rink zone. An innovative ground displacement ventilation system is proposed in the National Aquatics Centre, which will serve as the venue for the curling competition in the 2022 Beijing Winter Olympics. On-site measurement in the arena is carried out and computational fluid dynamics (CFD) simulation method is adopted in the present research. Measured thermal environment above the ice with different ventilation systems are compared and analysed. Result shows that the displacement ventilation system features a more obvious vertical stratification than jet ventilation system in this kind of large space buildings, and thus is more energy-efficient. A CFD model of the ice cube is setup and verified by measured data. The thermal environment in the ice rink with displacement ventilation under extreme condition is studied using the simulation method. The temperature and humidity in the ice field increases by 10.1 °C, 4.5 g/kg without air supply in the view stand, proving that the spectators in the view stand have a great impact on the thermal environment in the ice field.

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Numerical study on thermal stratification for impinging jet ventilation system in office buildings

Building and Environment ◽

10.1016/j.buildenv.2021.107798 ◽

2021 ◽

Vol 196 ◽

pp. 107798

Author(s):

Jun Hu ◽

Yanming Kang ◽

Jia Yu ◽

Ke Zhong

Keyword(s):

Thermal Stratification ◽

Numerical Study ◽

Ventilation System ◽

Impinging Jet ◽

Office Buildings ◽

Jet Ventilation

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Experimental Investigation of the Ventilation Performance of Different Air Distribution Systems in an Office Environment—Cooling Mode

Energies ◽

10.3390/en12071354 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1354 ◽

Cited By ~ 2

Author(s):

Arman Ameen ◽

Mathias Cehlin ◽

Ulf Larsson ◽

Taghi Karimipanah

Keyword(s):

Distribution System ◽

Distribution Systems ◽

Ventilation System ◽

Impinging Jet ◽

Air Distribution ◽

Displacement Ventilation ◽

Cooling Mode ◽

Distribution Method ◽

Ventilation Performance ◽

Velocity Turbulence

The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

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