Numerical Study on the Effect of Air Diffuser Angle on the Flow Field and Contaminant Dispersion in a Ventilated Room

Document Type : Research Article

Authors

1 Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran

2 Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran

3 Department of Mechanical Engineering, Razi University, Kermanshah, Iran

Abstract

Due to increasing application of air conditioning systems in various industries including cleanrooms, the optimized use of the applied equipment for less energy consumption and better contaminant distribution is essential. This paper investigates the effect of four-way ceiling diffuser angle effect on the ventilation system performance numerically using Eulerian-Lagrangian approach. In this study, the initial contaminant distribution is assumed to be uniform in the ventilated space and the room assumed to be without diffuser and with diffusers of 30, 90 and 30-90 blade angles is investigated. This work shows that the diffuser with 30 and 30-90 blade angles decrease the contaminant faster than 90° and without blade configurations. It is also shown that the 90° diffuser and without diffuser cases which shoot air vertically leads to less deposition and higher exit to deposition ratio. Based on flow field pattern, the flow field of cases with 30 and 30-90 degree could sweep particles from corners of the room better than W/O diffuser and 90° cases while their flow field role is less in sweeping corners and the main role is on central locations.

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[1] R.H. Mohammed, A simplified method for modeling of round and square ceiling diffusers, Energy and Buildings, 64 (2013) 473-482.
[2] B. Zhao, Y. Zhang, X. Li, X. Yang, D. Huang, Comparison of indoor aerosol particle concentration and deposition in different ventilated rooms by numerical method, Building and Environment, 39(1) (2004) 1-8.
[3] J. Wang, T.T. Chow, Numerical investigationof influence of human walking on dispersion and deposition of expiratory droplets in airborne infection isolation room, Building and Environment, 46(10) (2011) 1993-2002.
[4] P.V. Nielsen, Description of supply openings in numerical models for room air distribution, ASHRAE Transactions. Dept. of Building Technology and Structural Engineering, Aalborg University, 1991.
[5] H. Xu, J. Niu, A new method of CFD simulation of airflow characteristics of swirling floor diffusers, Building simulation, (2003) 429-1434.
[6] J.J. Martinez-Almansa, A. Fernandez-Gutierrez, L. Parras, C. del Pino, Numerical and experimental study of a HVAC wall diffuser, Building and Environment, 80 (2014) 1-10.
[7] E., Djunaedy, K.W.D. Cheong, Development of a simplified technique of modelling four-way ceiling air supply diffuser, Building and Environment, 37(4) (2002) 393-403.
[8] Y. Huo, F. Haghighat, J. Zhang, C. Shaw, A systematic approach to describe the air terminal device in CFD simulation for room air distribution analysis, Building and Environment, 35(6) (2000) 563-576.
[9] B. Sajadi, M.H. Saidi, A. Mohebbian, Numerical investigation of the swirling air diffuser: Parametric study and optimization, Energy and Buildings, 43(6) (2001) 1329-1333.
[10] J. Srebric, Q. Chen, Simplified numerical models for complex air supply diffusers, HVAC and R Research, 8(3) (2002) 277-294.
[11] E. Tavakoli, R. Hosseini, Large eddysimulation of turbulent flow and mass transfer in far-field of swirl diffusers, Energy and Buildings, 59 (2013) 194-202.
[12] S. Burhan Cuhadaroglu, A CFD analysis of air distributing performance of a new type HVAC diffuser, CLIMAMED, (2015).
[13] K., Zhong, X., Yang, Y. Kang, Effects of ventilation strategies and source locations on indoor particle deposition, Building and Environment, 45(3), (2010) 655-662.
[14] Q. Chen, Comparison of different k-epsilon models for indoor air flow computations, Numerical Heat Transfer, Part B Fundamentals, 28(3) (1995) 353-369.
[15] V. Yakhot, S.A. Orszag, S. Thangam, T.B. Gatski, C.G. Speziale, Development of turbulence models for shear flows by a double expansion technique, Physics of Fluids A: Fluid Dynamics, 4(7) (1992) 1510.
[16] S. Sadrizadeh, A. Tammelin, P. Ekolind, S. Holmberg, Influence of staff number and internal constellation on surgical site infection in an operating room, Particuology, 13 (2014) 42-51.
[17] Ansys Fluent 15.0, Ansys Inc., 2013.
[18] F. Chen, S.C.M. Yu, A.C.K. Lai, Modeling particle distribution and deposition in indoor environments with a new drift–flux model, Atmospheric Environment, 40(2) (2006) 357-367.
[19] J. Eslami, A. Abbassi, M.H. Saidi, M. Bahrami, Effect of supply/exhaust diffuser configurations on the contaminant distribution in ultra clean environments: Eulerian and Lagrangian approaches, Energy and Buildings, 127 (2016) 648-657.