EFFECT OF EXHAUST LAYOUT ON THE INDOOR THERMAL COMFORT UNDER HARSH WEATHER CONDITIONS

Year 2021, Volume: 7 Issue: 1, 148 - 160, 01.01.2021

Ahmed Khaleel Ahmed Ahmed Hassan Dakkama Wisam Al-shohani

https://doi.org/10.18186/thermal.847117

Cited By: 3

Abstract

The inlet and outlet size, number and location have a significant influence on the thermal environment indoor and air distribution for the temperature and velocity. In this work, numerical and experimental studies were performed to examine the influences of the inlet and outlet distribution, number and location, on the air movement and temperature distribution indoor. Also, the separation of the amount of the extracted air has been investigated in this study. To provide a comfortable environment for the occupants, important factors such as air temperature distribution, thermal sensation and draft rate should be evaluated carefully. Therefore, in this paper the occupant’s thermal sensation and the air movement and temperature distribution were used as the main evaluation index. In this investigation, three cases study were used tested. The experimental work was performed under the Iraqi weather conditions which are hot and dry in summer. The finding showed that the indoor thermal environments were significantly influenced by the opening locations of the exhaust. Also it was found that the satisfied human thermal comfort was obtained when the exhaust diffuser installed relatively far away from the supply diffuser. In addition, the best results were found by separate the amount of the exhaust air and extracted from the two exhausts opening. This will give the supplied air the ability to distribute inside room perfectly. Also, in order to prevent the air short circuit, the exhaust opening should not be located at the wall in front of the supply opening.

Keywords

Thermal Comfort, Exhaust Layer, Displacement Ventilation, CFD, Ventilation

References

• [1] Bauman FS, Daly A. Underfloor Air Distribution (UFAD) Design Guide. Atlanta: American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE); 2003.
• [2] Budaiwi I, Abdou A. HVAC system operational strategies for reduced energy consumption in buildings with intermittent occupancy: the case of mosques. Energy Conversion and Management 2013;73:37-50. https://doi.org/10.1016/j.enconman.2013.04.008
• [3] Li A, Qin E, Xin B, Wang G, Wang J. Experimental analysis on the air distribution of powerhouse of Hohhot hydropower station with 2D-PIV. Energy Conversion and Management 2010;51:33-41. https://doi.org/10.1016/j.enconman.2009.08.022
• [4] Nielsen PV. Velocity distribution in a room ventilated by displacement ventilation and wall-mounted air terminal devices. Energy and Buildings 2000;3:179-87. https://doi.org/10.1016/S0378-7788(99)00012-2
• [5] Kassas M, Hamanah WM, Al-Tamimi O, Sahin A, Yilbas BS, Ahmed CB. Operation of HVAC system for energy savings and economic analysis. Journal of Thermal Engineering 2019;5:181-197.
• [6] Al-Tamimi O, Kassas M, Hamanah WM, Yilbas BS. Cost effective operation of HVAC system under thermal distribution, Journal of Thermal Engineering 2019;5:302-318.
• [7] Seppänen O. Ventilation strategies for good indoor air quality and energy efficiency. International Journal of Ventilation 2008;6(4):297-306.
• [8] Melikov A, Ivanova T, Stefanova G. Seat headrest-incorporated personalized ventilation: thermal comfort and inhaled air quality. Building and Environment 2012;47(1):100-108. https://doi.org/10.1016/j.buildenv.2011.07.013 [9] Valkeapää A, Sirén K. The influence of air circulation, jet discharge momentum flux and nozzle design parameters on the tightness of an upwards blowing air curtain. International Journal of Ventilation 2010;8(4): 337-346. https://doi.org/10.1080/14733315.2010.11683857
• [10] Bagheri HM, Gorton RL. Verification of stratified air condition design (RP-388), ASHRAE Transactions and Conferences Programs, 1986: 211-227.
• [11] Huizenga C, Abbaszadeh S, Zagreus L, Arens, EA. 2006. Air quality and thermal comfort in office buildings: results of a large indoor environmental quality survey. Healthy Buildings: Creating a Healthy Indoor Environment for People 2006;3:393-397.
• [12] Bonnefoy XR, Annesi-Maesona I, Aznar LM, Braubachi M, Croxford B. Review of evidence on housing and health, background document for the Fourth Ministerial Conference on Environment and Health. Copenhagen, WHO Regional Office for Europe 2004.
• [13] Hong Kong Energy End-use data (HKEEUD) 2011. The energy efficiency office electrical & mechanical services department, 2011.
• [14] ASRAE Handbook-HVAC applications. Atlanta: American Society of Heating Refrigeration and Air Conditioning Engineering Inc. 2011.
• [15] Seppanen OA, Lic PE, Fisk WJ, Eto J, Grimsrud DT. Comparison of conventional mixing and displacement air conditioning and ventilating systems in US commercial buildings.‏ Symposium, ASHRAE Transactions 1989;95:pt.2.
• [16] Bagheri, Gorton. Verification of stratified air condition design. ASHRAE Transactions 1987;93:211-227.
• [17] Kuo JY, Chung KC. The effect of diffuser's location on thermal comfort analysis with different air distribution strategies. Journal of Thermal Envelope and Building Science, 1999;22(3):208-229. https://doi.org/10.1177/109719639902200305
• [18] Wan MP, Chao CY. Experimental study of thermal comfort in an office environment with an underfloor ventilation system. Indoor and Built Environment 2002;11(5):250-265. https://doi.org/10.1177/1420326X0201100502
• [19] Lau J, Niu JL. Measurement and CFD simulation of the temperature stratification in an atrium using a floor level air supply method. Indoor and Built Environment 2003;12(4):265-280. https://doi.org/10.1177/1420326X03035917
• [20] Hongtao X, Naiping G, Jianlei N. A method to generate effective cooling load factors for stratified air distribution systems using a floor-level air supply. HVAC&R Research 2009;15(5):915-930. https://doi.org/10.1080/10789669.2009.10390872
• [21] Lam JC, Chan AL. CFD analysis and energy simulation of a gymnasium. Building and Environment 2001;36(3):351-358. https://doi.org/10.1016/S0360-1323(00)00014-7
• [22] Awad AS, Calay RK, Badran OO, Holdo AE. An experimental study of stratified flow in enclosures. Applied Thermal Engineering 2008;28(17-18):2150-2158. https://doi.org/10.1016/j.applthermaleng.2007.12.017
• [23] Thool SB, Sinha SL. Numerical simulation and comparison of two conventional ventilation systems of operating room in the view of contamination control. International Journal of Computer Applications 2014;85(5):31-35.
• [24] Khan J, Feigley C, Lee E, Ahmed M, Tamanna S. Effects of inlet and exhaust locations and emitted gas density on indoor air contaminant concentrations. Building and Environment 2006;41:851–863. https://doi.org/10.1016/j.buildenv.2005.04.002
• [25] Kuo JY, Chung KC. The effect of diffuser’s location on thermal comfort analysis with different air distribution strategies. Journal of Building Physics 1999;22:208–229. https://doi.org/10.1177/109719639902200305
• [26] He G, Yang X, Srebric J. Removal of contaminants released from room surfaces by displacement and mixing ventilation: modeling and validation. Indoor Air 2005;15:367-380. https://doi.org/10.1111/j.1600-0668.2005.00383.x
• [27] Lin Z, Chow TT, Tsang CF, Fong KF, Chan LS. CFD study on effect of the air supply location on the performance of the displacement ventilation system. Building and Environment 2005;40:1051-1067. https://doi.org/10.1016/j.buildenv.2004.09.003
• [28] Verma TN, Sinha SL. Study of particle dispersion on one bed hospital using computational fluid dynamics. Materials Today: Proceedings 2017;4:10074-10079. https://doi.org/10.1016/j.matpr.2017.06.323
• [29] Verma TN, Sinha SL. Contaminant control in intensive care unit of hospital. Applied Mechanics and Materials 2014; 592-594: 2486-2490. https://doi.org/10.4028/www.scientific.net/AMM.592-594.2486
• [30] Verma TN, Sinha SL. Numerical simulation of contaminant control in multi-patient intensive care unit of hospital using computational fluid dynamics. Journal of Medical Imaging and Health Informatics 2015;5:1088-1092. https://doi.org/10.1166/jmihi.2015.1500
• [31] Ahmed AQ, Gao S, Kareem AK. A numerical study on the effects of exhaust locations on energy consumption and thermal environment in an office room served by displacement ventilation. Energy Conversion and Management 2016;117:74-85. https://doi.org/10.1016/j.enconman.2016.03.004
• [32] Ahmed AQ, Gao S, Kareem AK. Energy saving and indoor thermal comfort evaluation using a novel local exhaust ventilation system for office rooms. Applied Thermal Engineering 2017;110:821-834. https://doi.org/10.1016/j.applthermaleng.2016.08.217
• [33] Ahmed AQ, Gao S. Numerical investigation of height impact of local exhaust combined with an office work station on energy saving and indoor environment. Building and Environment 2017;122:194-205. https://doi.org/10.1016/j.buildenv.2017.06.011
• [34] Ahmed AQ. Modelling thermal comfort and energy saving enhancements in an office room served by stratified air distribution systems. UK: University of Leicester, Department of Engineering 2017. http://www.isni.org/isni/0000000464946006
• [35] Horikiri K, Yao Y, Yao J. Numerical study of unsteady airflow phenomena in a ventilated room. ICHMT digital library online; 2012.
• [36] Horikiri K, Yao Y, Yao J. Modelling conjugate flow and heat transfer in a ventilated room for indoor thermal comfort assessment. Building and Environment 2014;77:135-147. https://doi.org/10.1016/j.buildenv.2014.03.027
• [37] Srebric J, Chen Q. Simplified numerical models for complex air supply diffusers. HVAC&R Res 2002;8:277-294.
• [38] Yuan X, Chen Q, Glicksman LR, Hu Y, Yang X. Measurements and computations of room airflow with displacement ventilation. ASHRAE Transactions 1999;105:340.
• [39] Yakhot V, Orszag S, Thangam S, Gatski T, Speziale C. Development of turbulence models for shear flows by a double expansion technique. Phys Fluids A: Fluid Dynamic (1989–1993) 1992;4:1510–1520.
• [40] Fanger PO. Thermal comfort: Analysis and applications in environmental engineering. Copenhagen: Danish Technical Press, 1970. https://doi.org/10.1177/146642407209200337
• [41] ISO7730. Moderate thermal environments-determination of the PMV-PPD indices and specification of the conditions for thermal comfort, 1994