Numerical study on the influence of louver design on VRF system thermal performance in enclosed spaces in Erbil city

Abdullah, Kawa Abdulghany; Ibraheem Barwari, Ramzi Raphael

doi:10.30772/qjes.2024.144970.1053

	Numerical study on the influence of louver design on VRF system thermal performance in enclosed spaces in Erbil city
Al-Qadisiyah Journal for Engineering Sciences
Article 5, Volume 18, Issue 2, June 2025, Pages 140-147 PDF (17.78 M)
Document Type: Research Paper
DOI: 10.30772/qjes.2024.144970.1053
Authors
Kawa Abdulghany Abdullah; Ramzi Raphael Ibraheem Barwari^*
Mechanical and Mechatronics Department, College of Engineering, Salahaddin University, Erbil, Iraq.
Abstract
Variable Refrigerant Flow (VRF) systems are extensively employed for space heating and cooling, particularly in multi-story buildings where outdoor units are discreetly placed behind aluminum louvers for architectural considerations. However, these metal louvers can hinder ventilation and heat rejection of the VRF air-conditioning outdoor unit, adversely affecting system performance. This impact manifests in elevated suction temperatures, increased energy consumption, and a diminished coefficient of system performance due to hot air recirculation behind the louvers. Additionally, the expelled hot discharge air from outdoor units rises, increasing the suction air temperature for the upper floors' VRF system. This numerical analysis study investigates the impact of louver tilt angle and opening ratio factors on the thermal performance of VRF air conditioners when installed on building balconies. The objective is to optimize louver designs for concealing condensing units, thereby enhancing overall performance and minimizing power consumption. Two proposed louver designs, incorporating varying tilt angles and opening ratios, are presented as solutions and compared with the existing design. The optimal solution to alleviate the unintended "stuck and stack effects" in the current design involves a proposed modification. The first option suggests decreasing the louver's tilt angle to 20° while maintaining a 60% opening ratio to lower suction temperatures and improve thermal performance. Additionally, increasing the louver opening ratio to 80% effectively reduces air recirculation, providing an alternative solution to optimize the overall performance of the VRF system. Comparisons with previous studies underscore local climate variations and operational disparities, emphasizing the need for tailored louver designs specific to environmental conditions.
Keywords
VRF system; Louver opening ratio; Louver tilt angle; CFD Simulation; Thermal performance

References
H. Wan, Y. Hwang, and R. Radermacher, Variable Refrigerant Flow (VRF) System Field Test and Data Analysis Methodologies. Singapore: Springer Nature Singapore, 2023, pp. 223–245. [Online]. Available: https://doi.org/10.1007/978-981-19-6833-4 10 R. American Society of Heating and A.-C. Engineers, 2020 ASHRAE Handbook: HVAC Systems and Equipment. American Society of Heating Refrigerating and Air-Conditioning Engineers Incorporated (ASHRAE), 2020. [Online]. Available: https://books.google.iq/books?id=j22GzgEACAAJ T. Chow, Z. Lin, and X. Yang, “Placement of condensing units of split-type air-conditioners at low-rise residences,” Applied Thermal Engineering, vol. 22, no. 13, pp. 1431–1444, 2002. [Online]. Available: https://doi.org/10.1016/S1359-4311(02)00068-6 Y. Zhang, X. Zhang, S. Guo, and E. Long, “Thermal plume simulation of vrf air conditioners for cooling system in high-rise buildings: A case study in china,” Journal of Engineering Research, vol. 7, no. 3, 2019. T. Chow, Z. Lin, and Q. Wang, “Effect of building re-entrant shape on performance of air-cooled condensing units,” Energy and Buildings, vol. 32, no. 2, pp. 143–152, 2000. [Online]. Available: https://doi.org/10.1016/S0378-7788(99)00048-1 R. Permatasari and R. Khairunisa, “Optimization position variable refrigerant flow in building using cfd method,” International Journal of Electrical, Energy and Power System Engineering, vol. 6, no. 1, pp. 126–132, Feb. 2023. [Online]. Available: https://doi.org/10.31258/ijeepse.6.1.126-132 W. Jin, Y. Zheng, Y. Zhang, and Y. Jiang, “Experimental study of factors affecting the performance of a semi-enclosed outdoor air-conditioning unit,” Procedia Engineering, vol. 121, pp. 1713–1720, 2015, the 9th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC) joint with the 3rd International Conference on Building Energy and Environment (COBEE), 12-15 July 2015, Tianjin, China. [Online]. Available: https://doi.org/10.1016/j.proeng.2015.09.138 R. Duan, X. Wang, Y. Song, and J. Liu, “Influence of airconditioning outdoor unit arrangement strategy on energy consumption,” Procedia Engineering, vol. 146, pp. 350–358, 2016, the 8th international cold climate HVAC Conference. [Online]. Available: https://doi.org/10.1016/j.proeng.2016.06.409 V. H. Nguyen and M. P. Nguyen, “Influence of the louver angle on the performance of the air-conditioning outdoor units in highrise apartment buildings,” VNUHCM Journal of Engineering and Technology, vol. 5, no. 3, pp. 1586–1595, 2022. [Online]. Available: https://doi.org/10.32508/stdjet.v5i3.970 H. Sha and D. Qi, “A review of high-rise ventilation for energy efficiency and safety,” Sustainable Cities and Society, vol. 54, p. 101971, 2020. [Online]. Available: https://doi.org/10.1016/j.scs.2019.101971 J. Matsson, An Introduction to Ansys Fluent 2023. SDC Publications, 2023. [Online]. Available: https://books.google.iq/books?id=XLTFE AAAQBAJ S. E. Co., “Samsung dvm desert, technical data book 2013,” Technical Documents, pp. 217–226. [Online]. Available: https: //www.samsunghvac.com/discover-vrf K. Abdullah and B. R.R.I., “Cfd simulation of thermal plume of vrf air conditioners for cooling season in semi-closed spaces for Erbil climate conditions,” International Journal of Heat and Technology, vol. 40, no. 4, pp. 1079–1085, 2022. [Online]. Available: https://doi.org/10.18280/ijht.400426 S. Knotek, S. Schmelter, and M. Olbrich, “Assessment of different parameters used in mesh independence studies in two-phase slug flow simulations,” Measurement: Sensors, vol. 18, p. 100317, 2021. [Online]. Available: https://doi.org/10.1016/j.measen.2021.100317 P. J. LaNasa and E. L. Upp, “Basic flow measurement laws,” Butterworth-Heinemann, pp. 19–29, 2014. [Online]. Available: https://doi.org/10.1016/B978-0-12-409524-3.00002-2 Rank White and H. Xue, Fluid Mechanics, ISBN10: 1264238495 — ISBN13: 9781264238491. McGraw Hill, 2022. M. Keddar, B. Draoui, B. Mebarki, M. Medale, and K. Benhanifia, “3d-numerical simulation of free convection inside a cubical cavity filled with non-newtonian-bingham fluid,” Al-Qadisiyah Journal for Engineering Sciences, vol. 17, no. 3, pp. 273–281, 2024. [Online]. Available: https://doi.org/10.30772/qjes.2024.150673.1271 C.-W. S. and, “High-order finite difference and finite volume weno schemes and discontinuous galerkin methods for cfd,” International Journal of Computational Fluid Dynamics, vol. 17, no. 2, pp. 107–118, 2003. [Online]. Available: https://doi.org/10.1080/1061856031000104851 Y. C¸ engel, M. Boles, and M. Kano˘glu, Thermodynamics: An Engineering Approach. McGraw-Hill Education, 2019. [Online]. Available: https://books.google.iq/books?id=ikTxxgEACAAJ D. V. IV., “Installation and operation manual: Vrv iv system air conditioner.” [Online]. Available: https://www.daikin.com/ Y. Zhang, Z. Wei, E. Long, X. Zhang, and S. Guo, “Outdoor air thermal plume simulation of layer-based vrf air conditioners in high-rise buildings,” Energy Procedia, vol. 142, pp. 3787–3792, 2017, proceedings of the 9th International Conference on Applied Energy. [Online]. Available: https://doi.org/10.1016/j.egypro.2017.12.277
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