Document Type : Research Paper


Mechanical and Mechatronics Department, College of Engineering, University of Salahaddin, Erbil, Iraq



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.