CFD Simulation of Thermal Plume of VRF Air Conditioners for Cooling Season in Semi-Closed Spaces for Erbil Climate Conditions

Abstract

The variable refrigerant flow (VRF) system is extensively utilized for the purpose of space cooling and heating in residential and commercial buildings. The VRF outdoor units are frequently placed on balconies of multi-storey buildings, and the aluminum louvers conceal them to keep the aesthetic architecture appearance. This type of installation will cause the thermal plume influence of the dissipated heat discharged from condensing units to cause high suction temperature, high energy consumption, and low coefficient of performance of the system. The numerical results showed that the discharged heat from condensing units will lead to rising thermal plume influence, causing greater suction temperatures for VRF outdoor units on top floors, even overriding the operating temperature range. It also shows that removing the inward louver in front of the discharge duct on each floor is an efficient method to deteriorate the thermal plume influence for VRF air conditioners and enhance the thermal efficiency of the entire system. For the proposed design, the average suction temperatures could be reduced by 8%, 15%, and 19% for VRF outdoor units for floors 10th, 11th, & 12th, respectively. This work aims to provide guidelines for the placement of VRF air conditioners in buildings in the designing stage.

Wind Load of Low-Rise Building Based on Fluent Equilibrium Atmospheric Boundary Layer

“…2f, when the height of the Yangyi model is 1.2 m ~ 1.4 m, the maximum errors of the turbulent kinetic energy at other locations relative to the entrance are below 5%. At other heights, k and ε at other locations are quite different from those at the entrance; in the area close to the ground, at the entrance, the turbulent kinetic energy is 1.8 m 2 /s 2 , and the dissipation rate is 190 m 2 /s 3 ; at the exit, the turbulent kinetic energy is 0.5 m 2 /s 2 , and the dissipation rate is 40 m 2 /s 3 . They indicate that the flow field has not reached equilibrium at this time.…”

“…Computational fluid dynamics (CFD) is more and more widely used in civil engineering and other fields [1][2][3][4]. Accurate simulation of turbulence in the atmospheric boundary layer (ABL) is the premise and basis for CFD to study wind engineering problems.…”