Side Supply Air Conditioning, Paper CFD Validation

Description

Air Conditioning (Side Supply), Paper Numerical Validation using ANSYS Fluent Training

The present problem simulates the HVAC process through a side-supply air conditioning system in an office using ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

This simulation is based on the information from a reference article [Comparison of air-conditioning systems with bottom-supply and side-supply modes in a typical office room], and its results are compared and validated with the results in the paper.

The simulation is performed for a state of the paper where the side-supply air conditioning system is designed.

The present model is designed in three dimensions using the Design Modeler. The present model is related to the interior of a room with a length and width of 6 m, 4 m, and a height of 3.5 m.

Inside the room, four people, four desks, four computers, and six heat sources are designed, Assuming that these items have a very simple geometric structure in the form of cylinders and cubes. Four entrance borders are defined on the room’s sidewalls, and two exit borders are defined on the ceiling of the room.

The meshing of the present project has been done using ANSYS Meshing software. The element number is 1027974.

Side Supply Methodology

Based on the design of the air conditioning system in the mentioned article, two panels have been designed to enter fresh air in two opposite walls; In this way, air enters the room through four panels (each wall has two panels).

The air inside the room then exits to the outside environment through two panels on the room’s ceiling.

The inlet air of the air conditioner system has a velocity of 0.21 m/s and a temperature of 21 ºC. Inside the room, four people, four computers on the table, and six heat sources are designed.

In fact, according to the article, first the experimental work and then a numerical study was done; So that for each of the factors in the interior of the room, a certain amount of energy is considered, and to simplify the work, simple geometries are used to define these heat sources.

Four humans are defined as cylinders with 150 W energy, four computers as small cubes placed on tables with 150 W energy, and six heat sources with 200 W energy.

To define these heat sources, the thermal flux boundary condition on the walls of these energy sources is used; By dividing this energy on the outer surface of the walls of these heat sources, the desired amount of heat flux is obtained.

In addition, the room’s outer walls have a constant temperature of 26 ºC, and the surfaces of the tables are defined as insulation. Moreover, the RNG k-epsilon model and energy equation are enabled to solve the turbulent fluid equations and calculate temperature distribution.

Side Supply Conclusion

At the end of the solution process, two- and three-dimensional contours related to the temperature and velocity inside the room are obtained. The validation of the present simulation is performed based on diagrams “a” and “b” from Figure 9 of the mentioned article.

These diagrams show the temperature changes in terms of height from the floor of the room. A height of 2 meters from the ground floor includes ten measuring points at a distance of 0.2 meters from each other.

Figure a shows the location of E, which is longitudinally 3 meters from the two walls and transversely is 1.6 meters and 2.4 meters from the other two walls; While diagram b shows the location F, which is facing longitudinally at a distance of 3 meters from the two walls and transversely at a distance of 3.2 meters and 0.8 meters from the other two walls.

Then, for each of the locations E and F, ten sample points are considered for measuring from a distance of 0.2 m from the floor to a distance of 2 m from the floor, and a graph of temperature changes in these points is obtained.

Figures show the temperature changes in height in two locations, E and F, respectively. According to these graphs, the current numerical simulation results are compared with the results in the paper.