Radiation: Heat Transfer in a Computer Room

Radiation Heat Transfer in a Computer Room — ANSYS Fluent CFD Simulation

Description

This project simulates the air conditioning of a computer room containing four computers using ANSYS Fluent. The model represents a computer room with several distinct heat sources and was built in 3D using SpaceClaim. Because the geometry is symmetric, only one-quarter of the room is modeled to reduce computational cost.

Meshing was performed in ANSYS Meshing, producing 809,037 elements.

Methodology

In this simulation, steady airflow enters the domain through several inlets at the bottom of the room and exits through several outlets in the ceiling, with radiation heat transfer taken into account. This air-conditioning approach is widely used in office environments; it offers greater energy efficiency because the flow rises naturally through the density difference and buoyancy body force rather than being forced mechanically.

Fresh air enters the computational domain at a velocity of 0.61254 m/s and a temperature of 291.8 K. One of the room's four main walls is subjected to a constant heat flux of 194 W/m². The remaining heat sources include a laptop and a simulator, with heat fluxes of 153.25 W/m² and 90.56 W/m², respectively.

The Realizable k-epsilon model is used to solve the turbulent flow equations. The energy equation is enabled to compute the temperature variation within the domain, and the ideal gas model is used to capture the change in air density with temperature. Most importantly, the Surface-to-Surface (S2S) radiation model is employed to simulate the radiative heat exchange between surfaces inside the domain.

Conclusion

The mixture mass flow rate at the computer room outlet is 0.568 kg/s. Air density reaches its minimum on the surfaces subjected to heat flux: as the fluid temperature rises, its density falls, and the resulting upward buoyant force acts on the fluid volume. As a consequence, the air density decreases progressively with height up the room.

High temperatures of around 327 K are observed on the laptop surfaces and the hot walls. Intense turbulence appears near the hot wall and above the simulator, a direct result of the high heat fluxes assigned to the laptop, the simulator, and the hot wall.