Room with Air-Conditioning Vents

Overview

Central heating and air-conditioning units are used in homes, offices and shopping malls for indoor climate control. These units are commonly referred to as heating ventilation and air-conditioning systems or, in short, HVAC systems.

Traditionally, air-conditioning is done by cycling either cool or hot air into an indoor space. In this cooling example, hot air inside the room is vented out of the room and is replaced by cooler air from the air-conditioning unit. The injected cooler air exchanges heat energy with the room walls and other heat-generating sources present in the room, which increases the air temperature. The hot air is then expelled from the room and is again replaced by cooler air-conditioned air. Although the internal working principle behind air-conditioner units is fairly complex, the physical mechanism of how the room is cooled is primarily based on the principles of convective heat transfer. The cold air inside the room exchanges heat with surrounding hot walls primarily through convection. The heat transfer rate from the walls is dependent on the velocity and temperature of the circulating fluid inside the room and the wall temperature. The cycle of replacing hot air with cool air continues, and the room temperature goes down.

In this simulation example, we model airflow and heat transfer in a room with one door and two windows, which is being cooled by a central air-conditioning system.

 

Objectives

The primary objective is to model the process of convective heat transfer rate in the room. We will also:

  • Understand the airflow inside the room
  • Estimate the outlet air temperature
  • Quantify the temperature of the room walls

Setup

Download the Mesh file needed for setting up the simulation and the associated Case & Data files here. Follow the instructions below to set up this simulation in Ansys Fluent starting with a Mesh file. In case you face any issues setting up or running the simulation, please refer to the corresponding initial and final Case and Data files.

Results and Discussion

The following slides discuss simulation results to give additional insights into the airflow circulation and heat transfer in the room. They also provide some modeling insights necessary to solve this heat transfer problem.