The need for improved Ventilation Equipments came into light with the onset of the COVID-19 pandemic. It became evident that many indoor spaces lack proper air ventilation. This adversely affects the health and well beings of the people living or working in those spaces.

Such cases can be easily solved if the HVAC systems are readily available and accessible to the architects when the buildings are at the initial stage of construction. Along with the designs, engineers can also focus on CFD Simulation, which is yet another important aspect of HVAC installation.

Why is CFD Simulation important?

A Computational Fluid Dynamics Simulation holds an important place in the design procedure. After three-dimensional modelling of any desired object or space, it is crucial to run a simulation. This not only helps in examining the errors and issues in the design but also hints at the possible areas of improvement. In HVACs, CFD Simulation helps get an insight into the air barriers and the performance of ventilation equipment.

What are HVACs?

Heating Ventilation Air Conditioning or HVACs are temperature control devices for indoors. It focuses on controlling indoor humidity, heat, cold, and, most importantly, the air quality. However, it is quite different from a regular Air Conditioner. An HVAC focuses not only on Cooling an indoor space but also on proper heating and ventilation. Even though the Heating and Cooling mechanism are different from the Ventilation System, they work synchronously for efficient output. The HVAC system is huge, and the central unit is set up on the top of the building with vents going around inside the building.

CFD Simulation workflow for Ventilation Equipment in an HVAC

1. Prepare the arena

Before moving to the simulation bit, the designer first needs to create a 3-D space for which the Ventilation System is being built. For instance, a parametric model of a room whose area and number of insiders are easy to change and alter.

2. Application of loads

Once a proper parametric model is designed, the next step will be to apply loads in the specified space. These include internal loads like heat gains from electrical equipment, including lights, computers, laptops, display screens and humans.

3. Application of withdrawal

In order to reflect building infiltration from outside, a leakage (adventitious) of 0.1 ACH (i.e., air changes per hour) is necessary to apply to the rooms. The windows act as passive natural ventilation openings. It is essential to note that even a slight change in boundary conditions lead to a much higher degree of flexibility to come up with ventilation strategies.

4. Simulation under different scenarios

In order to gain a better understanding, we will set up three different scenarios:

i) Base Scenario – Supply of Air only from horizontal diffusers.

ii) First Case – Supply of Air for good air distribution from diffuser having upward directed grills.

iii) Second Case – Along with first case conditions, also open top hung windows.

Results of Different Simulation Scenario

• Air Quality

i) Base Scenario – A very high rate of heat gain can be observed along with a build-up of carbon dioxide. This is due to a lack of proper ventilation, fresh air and mixing of fresh air with old air. The diffuser grills are horizontally set up at the room inlet, which lets the cold air get into the room. This cold air tends to move downward, creating a down drought with poor ventilation, which results in lesser comfort.

ii) First & Second Case – The first and second case have an upward-facing grill at the diffusion as a common element. This assists in fresh air circulation inside the room. While in the context of air quality, it is much different than the base case too. Unlike high concentrations of carbon dioxide at the ceiling level because of improper ventilation of fresh air, the first and second case give better results. The first and second cases can successfully reduce carbon dioxide concentration levels drastically inside the room. Thus, giving a better air quality.

• Thermal Comfort

i) Base Scenario – In the base case scenario, the effect of buoyancy domination is drastic. It has an adverse effect on air movement as well as temperature in the indoor space. Moreover, there is a crucial lack of air movement because of the downward supply of fresh air from horizontal diffusers and pressure distribution in space.

ii) First and Second Case – Due to a better setup in First and Second Cases the air circulation in the indoor space is much better than in the base case. There is a better mixing of the temperature in the First and Second Cases. The reason behind quality air distribution in the second case is the windows (openable) which can occasionally provide fresh air at low carbon dioxide levels.

Why does air quality matter?

When we talk about the need for proper ventilation in an enclosed space, there are many reasons behind it. Higher levels of carbon dioxide in a working or learning space is a big reason for declining cognition activity. An acceptable level of carbon dioxide concentration in a classroom must be less than 1000 PPM, whereas, in a work area, it must be less than 1000 to 1500 PPM.

Along with the concentration of carbon dioxide in the air, it is also a major concern that the temperature of the ambience must be maintained. CFD Simulations are therefore required to understand the spatial distribution of carbon dioxide concentration, which can be used to identify stale and stagnant air.

Conclusion

At Mechartes, we tirelessly go through research, studies, and present-day scenarios to provide the perfect solution for your HVAC and CFD Simulation related queries. With the advancement of technology and the amazing invention of HVAC, it is equally important to ease the accessibility of such great resources to the right hands. We have a pile of information regarding CFD Simulation and related techniques on our blog page. Visit our website for more quality insight.