The Role of CFD in HVAC Design
It's hard to imagine our cars or trucks without an HVAC system, and it has become a standard installation that we all rely on for a comfortable and safe environment while we're on the road.
Whether using our vehicles for work or leisure, an all-season HVAC (Heating, Ventilating, and Air Conditioning) system ensures that we are always comfortable and protected from the elements.
We will explore the importance of Computational Fluid Dynamics (CFD) simulation in the HVAC design process and show present and future AI applications in car manufacturing. We will see how CFD /HVAC predicts thermal and acoustic comfort.
How can onboard thermal and acoustic car occupant comfort and safety be satisfied while ensuring energy efficiency?
The Role and Importance of Conducting CFD Analysis
Designers need to investigate physics to find optimal designs in the ventilation system. The physics of ventilation is quite diversified:
- thermal exchange,
- fluid mechanics,
- ... and even aeroacoustics
Could it all be simulated in one platform? A Computational Fluid Dynamics analysis software platform can reproduce all of them!
Using computational fluid dynamics simulation technology, we can now accomplish design objectives with greater speed and cost-effectiveness, eliminating the need for costly physical experimentation that was once the norm in the industry.
The Use of CFD Analysis
Engineers can use CFD analysis to predict the airflow and temperature distribution within internal HVAC systems. Furthermore, computational analysis can also be applied to assess the acoustic properties of these systems, making the design process faster, more cost-effective, and less reliant on physical experimentation.
How CFD Analysis Revolutionizes HVAC System Design
CFD simulation is a more efficient and cost-effective way to design products than experimental testing, resulting in an improved system design process based more on quantitative preemptive analysis than trial-and-error.
Assessing Thermal Comfort Parameters
Assessing thermal comfort parameters (such as the Draft Rating Index) with CFD simulation enables engineers to accurately predict the temperature distribution and effective draft temperature inside the indoor space of the vehicle cabin provided by the device.
Since solar radiation, heat transfer, and air properties affect the system's thermal performance, capturing them during the early stages of building design is essential to meet occupant satisfaction.
Modes of Heat Transfer That Can Be Simulated
CFD can analyze all modes of heat transfer:
- Radiation simulation
- Natural Convection simulation
- Forced Convection simulation (e.g., due to the presence of a fan)
- Conduction simulation (including conjugate heat transfer also incorporating solid objects)
With such a flexible physical modeling software platform, engineers can optimize designs to ensure satisfaction for thermal comfort and ameliorate air distribution with an early-stage design approach.
Explaining the HVAC System
The HVAC system influences the ventilation dashboard's look (figure) since the vent location distributes air throughout the cabin spaces. The ventilation dashboard is located downstream of the internal system.
Insight on the Internal System
The HVAC system regulates the vehicle's temperature, humidity, and air quality. The system includes a compressor, evaporator, condenser, and refrigerant; those components work together for air cooling and dehumidification.
In addition to core cooling components, the system includes fans, filters, and sensors.
- Fans circulate the air throughout the cabin
- The filters remove pollutants
- Sensors measure the temperature and humidity inside the cabin and adjust the HVAC system accordingly.
CFD Analysis Examples
To maintain good indoor air quality, the Automotive HVAC Industry has turned to CFD analysis software to improve the design of HVAC systems and cabin spaces.
Optimal design shapes fit the vehicle's geometrical constraints and guarantee energetic efficiency, reduce noise, and maximize flow ventilation performance at the outlets (see figure illustrating the typical engineering simulation software results).
CFD analysis can help analyze (in a few hours) and optimize (in a few days) design regarding flow parameters. The figure shows a sample of 100 HVAC system designs.
The next chapter will show how to leverage those data to create a powerful tool to predict fluid and thermal behavior based on Artificial Intelligence (AI).
What's Beyond Classic Simulation? AI!
We will see a striking example of how AI transforms the HVAC industry.
AI simulates specific human intelligence functions; its Machine Learning branch uses data and statistical models to improve AI performance.
AI & Deep Learning
Deep Learning uses deep neural networks to learn from vast amounts of data and to simulate engineering systems.
AI: Deep Learning Use Case
A Deep Learning model (NCS) leveraged project design data, i.e., CAD and CFD results files, learning to predict the association between design changes (CAD) and engineering results.
Practical Visual Benchmark: AI vs CFD Analysis
The degree of accuracy can be seen from the figure, with a potential for deployment in system design. In HVAC system design, deep learning only uses CAD inputs bypassing CFD analysis steps, thus democratizing it for a wider population without specialist skills.
The Engineering Simulation Journey: What's Next?
The article delved into two groundbreaking advancements in HVAC system design that are or will revolutionize the industry.
First, digital technologies that produce data have replaced costly trial-and-error methods.
Second, the digital thread is going to be improved through the utilization of this data. Deep Learning makes engineering predictions accessible to all engineers, regardless of their specialization.
The system's performance will improve continuously with the AI learning process, drawing on a more diverse range of CFD analysis data and scope. Beyond HVAC interiors analysis, it will be possible to predict flows inside the cabin, combined with digital twins, for human comfort.
As an engineer once said to the author, "The only limit here is imagination!"