More and more HVAC designers and consultants are using computational fluid dynamics (CFD) in the design of air conditioning systems to understand airflow and temperature distribution, and to design optimized and efficient cooling systems. Essentially, CFD is a computational technology that uses numerical methods to solve and analyse the problems that involve fluid flows and thermal issues. Don't worry though, you don't need to be a CFD engineer to be able to benefit from simulation.
Over recent years, vendors like Envenio have worked to make CFD simulation software more affordable and accessible for HVAC designers and consultants, creating easy-to-use platforms running in the cloud (like EXN/Aero). In this article, we examine why simulation is so useful in the design, validation and optimization of air conditioning systems.
HVAC engineers face a number of daily challenges. Whether trying to cool a data center full of servers, or maintain a consistent and comfortable temperature in an office, their goal is to design the most effective yet efficient systems fit for purpose.
Air conditioning systems can account for as much as 25% of some businesses total energy consumption and it is perhaps unsurprising that advancing IoT (internet of things) research has resulted in smart building technologies. Smarter air conditioning systems such as those controlled remotely from cell phones or wearable devices are proving incredibly effective at assessing conditions and initiating a response from air conditioning systems. However, the system must still perform effectively to achieve the desired result as well as satisfying energy efficiency targets. Step forward, CFD simulation.
The use and effectiveness of chilled beams is a particularly hot topic at present, particularly across North America. This was highlighted in a recent paper presented at the ASHRAE 2018 Winter Conference by Abdullah Karimi, of Southland Industries, Dulles, Virginia.
Diagram demonstrating how a chilled beam system works
He noted that chilled beams performance was determined by several parameters, including placement, primary supply airflow, mixed-air throw angle, and the effective rate of induced air. These combine to make the design optimization of active chilled beams particularly challenging when employing conventional one-dimensional calculations, and performing experimental tests for many design variables is cost-prohibitive.
Karimi introduced CFD as a cost-effective and accurate design-optimization tool, specifically employing large eddy simulations (LES), which – with proper flow-resolving computational grids – can give a more accurate prediction of the flow distribution. The placement of cool beams can then be decided with greater confidence. He provided a case study of a typical office space application, validating against experimental data. Read the paper here.
Why Should I Use CFD & How Does It Work?
Optimizing Air Conditioning Systems
With simulation, designers can build detailed virtual models of existing and new air conditioning units, even importing complex geometries from existing CAD designs, before analyzing airflow and heat transfer in explicit detail. In turn, they can gain a greater understanding of intakes and returns, age-of-air, and any issues with stagnation or fluctuations. Such an approach not only reduces and limits traditional inefficiencies in prototyping at the design stage, but also improves performance once a system is installed.
Predicting Air Conditioning System Performance
Simulation also enables designers to predict how an air conditioning unit or system will perform in a particular environment - something that is particularly useful for HVAC engineers managing client consultancy projects. The ability to predict how an air conditioning system will perform is ideal for those working in the built environment, who are looking to make choices early in the design process and potentially save costs down the line.
Overall, the benefits of using simulation for air conditioning include:
- Uptime: Designers can better understand failure scenarios and reduce areas of system redundancy.
- Operational Costs: By simulating various scenarios, optimal operational costs can be achieved.
- Capital Costs: Designers can make large investment decisions with full confidence and information.
- Maximise Available Space: Designers can optimize use of their available equipment and systems.
- Satisfy Legislation: Through simulation, designers can satisfy legal standards and legislation around thermal comfort.
Where To Use CFD
CFD simulation tools can be used broadly across a number of environments. Areas of application for simulation in the air conditioning sector include:
- Atrium Deigns
- Concert Halls & Auditoriums
- Operating Rooms & Clean Rooms
- Manufacturing faciliteis
- Apartment Blocks
- Restaurants & Hotels
- Aircraft, Boats & Cars
EXN/Aero: Accessible CFD
- Pay as you go: EXN/Aero is accessed on-demand on a pay-as-you-go model, so costs much less than you may think.
- Ditch the licenses: Access simulation software on the fly, as and when needed. No more restrictive licenses.
- Easy to use: You don't need to be a CFD specialist. Our platform is easy to use and we'll support you all the way.
- High Performance Software: You'll benefit from the latest high performance software from your laptop or desktop.
Try It For Yourself
There's no excuse to not being able to take advantage of simulation. Envenio has created the Discovery Project and Onboarding Program to further assist those air conditioning engineers and designers without CFD experience. With the Discovery Project, Envenio executes a HVAC project on the client's behalf, returning engineering data and results according to an agreed set of objectives. With the Onboarding Program, Envenio works alongside the HVAC engineer or consultant to kick start their simulation project while training them fully on the platform. It guarantees the client is successful in using affordable simulation software tool, EXN/Aero, and minimizes the learning curve.