In contrast, the displacement ventilation strategy places air inlets near floor level and uses relatively low flow speeds. In the traditional mixing ventilation strategy, conditioned air inlets are placed at the top of the space and at high flow speeds. Performance curves were extracted and areas of improvement were identified.įigure 2. In this example study (Figure 2), the aerodynamic performance of a centrifugal fan was investigated with the use of CFD simulation. Design variations can then be tested and compared in a rapid manner, all in a virtual environment. It allows engineers to predict performance in terms of pressure distributions, flow paths and velocities. This is achieved through the implementation of fans, blowers or compressors to create pressure differences and drive air changes in the target space.ĬFD provides great assistance in the design process of air movement equipment. When a passive ventilation strategy is not enough to comply with performance requirements, a forced ventilation strategy is needed.
Results are extracted to compare against code requirements, and we discover that these are not sufficiently met.įigure 1: Results of natural ventilation simulation of a three-story building. In this example case (Figure 1), the natural ventilation of a three-story shopping mall building is simulated using CFD. It can also take into account virtually any geometrical feature, so innovative solutions can be tested and validated before prototyping or construction. For this to happen, special features have to be implemented in the design, such as envelope openings, heat accumulation boxes and exhaust ducts.ĬFD is a very powerful tool to predict the behavior of passive ventilation systems because it can precisely model special phenomena, such as buoyancy due to temperature or humidity differences. In this article, we will take a look at some common ventilation system design examples and the benefits of tackling the analysis with CFD.Īlso known as natural ventilation, this strategy takes advantage of natural phenomena, such as wind flow and buoyancy, to create the pressure differences that drive air changes within the building. CFD comes to the rescue in this situation, allowing precise forecasting of the performance of a ventilation system by modeling the physical phenomena, ambient conditions and the detailed geometry of the precinct. in the commercial field and 6% in residentials. In fact, fans constitute 13% of total energy consumption in the U.S. The typical result of this approach is the specification of oversized equipment and, consequently, an increase in upfront costs and energy consumption. However, this approach relies on established safety margins and late-stage physical testing and adjustments to guarantee requirements compliance. Traditionally, rules of thumb and approximate hand calculations are used to dimension ventilation equipment capacities and parameters.
Ventilation (understood as air moving through an enclosed space) is the main mechanism for HVAC systems to achieve their goal, be it to provide thermal comfort or other special indoor conditions.
For example, the latest trend of cloud computing has given small companies and consultancies the power to run large and complex simulations with minimal hassle and without the related hardware and software costs. And the limits of its application continue to grow as computational power increases. It has allowed scientists and engineers to model and predict flow performance in innumerable fields of application for many decades. Computational fluid dynamics (CFD) is an already established technology.