Written by Megan Jenkins on July 19, 2019
May 6th, 2019
approx reading time
As an HVAC engineer, you routinely go through the process of analyzing the designs being forwarded to you from the design department. Imagine having a Eureka moment! You think of a novel air conditioning design that would significantly enhance the overall performance, with just a minor design change. Here comes the real challenge—how would you convince your manager of the validity of this design? Why would it be better than the current one?
This is where the power of computational fluid dynamics can be exploited.
This webinar examines how web-based CFD simulation can help engineers design more efficient air conditioning systems.
We proposed a new air conditioning design for server rack cooling and explained why the new design is better than conventional air conditioning systems. Watch the recording for free.
The cost and performance of any physical product, including HVAC systems, are determined quite early in the design process, typically when you begin to define your product concept. This is when the most impactful design decisions are made, and it is a time when changes can be implemented at relatively low costs. It is, after all, much cheaper to have a design engineer sit in front of the computer than to perform field testing and building physical prototypes. This not only impacts the design process but also the performance of the final product, meaning lower production costs, more efficient energy consumption, lower failure risk, and more.
Despite the numerous benefits, until relatively recently, CFD simulation tools have been inaccessible for many air conditioning system designers. This was due to the high software and hardware costs, as well as the complexity of the multiphysics involved. This status quo has been challenged with the emergence of cloud-based CFD tools, which are rapidly turning CFD into an industry standard for heating, ventilation and air conditioning (HVAC) by making it:
To illustrate the benefits of integrating simulation into your product design process, let’s consider a real-life engineering problem of an air conditioning design validation for a server room.
Always required, but often overlooked, air conditioning design validation is an integral component of every data center or server room. With the recent technological developments, low-heat emitting servers are becoming more available, but they are still relatively new to the market and rare. Most organizations cannot afford to set up their data centers in sub-Arctic zones, making it the responsibility of a building’s AC system to maintain their performance by keeping them cool. And it’s the job of the HVAC engineer to design the most efficient and effective system as a solution.
To illustrate how cloud-based flow simulation helps engineers to design more efficient air conditioning systems, we will use one of the projects publicly available in the SimScale simulation project library: Novel Air Conditioning Design for Server Room Cooling. It can be freely copied and used as a template by any SimScale user. In this project, we’ll propose a new air conditioning design for server rack cooling by creating a visual demonstration of why the new design is better than conventional air conditioning systems, thereby validating it.
The underlying simulation project considered two air conditioning systems of equal capacity. The design change here is a variation in the vent placement. In the new design, air conditioning vents were placed on the floor of the server room. The cooling capacity was maintained at a constant value in the two simulations by maintaining an equal mass flow rate.
As demonstrated by the chart, the new design creates a better cooling effect, reducing the server rack temperature by an additional 10%. This enhances the energy efficiency, and although it may incur a higher installation cost, it would significantly reduce the recursive cost of the air conditioning system in the long run.
The highly efficient cooling effect of the new air conditioning system can be attributed to a more localized distribution of cooling air around the server rack in the server room.
In the above images, the dark blue regions illustrate how the cooling air is distributed in the room. As can be seen, there is a stronger concentration of the cooling air around the server racks, leading to a better overall cooling efficiency.
To gain further insight into the distribution of the cooling air, we must ensure that the results have reached a steady state, i.e., the temperature in the two rooms is not changing over time. This is demonstrated by the temperature convergence plots, as below:
Now that it has been established that we are looking at results over a steady state, the three-dimensional distribution of the cooling air in the server room can be analyzed.
The above animation of the cooling air distribution for the two designs brings us to the conclusion that it is distributed in a more uniform fashion for the new server rack design, leading to more effective convection of heat away from the rack.
With this air conditioning design validation project, we aimed to demonstrate how a minor change to a conventional air conditioning design can lead to a significant improvement in performance efficiency. Such novel designs often never get validated because their impact is underestimated and the manufacturing costs are perceived as too high. With simulation, design engineers can validate their innovative design ideas in a matter of hours, and with a minimal investment of manual effort on their part. As a result of our air conditioning design validation, we were able to test a novel design and achieve a 10% reduction in the server rack temperature, as well as create a more efficient and reliable system overall. Over time, the implementation of this solution can save a considerable amount of energy.
This is just one example of how an HVAC engineer can leverage CFD for air conditioning design validation. The SimScale Public Projects library has a wide selection of simulation templates covering various aspects of HVAC simulation, including thermal comfort, cleanroom design, wind engineering, and much more.
Download this case study for free to learn how the SimScale CFD platform was used to investigate a ducting system and optimize its performance.
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