TriMech is fortunate to work with clients from Maine to Florida and out to Arkansas, offering a range of engineering solutions. This week's client story showcases how TriMech's Project Engineering Group (PEG) helped a client improve their design through CFD analysis.
As engineers, we tend to be perfectionists. Most of us agonize over details to make sure that whatever we’re designing can stand up to almost any practical use imaginable and still get the job done. Sometimes a design doesn’t work as we would like it to, for different reasons such as a miscalculation in engineering, an error in manufacturing or an unexpected situation. Regardless of the cause, there can be multiple solutions to help modify the product to work for the customer. Our team of experienced engineers can help you find solutions to some of the design issues you might be facing.
Understanding Different Design Needs and Scenarios
When helping our customers, our Project Engineering Group engineers take two main things into consideration: providing a solution that works and implementing that solution as quickly as possible. Understanding the client’s design needs is important so we can figure out the solution. It could be an easy fix, but other times it can be complex and could require simulating the problem to fully understand the situation and then we need to simulate proposed fix to make sure it works the first time.
This scenario can play out in almost any industry that supplies a physical, functioning product to their customers. Companies that make industrial equipment are no exception. In fact, they may see this happen more than other industries. Industrial equipment is often custom made for a specific customer. While the general function may be the same for a line of equipment, an individual client may need their specific unit modified to handle different throughput, fit in a specific workflow, or even fit in a unique space with unique environmental conditions. Industrial equipment engineers leverage their existing technologies and their experience. Typically, that’s enough and everything works for the client as soon as the equipment is commissioned.
How PEG Can Help Solve Your Engineering Problems
I’m reminded of a manufacturer of conveyor ovens that came to us with such a problem. Conveyor ovens consist of a heated space through which a conveyor belt takes a product. You may have seen one of these at a restaurant cooking your pizza or toasting your sandwich. And while these ovens are largely used in the food industry, you can find conveyor ovens used for sterilizing, metal treatment, ceramic tile baking and more. They come in all shapes and sizes. In most cases, these ovens use a fan to circulate the hot air in the oven and a mesh conveyor belt to allow the heated air to pass through and reach the product on the belt. Uniform heating is almost always the goal.
Figure 1: A typical conveyor oven conveys product through the oven (blue arrows) on a mesh conveyor. Air is recirculated in the oven by a fan that forces air over a heater and through passages that lead to nozzles, holes or slots that force that heated air (red arrows) into the oven to heat the product to the desired temperature.
This particular manufacturer had installed a slightly modified piece of equipment at their customer’s site only to find that, due to various unexpected loading conditions, the belt was sagging. They switched out the belt with a tighter mesh pattern. That made the belt stronger and eliminated the sagging. However, the tighter mesh pattern was preventing the air from reaching the bottom of the product. The non-uniform heating was causing quality issues and affecting throughput for their customer.
There were two components that the manufacturer could modify. The first was changing the conveyor belt to use a different mesh and allow more air through. The second was increasing the power of the fan that circulated the air. Both had trade-offs. There was a limit to how open the belt could be before it would start failing due to the load it needed to carry. There were only a couple of options for increasing the fan throughput due to the housing size. The engineers knew that there were several different combinations of these solutions at their disposal. They also knew that they couldn’t afford to try all of these combinations in the field. It would cost too much time and too much money.
Figure 2: A cross section view of a typical conveyor oven. This oven uses a fan that moves air over a heater and forces the heated air (red arrows) through slots in the sheet metal inner shell to heat the sides and top of the product (not shown). Hot air also comes from the bottom of the oven and must pass through the mesh conveyor to reach the product that is to be heated.
TriMech’s Project Engineering Group was able to shorten this process by leveraging our CFD expertise to simulate air flow and heat transfer for potential options and hone in on the best solution. By simulating the options using CFD (computational fluid dynamics) we were able to not only simulate the performance of the different options, but we were also able to understand why the options performed the way they did.
First, we took their CAD model of the oven and prepared its simulation by removing some of the manufacturing-level detail to make for a more efficient for simulation without sacrificing the accuracy of the model. Next, we simulated the original design and confirmed that the computer model predicted the same behavior that was seen in the actual oven at the end user’s site. Simulation resulted in airflow patterns that confirmed the belt was restricting the flow upward which was causing the uneven heating of the end-user’s product.
We then simulated several what-if scenarios. We looked at various combinations of fan speeds and conveyor belt mesh patterns over the course of a couple of weeks and were able to determine the best combination. Our customer was able to move forward with implementing the change with confidence. As an added bonus, simulations revealed some unexpected air flow patterns in the oven and we were able to explain exactly why those patterns were occurring. Their engineers are now considering modifications to future ovens to improve performance and efficiency. Ultimately, the oven manufacturer saved valuable time and was able to modify their oven quickly and make their customer happy.
Figure 3: Above are images of air velocity within the oven. Red is for higher velocities, blue shows lower velocities. The image on the left reflects the original design that did not allow enough air through the mesh conveyor. The red circle highlights the low velocity region that translates to insufficient heating. After multiple simulations of possible fans and belt types, an improved design was determined via CFD simulations that allowed just the right amount of heated air to reach the product. The red circle in the image on the right shows higher velocity air in that region and represents the desired performance.
TriMech’s Project Engineering Group is built to be an extension of our clients’ engineering departments to help with a sudden surge of engineering work or to provide the expertise that those clients may only need occasionally. The simulation engineers on the team have decades of experience working with a wide variety of industries. Naturally, we help clients at any stage in their design process, but we pride ourselves on being able to help organizations quickly address the unexpected. If you find yourself in a spot where you need to solve a design problem quickly – before or after it leaves the manufacturing floor – just let us know.
If you are interested in learning more about our Project Engineering Group and what our team can do for you, take a look at our infographic.