By Mark Schnepel, CEO, Heat Recovery Innovations (HRI)
My team and I have been working in the high-temperature heat exchanger field for over 20 years, and we’ve been a part of incredible innovations over these past decades. One thing that holds businesses back are misconceptions that cost them in performance, time, and money. There is an industry misconception that a heat exchanger is simply an interchangeable part — get this one or that one, and simply install it in your system. This mindset leads to lost opportunity, as well as additional complexity and costs. Whatever your application — gas to gas, gas to liquid, or liquid to liquid — and whatever your industry, a one-size-fits-all approach is rarely going to work. You need a solution that meets your application and specifications.
This is an era when nearly every industry depends on efficiency, high performance, and maximizing your functional space. Finding the right heat exchanger can pull your teams away from the challenges of your core products and lead to confusion on needs and required results. Further, when you’re dealing with high temperatures in the range from 600º to 2000ºF, there’s not much margin for error. The most expedient solution will take design, ingenuity, experience, and collaboration — with a partner who understands your complex needs.
I sat down with my team to gather their need-to-knows about high-temperature heat applications, challenges to performance, and how to achieve peak performance and efficiency. Then I’ll share two instances of our HRI solutions in action — where teamwork truly paid off.
High-Temperature Applications: What to Know
Two key things to realize when you’re dealing with a high-temperature range from 600º to 2000ºF: first, the wrong solution can add very unwelcome complexity. Second, the concept of a custom heat exchanger is actually not that novel at all. If you drive a car, whatever car you drive has its own heat exchanger — a radiator. But your car’s heat exchanger is not the same as my car’s. Same component, same role, likely the same materials, but entirely different in terms of form, fit, and capacity.
Can we take a cue from the auto industry here? Absolutely. The truth is, if it were cost-effective for the auto industry to just create one standardized radiator and design cars so it fit in all of them, they would have. But they don’t. In fact they not only produce a wide range of different designs, they continually improve upon them to gain the best performance in the smallest allowable space.
High-heat industrial applications work on an entirely different scale than the auto industry, granted. But the principle is the same. Put the wrong radiator in a car and you may have a breakdown. With high-heat thresholds, the stakes are even higher. High heat interacting with metal triggers thermal growth, impacting material strength and component life. All metals expand and lose strength as the temperature increases. Depending on conditions, we’ve built heat exchangers that grow an inch or two in response to high temperatures. We’ve added bellows and additional gussets, increased thicknesses, and reconfigured connections to address thermal stress. If the unit can’t withstand thermal growth, the result can be failure or additional cost and complexity in terms of connection plumbing.
Pressure drop is another issue. It’s not cut and dry and it’s often misunderstood. Mismatched heat exchangers of additional connection plumbing can increase pressure drop, resulting in lower overall performance. A common industry goal is to recover as much high-temperature heat as possible, but with low pressure drop. Off the shelf heat exchangers are often compromised with limited manifold sizes and arrangements, while custom heat exchangers can be configured to optimize heat recovery and pressure drop at the same time.
Challenges to Performance
But what my team reminded me is that what interferes with optimal performance can start well before an actual heat exchanger is installed. For instance, a business wants a new heat exchanger for its new application, but the focus is on short-term costs: how much can be saved in the near term by skipping any design phase and going with an off-the-shelf heat exchanger? At that point, the business’ team tasked with specifications may try to modify the specs themselves to better fit a generic unit.
Or, the business’ team just isn’t well versed in high-temperature technology (why should they be), and doesn’t realize how problematic a particular aspect could be. Take multiple elbow connections: from experience, we know that every additional flow direction change adds pressure drop and reduces performance. So you have to accommodate for that in the design in other ways. Or the planned location of a unit requires a tangle of ductwork that will be extremely tricky to maintain. Or the chosen heat exchanger is either way too small or way too large. The costs of having a heat exchanger that can’t operate efficiently tend to grow over time. If we can, we’ll help a business as early on in the process as we can to ensure that everyone is heading in the right direction.
Achieving Peak Performance and Efficiency
If the agreed-upon time horizon is simply too short to do anything but an off-the-shelf unit, that’s another story. But say your team decides it wants a heat exchanger that’s truly going to match your application. You’ve costed out the off the shelf version, but the problems and risks it poses cancel out the initial savings.
The best next step is to start a conversation with a group (such as HRI) who have the expertise, decades of practical experience, and substantial depth of data and analysis in different scenarios. They will work with you from Day One to come up with the right solution, considering every factor: temperature, pressure, application, and your priorities. You’ll wind up with carefully designed technology that operates at peak performance and efficiency, composed of the best materials in the best configuration, and rigorously tested, analyzed, and refined. The end result may well surpass your original expectations: my team often creates additional integrations and modifications that improve output even more. And when it comes time to scale, we’re there to help plan out what comes next.
What Success Looks Like
Ultimately what you want are results. I’ll share two examples of high-heat temperature applications with unique challenges we were able to successfully navigate for clients:
Solid Oxide Fuel Cell
The first is a company that was designing a small solid oxide fuel cell. They needed a heat exchanger assembly that could meet multiple heat transfer requirements within one mostly integrated unit — in a compact space, with temperatures up to 1580ºF and pressure of 0.35 barg.
We embarked on a multiphase process from engineering to concept to production, including continuous conversations and feedback, to create the right design. Made of super-nickel alloys and stainless steel, it integrates four HRI refold heat exchanger cores within the exhaust flow path in a height configuration that worked within the space with a low system pressure drop. We ran leak and heat transfer tests on the cores and simulated boiler conditions.
When the client integrated the heat exchanger design into their solid oxide fuel cell test systems, they got the level of performance they were after with no quality issues. Here, a tricky set of challenges resulted in a stellar outcome — in large part due to the collaborative nature of the whole project.
Industrial Humidifier
In this instance, my team wound up suggesting changes to the customer based on our experience — and they wound up with an even better solution than they had requested. The client had a high-temperature humidifier project — the humidifier takes the exhaust heat off of a fuel cell, adds water and fuel, which effectively adds water content into the fuel. When you introduce room temperature water (which has a really high thermal conductivity rating versus air), into an exhaust stream that’s running pretty hot, you tend to pull a lot of heat quickly, which flashes to steam and causes a lot of thermal stress on the components. With the company’s original heat exchanger, the steam had nowhere to go, and triggered failures. But the challenge was that they couldn’t change the whole process. It was very much an “it is what it is” situation.
Changing the customer’s process wasn’t an option, but my team realized that there was one specific place within the heat exchanger that always failed, while the rest of the heat exchanger was fine. If we changed the design so that we could replace only the failed section, that would be far more cost-effective than replacing an entire unit that could otherwise last for 10 years.
This wasn’t their original concept, but the client saw this was a better approach and got on board. We created a new module with a replaceable core that drops into the exact same place and fits all the same connections. It just slides in and out like a cartridge. So while we couldn’t fix the source of the problem — cold water spraying on high heat — we were able to innovate a simple solution. As my colleague Michael Baier explained, “It meant they didn’t have to rent a crane, ship a thousand-pound unit back overseas for repairs, and shut down for two weeks. All they have to do is slide out one part and replace it.” Ultimately, it was a far better fix than what they’d originally come to us asking for.
Over Two Decades of Solutions
I’m part of a team that represents over 100 years of combined practical engineering experience. We’ve run countless scenarios and have a tremendous archive of data and analysis at our disposal that we bring to the table. We’re dedicated to creating high-performance, high-temperature heat exchangers that work at peak efficiency for specific applications. The results are changing the game for industries, and there’s more to come. The payoff for having the right heat exchanger is unquestionable.
Looking for guidance and inspiration for your application? We’d love to talk.