Designing new wood-burning products with Condar catalysts
Inventors, manufacturers, and new product developers inquire regularly to Condar Company about catalysts for wood heating stoves,
inserts, fireplaces, wood-fired cooking stoves, indoor wood-fired boilers, and outdoor furnaces.
The following information is provided to assist application engineers and managers to understand the basic facts. Please read carefully and be sure
to understand this information to the best of your ability before consulting Condar, the catalyst experts, about your needs.
Catalytic technology Is not "retrofit" technology.
This technology can't be added successfully to an existing wood-burning product. A product must be purpose-designed for a catalyst to
work properly with one. For example, simply putting a combustor in an exhaust pipe won't work. It will clog up with ash and it will be
A catalyst is not a filter.
Catalytic combustion doesn't "capture" particulate emissions. It generates heat and adds water vapor into exhaust. Therefore do not plan to use a
catalyst as a simple filter.
Your catalytic design must have a "bypass."
When exhaust temperature isn't high enough for a catalyst to "light-off" the wood-smoke exhaust must have an alternate route to go, until the
catalyst is hot enough to perform its function. The most difficult part of designing your new catalytic product, therefore, is designing the
correct "bypass" route.
Operating temperatures must be hot enough.
The catalyst and air-particulate stream must be at least 200° Celsius or 400° Fahrenheit, minimum, to initiate the reaction chemistry.
Open-chamber fireplaces, woodstoves and cookstoves that aren't air-tight, and outdoor wood furnaces don't operate at temperatures hot enough to
achieve the chemical reaction.
If you are designing any of these product types, be aware that no successful catalytic designs of these exist
anywhere in the world. It is generally understood that theoretically the catalyst could be artificially heated "outside the system" but this is
expensive, and hasn't yet been simplified from industrial-scale technologies to small-scale utility.
Pre-heating your catalyst.
Your design should incorporate the catalyst in a position where the start-up fire will heat and keep the combustor hot enough to function.
Not over-heating your catalyst.
Your design must avoid a thermal "feedback loop" where the catalyst heats air and solids to the extent it destroys itself by overheating.
The path of entry air and exit air is vital. Locating refractory materials adjacent to the catalyst aren't enough to guarantee safety and
longevity of the catalyst. You must understand thermal design principles!
Take advantage of the extra heat the catalyst generates.
The best catalytic designs radiate the extra heat in a positive direction. If a heating stove, this is forward toward the room, not toward the
floor or behind the unit. If designed for stove-top cooking, the design directs heat upward.
Air flow rate and pressure drop.
The nature of wood fuel presents unique challenges for catalytic design. Wood fires generate ash and wood-smoke particulates are large. Exhaust'
streams are not fan-driven, for safety reasons, and thus require much larger cells to maintain air flow than the exhausts of many catalytic
applications such as an automobile catalyst.
Planning for examination and replacement.
You should locate the catalyst in a position that is easy for inspection and maintenance. Eventually the catalyst will outlive its useful
economic life. Performance decline begins after about 12,000 hours of active burn time in practical use with wood fuel.
Don't use a conventional gasket around a catalyst.
It is improper (and potentially dangerous) to use a conventional Fiberglass gasket such as those typically used around woodstove doors. In fact, it
isn't necessary to have an airtight seal at all for the catalyst to work properly. A simple drop-in design is satisfactory.
Ceramic or steel?
Ceramic catalyst continue to be the best choice for designers of new products. They are easily manufactured in low quantity, are essentially
"modular" and no custom tooling is involved. Once a product design is proven and market volume is sufficient, it then makes sense to consider design
of a steel-based version. A steel catalyst should never be chosen because the product design doesn't work with a Condar ceramic catalyst. If the
ceramic is overheating, plugging, etc. you have a fundamental product design problem that a steel version simply won't overcome.
Are all ceramic and steel catalysts essentially the same?
No. There are important quality differences among suppliers of ceramic and steel catalysts for woodburning. Condar has decades of experience to
know what works best in these applications. We carefully control our sources and specify best materials. Much of our materials expertise is
proprietary information and cannot be revealed, even to our valued clients.
How does a client determine a new design will work?
Since the first catalytic woodstoves passed American emissions-control tests 25 years ago, catalytic designs have improved and changed. Be aware
that the many different configurations have advantages and disadvantages. Some designs operate well in tests and certification, but are difficult
to maintain. Others are easy to maintain, but are more costly or sacrifice efficiency. The inventor must study and learn from the existing
products currently available in the market, which are virtually all experienced USA or Canada manufacturers. Condar does not, at this
time, provide engineering and consulting services to designers and marketers of new products.
Condar does not guarantee the catalyst will pass your nation's emission tests.
Each nation has different expectations and standards for efficiency and emissions. From a practical standpoint, passing the test is more a matter
of product design than the catalyst design. While Condar's products have passed the strict tests of USA and are used in products in Europe, Japan
and around the world, you are responsible for your own laboratory and government testing.
Condar does not provide free samples for research & development purposes.
There are no discounts to engineers, inventors, and product developers, and we don't invoice on open-account. Please use the conventional shopping
cart to order catalysts. Catalysts used for R&D purposes aren't covered by warranties.
Volume discounts to the trade.
Condar supplies manufacturers and distributors around the world from its factory in North Carolina. Arrangements can be made to ship Condar
catalysts to volume customers from our warehouses in Angers, France and Ottawa, Canada. To obtain price quotations at discounted trade
prices, kindly contact Timothy Williams to obtain a credit application.
Standard sizes and shapes.
Best cost-efficiencies today are rectangular shapes, not round shapes. We recommend you begin your application engineering using our Condar code
number CC-251, a compact standard rectangle, 6.4 cm wide x 33 cm long x 5.1 cm thick. Nicely wrapped in a flanged highest-quality stainless steel
metal can. This size fits compactly inside modern stoves, with plenty of capacity to accommodate exhaust flow.
Measuring temperature of the catalyst.
During your research and development, use standard thermocouples to monitor temperatures. Any digital multi-meter can be fitted to the
thermocouples. Begin to think about how your customers will monitor the catalyst for most-efficient performance of the woodstove. Some woodstove
brands use simple thermometers on the stove surface, outside and near the catalyst. Others use probe thermometers, the probe ending as much as 1
cm away from the catalyst (they must not actually touch). Others require more-expensive digital catalytic monitoring (remotely, by cable). Condar
manufactures all these monitoring products for woodstove manufacturers, in Celsius and Fahrenheit scales. Click here to learn more about catalytic thermometers.
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