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Optimizing Passive Regeneration

August 23, 2011

 by admin

This excerpt was originally posted on the John Deere, Straightforward Blog August 15, 2011. You can view the original post here.

Passive Regeneration

In June, we revisited exhaust filter regeneration in a post titled “Exhaust Filter Cleaning: A Return to Basics.” Now that you have a better handle on the fundamentals, let’s take a closer look at the process — starting with passive regeneration.

John Deere Interim Tier 4 engines and exhaust filter components are designed for uninterrupted operation using passive regeneration, a natural cleaning process where engine exhaust heat is sufficient to oxidize the particulate matter (PM) trapped in the filter. Passive regeneration continuously occurs during normal engine operating conditions (greater than 30 percent load factor) and is the most efficient way to clean, as it does not interrupt machine operation, require operator involvement, or require additional fuel.

If passive regeneration can’t be achieved due to low temperature, load, or speed, then PM must be removed using active regeneration. In most applications, it serves as a backup system, only occurring when passive regeneration isn’t possible.

With John Deere engines above 174 hp, lightly loaded applications (less than 30 percent load factor) will typically operate using passive regeneration for about 25 hours before an active regeneration is required. Operators in applications with load factors greater than 30 percent experience an increased interval before an active regeneration. Fully loaded applications are capable of using passive regeneration for extended periods of time.

There are several ways to increase the amount of passive regeneration. Operators can increase the time before an active regeneration by avoiding light-load and lower-speed conditions, which reduce an engine’s exhaust temperatures and its ability to regenerate passively. We also recommend that operators minimize idling, which can shorten the interval before an active regeneration

Many equipment owners and operators have the mistaken impression that active regeneration is the same as parked or stationary regeneration, which reduces machine productivity. In actuality, active regeneration is an automatic cleaning process and doesn’t affect machine operation or require operator involvement. Other than seeing a light on their display, most operators won’t even know that an active regeneration occurs.

For our engines between 75 hp and 174 hp, we expect to achieve a minimum 100-hour interval before inactive regeneration. Just as with our larger displacement engines, applications with load factors greater than 30 percent could realize increased interval times before an active regeneration.

The main point to remember is that John Deere has optimized exhaust filter cleaning — for our entire Interim Tier 4 lineup — to make it a transparent, convenient and reliable process for the operator.

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