X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web57502.mail.re1.yahoo.com ([66.196.100.69] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with SMTP id 3581855 for flyrotary@lancaironline.net; Wed, 15 Apr 2009 08:19:15 -0400 Received-SPF: none receiver=logan.com; client-ip=66.196.100.69; envelope-from=casey.gary@yahoo.com Received: (qmail 8583 invoked by uid 60001); 15 Apr 2009 12:18:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1239797919; bh=Gj+b/HKoejZ6srwLAGZjJ4BoM2sXpgH4+Nv/S6H/nAw=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type; b=2y8QCGKgVCzvVnHOgeRiI3Dw6EE2ChgYTkrYkhdzqHgsWJvD9aq5LJNmAE54jToqW9aAKBGi6bq5svAVDBd1uV5kOwxZbtFd3v4ZPeNgXf3L3vmZu/+8pOu5Cak2ujpaHjAm1IhJu0CbA0qbQpnutuVhR7ZlTFINkieBo2d9A4s= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type; b=BxskClKGAGlV4kq5/WUx7hj5ZffGuk3FP/nLDEo/EdoFFGXx7gcRdw2ro1tfgqLcr9qM7p+3DHwd3ij/NaBSY4D1YSwVpoH3rpLHuSg602atbT+PkRMeJbtNpiqclsUC5HCz0Yk4uOsFLzsR/f+N17ZzWUmEW/IG8ATSePA7II4=; Message-ID: <925322.99511.qm@web57502.mail.re1.yahoo.com> X-YMail-OSG: n5SV0LwVM1lBAgy_LNMuTkHeRmilk8gbH.udvmnXf03Fupq1aA5saX0k2y9RsQcqMpkhc3ISJv5jo2PdQljXoowjxlMsYm9sVQD8lYtD_iLpJXxxsGhKUP.cS2WEEfdV5Etw.LLb2Ny_4oBwgRPi6I9Q4zwC.yt7KWfc.LFH.A_sZCN7whDIJ4Ke1NYyj8vc199Lt166.S5sDSD77XzdRpAKla0eKjipbXvOUh1TT4O1qgQ5YQVrJtplh8.OQQO7ChVNzjJbDYavqQZb2dU8TKlO Received: from [97.122.154.197] by web57502.mail.re1.yahoo.com via HTTP; Wed, 15 Apr 2009 05:18:38 PDT X-Mailer: YahooMailRC/1277.35 YahooMailWebService/0.7.289.1 Date: Wed, 15 Apr 2009 05:18:38 -0700 (PDT) From: Gary Casey Subject: Re: Catalyst in an aircraft application To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1826121532-1239797918=:99511" --0-1826121532-1239797918=:99511 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable I read a variety of replies to the question from Chris, many well thought o= ut and some, like the one below, remind me that there are still some that t= hink the world is flat :-). A catalyst doesn't create any new compounds it= just allows a chemical reaction to take place at a lower temperature than = it otherwise could. At any rate it is a good question, and catalysts are n= ot being ignored because they are a bad idea. It's just the difficulties i= nvolved. First, as some suggest, they add weight and cost and as most anyt= hing added, potentially reduce reliability. All normal catalysts are adver= sely affected by lead contamination and one tank of leaded fuel will probab= ly make the catalyst ineffective. But there are real benefits and they dep= end on the type of catalyst and the engine operation. Any catalyst will wo= rk in the rich mode (reducing), lean mode (oxidizing) and at stoiciometric = (both simultaneously), but some work better in one mode than another. Stoiciometric is the mixture that has the chemically correct amo= unt of fuel and air, just rich of peak EGT. In the rich mode oxides of nit= rogen (NOX) will be "reduced", creating nitrogen and oxygen, which then rea= cts with the hydrocarbons to create CO2 and water. In the lean mode it wil= l oxidize CO and HC, creating CO2 and water, but ignores NOX. In the stioc= mode it does both. Catalysts are typically very effective, reducing the a= bove pollutants by at least 90%. Even in the lean mode and engine will emi= t significant amounts of HC - about 300ppm. In the rich mode HC and CO emi= ssions can be very high - at least 10 times what they are in the lean mode,= but a catalyst cannot oxidize in the lean mode. So the first step to take= if you are concerned about emissions is to operate LOP. Only one problem = - operating lean of stoic will increase the production of NOX to several th= ousand ppm. Peak EGT will produce maximum NOX. Then why not use an O2 sensor and operate at stoic, like all modern cars? That would work jus= t fine, except for the potential lead contamination. Unlike some posts wou= ld indicate, there is no such thing as "complete combustion" and an engine = operating in any regime, whether in a car or aircraft will produce signific= ant amounts of HC, CO and NOX. The Feds have left us alone because we don'= t produce very much and the difficulty of improving things is large. Incid= entally, the crankcase breather probably emits half of the HC produced by t= he engine. Feed it back to the intake and you've done a lot to reduce emis= sions. Have I done it? No, because even a simple thing like that creates = a number of problems.=0A=0AGary Casey=0A=0A=0AGood afternoon all, =0A =0AIn= this day and age of EPA, pollution control, green earth, etc., I wondered = about the viability of an exhaust catalyst in an aircraft application. Are = there any reasons not to use a catalytic converter in this capacity? Weight= ? Exhaust restrictions? Other? =0A =0AMany thanks and looking forward to yo= ur feedback. =0A =0ABest regards, =0AChris =0A =0AHow about all of the abov= e, and additionally expense! Some people really don't care what they spend = on their plane, I do! The engineer in me also begs me to ask if the alterat= ion of hydrocarbon to another chemical in the atmosphere is really helpful = AT ALL. Most "environmentalists" are ignorant idiots and the sooner we star= t listening to real scientists as opposed to paid "advocates" I'll feel a l= ot better about it. Anthropomorphic global warming is BS, get over it. Sorr= y for the rant.=0A=0A=0A --0-1826121532-1239797918=:99511 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
I read a variety of replies to the question from C= hris, many well thought out and some, like the one below, remind me that th= ere are still some that think the world is flat :-). =A0A catalyst doesn't = create any new compounds it just allows a chemical reaction to take place a= t a lower temperature than it otherwise could. =A0At any rate it is a good = question, and catalysts are not being ignored because they are a bad idea. = =A0It's just the difficulties involved. =A0First, as some suggest, they add= weight and cost and as most anything added, potentially reduce reliability= . =A0All normal catalysts are adversely affected by lead contamination and = one tank of leaded fuel will probably make the catalyst ineffective. =A0But= there are real benefits and they depend on the type of catalyst and the engine operation. =A0Any catalyst will work in the rich mode (reducing), l= ean mode (oxidizing) and at stoiciometric (both simultaneously), but some w= ork better in one mode than another. =A0Stoiciometric is the mixture that h= as the chemically correct amount of fuel and air, just rich of peak EGT. = =A0In the rich mode oxides of nitrogen (NOX) will be "reduced", creating ni= trogen and oxygen, which then reacts with the hydrocarbons to create CO2 an= d water. =A0In the lean mode it will oxidize CO and HC, creating CO2 and wa= ter, but ignores NOX. =A0In the stioc mode it does both. =A0Catalysts are t= ypically very effective, reducing the above pollutants by at least 90%. =A0= Even in the lean mode and engine will emit significant amounts of HC - abou= t 300ppm. =A0In the rich mode HC and CO emissions can be very high - at lea= st 10 times what they are in the lean mode, but a catalyst cannot oxidize i= n the lean mode. =A0So the first step to take if you are concerned about emissions is to operate LOP. =A0Only one problem - operating lean of stoic= will increase the production of NOX to several thousand ppm. =A0Peak EGT w= ill produce maximum NOX. =A0Then why not use an O2 sensor and operate at st= oic, like all modern cars? =A0That would work just fine, except for the pot= ential lead contamination. =A0Unlike some posts would indicate, there is no= such thing as "complete combustion" and an engine operating in any regime,= whether in a car or aircraft will produce significant amounts of HC, CO an= d NOX. =A0The Feds have left us alone because we don't produce very much an= d the difficulty of improving things is large. =A0Incidentally, the crankca= se breather probably emits half of the HC produced by the engine. =A0Feed i= t back to the intake and you've done a lot to reduce emissions. =A0Have I d= one it? =A0No, because even a simple thing like that creates a number of pr= oblems.

Gary Casey


Good afternoon all,=A0
=A0In this day and age of EPA, pollution control, green earth, etc., I wonde= red about the viability of an exhaust catalyst in an aircraft application. = Are there any reasons not to use a catalytic converter in this capacity? We= ight? Exhaust restrictions? Other?=A0
=A0
Many thanks and looking for= ward to your feedback.=A0
=A0
Best regards,=A0
Chris=A0
=A0
= How about all of the above, and additionally expense! Some people really do= n't care what they spend on their plane, I do! The engineer in me also begs me to ask if the alteration of h= ydrocarbon to another chemical in the atmosphere is really helpful AT ALL. = Most "environmentalists" are ignorant idiots and the sooner we start listen= ing to real scientists as opposed to paid "advocates" I'll feel a lot bette= r about it. Anthropomorphic global warming is BS, get over it. Sorry for th= e rant.

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