enginehistory.org

ckuhns · Joined: 13 Jul 2003 Posts: 36

I know that the function of an intercooler/aftercooler is to reduce intake charge heating but I wonder what the difference is between an intercooler and an aftercooler. Carl

kmccutcheon · Posted: Sun Oct 05, 2003 17:27 Post subject:

An intercooler is placed between superchargers or supercharger stages. For example, the B-17 had an intercooler between the turbocharger and the engine where there was another gear-driven supercharger.
An aftercooler is placed between the supercharger(s) and the cylinders, performing final cooling of the charge before it enters the cylinders.
Hope this helps.
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Kimble D. McCutcheon

ckuhns · Joined: 13 Jul 2003 Posts: 36

Thanks for you reply.That is what I thought the answer is but there was some confusion in my mind as I recall a turbo charged diesel truck engine being labeled intercooled and I beleive it was only aftercooled. Carl

kmccutcheon · Posted: Tue Oct 07, 2003 11:21 Post subject:

>>there was some confusion in my mind as I recall a turbo charged diesel truck engine being labeled intercooled and I beleive it was only aftercooled.

I forgot to qualify that what I wrote pertained to big aircraft engines only -- ones with gear-driven superchargers. In the case of trucks cars, and small general aviation aircraft engines, "intercooler" is the name of that heat exchanger between the turbo and the engine. I am not aware of ground applications that are aftercooled, or even any with two-stage superchargers, for that matter. Someone smarter than I needs to field that one.
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Kimble D. McCutcheon

jwells · Joined: 16 Sep 2003 Posts: 57 Location: Victoria, AUSTRALIA

My feeling is that the term "aftercooler" is (or was) a needless terminology complication introduced by the Americans!
The literature is full of confusion and contradiction re the definition of inter-and aftercooler.
Some sources give a definition in terms of the heat exchanger being upstream or downstream of the supercharger - others define in relation to the carburettor. eg CAA Handbook 1949, p 151 "...the use of special radiators, which are called "intercooler" or "aftercooler" depending on their location with respect to the carburettor" but on p 341, under "Definitions" it says, "Intercooler - A heat exchanger used to lower the temperature of the discharge from an auxiliary supercharger."
Most American wartime books insist that only an engine with two (or more) stages of supercharging can have an INTERcooler but all modern U.S. aero-engines that have turbos are always described as INTERCOOLED if, in fact, a heat exchanger is fitted.
I don't think the term "aftercooler" is used at all these days, is it?

Jerry W.