Active cooling of scopes? Impractical?

I've wondered for a while about the cool down time of scopes and air currents in tubes. There are newt fans, SCT coolers, mak and mak newt-fans. But I've never heard of refractor fans. And these methods only use fans, never something like refrigerated air or some more active cooling method. Or the metal tube can be cooled by a peltier cooler, water filled coils etc. Okay, all this is brainstorming, which means most of the ideas will not be workable.

But in general, has anyone ever tried this? Or are there reason(s) it hasn't been tried: too kludgy, $$$, not portable? Is the main issue some danger to the lens?

I find it hard to believe it hasn't been done due to lack of imagination!

A refractor is a somewhat different creature. In a Newt the primary is way down in the bottom of the tube where it can not radiate well. In SCTs the mirror is closer to the front, but the tube is sealed.

A refractor objective is up at the top of the tube where it can radiate heat effectively, especially if you leave the dew cap off. I don't really see a need for active cooling.

Clear skies, Alan

Ok, this is for the distant future- nanotubular circulatory system going through the body of the lens, with liquid of the same refractive index forced through it, bringing temperature up or down depending on need. Attached to radiator fins on the outside of the tube. Magnetically driven micropumps. A scope with a pulse?

Jess Tauber