is it a good idea to coat titanium with black colored anodized aluminium on the outside as a bimetallic cylinder to increase the heating time rate of a distillation equipment?
You can anodize titanium black directly. You want to minimize any additional layers of material. A bimetallic coupling of aluminum and titanium sounds troublesome as well.
You might want to double check emissivity/absorbance values.
Often a dull grey will be just as good as a black surface.
The real key with metals is reducing the reflectivity.
Anodizing Ti is straightforward.
Thermal radiation emmissivity and absorptance values ( as a function of wavelength) are available for aluminum and titanium in textbooks written by Nasa's Siegel and Howell and also another similar text by Mike Modest. There may also be additional tabulation in the software that Nasa distributes at the University of Georgia's Cosmic server.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick