energies Article Exhaust Emissions and Physicochemical Properties of n-Butanol/Diesel Blends with 2-Ethylhexyl Nitrate (EHN) or Hydrotreated Used Cooking Oil (HUCO) as Cetane Improvers Iraklis Zahos-Siagos , Vlasios Karathanassis and Dimitrios Karonis * Laboratory of Fuels Technology and Lubricants, ...