The effect of different in-line mixers producing emulsifier-free bio-diesel emulsion on the diesel engine combustion performance and exhaust emission by Wan Mahdi, Wan Nur Izzati, Ithnin, Ahmad Muhsin, Yahya, Wira Jazair, Abdul Rashid, Muhammad Adib, Abd. Kadir, Hasannuddin, Dhani Avianto Sugeng, Dhani Avianto Sugeng, Eiji, Kinoshita