Technical aspects of ethyl tert-butyl ether (ETBE) for large-scale use as gasoline improver

Ethyl tert-butyl ether (ETBE) is a promising gasoline improver and this study shows its comparison with other prospective oxygenated fuel additives. ETBE synthesis and its economics are reviewed with emphasis on sustainable production. Furthermore, an experimental investigation is performed on the impact of employing relatively large proportions of ETBE in fuel blends and a particular emphasis is put on the magnitude of cyclic variations at different operating conditions. Tests involved a primary reference fuel (95PRF and two mixtures of ethyl tert-butyl ether (ETBE) with 95PRF. To provide a baseline for comparison, a commercial gasoline fuel containing 5 % by volume of ethanol (E05) was also tested. The experiments were performed by using a well-controlled single-cylinder research engine, which has a disc-shaped combustion chamber with a full-bore overhead optical access. The pressure recording method was used simultaneously with natural-light video photography for recording the flame propagation. To quantify the cyclic variations, the indicated mean effective pressure (IMEP), the peak pressure and the crank value at which it is attained, and the time for 90 % mass fraction burnt (MFB) were used. Increasing proportion of ETBE in the fuel has very little effect on both the average rate of combustion and its cyclic variability, regardless of what parameter is chosen to characterize the it.