COMPARISON OF EMISSIONS AND EFFICIENCY OF A TURBOCHARGED LEAN-BURN NATURAL-GAS AND HYTHANE-FUELED ENGINE

An experiment was conducted to evaluate the potential for reduced exha ust emissions and improved efficiency, by way of lean-bum engine fuell ing with hydrogen supplemented natural gas (Hythane). The emissions an d efficiency of the Hythane fuel (15 percent hydrogen, 85 percent natu ral gas by volume), were compared to the emissions and efficiency of p ure natural gas using a turbocharged, spark ignition, 3.1 L, V-6 engin e. The feasibility of heavy duty engine fueling with Hythane was asses sed through testing conducted at engine speed and load combinations ty pical of heavy-duty engine operation. Comparison of the efficiency and emissions at MBT spark timing revealed that Hythane fueling of the te st engine resulted in consistently lower; brake specific energy consum ption and emissions of total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO2), at a given equivalence ratio. There was no clear trend with respect to MBT oxides of nitrogen (NOx) emissions. It was also discovered that an improved NOx-THC tradeoff resulted when H ythane was used to fuel the test engine. Consequently, Hythane engine operating parameters can be adjusted to achieve a concurrent reduction in NOx and THC emissions relative to natural gas fueling.