Technical feasibility study of scroll-type rotary gasoline engine: A compact and efficient small-scale Humphrey cycle engine

This paper reports the study of a conceptual gasoline Internal Combustion Engine (ICE) using scroll type rotary device rather than conventional piston as the main engine component. The proposed innovation engine adopts Humphrey Cycle to maximise the power performance of ICE. A performance comparison of the Humphrey Cycle, Otto cycle and Brayton cycle has been conducted and studied. The effects of using different designed compression ratio under variable expansion ratio have been investigated, which identify the optimal operational conditions under different compression/expansion ratio of the engine. Optimal performance can be achieved under the compression/expansion ratio at 2:1/4.8:1, 4:1/7.4:1, 6:1/9.9:1, 8:1/11.8:1 and 10:1/14.1:1, when the energy efficiency of the system can be respectively achieved at 42.22%, 49.13%, 52.82%, 55.08% and 56.96%. A case study has been conducted to study the performance of small-scale scroll-type rotary ICE. Results pointed out under designed compression ratio from 2:1 to 10:1 the effective power from the system ranges from 3.343 to 19.01 kW. The analysis of fuel efficiency pointed out the Brake Specific Fuel Efficiency (BSFC) of the scroll-type rotary engine burning gasoline ranges from 130.5 to 148.5 g/kWh, which improve the fuel efficiency by 28.02% and 65.89% compared to that of the conventional gasoline engine.