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The internal combustion (IC) engines exploits only about 30% of the chemical energy ejected through combustion, whereas the remaining part is rejected by means of cooling system and exhausted gas. Nowadays, a major global concern is finding sustainable solutions for better fuel economy which in turn results in a decrease of carbon dioxide (CO2) emissions. The Waste Heat Recovery (WHR) is one of the most promising techniques to increase the overall efficiency of a vehicle system, allowing the recovery of the heat rejected by the exhaust and cooling systems. In this context, Organic Rankine Cycles (ORCs) are widely recognized as a potential technology to exploit the heat rejected by engines to produce electricity. The aim of the present paper is to investigate a WHR system, designed to collect both coolant and exhausted gas heats, coupled with an ORC cycle for vehicle applications.

Small off-road engines (SORE) have been recognised as a major source of air pollution. It is estimated that non handheld SORE annually produce over 1 million tonnes of HC+NOx and over 50 million tonnes of CO2. The fuel system design and its operating AFR are of key importance with regard to engine operation and engine out emissions. The conventional low-cost float carburettors used in these engines are relatively ineffective at atomising and preparing the fuel for combustion requiring a rich setting for acceptable functional performance. EPA and CARB have confirmed that Phase 3 limits are achievable for a “durable” engine fitted with a conventional well calibrated and manufactured “stock rich setting” float carburettor together with catalytic oxidation after-treatment and passive secondary air injection.

With annual worldwide production of over 100 million units, small off-road engines (SORE) have been recognised as a major source of air pollution. It is estimated that non handheld SORE products in circulation annually produce over 1 million tonnes of HC+NOx and over 50 million tonnes of CO2. These SORE did not have to meet any emissions control legislation until its introduction in the USA in 1995. Since then the gradual implementation of several stages of increasingly more severe legislation has resulted in a decade of intensive emissions control development for utility engines. New carburetted stratified charge 2-stroke engines and catalytic after-treatment are being developed for the handheld products where weight and multi-orientation operation are key requirements. For the non-handheld 4-stroke dominated market, manufacturers are looking at improved fuel system design, improved engine design and the use of after-treatment to meet current and future legislative requirements.

A preliminary test bed evaluation of a potentially simple and low cost stratified charging concept is presented for small capacity 2-stroke scooter engines. The end development objectives of the concept are to reduce engine out hydrocarbon emissions and to improve fuel economy while providing engine fuelling by a simple carburettor type fuel metering device. Such a concept, when combined with a catalyst, could achieve significant vehicle emissions reductions with potentially improved catalyst durability. The results presented in this paper, from a preliminary test bed evaluation of the stratified charging concept using electronic fuel injection to provide the fuelling, have shown that engine out hydrocarbon emissions can be effectively reduced at medium to high load without a loss in wide open throttle torque.

The implementation of the IFP-developped Compressed Air Assisted Fuel Injection process (named IAPAC) on a two-stroke engine allows the introduction of the fuel separately from the scavenging air in order to minimize fuel short-circuiting. The IAPAC process does not require an external air pump since the compressed air used to atomize the fuel is supplied, at no expense, by the crankcase. The premixed charge is delivered directly into the cylinder with a high spray quality and its stratification, for optimized combustion, is controlled by a valve. This process, therefore, provides the advantages of the direct injection but uses conventional low-pressure automotive type injection technology with commercially available gasoline injectors. In earlier work we showed how the qualities of light weight, compactness, high specific power, high efficiency and low emissions make this concept particularly well-adapted for future automotive applications.