Development of Dual Fuel Engine with Prins Dual fuel system

A duel fuel diesel engine is a diesel engine fitted with fuel conversion kit to enable use of clean burning alternative fuel like compressed natural gas. Dual fuel engines have number of potential advantages like fuel flexibility, lower emissions, retaining diesel compression ratio, better efficiency and easy conversion of existing diesel engines without major hardware modifications. In view of energy depletion and environmental pollution, dual fuel technology has caught attention of researchers. It is ecologically-friendly and efficient combustion technology. This technology has been used worldwide for multiple applications such as genset, marine, locomotives and automotive. In India the technology of dual fuel was not explored for automotive applications. In this context, ARAI took the lead in developing a dual fuel automotive engine in India using its pioneering experience and strength in development of CNG and Diesel engines. ARAI cooperates with Prins Alternative Fuel Systems as a technology partner.

Fig. 1: Dual Fuel Engine at ARAI with Prins system installed

ARAI has developed a 6-Cylinder Diesel-Natural gas dual fuel engine using injection technology (Refer Fig.1). Six cylinder engine was chosen due to its importance for intercity bus and truck applications. Major advantage of this system is that no modifications are required in baseline diesel engine, except addition of Prins dual fuel kit. Dual fuel vehicle has flexibility of operation by way running on diesel and natural gas in cities where CNG is available and on pure Diesel in remote regions where CNG is not available.

The dual fuel combustion technology demonstrated by ARAI uses the Prins dual fuel CNG injection kit, which facilitates CNG single point and multi-point injection with diesel replacement up to 60% for part load conditions. At idling and full load conditions the engine operates solely on diesel fuel. This ensures that there is no power drop as compared to neat diesel operation. This also prevents thermal overloading of engine. It is observed that dual fuel operation reduces smoke and PM emissions by approx. 35-40%, CO is marginally reduced and NOx and HC are comparable with diesel operation. The dual fuel engine developed by ARAI has successfully met BS-III norms with sufficient margin using suitable low loading oxidation catalyst. (Refer Fig. 2).

Fig. 2: Dual Fuel Experimental Results

With increase in number of control variables for the engine (gas supplement ratio), it becomes more difficult to evaluate all possible operating points experimentally, and this necessitates simulation of such combustion cycle. CFD and chemical kinetic simulation has been performed. Thereafter, combustion in the engine under consideration at ARAI has been simulated using this mechanism.

The Prins dual fuel technology has been evaluated in detail, with respect to its effect on engine performance, emissions, ease of commercialization and importance and scope in the Indian context. The following can be concluded about the application of dual fuel diesel natural gas technology in India. During the past decade, appreciable CNG distribution and dispensing infrastructure has been set up across India, hence in Indian context, diesel natural gas dual fuel engine concept can be implemented and commercialized easily. This technology can be used for all generation of diesel engine technologies such as mechanical in line pump, mechanical rotary pump, Electronic Diesel Control (EDC) and Common Rail Direct Injection (CRDI).

ARAI is fully equipped and has the expertise to undertake development projects for all types of Dual fuel Diesel – CNG engines for the automotive industry.

Source: ARAI