-BY HARSH PATEL & AADESH PATANKAR DUAL FUEL ENGINES -BY HARSH PATEL & AADESH PATANKAR

INTRODUCTION As in this modern world the liquid fuels such as diesel and petrol are not cheaper now a days. Gaseous fuels are much cheaper than liquid fuels. This gave rise to dual fuel engines. From recent air and water pollution concern it became necessary to utilize sewage gas. In dual fuel engines there are 2 types of fuel used at the same time.

WORKING It works on diesel cycle. Gaseous fuel (primary fuel) is added to air inducted into the engine or supplied by supercharger. The mixture of air and gaseous fuel gets compressed into the cylinder. Liquid fuel (pilot fuel) injected which acts as a source of ignition. Gas-air mixture ignites establishing a number of flame-fronts.(The flame speed is the measured rate of expansion of the flame front in a combustion reaction.) Let us take an example of Methane + Diesel Dual fuel engines

This system blends diesel with methane to allow diesel engines to offer all the benefits of methane: lower cost and less polluting emissions.  The system's sophisticated special electronics blend the two fuels, giving preference to use of methane. This technology permits conversion with no changes to the engine; ignition begins with diesel and is then extended to methane. Use of a minimal amount of diesel is necessary to guarantee the vehicle's original performance, driveability and lifespan. The electronic DDF unit calculates the correct amountof each fuel in real time, replacing a portion of the diesel with methane in optimised percentages

The electronic DDF unit calculates the correct amount of each fuel in real time, replacing a portion of the diesel with methane in optimised percentages. The percentages of natural gas and diesel are calculated on the basis of engine rpm and load to guarantee maximum benefits in terms of durability, emissions and fuel savings.

As you can see in the first graph only diesel is used in the engine As you can see in the first graph only diesel is used in the engine. We can also see torque generated by the engine and RMP Now in the second graph, a mixture of METHANE & DIESEL is used. We can observe that the same amount of fuel generates same amount of TORQUE and RPM This is what we call a methane diesel dual fuel engine

Performance Produces equal power when operating on liquid fuels as with gaseous fuel. Dual fuel engines are slightly more efficient to conventional diesel at full load. Efficiency of dual in part load is slightly poor Typical diesel efficiency is 41% and dual efficiency is 38.5%

An Iran diesel engine manufacturing company, DESA, is designing an advanced dual-fuel engine that runs on a blend of natural gas (NG) and diesel fuel.

Advantages Efficient utilization of cheap gas available from various sources. Gas burns without leaving any residue (no pollution) Clean combustion results in reduced wear of engine parts and reduced consumption of lubricating oil.

Increased utility of the power plant as the versatility of change-over from gas to diesel and vice-versa. Only a small amount of liquid fuel needed to run engine. Suitable for total energy installation (sewage gas)

The system is added to the existing diesel motor as a "slave" system, ensuring: Lower fuel costs Same performance in terms of torque/power and driveability Maintenance of the same emissions class (where required for HC, CO, NOx) Greater mileage than the original vehicle (addition of a second fuel) Switchback, meaning you can go back to diesel operation automatically or by flipping a switch Maximum flexibility for adaptation to various types of diesel engines Less CNG containers  than Mono-fuel CNG vehicles.

BENEFITS FOR THE ENVIRONMENT 40% - 50% less PM10 than with diesel 50% less exhaust opacity Up to 14% less CO2 emissions Up to 40% less noise With the same power as a gasoline engine emitting 100g/km of CO2  Cycle EightGasoline: 100 g/km LPG: 89 g/km CNG: 80 g/km Diesel CycleDiesel: 85 g/km DDF: 73 g/km

REFFERED FROM- THANK YOU http://www.dieselmetano.it/en/dual_fuel.php Wikipedia Google THANK YOU