Friday, 21 February 2014

HEAT TRANFER ENHANCEMENT BY NANOFLUIDS


ABSTRACT
           
           

Nano fluids  are suspensions of nanoparticles in fluids that show significant enhancement of their properties at modest nanoparticle concentrations. Many of the publications on nanofluids are about understanding their behaviour so that they can be utilized where straight heat transfer enhancement is paramount as in many industrial applications, nuclear reactors, transportation, electronics as well as biomedicine and food. This seminar focuses on explaining the basic mechanisms of improvement in heat transfer by addition nano particles.






HCCI Engine


ABSRACT

      HCCI has characteristics of the two most popular forms of combustion used in IC engines: homogeneous charge spark ignition (gasoline engines) and stratified charge compression ignition (diesel engines). As in homogeneous charge spark ignition, the fuel and oxidizer are mixed together. However, rather than using an electric discharge to ignite a portion of the mixture, the concentration and temperature of the mixture are raised by compression until the entire mixture reacts spontaneously. Stratified charge compression ignition also relies on temperature increase and concentration resulting from compression, but combustion occurs at the boundary of fuel-air mixing, caused by an injection event, to initiate combustion.
The defining characteristic of HCCI is that the ignition occurs at several places at a time which makes the fuel/air mixture burn nearly simultaneously. There is no direct initiator of combustion. This makes the process inherently challenging to control. However, with advances in microprocessors and a physical understanding of the ignition process, HCCI can be controlled to achieve gasoline engine-like emissions along with diesel engine-like efficiency. In fact, HCCI engines have been shown to achieve extremely low levels of Nitrogen oxide emissions (NOx) without aftertreatment catalytic converter. The unburned hydrocarbon and carbon monoxide emissions are still high (due to lower peak temperatures), as in gasoline engines, and must still be treated to meet automotive emission regulations.













Thursday, 20 February 2014

PLASMA GASIFICATION MELTING PROCESS


ABSTRACT 


Many areas have a need for establishing or extending landfill. As an alternative to the existing   concept   of   a   landfill,   a   new   waste-disposal technology    named    Plasma    Gasification  Melting  (PGM)  was  developed.  Plasma  Arc technology has been applied to the treatment of municipal solid waste (MSW).  This  recent development  would  eliminate  or  minimize  the need  for  a  landfill  and  this  approach  is known   as   Plasma   Arc   Gasification   process   for   the treatment of MSW. A pilot PGM reactor was constructed in northern Israel. The reactor is an updraft   moving-bed   gasifier,with  plasma  torches  placed  next  to  air  nozzles  to  heat  the incoming air to 6000oC. The inorganic  substances  of  the  feedstock  are  melted  by  the  high-temperature  air  to  form  a vitrified slag in which undesirable materials such as heavy metals are trapped. The residual heat in the air supplies additional heat for the gasification process. A  series  of  tests  were conducted   to   study   the   performance   of   PGM   gasification.   For air   gasification,   the syngas   LHV (Lower Heating Value) decreased   with   increasing   ER( equivalence ratio ), whereas   the  gas  yield   and energy efficiency increased with ER. When high-temperature steam was fed into the reactor,  the overall gas yield was increased  significantly,  and the syngas LHV also increased slightly. The  positive  effect  may  be  attributed  to  the  steam reforming   of   tar.   The maximum  energy efficiency of the tests reached 58%. The main energy loss was due to the formation of tar.







LASER IGNITION


Abstract :

Laser ignition has become an active research topic in recent years because it has the potential to replace the conventional electric spark plugs in engines. Compared to conventional spark ignition laser ignition allows more flexible choice of the ignition location inside the combustion chamber with the possibility to ignite even inside the fuel spray. Modern engines are required to operate under much higher compression ratios, faster compression rates, and much leaner fuel-to-air ratios than gas engines today. It is anticipated that the igniter in these engines will face with pressures as high as 50MPa and temperatures as high as 4000 K. Using the conventional ignition system, the required voltage and energy must be greatly increased (voltages in excess of 40 kV) to reliably ignite the air and fuel mixture under these conditions. Increasing the voltage and energy does not always improve ignitability but it does create greater reliability problem. Experiments with the direct injection engine have been carried out at the fundamental wavelength of the Nd:YAG laser as well as with a frequency doubled system Experiments show that above a certain threshold intensity of the laser beam at the window even highly polluted surfaces could be cleaned with the first laser pulse which is important for operation in real world engines.


laser ignition ppt


laser ignition report



Dual Clutch Transmission


ABSTRACT:
           
            The twin-clutch transmission, also known as the Direct Shift Gearbox (DSG) or dual-clutch transmission, is an automated transmission that can change gears faster than any other geared transmission. Twin-clutch transmissions deliver more power and better control than a traditional automatic transmission and faster performance than a manual transmission. Two separate clutches for odd and even gear sets are utilized by it. It can be imagined as two separate manual transmission working as one unit. They are operated in a fully automatic mode. It eliminates torque converter as used in conventional epicyclical-geared automatic transmissions but use two oil-bathed two wet multi-plate clutches. It eliminates the lag, thus improving acceleration and engine performance overall. One of them is responsible for controlling the odd gears, such as first, third and reverse, while the other manages the even gears – second, fourth and others.