Cold-starting diesel engine

The first engines invented by Rudolf Diesel ran on groundnut oil, but because of the advent of relatively cheap oil this type of biodiesel never became commercially viable. Since about 1930 the diesel engine has been refined and fine tuned to run on the diesel fraction of crude oil, which consists mainly of saturated hydrocarbons. For this reason the modem diesel engine cannot run satisfactorily on a pure vegetable oil feedstock because of problems of high viscosity, deposit formation in the injection system and poor cold-start properties. Today, however, environmental... 

In the case of diesel fuel, an important property that defines the fuel quality is the cetane number (CN). Fuels with low-CN have poor ignition quality (i.e. knocking, noise, PM emissions) and make starting the engine difficult on cold days.6,7 It is well known that CN is lowest for PAHs and highest for w-paraffins.8,9 In normal paraffins, CN increases with the number of carbon atoms in the molecule. For naphthenic compounds and iso-paraffins the CN falls between those of aromatics and w-paraffins. In iso-paraffins, the CN decreases as the degree of branching increases.10... 

Initial starting of a cold diesel engine can be related to the volatility of the fuel. The IBP of diesel fuel and the T-10 provide some information on the startability of a diesel engine. If the fuel T-10 is high, for example >350°F (176.7°C), startability problems may be experienced. 

Glow Plug A device used to provide heat to the prechamber of an indirect injected diesel engine. It is used in cold conditions to permit ease of starting. The glow plugs have a preheating time of about seven seconds. 

Very few heavy-duty propane vehicles have been developed and put into use therefore, a database of knowledge about their performance characteristics does not exist. However, their characteristics should be similar to the relative differences between natural gas heavy-duty vehicles and their diesel engine counterparts. If this supposition holds true, heavy-duty propane vehicles should have similar or better power, the same or better driveability, and better cold-start performance compared to the same vehicle with a diesel engine. (Unlike light-duty vehicles, heavy-duty propane vehicles should have better cold-start performance compared to diesel engines because of the many cold-start challenges diesel engines face.)... 

However, one of the limitations of using biodiesel fuel for diesel engines is higher cold flow properties compared with petroleum diesel fuel (4). Cold properties consist of cloud point, pour point, and cold filter plugging point. The cloud point is a temperature at which the fuel starts to thicken and cloud, the pour point is a temperature at which the fuel thickens and no longer pours, and the cold filter plugging point is the lowest temperature at which fuel still flows through a specific filter. These... 

However, diesel engines and some gasoline engines are operated under lean-burn conditions, where the oxygen is fed in excess, i.e., 10-20% more than is required to meet the stoichiometry for combustion of the fuel [132,489]. Gold catalysts have therefore been examined for their potential in low-temperature activity to combat cold-start emission problems and removal of NOj, from lean-burn engines [202]. 

The Calculated Cetane Index (CCI), though not an accurate predictor of Cetane Number for biodiesel, since it is based on a calculation using specific gravity and the distillation curve, was used to estimate the Cetane Number of the biodiesel and two diesel fuels. From the results it can be seen that biodiesel has a CCI value higher (55) than that of diesel No.2 (49). This accords the biodiesel with better cold-start properties, minimizes the formation of white smoke (emissions), and leads to less engine noise and hence improved engine durability and reduced fuel consumption. ... 

In addition to the above, higher-cetane-number fuels tend to result in easier starting, particularly in cold weather, and faster warm-up. The higher-cetane-number fuels also usually form softer and hence more readily purged combustion chamber deposits and result in reduced exhaust smoke and odor. High-speed diesel engines normally are supplied with fuels in the range of 45-55 cetane number. 

Engine starting fluids include ethers or other extremely volatile hydrocarbons used in gasoline and diesel engines to help in cold-weather starting. 

There is a good correlation between autoignition temperatures and octane or cetane numbers in motor fuels. Thus, toluene and diisopropyl ether make attractive additives for petrol while the low autoignition temperature of glycol ethers, diethyl ethers and some normal paraffins show them to have high cetane numbers and to be useful as cold start improvers for diesel compression/ignition engines. 

There is a very large use of diethyl ether for cold starting formulations for diesel engines and in many cases this is a better outlet for recovered diethyl ether than attempting to return it to reagent or pharmaceutical quality. The shelf life of diethyl ether in an aerosol can needs to be very long and impiuities that could corrode the can internally must be carefully avoided. 

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