hi,

theoretically, they are all made of methyl esters of any vegetable oil being almost C18 molecules. Then viscosity is very close for each biodiesel sort (rapeseed, sunflower, etc...).

you can have a look to papers by Ayhan Demirbas. He has done on lot on that

regards

Hello,

These papers may help you out:

you have to convert it into diglycerides and mono glycertides and finally alkyl esters.

You can decrease the v decrease the viscosity for biodiesel by transestrificaion by converting it into methyl ester using basic catalyst like sodium methoxide.

Please refer the attachment

There are two ways that commonly used to reduce the viscosity of biodiesel. 

1. by heating the biodiesel at 50 C ad 70C for period of time

2. by addition of low density diethyl ether (DEE) to the biodiesel.

AS a result, the viscosity maybe reduce and ignition delay period normally reduced also, but the exhaust gas temperature and other cycle temperature not change.. 

You can also use Methanol for Transesterfication. This will give you lower viscosity biodiesel than using Ethanol.

The viscosity of biodiesel depends on the length of the chain and the short-chain alcohol you use in the transesterification. Therefore, if you want to reduce the viscosity of biodiesel I would recommend to use blends from different raw materials such as babassu oil or coconut oil whose viscosity is below 4 cSt. If the oil you use to produce biodiesel is castor oil you will have problems to reduce its high viscosity and I would recommend to mix it such as B10 because its excellent oxidation stability properties.

In general, the biodiesel viscosity highly depends on the number of percent conversion of triglyceride into the alkyl ester compounds. if the total amount of triglyceride converted is 99%, the viscosity of alkyl ester will meet the standard requirement (for example: ASTM D6751). The trace compounds (such as: triglyceride, diglyceride and monoglyceride) contain in biodiesel also should be less than 1.0%.

The long chains of hydrocarbon compound is highly impact on alkyl ester compounds (biodiesel)viscosity. The heat and physical treatment is able to reduce the viscosity of biodiesel, although it is not significantly.

Viscosity of biodiesel can be reduced in the following way:

1. Inclusion of ethanol/methanol

2. Subjecting the biodiesel to higher temperature

3. mixing low fraction of biodiesel with diesel

Sutible of Density in condition reaction with temperature constant

Following five techniques can be used to reduce the viscosity of vegetable oils:

· Preheating.

· Blending.

· Micro-emulsion.

· Pyrolysis (Thermal cracking).

· Transesterification

To decrease the viscosity for biodiesel best way to carry out trans- esterification by sodium methoxide in methanol.