Therefore, our purpose has been to develope a new system which makes it possibe to use LO semi-permanently without oil renewal and without any waste oil.
2.2 Principle
The main and key element of the new system is a new type filter which is shown in Fig. 1 (b). While contaminant particles are stopped and taken away by the small holes in the conventional type filters as shown in Fig. 1 (a), in the new type filter LO flows between the filter papers and the contaminants sit on the paper surface.
The new type filter is also called nephron filter. The main performance features of the nephron filter are as follows. (1) It can pick up contnminant particles of 0.1 / μm and even smaller. This is because the fine particles or bunches of the particles sit on the filter paper in the course of Brownian motion. (2) It can take away such contaminant which the conventional centrifugal separator can not separate because of almost no density difference between LO and the contaminant, (3) It has filter area of 50〜100 times larger than the conventional type in the filter cases of the same size. Therefore, filtration is much more speedy in the nephron filter.
3. FIELD TESTS
3.1 Fundamental Tests
The most important fundamentals in this development are to verify that the kidney system always keeps LO clean and that it makes possible to use LO semi-permanently. It must be also verified that LO deterioration is negligibly small.
Fig. 3 shows a result obtained in a four cycle cogeneration diesel engine in practical use at a super shop. As is shown, normal pentane insoluble (n-P insoluble) was below 0.6%. which means very clean LO in general. Since the engine was brought into service in August 1992, the engine has been always clean and, therefore, there have been almost no troubles in LO system as well as no LO renewal and no waste oil.
