We are working on microgrid projects consisting of diesel engines, solar PV plants, wind power, energy storage system (batteries). In most of these cases we are competing against the electricity price produced from a diesel engine. One element of optimising the fuel consumption of the diesel generator is to operate it close to the optimal point. The other element is how old is the diesel generator and how its age affects its fuel consumption / efficiency of operation.
We are looking for research on experimental or theoretical curves of fuel consumption / efficiency curves varying with operating hours.
My recommendation is that you calculate the diesel generator reliability as a function of time. There are reliability models like Weibull that can predict the reliability of this engine as a function of its operating hours. You will find that the reliability at the beginning is close to 100% and it declines as a function of the operating hours.
The reliability correlates with the efficiency of the diesel engine. Hence, you would expect the efficiency will decline as a function of the operating hours. However, if you take maintenance into consideration, then you can consider the efficiency could be maintained at a desired level depending on the maintenance interval.
Hope this helps answer your question.
Professor Yehia Khalil
Yale University
USA
HI Niko,
Apart from the suggestions provided by Prof. Khalil, I feel you should obtain a tentative daily load curve of the microgrid for configuration and design purposes.
Diesel engines loose a lot of energy at startup and shutdown, so without any clue about load variation you may end up with incorrect estimates.
-Sanjay
Diesel generator set gives maximum efficiency at designed value(HP/KW),, at the lower or higher value of operation the efficiency of generator and diesel eengine would be reduced. When is used with other alternative source, care should be taken to utilise the set for maximum time, at the rated value, and could be obtained by plotting regular load curve,with time, and the available other source at the time....
The brake specific fuel consumption (BSFC) of the Diesel engine is usually provided by the manufacturer as contours because the BSFC is a function of the speed and the output torque of the Diesel engine, in general. However, these curves usually need some modifications when the engine gets old because the efficiency varies with use. As another suggestion, when it comes to the aging problem, I think you need a better model of the BSFC that takes in consideration the performance of the engine and its efficiency. This is really complicated because the efficiency of the engine by itself is a complicated function of thermal and mechanical efficiency and other factors. I recommend the following papers for such models:
1] H. D. Harris and F. Pearce, "A Universal Mathematical Model of Diesel Engine Performance", Journal of Agricultural Engineering Research. vol. 47, pp.165-176, 1990
2] C.E. Goering and H. Cho, "Engine Model for Mapping BSFC Contours", Mathematical and Computer Modelling, vol. 11, pp. 514-518, 1988
Mutaz
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