An Investigation of a Nonlinear Fuel Oil Viscosity and Temperature Control System for Ships

In this paper, the differential equation of the fuel oil viscosity and temperature control system was derived, according to the working processes and principles of the heating of heavy oil in ocean vessels. By analyzing the characteristics of the heat transfer model, a multi-input coupling nonlinear heat transfer model was developed, in which the temperatures at the inlet and the outlet of the heavy oil heater were used as the state variables, while the openings of the regulating valve of the mixed oil tank and the steam flow rate regulating valve of the heater were used as the control inputs. This model can be decomposed into a single-input nonlinear system and single-input second-order linear system for further investigation, and the sliding mode variable structure controller can then be solved by performing linear reductions on the nonlinear model. Finally, using KING VIKW software, experiments were performed in order to examine the controlling performances of the PID and sliding mode variable structure ( SMVS ) controller respectively. The results show that the sliding mode variable structure controller exhibits a series of superiorities, which mainly include a small overshoot, fast response and strong anti-interference capability.