Development of oil-mist-detector with capacitance sensor

Low speed and high load operating conditions of large diesel engines can cause structural damage which results in frictional heat. When the frictional heat increases in the crank case of a diesel engine it causes the lubricants to evaporate and thus the oil mist density increases. Flames from a damaged structure or heat from the engine starts ignites easily under a high density condition of the oil mist. The resultant explosion due to a heavy oil mist causes not only engine fracture but can also cause casualties. The oil-mist-detector (OMD) is used to prevent engine explosions by checking the density of the oil mist in the diesel engine. Current OMDs use the light scatter method and an absorption method. The first detects the oil mist by checking the quantity of light scattered due to oil mist and the absorption method detects the density by sensing the quantity of light penetrated through oil mist from a transmitter to a receiver. However, these two methods are not conducive to long-term use because the transmitter and receiver become polluted by cohesion or electrification of the oil mist. In this study, the OMD equipped with a capacitance sensor is proposed to detect the oil mist density and the performance is investigated. The capacitance sensor is proposed and designed for effective detection of oil mist and the experiments are conducted under various oil mist size and density conditions. The results show the capacitance sensor detects the oil mist density effectively and the OMD with a capacitance sensor shows the linear response according to density changes even in polluted conditions.