Asset management of aging devices in energy systems based on probabilistic modelling : a case study on diesel engines

Abstract

The purpose of maintenance is to lengthen the equipment lifetime. Too little maintenance may have costly consequences; whereas too frequent maintenance may not be economical. Hence the two costs, i.e. the cost of failures and the cost of maintenance must be balanced. In practice, the attempts to approximate this balance have often been based on trial and error. Here, a probabilistic maintenance model is developed for inspection based preventive maintenance of diesel engines based on the practical model concepts discussed in the literature. Developed model is solved using real data obtained from inspection and maintenance histories of diesel engines and experts’ views. Reliability indices and costs were calculated for the present maintenance policy of diesel engines. A sensitivity analysis is conducted to observe the effect of inspection based preventive maintenance on the life cycle cost of diesel engines. Optimal rates are obtained for inspection based preventive maintenance of diesel engines using the developed model and a grid search algorithm. The reliability and cost measures of the present maintenance practice and the optimal maintenance practice are compared. It is found that the current maintenance practice maintains the reliability and the life cycle cost of diesel engines at an acceptable level. However, the optimal policy suggested by the model is capable of further reducing the life cycle cost and increasing the reliability. Further, a state prediction tool is developed to validate the model. The same can be used to predict the deterioration condition of the diesel engine. A software tool is also developed with GUI interface for calculating purposes and presenting results.