Performance Improvement of a Diesel Engine Power Plant with Optimal Utilization of Waste Heat

Abstract: Due to temperature and humidity deviations from the standard ISO conditions in real operational conditions in the tropical countries the performance of diesel engines used for power generation drops significantly. One of the reasons for dropping the engine performance is due to engine de-rating, hence increasing the specific fuel consumption. The present study was undertaken to develop a model for predicting whether the prevailing site conditions cause de-rating at a specific power plant in Sri Lanka.   The model was developed with the aid of recorded information in previous studies and was validated with site conditions revenant to a selected location in Sri Lanka. In the study a set of equations was developed corresponding to different temperatures to predict engine de-rating as a function of relative air humidity.   To achieve the required standard conditions in view of avoiding any de-rating of the engines, the charge air temperature needed to be reduced. For this purpose an absorption chiller system was proposed and designed to be operated with the waste heat recovery from the power plant. It proved that implementation of such a system is technically and economically feasible with a simple payback period of three and a half years on the capital invested.   This derived model was applied to actual operational data of the selected power plant and finally it was found a derated power of 417 kW could be fully recovered by conditioning the temperature and humidity of charge air to obtain the ISO conditions, giving a benefit equivalent fuel savings of 2233 kg/day.