디젤기관의 배기폐열량 예측에 관한 기초 연구

Abstract

Our country which has little natural resources has been faced with serious problem of gradually increasing energy cost with additional environmental pollution, and of balancing the supply of gas/electric power during winter/summer season, due to the cost rise and increasing consumption of fossil fuel. And according to increase of population and development of industries in addition to the decrease of water supply due to the pollution, the solution of water demand also became serious problem.

Therfore, Korea and Japan which don't have a lot of natural resources are studing the method raising engine thermal efficiency and total efficiency using waste heat of plants at the same time. Waste heat, is mentioned above, can be defined as heat which is generated in a process but then dumped to the environment even though it could still be reused for some useful and economic purpose. There are several methods using waste heat and representative methods are as follow

The cogeneration system can be defined as system which produces secondary energy of heat and electric power by being based on one energy(that is heat). It can be generated the electric power by driving, and generate heat by way of recovering the waste heat of exhaust gas and engine cooling water for diesel engines or gas turbines. In case of best condition for heat and electric power load , overall thermal efficiency can be raised to 75∼85 percents.

In the ship, economizer is equipped to the stack, the heat of exhaust gas passing to the environment is recovered and the steam generated in the process of recovering is used as fuel oil heating and general use for on board, or for driving turbo generator.

Especially, the islands separated from land are suffered from water supply because the underground water resources is lack. These facts seem to increase gradually. These islands have a self-generator, diesel engine is used a the prime mover. In the energy use aspect, fresh water generator plants that can supply water by using self-generator is useful.

In this paper, the exhaust gas temperature of diesel engine and quantity of waste heat recovery were investigated and the predictions of performance of waste heat recovery systems were studied. Comparisons were commanced between predicted results and measured results of data from a couple of 2-stroke cycle main diesel engines and another couple of 4-stroke cycle dynamo engines which are equipped on board the two training ships (M/V Hanbada & Hannara).

Three methods were adapted to predict exhaust gas temperature at T/C outlet ie. utilizing heat quantity ratio of exhaust gas, sabathe cycle analysis and SNAME's equation. As a result the authors found that the calculated values from the first method and second method were approximated fairly well between one another, but not between that from the third method. And further the authors assured that the waste heat quantity of exhaust gas was mostly affected by the temperature and the mass flow rate of exhaust gas.