Influence of Low-Speed Marine Diesel Engine Settings on Waste Heat Availability

摘要

Sporohodni dizelski motori su najefikasniji pogonski sustav broda. Osim za mehani?kom snagom za pogon vijka, na brodu postoji i velika potreba za toplinskom energijom. U ispu?ni sustav mogu?e je ugraditi utilizacijski izmjenjiva? topline koji iskori?tava osjetnu toplinu ispu?nih plinova. Takva kombinirana proizvodnja mehani?ke i toplinske energije naziva se kogeneracija. Suvremeni motori omogu?uju promjenu vremena ubrizgavanja te otvaranja ispu?nog ventila ?to rezultira fleksibilno??u u eksploataciji. U radu je prikazan ra?unalno-simulacijski model sporokretnog brodskog motora. Izra?unata je raspolo?iva toplinska energija ispu?nih plinova za pogon izmjenjiva?a topline. Variran je trenutak po?etka ubrizgavanja goriva te trenutak otvaranja ispu?nog ventila. Analizirano je kako ovi parametri utje?u na snagu, specifi?nu potro?nju, iskoristivost motora, na temperaturu ispu?nih plinova, na koli?inu topline u ispu?nim plinovima koju je mogu?e iskoristiti, na ukupni stupanj djelovanja sustava te na omjer mehani?ke i toplinske energije.%The low-speed marine diesel engine is the most effective of all the ship propulsion systems. On every ship there is a need for thermal energy besides mechanical power to drive the propeller. It is possible to install a heat exchanger in the exhaust system that makes use of waste heat of the exhaust gasses of the diesel engine. Such a combined mechanical and thermal energy generation is called cogeneration. Modern engines allow the variation of the fuel injection timing and the variation of the exhaust valve timing, which results in a great usage flexibility. In the current work a computer simulation model of a low-speed marine diesel engine is presented. The exhaust gas heat energy available to power a heat exchanger was calculated. The time of the beginning of fuel injection and the time of the opening of the exhaust valve was varied. It was analyzed how these parameters influence the power, the fuel consumption, the engine efficiency, the exhaust gas temperature, the heat energy available in the exhaust gasses, the overall efficiency of the cogeneration system, and the power to heat ratio.