• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1427-1433
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• 2019

In this paper, Gas engine was tested for the energy of synthesis gas. As excess air ratio increase 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 in 1800 rpm and synthesis gas, thermal efficiency generally decrease and power generation was 34 kWm at λ 1.4. And excess air ratio increase 1, 1.1, 1.2, 1.3, 1.4 in power generation 34 kWm, thermal efficiency generally increase 34.2%, 36.9%, 37.2%, 37.4%, 38.1%. Total efficiency through power generation consumes 38.7 kg/h of fuel at 30 kWe load and recovers 57.3% of waste heat by recovering 57.3 kW of waste heat through 32.1% power generation efficiency and heat recovery from cooling water and exhaust gas. The total efficiency was 85.8%.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.835-842
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• 2009

The present thesis carried out a research on a compression pressure's reduction phenomenon and its countermeasure according to the thermal efficiency improvement method by a Miller method in 4-cycle low speed diesel engine. In case of retardation of intake valve closing time in a engine, the theoretical heat efficiency shows a remarkably reducing trend when a compression ratio is not compensated. Accordingly, the thermal efficiency showed an increasing trend in case of compensating the compression ratio. Especially, it could be understood that the theoretical heat efficiency at near ABDC $100^{\circ}$ of intake valve closing time in case of compensation of the compression ratio was improved by around 25.1%, and the mean effective pressure was also increased by around 18.6%. Also, as the retardation of intake valve closing time increases, air quantity becomes insufficient due to a backflow phenomenon of intake air and thus thermal efficiency was decreased in a high load operation domain. The solving method of this problem is possible by supercharge. Therefore, in order to improve thermal efficiency by retardation of ntake valve closing time, the thermal efficiency improvement according to low compression is possible when there are a compensation device of a compression ratio and a supercharge device. This is a problem-solving method of low compression and high expansion cycle.