Low Output Range Research Articles

Performanc Investigation of a 500W Stirling Engine for Solar Powor System

Aiming at reduction of the energy consumed in domestic and business use, research of an energy system corresponding to ZEB/ZEH (Zero Energy Building/House) is advanced. The authors are developing a hybrid heat source Stirling engine ぽ power generation and heat supply system, which uses solar and woody biomass as heat source. This paper describes the 500W Stirling engine generator installed in a basic solar power generation system only with solar energy. The system has a solar tracking type collector which is made by the Fresnel lens. The performance test in low output range was conducted for testing the solar power generation system. From the test results, it's clear that indicated powers and an electric output increase with a rise of engine speed and also they are proportional to the working gas mean pressure.

Performance and Exhaust Emissions in a Natural-Gas Fueled Dual-Fuel Engine

In order to establish the optimum fueling in a natural gas fueled dual fuel engine, experiments were done for some operational parameters on the engine performances and the exhaust emissions. The results show that the pilot fuel quantity should be increased and its injection timing should be advanced to suppress unburned hydrocarbon emission in the middle and low output range, while the quantity should be reduced and the timing retarded to avoid onset of knock at high loads. Unburned hydrocarbon emission and thermal efficiency are improved by avoiding too lean natural gas mixture by restricting intake charge air. However, the improvement is limited because the ignition of pilot fuel deteriorates with excessive throttling. It is concluded that an adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation.

Performance and Exhaust Emissions in a Natural-Gas Fueled Dual-Fuel Engine.

In order to establish the optimum fueling in a natural gas fueled dual fuel engine, tests were made for some operational parameters and their combination on the engine performances and the exhaust emissions. The results show that the gas oil quantity should be increased and gas oil injection timing should be advanced to suppress unburned hydrocarbon emission at middle and low output range, while the quantity should be reduced and the timing should be retarded to avoid onset of knock at high loads. The unburned hydrocarbon emission and the thermal efficiency are improved at the same load avoiding too lean natural gas premixture by restriction of intake charge air. However the improvement is limited because the ignition and initial combustion of pilot diesel fuel is deteriorated when the cylinder pressure is excessively lowered by throttling. The increase in pilot gas oil amount is effective for low-load operation and the adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation.

新DK型ディーゼル機関の気筒数展開によるシリーズ化

The new DK series engines are developed as the next generation of engines, with 5 common concepts: environmental protection, high output with smaller engine size, high efficiency, reduction in maintenance and running cost, and increase in reliability and durability.Other than the in-line 6 and 8 cylinder types, the DK-20 model comes with 3 and 5 cylinders, and the DK 26 model with a 5 cylinder type. Development of various cylinder number types within the same model allows the new DK series to cover a wide range of output with a small engine model lineup.With the development of 3DK-20, the low output range that had been covered by high revolution engine running on marine diesel oil can now be covered by engine running on heavy diesel oil. Also, when looking at parts around the piston area, a 3 cylinder engine effectively halves the parts number compared to 6 cylinder engines with the same output. This achieves great reduction inrunning cost and maintenance costs.The follwing will introduce the new DK series engines, with details on design, performance, and benefits.