Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry＇s viability. At present, outboard petrol engines are the p...Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry＇s viability. At present, outboard petrol engines are the preferred choice for use in small-scale fishing boats because they deliver the advantages of high speed and low weight, they are easy to install, and they use minimal space. Petrol outboard engines are known to consume a greater amount of fuel than inboard diesel engines, but installing diesel engines with conventional submerged propellers in existing small-scale fishing boats is not economically viable because major hullform modifications and extra expenditure are required to achieve this. This study describes a proposal to enable reductions in fuel consumption by introducing the combined use of a diesel engine and Surface-Piercing Propeller （SPP）. An analysis of fuel consumption reduction is presented, together with an economic feasibility study. Resulting data reveal that the use of the proposed modifications would save 23.31 liters of fuel per trip （40.75%） compared to outboard motors, equaling annual savings of RM 3962 per year.展开更多
As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was...As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a CFD(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the CFD model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.展开更多
There is a high potential for small-scale and medium scale wood-fired cogeneration in Estonia. The purpose of this research is to define the eligible capacity for wood fuel based cogeneration plant operating on the ba...There is a high potential for small-scale and medium scale wood-fired cogeneration in Estonia. The purpose of this research is to define the eligible capacity for wood fuel based cogeneration plant operating on the base of district heating systems in small towns. Results were checked and approbated by economical and environmental factors. Two optimal sizing methods were used maximizing of amount of heat year-round while working at full installed capacity and maximizing of amount of heat year-round while working with partial loads. Results of defining optimal capacities for wood-fired cogeneration plants in small Estonian towns showed that method of maximizing of amount of heat year-round while working with partial loads is more adequate to real situation.展开更多
文摘Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry＇s viability. At present, outboard petrol engines are the preferred choice for use in small-scale fishing boats because they deliver the advantages of high speed and low weight, they are easy to install, and they use minimal space. Petrol outboard engines are known to consume a greater amount of fuel than inboard diesel engines, but installing diesel engines with conventional submerged propellers in existing small-scale fishing boats is not economically viable because major hullform modifications and extra expenditure are required to achieve this. This study describes a proposal to enable reductions in fuel consumption by introducing the combined use of a diesel engine and Surface-Piercing Propeller （SPP）. An analysis of fuel consumption reduction is presented, together with an economic feasibility study. Resulting data reveal that the use of the proposed modifications would save 23.31 liters of fuel per trip （40.75%） compared to outboard motors, equaling annual savings of RM 3962 per year.
基金Projects(51475464,51175500) supported by the National Natural Science Foundation of China
文摘As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a CFD(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the CFD model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.
文摘There is a high potential for small-scale and medium scale wood-fired cogeneration in Estonia. The purpose of this research is to define the eligible capacity for wood fuel based cogeneration plant operating on the base of district heating systems in small towns. Results were checked and approbated by economical and environmental factors. Two optimal sizing methods were used maximizing of amount of heat year-round while working at full installed capacity and maximizing of amount of heat year-round while working with partial loads. Results of defining optimal capacities for wood-fired cogeneration plants in small Estonian towns showed that method of maximizing of amount of heat year-round while working with partial loads is more adequate to real situation.
