| Total flow screw expander is known as a kind of high efficiency, lowcost, safe and none pollution expansion power machine. It is thought of thenew pattern of energy utilization different from traditional turbine in thearea of advanced energy technologies in21st century. At present,effectiveness of total flow screw expander has been validated in the area ofgeothermal generation of our country. Two total flow screw expandergenerators which were developed, designed and manufactured by JiangxiHuadian Company have already been put into trial operation in YangyiTibet separately on September2011and August2012. Two phase flow isone of the key problems of screw expander. The research has significancefor improving energy utilization rate of screw expander. This articlefocused on mathematical modeling, theoretical calculation analysis for thethermodynamic properties of gas-liquid flow type in two phase flow andmade improvement for total flow power generation system with screwexpander aiming at improving the utilization efficiency of total flowsystem.Firstly, a thermodynamic model of the screw expander was built inthis article. With the first and second law of thermodynamic, this articletheoretically analyzed gas-liquid two phase flow expansion to work in themodel of screw expander. In the working process, the temperature,pressure and dryness of the working fluid changed. The power producedby gas-liquid and the work efficiency of screw expander were derive. Secondly, the influence factors on the screw expander efficiency wereanalyzed theoretically according to the basic principles of fluid mechanics,such as the leakage loss and the power loss. Leakage loss is mainly due tothe clearance between the rotor and the casing and between the rotors. Thepower loss is mainly due to the channel and the fluid itself which reflectsin the frictional resistance loss. This article discussed the analysis methodof leakage loss and power loss and the relationship between losses and thedryness of working fluid.Thirdly, based on the total flow generation system, this articlecombined it with Organic Rankin cycle to realize rundle utilization ofenergy. At the same time, Organic Rankin cycle used refrigerant organicworking fluid to effectively overcome the limit of screw expanderexpansion ratio.At last, performance calculation of the total flow system with ORCwas conducted according to the actual operation parameters in Yangyigeothermal power plant in Tibet. Comparison was made between the totalflow system with ORC and traditional double flash system. Exergy lossesof total flow system with ORC were analyzed.The research results of this article lay a theoretical foundation for theoptimization of screw expander and total flow system for two phase flow.The research has important value and practical significance to promote thedevelopment of new energy, the energy saving and emission reductionwork. |
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