A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature rang...A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.展开更多
The present paper introduces a new concept for passive turbine tip-leakage control. The basic idea of the method is the connection of the blade leading edge and the blade tip by an internal channel. Due to the differe...The present paper introduces a new concept for passive turbine tip-leakage control. The basic idea of the method is the connection of the blade leading edge and the blade tip by an internal channel. Due to the difference between the stagnation pressure at the leading edge and the low pressure at the blade tip, a small amount of the working fluid is extracted from the blade passage. At the blade tip, a jet is injected roughly perpendicular to the tip gap flow driven by the blade pressure difference. It is proposed that the jet blocks at least a part of the tip gap flow. Since the tip-leakage losses are proportional to the tip gap mass flow rate, the tip injection results in a reduction of the associated losses. After the introduction of the concept, an analytical model is presented which describes the reduction of the tip gap discharge coefficient due to the tip injection. Furthermore, the analytical model is supported by the results of a preliminary CFD analysis. Finally, the potential of the efficiency improvement by the passive blade tip injection method is reported.展开更多
文摘A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.
文摘The present paper introduces a new concept for passive turbine tip-leakage control. The basic idea of the method is the connection of the blade leading edge and the blade tip by an internal channel. Due to the difference between the stagnation pressure at the leading edge and the low pressure at the blade tip, a small amount of the working fluid is extracted from the blade passage. At the blade tip, a jet is injected roughly perpendicular to the tip gap flow driven by the blade pressure difference. It is proposed that the jet blocks at least a part of the tip gap flow. Since the tip-leakage losses are proportional to the tip gap mass flow rate, the tip injection results in a reduction of the associated losses. After the introduction of the concept, an analytical model is presented which describes the reduction of the tip gap discharge coefficient due to the tip injection. Furthermore, the analytical model is supported by the results of a preliminary CFD analysis. Finally, the potential of the efficiency improvement by the passive blade tip injection method is reported.
