Tham khảo tài liệu 'gas turbine engineering handbook 2 episode 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Compressor and Turbine Performance Characteristics 135 be when the turbine s automatic controls took over. These controls are actuated by the exhaust temperature. Figure 3-16 shows the effect of efficiency as a function of the load for both the compressor and turbine. Part-load turbine efficiencies are affected more than compressor efficiencies. The discrepancy results from the compressor operating at a relatively constant inlet temperature pressure and pressure ratio while the turbine inlet temperature is greatly varied Figure 3-17 . Figure 3-16. Compressor and turbine efficiency as a function of load. load in kWh Figure 3-17. Turbine inlet temperature as a function of turbine load. 136 Gas Turbine Engineering Handbook The turbine pressure ratio however remains relatively constant. The backpressure on the turbine was measured at a relatively constant value of inches Hg abs Bar . This value creates about a 9-inch H2O 228 mm H2O back-pressure on the turbine. The efficiency of the compressor is based on the following equation T 1 h ------ A Tact 3-43 where Tn inlet temperature pt2 pressure at compressor outlet Pn pressure at compressor inlet ATact actual temperature rise in the compressor 7 specific heat ratio average value between inlet and outlet temperature was used The turbine efficiency calculation is more complex. The first part is the calculation of the turbine inlet temperature. The calculation is based on the following equation macp2Tt2 nbmf LHV natural gas ---------- 7-7 7-7-------------- 3-44 cí3cí3 rá m a where Tt2 temperature at the outlet of the compressor Cp specific heat at constant pressure mf mass flow rate for the fuel ma mass flow rate of the air combustion efficiency LHV lower heating value of the natural gas supplied 950Btu cu ft 35 426 kJ cu m and specific gravity Compressor and Turbine Performance Characteristics 137 The mass flow value of the air was obtained by measuring the flow at the inlet of the gas turbine using an .
