Design And Cfd Analysis Of A 150 Kw 8-Stage Orc-Rot (Organic Rankine Cycle - Radial Outflow Turbine) And Performance Degradation Due To Blade Tip Clearance Of Labyrinth Seal
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Tarih
2018
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Amer Soc Mechanical Engineers
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In this study, blade tip leakages were calculated for a Radial Outflow Turbine (ROT) designed for an Organic Rankine Cycle (ORC) at a 150kW power output. Since the turbine blade sizes are relatively very small for low-capacity systems, the leakages through the blade tip clearances considerably affect the turbine isentropic efficiency. Therefore, labyrinth seals were applied at the blade tips and the ROT's performance degradation due to blade tip leakages was investigated. In order to determine the preliminary ROT sizes, an in-house developed 1-D code was utilized. The blade profiles were optimized with CFD analyses to reach high power output and isentropic efficiency. The designed ROT has 8 stages. Toluene is used as the cycle fluid at inlet conditions of 24bar of total pressure, 310 degrees C and outlet conditions of 0.25bar of static pressure. These conditions are chosen for exhaust conditions of a common biogas engine. Thus, the ORC is supposed to operate at a heat source temperature of 460 degrees C and a heat sink temperature of 35 degrees C. The turbine speed of 14000 rpm is determined. The CFD model for the entire 3-D turbine geometry is built in the FlowVision software. The real gas equation is employed for the compressible flow. The SST turbulent flow model is employed. The CFD model uses transient state and rotating frame approaches. Four blade tip configurations were analyzed. The CFD results reveal the followings. The turbine isentropic efficiency is calculated to be 87.62% for the unshrouded geometry with no clearance, which is an ideal case. For a manufacturable and manageable blade tip clearance of 0.2 mm, the turbine isentropic efficiency is calculated to be 71.03% for the unshrouded geometry. The shrouded geometry with the same clearance increases the efficiency to 74.03%. When a labyrinth seal is applied to the shrouded geometry, the efficiency reaches to 77.03%. The best practice in terms of turbine power output and efficiency is the shrouded geometry with labyrinth seal applications.
Açıklama
ASME Turbo Expo: Turbomachinery Technical Conference and Exposition -- JUN 11-15, 2018 -- Oslo, NORWAY
Dogu, Yahya/0000-0003-0474-2899
Dogu, Yahya/0000-0003-0474-2899
Anahtar Kelimeler
Kaynak
Proceedings Of The Asme Turbo Expo: Turbomachinery Technical Conference And Exposition
WoS Q Değeri
N/A
Scopus Q Değeri
N/A
Cilt
8
Sayı
Künye
closedAccess
