Design a Cooling Pillow to Support a High-Speed Supercritical CO2 Turbine Shaft

2021 ◽  
pp. 117345
Author(s):  
Md. Uddin ◽  
Halim Gurgenci ◽  
Zhiqiang Guan ◽  
Alex Klimenko ◽  
Jun Li ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
High Speed ◽  
Turbine Shaft

An integrated methodology for estimating the remaining useful life of high-speed wind turbine shaft bearings with limited samples

2021 ◽  
Author(s):  
Boualem Merainani ◽  
Sofiane Laddada ◽  
Eric Bechhoefer ◽  
Mohamed Abdessamed Ait Chikh ◽  
Djamel Benazzouz
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Remaining Useful Life ◽  
Integrated Methodology ◽  
Turbine Shaft ◽  
Useful Life

The Analysis and Design of Turbocharger Thrust Bearing

2011 ◽  
Vol 308-310 ◽  
pp. 1333-1336 ◽  
Author(s):  
Li Jun Qiu ◽  
Jia Yang ◽  
Su Ying Xu
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Dynamic Pressure ◽  
Film Structure ◽  
Lubricating Oil ◽  
Axial Position ◽  
Analysis And Design ◽  
Bearing Life ◽  
Bearing Stiffness ◽  
Turbine Shaft

Turbocharger turbine shaft thrust bearing is the role of high-speed rotating turbine to withstand the axial force generated by the turbine shaft and a part of the axial position. Fixed on the intermediate thrust bearing on the two sides and both sides of the ring, respectively, relative sliding. Sliding contact surface produces a condition of dynamic pressure oil film structure and shape of the oil wedge. Bearing the sides of the structural design of the oil wedge slot and forming a design to solve the main content. Bearing thrust bearing stiffness and rotation in the process of stress state and the smooth line is to improve the bearing life. Rotating turbine shaft to ensure the accuracy of key factors. Method of lubricating oil to the oil and oil Xie in the shape and precision bearings to ensure the prerequisite conditions and service life.

An Investigation of Laminar Flame Speed of CH4-O2-CO2 Mixtures

2019 ◽  
Author(s):  
Mattias A. Turner ◽  
Tyler Paschal ◽  
Waruna D. Kulatilaka ◽  
Eric L. Petersen
Keyword(s):  
Supercritical Co2 ◽  
Carbon Capture ◽  
High Speed ◽  
Laminar Flame ◽  
Full Range ◽  
Methane Combustion ◽  
Fuel Combustion ◽  
Flame Speed ◽  
Working Fluid ◽  
Laminar Flame Speed

Abstract The push for lower carbon emissions in power generation has driven interest in methods of carbon capture and sequestration. One such promising method involves the supercritical CO2 (sCO2) power cycle, a system which is powered by oxy-fuel combustion where supercritical carbon dioxide is used as the working fluid. The high CO2 concentration in the combustion products allows for relatively simple extraction of CO2 from the system. Although this is an active field of research, the design of such a combustor requires continued study of oxy-fuel combustion in high levels of CO2 diluent. With that objective in mind, laminar flame experiments were conducted for CH4-O2-CO2 mixtures at one atmosphere and room temperature, where the relative concentrations of O2 and CO2 in the oxidizer mixture were 34.0% and 66.0% by mole, respectively. These concentrations were chosen to ensure the flame would propagate quickly enough to overcome the effects of buoyancy, which were observed to become significant below laminar flame speeds of roughly 15 cm/s. A high-speed chemiluminescence imaging diagnostic was employed in place of the traditional schlieren technique. Laminar flame speed was measured from OH* emission at 306 nm for a full range of equivalence ratios, varying from 15.2 cm/s at 0.7 to 24.8 cm/s at stoichiometric. Additionally, images of OH* chemiluminescence of turbulent CH4-O2-CO2 flames and of quiescent, 5-atm CH4-O2-CO2 flames at stoichiometric concentration are also presented. These experiments provide useful data for validation of chemical kinetics models for oxy-methane combustion in a CO2 diluent, which can be applied to the modeling of oxy-methane combustion for supercritical CO2 power cycles.

Leakage and Rotordynamic Characteristics for Three Types of Annular Gas Seals Operating in Supercritical CO2 Turbomachinery

2021 ◽  
Author(s):  
Zhigang LI ◽  
Zhuocong Li ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Supercritical Co2 ◽  
High Speed ◽  
Dynamic Pressure ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Real Gas Effect ◽  
Nist Database ◽  
Swirl Velocity ◽  
Fluid Properties ◽  
Gas Seals

Abstract This paper presents a comprehensive assessment and comparison on the leakage and rotordynamic performance of three types of annular gas seals for application in a 14 MW supercritical CO2 turbine. These three seals represent the main seal types used in high-speed rotating machines at the balance piston location in efforts to limit internal leakage flow and achieve rotordynamic stability, including a labyrinth seal (LABY), a fully-partitioned pocket damper seal (FPDS), and a hole-pattern seal (HPS). These three seals were designed to have the same sealing clearance and similar axial lengths. To enhance the seal net damping capability at high inlet preswirl condition, a straight swirl brake also was designed and employed at seal entrance for each type seal to reduce the seal inlet pre-swirl velocity. Numerical results of leakage flow rates, rotordynamic force coefficients, cavity dynamic pressure and swirl velocity developments were analyzed and compared for three seal designs at high positive inlet preswirl (in the direction of shaft rotation), using a proposed transient CFD-based perturbation method based on the multiple-frequency elliptical-orbit rotor whirling model and the mesh deformation technique. To take into account of real gas effect with high accuracy, a table look-up procedure based on the NIST database was implemented, using an in-house code, for the fluid properties of CO2 in both supercritical and subcritical conditions.

Computational Fluid Dynamics of a Radial Compressor Operating With Supercritical CO2

2012 ◽  
Author(s):  
Rene Pecnik ◽  
Enrico Rinaldi ◽  
Piero Colonna
Keyword(s):  
Critical Point ◽  
Gas Turbine ◽  
Supercritical Co2 ◽  
High Speed ◽  
Power Plants ◽  
Compressible Flows ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Maximum Pressure

The merit of using supercritical CO2 (scCO2) as the working fluid of a closed Brayton cycle gas turbine is now widely recognized, and the development of this technology is now actively pursued. scCO2 gas turbine power plants are an attractive option for solar, geothermal and nuclear energy conversion. Among the challenges which must be overcome in order to successfully bring the technology to the market, the efficiency of the compressor and turbine operating with the supercritical fluid should be increased as much as possible. High efficiency can be reached by means of sophisticated aerodynamic design, which, compared to other overall efficiency improvements, like cycle maximum pressure and temperature increase, or increase of recuperator effectiveness, does not require an increase in equipment cost, but only an additional effort in research and development. This paper reports a three-dimensional CFD study of a high-speed centrifugal compressor operating with CO2 in the thermodynamic region slightly above the vapor-liquid critical point. The investigated geometry is the compressor impeller tested in the Sandia scCO2 compression loop facility [1]. The fluid dynamic simulations are performed with a fully implicit parallel Reynolds-averaged Navier-Stokes code based on a finite volume formulation on arbitrary polyhedral mesh elements. The CFD code has been validated on test cases which are relevant for this study, see Ref. [2,3]. In order to account for the strongly nonlinear variation of the thermophysical properties of supercritical CO2, the CFD code is coupled with an extensive library for the computation of properties of fluids and mixtures [4]. Among the available models, the one based on reference equations of state for CO2 [5,6] has been selected, as implemented in one of the sub-libraries [7]. A specialized look-up table approach and a meshing technique suited for turbomachinery geometries are also among the novelties introduced in the developed methodology. A detailed evaluation of the CFD results highlights the challenges of numerical studies aimed at the simulation of technically relevant compressible flows occurring close to the liquid-vapor critical point. The data of the obtained flow field are used for a comparison with experiments performed at the Sandia scCO2 compression-loop facility.

Demonstration of Supercritical CO2 Closed Regenerative Brayton Cycle in a Bench Scale Experiment

2012 ◽  
Author(s):  
Motoaki Utamura ◽  
Hiroshi Hasuike ◽  
Kiichiro Ogawa ◽  
Takashi Yamamoto ◽  
Toshihiko Fukushima ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
High Speed ◽  
Flow Instability ◽  
Internal Flow ◽  
Ideal Gas ◽  
Test Facility ◽  
Brayton Cycle ◽  
Bench Scale ◽  
Compressibility Coefficient ◽  
Scale Experiment

Power generation with a supercritical CO2 closed regenerative Brayton cycle has been successfully demonstrated using a bench scale test facility. A set of a centrifugal compressor and a radial inflow turbine of finger top size is driven by a synchronous motor/generator controlled using a high-speed inverter. A 110 W power generating operation is achieved under the operational condition of rotational speed of 1.15kHz, CO2 flow rate of 1.1 kg/s, and respective thermodynamic states (7.5 MPa, 304.6 K) at compressor and (10.6 MPa, 533 K) at turbine inlet. Compressor work reduction owing to real gas effect is experimentally examined. Compressor to turbine work ratio in supercritical liquid like state is measured to be 28% relative to the case of ideal gas. Major loss of power output is identified as rotor windage. It is found the isentropic efficiency depends little on compressibility coefficient. Off design performance of gas turbine working in supercritical state is well predicted by a Meanline program. The CFD analysis on compressor internal flow indicates that the presence of backward flow around the tip region might create a locally depressurized region leading eventually to the onset of flow instability.

Investigation of Magnetic Journal Bearing Instability Issues in Supercritical CO2 Turbomachinery

2019 ◽  
Author(s):  
Dokyu Kim ◽  
SeungJoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
Supercritical Co2 ◽  
High Speed ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Physical Contact ◽  
Analysis Model ◽  
Rotating Shaft ◽  
Power Cycles ◽  
Power Cycle ◽  
Lubrication Performance

Abstract With the increasing emphasis on reducing the CO2 emission while improving power generation efficiency, new power cycles are being developed. One of those promising power cycles is a supercritical CO2 (S-CO2) power cycle. To generate over 10MW electricity with S-CO2 power cycle, a magnetic bearing can be a good option for the hermetic type turbomachinery. However, from several studies on the magnetic bearing, the instability issues under high density fluid and high speed operating conditions were repeatedly mentioned. The instability in the magnetic bearing was observed to be related to the fluid conditions, mostly pressure and density. Because of this issue, the magnetic bearing sometimes cannot maintain enough clearance for the rotor leading to physical contact and consequently damaging the system. Thus, these instability issues should be thoroughly studied and be resolved for the successful and steady operation of the power system. The instability due to fluid force around the rotating shaft can be modeled with the Reynolds lubrication equation. The steady lubrication force analysis model is developed based on this equation. The model results imply that the lubrication performance is quite sensitive to the thermal condition of the CO2 especially density gradient around the shaft. Based on the modeling results, an experimental system is designed to investigate the issue. To study the instability issues experimentally, an impeller of the operating S-CO2 compressor is removed and the discharge line is blocked. Therefore, the main instability factor in this experiment will be the interaction between the rotor and the bearing only. The shaft position can be measured with inductive sensors. The forces exerted from the electromagnet is calculated from the electric current data which is applied by the controller. From these experimental data, the lubrication force is calculated. These results are compared with the analytical lubrication model to verify the model. From this study, it is expected that it will be possible to define the unstable operating conditions and suggest the required magnetic bearing performance for S-CO2 conditions.

An Advanced Turbocharging System for Improved Fuel Efficiency

2007 ◽  
Author(s):  
Edward A. VanDyne ◽  
Michael B. Riley
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Peak Power Output ◽  
Variable Speed ◽  
Natural Gas Engines ◽  
High Speeds ◽  
Turbine Shaft ◽  
Exhaust Energy

Turbochargers provide an efficient method of utilizing exhaust energy to boost intake air pressure for improved engine performance and efficiency. However transient operation requires increased air delivery (via quicker compressor response) to allow more rapid fueling for acceleration in both diesel and natural gas engines. In diesel engines rapid boosting will avoid increased particulates caused by excessive fueling during acceleration. Further, in applications that use either a wastegate, inlet bypass or variable vanes in the turbine to limit boost pressures, the excess energy in the exhaust is thrown away. The SuperTurbo™ (or superturbocharger) can recover much of the wasted energy and return it to the crankshaft, increasing overall efficiency. Woodward has developed a mechanical geartrain connected to the turbine shaft that transmits power through a variable speed hydraulic transmission to the crankshaft of an engine. This combination, a superturbocharger, provides the needed characteristics of (a) recovery of energy at high speed/load operating points (turbocompounding), (b) very rapid acceleration of the turbine shaft during transients (supercharging), (c) elimination of boost limitation devices, and (d) a variable speed hydraulic transmission that will be lower cost than a high-speed, high-power electrical system. While the air requirements are different for diesel and natural gas engines, both have sufficient exhaust energy to drive a turbine beyond the needs of the compressor for much of the performance map. Part load operation may be different as natural gas engines are usually throttled. The choice of a diesel or natural gas application was influenced by the availability of a suitable engine. The first prototype superturbocharger was built and tested on a Mack E7G natural gas engine, replacing the wastegated turbocharger of the stock engine. Preliminary results show fuel economy improvements of almost 6% at high speeds and high loads. In addition the load response of the engine was greatly increased due to the ability to accelerate turbine shaft speed, increasing boost. However there was a peak power output drop due to limitations in boost and imperfect sizing.

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