Performance characteristics of an integrated power generation system combining gas turbine combined cycle,carbon capture and methanation

This study analyzes the performance of an integrated power generation system that combines a gas turbine combined cycle (GTCC) with a methanation process. The methanation process uses hydrogen provided by a power-to-gas (PtG) process and carbon dioxide captured from the exhaust gas of the GTCC. The research aim was to maximize the GTCC performance through an effective integration between the GTCC and methanation. Two methods were proposed to utilize the steam generated from the methanation process. One was to supply it to the steam turbine bottoming cycle of the GTCC, and the other was to inject it into the GT combustor. Also investigated was the injection of oxygen generated in the PtG process into the gas turbine combustor. The largest improvements in the power and efficiency were predicted to be 19.3 % and 4.9 % through the combination of the steam supply to the bottoming cycle and the oxygen injection to the combustor.

     

Behavior characteristics of abrasives for improving surface integrity in magnetic pin polishing

Journal of Mechanical Science and Technology - Since surface finishing is a necessary process to meet various requirements in a manufacturing stage, numerous finishing method have been studied to...     

Assessment of two-parameter mixed models for large eddy simulations of transitional and turbulent flows

In the present study, improved two-parameter mixed models for large eddy simulations are proposed based on previous two-parameter mixed models of Salvetti and Banerjee [1] and Horiuti [2]. The subgrid-scale (SGS) stress in our models is decomposed into the modified Leonard stress, modified cross stress and modified SGS Reynolds stress terms. Although the modified Leonard stress term is explicitly calculated based on the scale-similarity, the modified cross stress term is built using an extension of the filtered Bardina model proposed by Horiuti [3] for better predictions of the interaction between resolved and unresolved scales (i.e., energy exchange). The modified SGS Reynolds stress is modeled by the dynamic Smagorinsky model or by a dynamic global model, leading to two unknown model coefficients for the modified cross stress and the modified SGS Reynolds stress terms. In order to demonstrate the reliability of the proposed SGS models, large eddy simulations of two types of flows (i.e., a fully developed turbulent channel flow and a transitional boundary layer flow) are performed. It is shown that the modified cross stress term makes an important contribution to the accurate predictions of such flows because the emergence of negative SGS dissipation (backward scatter) by the modified cross stress term decreases the excessive positive SGS dissipation (forward scatter). A direct comparison of the turbulent statistics with those from previous SGS models shows that the proposed SGS models result in better prediction performance both in transitional and turbulent flows.

     

A study on an equivalent model of the threaded fasteners in complex structures through tightening and loosening analysis

Journal of Mechanical Science and Technology - The threaded fasteners are typical machine components in tightening of the machine parts and structures. In addition, as threaded fasteners are easy...     

Reduction of flow-induced noise in a household air purifier

Journal of Mechanical Science and Technology - In this study, we propose a design for a household air purifier that reduces the flow-induced noise caused by the impeller of the fan system. The...     

Effects of process parameters on the high temperature strength of 17-4PH stainless steel produced by selective laser melting

Journal of Mechanical Science and Technology - In this study, the effects of process parameters on the high temperature strength of 17-4PH stainless steel manufactured by selective laser melting...     

采用金属推带无级变速器换档控制改进燃油经济性

推荐采用CVT换档速度控制的一种算法来改进金属推块无级变速器车辆的燃油经济性.重新调整CVT换档动力学方程式,可以找到CVT换档速度与工作油压以及初始油压有关,绘制换档速度图估算工作油压对换档速度的影响,以求出换档速度为目标,提出工作油压计算的一种算法.为了估算换档速度和液体的损耗,采用考虑CVT换档动力学的试验证实求得工作油压控制阀和比例控制阀的动力学模型.根据仿真的结果,尽管由于工作压力增加液体损失增加,发觉燃油经济改进为2%.     

The technology combined electrochemical mechanical polishing

Electrochemical mechanical polishing (ECMP) is a polishing process combining electrochemical and mechanical action. It has higher efficiency and better quality.

Mechanism, processing regulation and application are introduced in the paper.     

The influence of titanium on the electrochemical properties of the AB5-type metal hydrides

AB₅-type intermetallic compounds were prepared by arc-melting in argon atmosphere. The composition of a stoichiometric compound LaNi_3.6Al_0.4Co_0.7Mn_0.3 with a hexagonal CaCu₅ structure was varied by stoichiometric and nonstoichiometric addition of Ti. With the increase of the Ti y0.05 content in LaNi_3.6Al_0.4Co_0.7Mn_0.3Ti_y, the hydrogen storage capacity is enhanced, whereas when y=0.1–0.3, it is decreased. The discharge capacity and cyclability are increased considerably by addition of titanium in the range of 0.02–0.1 with a maximum value at about 0.1%. The highest maximum capacity is achieved for a nonstoichiometric addition of 0.05% Ti. The kinetic properties are also additionally improved by the formation of a titanium-rich second phase. This can explain the improvement of the capacity for alloys with low Ti content. The decrease in capacity for high Ti content was also correlated with the amount of the Ti-rich phase. Therefore, the improvement of kinetics are due to the catalytic effect, grain boundary diffusion effect or more pronounced alloy pulverization upon cycling. This study has been aimed to improve the electrode properties of a series of multicomponent LaNi_3.6Al_0.4Co_0.7Mn_0.3Ti_y (y=0.0, 0.02, 0.05, 0.1, 0.2, 0.3) alloys which have mutual complementary properties. All the prepared alloys have been subjected to analyses by EDS, SEM and XRD. In order to determine the hydrogen storage capacity, the pressure composition isotherms (P–C–T curves) have been used. The metal hydride electrodes were characterized by galvanostatic cycling test.     

The effect of compaction temperature and pressure on the pores in nanostructured metal compacts prepared by magnetic pulsed compaction

The pore behavior of nano Al compacts prepared by magnetic pulsed compaction in a temperature range from 20°C to 300°C and under pressure of 0.7 and 1.6 GPa was studied by small angle neutron scattering (SANS) analysis. The size distribution and volume fraction of pores in the compact were determined by corrected scattering curves using a direct model fitting, under the assumption that the pores were spherical in shape. The densities obtained from the SANS analysis were well matched with those of direct measurement in the range of 76–95% of theoretical density. As the compaction temperature increased from 20°C to 300°C, the size of pores increased from 1.69 to 2.31 nm; however, the number of pores decreased from 169 to 71 (1/cmŲ) in the case of 1.6 GPa compaction pressure. As a result, the density increased as the compaction temperature increased.