A techno-economic analysis of partial repowering of a 210 MW coal fired power plant

Samanta, Samiran,Ghosh, Sudip Techno-Press 2015 Advances in energy research Vol.3 No.3

This paper presents a techno-economic analysis of a partial repowering scheme for an existing 210 MW coal fired power plant by integrating a gas turbine and by employing waste heat recovery. In this repowering scheme, one of the four operating coal mills is taken out and a new natural gas fired gas turbine (GT) block is considered to be integrated, whose exhaust is fed to the furnace of the existing boiler. Feedwater heating is proposed through the utilization of waste heat of the boiler exhaust gas. From the thermodynamic analysis it is seen that the proposed repowering scheme helps to increase the plant capacity by about 28% and the overall efficiency by 27%. It also results in 21% reduction in the plant heat rate and 29% reduction in the specific $CO_2$ emissions. The economic analysis reveals that the partial repowering scheme is cost effective resulting in a reduction of the unit cost of electricity (UCOE) by 8.4%. The economic analysis further shows that the UCOE of the repowered plant is lower than that of a new green-field power plant of similar capacity.

Effects of Constrained Groove Pressing (CGP) on the plane stress fracture toughness of pure copper

Mohammadi, Bijan,Tavoli, Marzieh,Djavanroodi, Faramarz Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

Among severe plastic deformation methods, groove pressing is one of the prominent techniques for producing ultra-fine grained sheet materials. This process consists of imposing repetitive severe plastic deformation on the plate or sheet metals through alternate pressing. In the current study, a 2 mm pure Cu sheet has been subjected to repetitive shear deformation up to two passes. Hardness and tensile yield and ultimate stress were obtained after groove pressing. Fracture toughness tests have been performed and compared for three conditions of sheet material namely as received (initial annealed state), after one and two passes of groove pressing. Results of experiments indicate that a decrease in the values of fracture toughness attains as the number of constrained groove pressing (CGP) passes increase.

Simulation of tissue differentiation around acetabular cups: the effects of implant-bone relative displacement and polar gap

Mukherjee, Kaushik,Gupta, Sanjay Techno-Press 2014 Advances in biomechanics & applications Vol.1 No.2

Peri-acetabular bone ingrowth plays a crucial role in long-term stability of press-fit acetabular cups. A poor bone ingrowth often results in increased cup migration, leading to aseptic loosening of the implant. The rate of peri-prosthetic bone formation is also affected by the polar gap that may be introduced during implantation. Applying a mechano-regulatory tissue differentiation algorithm on a two-dimensional plane strain microscale model, representing implant-bone interface, the objectives of the study are to gain an insight into the process of peri-prosthetic tissue differentiation and to investigate its relationship with implant-bone relative displacement and size of the polar gap. Implant-bone relative displacement was found to have a considerable influence on bone healing and peri-acetabular bone ingrowth. An increase in implant-bone relative displacement from $20{\mu}m$ to $100{\mu}m$ resulted in an increase in fibrous tissue formation from 22% to 60% and reduction in bone formation from 70% to 38% within the polar gap. The increase in fibrous tissue formation and subsequent decrease in bone formation leads to weakening of the implant-bone interface strength. In comparison, the effect of polar gap on bone healing and peri-acetabular bone ingrowth was less pronounced. Polar gap up to 5 mm was found to be progressively filled with bone under favourable implant-bone relative displacements of $20{\mu}m$ along tangential and $20{\mu}m$ along normal directions. However, the average Young's modulus of the newly formed tissue layer reduced from 2200 MPa to 1200 MPa with an increase in polar gap from 0.5 mm to 5 mm, suggesting the formation of a low strength tissue for increased polar gap. Based on this study, it may be concluded that a polar gap less than 0.5 mm seems favourable for an increase in strength of the implant-bone interface.

Measurement and prediction of geometric imperfections in structural stainless steel members

Cruise, R.B.,Gardner, L. Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.1

Geometric imperfections have an important influence on the buckling response of structural components. This paper describes an experimental technique for determining imperfections in long (5.7 m) structural members using a series of overlapping measurements. Measurements were performed on 31 austenitic stainless steel sections formed from three different production routes: hot-rolling, cold-rolling and press-braking. Spectral analysis was carried out on the imperfections to obtain information on the periodic nature of the profiles. Two series were used to model the profile firstly the orthogonal cosine and sine functions in a classic Fourier transform and secondly a half sine series. Results were compared to the relevant tolerance standards. Simple predictive tools for both local and global imperfections have been developed to enable representative geometric imperfections to be incorporated into numerical models and design methods.

Techno-economic design of a grid-tied Photovoltaic system for a residential building

Asad A. Naqvi,Talha Bin Nadeem,Ahsan Ahmed,Muhammad Uzair,S. Asad Ali Zaidi Techno-Press 2022 Advances in energy research Vol.8 No.1

Increasing cost of electricity due to rising price of fuel is one of the local community's main issues. In this research, switching of grid dependent system to the grid-tied Photovoltaic (PV) system with net metering for a residential building is proposed. The system is designed by considering the maximum energy demand of the building. The designed system is analyzed using RETScreen on technical, economic and environmental grounds. It is found that the system is able to produce 12,000 kWh/year. The system is capable to fulfill the electricity demand of the building during day time and is also capable to sell the energy to the local grid causing the electric meter to run in reverse direction. During night time, electricity will be purchased from grid, and electric meter will run in the forward direction. The system is economically justified with a payback period of only 3 years with net present value of PKR. 4,758,132. Also, the system is able to reduce 7.2 tons of CO₂ not produced in the entire life of the project.

Ultra-robust bonding between MXene nanosheets and stretchable, self-healable microfibers

Shin, Yoo Bin,Kim, Youngmin,Kang, Chang Goo,Oh, Jung-Min,Kim, Jong-Woong Techno-Press 2021 Advances in nano research Vol.11 No.5

To develop a reliable fibrous device, a strong bond between conducting materials and fibers must be ensured. While the external surface of the film is relatively flat, making it easy to deposit the electrode materials uniformly, the walls of the polymer fibers inside the porous film pose a greater challenge for ensuring a uniform coating and robust bonding with electrode material. Herein, a microfibril-based porous film was prepared by electrospinning polybutadiene-based urethane (PBU), a newly synthesized self-healing polymer, and Ti₃C₂-based MXene nanosheets were coated thereon to fabricate a pressure sensor whose resistance decreases with pressure. The PBU microfibrils were crosslinked under mild conditions via Diels-Alder (DA) reaction by exploiting low activation energy of the PBU. An exceptionally robust bonding between the PBU and MXene was enabled by subjecting the PBU to a retro-DA and subsequent DA reactions. The temporary increase in surface fluidity of the PBU leaded to a conformal contact between the MXene and fibers without collapse of fibrous structure, resulting in an ultra-robust bond between them. A stretchable and self-healable pressure sensor was implemented by removing unnecessary MXenes by applying ultrasonic energy to the thus-fabricated sample. The fabricated sensor showed a pressure sensitivity of around 27.9 /kPa for a wide range of pressure which is the highest level among the reported stretchable self-healing pressure sensors, while maintaining its performance even after 1000 cycles of stretching and pressing. Further, sensors attached around the carotid artery could be used to precisely detect P-, T-, and D-waves arising from blood pressure.

Testing and evaluation of the corrosion behavior of Aluminum/Alumina bulk composites fabricated via combined stir casting and APB process

Abdalkareem Jasim,Ghassan Fadhil Smaisim,Abduladheem Turki Jalil,Surendar Aravindhan,Abdullah Hasan Jabbar,Shaymaa Abed Hussein,Muneam Hussein Ali,Muataz S. Alhassan,Yasser Fakri Mustafa Techno-Press 2023 Advances in materials research Vol.12 No.4

In this study, AA1060/Alumina composites were fabricated by combined stir casting and accumulative press bonding (APB). The APB process was repeated up to six press bonding steps at 300Ċ. As the novelty, potential dynamic polarization in 3.5Wt% NaCl solution was used to study the corrosion properties of these composites. The corrosion behavior of these samples was compared and studied with that of the annealed aluminum alloy 1060 and versus the number of APB steps. So, as a result of enhancing influence on the number of APB process, this experimental investigation showed a significant enhancement in the main electrochemical parameters and the inert character of the Alumina particles. Together with Reducing the active zones of the material surfaces could delay the corrosion process. Also, at higher number of steps, the corrosion resistance of composites improved. The sample produced after six number of steps had a low corrosion density in comparison with high corrosion density of annealed specimens. Also, the scanning electron microscopy (SEM), was used to study the corrosion surface of samples.

CFD Simulation of NACA 2412 airfoil with new cavity shapes

Merryisha, Samuel,Rajendran, Parvathy,Khan, Sher Afghan Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.2

The paper presents the surface-modified NACA 2412 airfoil performance with variable cavity characteristics such as size, shape and orientation, by numerically investigated with the pre-validation study. The study attempts to improve the airfoil aerodynamic performance at 30 m/s with a variable angle of attack (AOA) ranging from 0° to 20° under Reynolds number (R_e) 4.4×10⁵. Through passive surface control techniques, a boundary layer control strategy has been enhanced to improve flow performance. An intense background survey has been carried out over the modifier orientation, shape, and numbers to differentiate the sub-critical and post-critical flow regimes. The wall-bounded flows along with its governing equations are investigated using Reynolds Average Navier Strokes (RANS) solver coupled with one-equational transport Spalart Allmaras model. It was observed that the aerodynamic efficiency of cavity airfoil had been improved by enhancing maximum lift to drag ratio ((l/d) max) with delayed flow separation by keeping the flow attached beyond 0.25C even at a higher angle of attack. Detailed investigation on the cavity distribution pattern reveals that cavity depth and width are essential in degrading the early flow separation characteristics. In this study, overall general performance comparison, all the cavity airfoil models have delayed stalling compared to the original airfoil.

Eigenfrequencies of advanced composite plates using an efficient hybrid quasi-3D shear deformation theory

Guerroudj, Hicham Zakaria,Yeghnem, Redha,Kaci, Abdelhakim,Zaoui, Fatima Zohra,Benyoucef, Samir,Tounsi, Abdelouahed Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.1

This research investigates the free vibration analysis of advanced composite plates such as functionally graded plates (FGPs) resting on a two-parameter elastic foundations using a hybrid quasi-3D (trigonometric as well as polynomial) higher-order shear deformation theory (HSDT). This present theory, which does not require shear correction factor, accounts for shear deformation and thickness stretching effects by a sinusoidal and parabolic variation of all displacements across the thickness. Governing equations of motion for FGM plates are derived from Hamilton's principle. The closed form solutions are obtained by using Navier technique, and natural frequencies are found, for simply supported plates, by solving the results of eigenvalue problems. The accuracy of the present method is verified by comparing the obtained results with First-order shear deformation theory, and other predicted by quasi-3D higher-order shear deformation theories. It can be concluded that the proposed theory is efficient and simple in predicting the natural frequencies of functionally graded plates on elastic foundations.

Computer analysis of rarefied aerodynamics around a winged space-plane for Mars entry

Zuppardi, Gennaro,Mongelluzzo, Giuseppe Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.2

The forthcoming use of Orion for Mars landing stimulated Zuppardi to compute global aerodynamic coefficients in rarefied flow along an entry path. Zuppardi and Mongelluzzo also studied Aerodynamics of a blunt cylinder, provided with flapped fins, as a possible alternative to Orion for Mars Entry, Descent and Landing. Computer tests were carried out, in the altitude interval 60-100 km, by three codes: i) home made code computing the entry trajectory, ii) Direct Simulation Monte Carlo code (DS2V), solving 2D/axisymmetric flow field and computing local quantities, iii) Direct Simulation Monte Carlo code (DS3V) solving 3D flow field and computing global aerodynamic coefficients. The comparison of the aerodynamic behaviour of the two capsules in axisymmetric flow field verified that heat flux and wall temperature for the finned-cylinder are higher than those of Orion. The DS3V results verified that Orion is better than the finned-cylinder to produce an aerodynamic force for slowing down the capsule. On the contrary, the results indicated that the finned-cylinder is better in terms of attitude control capability. The purpose of the present paper is to compare Aerodynamics of: Orion, finned-cylinder, a hypothetical, winged space-plane in high altitude Mars entry path. Computations were carried out by means of the two above mentioned DSMC codes, along both orbit and direct entry trajectories. While the global aerodynamic coefficients of the space-plane are comparable with those of the finned cylinder, the aerodynamic and thermal stresses (or pressure, temperature and heat flux) at the nose stagnation point are higher for the space-plane. Therefore, the finned-cylinder seems to be a valid alternative to Orion.