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Improving the Energy Efficiency of Petrochemical Plant Operations: A Measurement and Verification Case Study Using a Balanced Wave Optimizer
Get PDFThe Chinese petrochemical industry is facing pressure to meet strict targets of energy consumption and carbon emission reductions. Water pumps are the primary equipment used in most chemical and agrochemical industries sectors since water is commonly used for cooling and heating purposes, but these pumps also consume a large amount of energy. Other uses of water pumps in these industries include producing steam for heating, preparing reaction media or absorptive reagents, rinsing products, and distilling. As for the electrical components of the water pump systems, current technologies of variable frequency drives and superconducting transmission lines are unable to increase the energy efficiency of these systems with a fixed load. However, the Balanced Wave Technology (BWT) is offered as a solution to overcome these limitations. In this report, a case study using a BWT optimizer is conducted on a closed loop water circulation system. Two BWTs are added to the individual motor-controlled section of each pump that is being used on the switchboard. For the first time, a detailed example was provided on how to implement option B of the International Performance Measurement and Verification Protocol (IPMVP) in China by evaluating the performance of BWT as an energy conservation measure. The evaluated periods included those of the baseline, post-installation, and actual performance of the optimizers. An average saving of energy of about 10.46% is recorded in a 5-week reporting period. On this basis, that annual electricity saved is estimated to be 66,447.18 kWh, which is equivalent to the emission of 68.94 metric tons of CO2e. This case study demonstrates in detail how option B of IPMVP can be implemented for BWTs applied on pumping systems. In addition to petrochemical production plants, other industries like textile and clothing sections, which are heavy users of water and electrical energy with fixed loads in the production processes of raw materials, fiber, yarn, and fabric, as well as textile-dyeing and final treatment, could benefit from applying this new technology
Effect of limited tension stiffening in RC elements under cyclic loads.
No full textThe tension capacity in cracked concrete is not well defined in existing shear models for reinforced concrete (RC) membrane elements under cyclic reversed loading, and the shear strength of RC elements is consequently overestimated due to the deviated decreasing branch of envelope of cyclic tensile stress-strain relationship. In this paper, the cyclic effect of limited tension stiffening of cracked RC elements is evaluated by proposing an analytical model named as the cyclic tension-stiffening fixed-angle truss model (CTFTM). The proposed model, based on fixed-angle theory, integrates unloading and reloading rules and accumulated damage into the limited tension-stiffening effect under cyclic loading and considers the consequent local stress variation at crack surface. The cyclic effect of limited tension stiffening of RC elements is verified by comparing with experimental results in the literature. The predictions show good agreement, and the effect of biaxial loading is also examined
Effects of eccentricity on seismic behavior of non-seismically designed reinforced concrete beam-column joint
Get PDFThe staggering numbers of eccentric reinforced concrete beam-column joints without seismic design details were used in existing RC frame building due to geometrical constraints, which implied high susceptibility of the building structures to anticipated seismic risk. Three exterior RC beam-column joints were fabricated and tested, which were applied reversed cyclic loads to simulate seismic action. In this study, the effects of stirrup ratio in joints and the eccentricity which is defined as the distance between the axis of the beam and column on seismic performance are investigated. The test results provide a further understanding of the failure mode and shear strength of exterior beam-column joints. It is shown that the eccentricity will significantly reduce the seismic performance and shear strength of the joints, which will cause the brittle failure of frame buildings, while the stirrups in the joint core can improve the seismic performance. To verify the availability of current codes in predicting the shear strength of eccentric beam-column joints with non-seismic detailed, the experimental results are compared with the predicted shear force of two nonseismic codes (HK code and Eurocode 2) and three seismic codes (Eurocode 8, NZS 3101 and ACI 318-14). The comparison results indicate that the existing non-seismic and seismic design codes of practice do not predict the shear strength of the exterior non-seismically designed joints precisely
A Review on High Catalytic Efficiency of Solid Acid Catalysts for Lignin Valorization
No full textIt is imminent to develop renewable resources to replace fossil-derived energies as fossil resources are on the brink of exhaustion. Lignin is one of the major components of lignocellulosic biomass, which is a natural amorphous three-dimensional polymer with abundant C-O bonds and aromatic structure. Hence, valorization of lignin into high value-added liquid fuels and chemicals is regarded as a promising strategy to mitigate fossil resource shortages. Solid acid catalysts are extensively studied due to environmentally friendly in terms of the ease of separation, recovery and reduced amount of wastes. Hence, this review focuses on summarizing the recent progress of catalytic valorization of lignin over different kinds of solid acid catalysts including zeolites, heteropolyacids, metal oxides, amorphous SiO2-Al2O3, metal phosphates, and Lewis acid. Based on reviewing of current progress of lignin conversion, the challenges and future prospects are emphasized
Micro/nanostructured MnCo2O4.5 anodes with high reversible capacity and excellent rate capability for next generation lithium-ion batteries
No full textLithium-ion batteries have already achieved great success in consumer electronics. However, the electrochemical characteristics of the existing electrodes have constrained their widespread applications in electric vehicles, which need technical demands of high energy density and fast charging. Thus, it is highly desirable to explore high-performance electrodes with high reversible capacity and excellent rate capability. In this study, micro/nanostructured MnCo2O4.5 anodes were synthesized by hydrothermal treatment with the presence of positively charged poly(diallyldimethylammonium chloride). Physicochemical property studies suggested that the as-prepared MnCo2O4.5 of 2–5 µm in diameter was mainly composed of numerous nanoneedles, which were further comprised of many inter-connected nanoparticles. Also, poly(diallyldimethylammonium chloride) played the key roles as morphology controlling agent for the formation of the unusual MnCo2O4.5 crystal phase. The unique properties of micro/nanostructured MnCo2O4.5 including multi-scale dimensions, mesoporous structure, and multivalent states guaranteed the superior electrochemical characteristics in the repeated charge-discharge cycles. When evaluated as anodes for electrochemical lithium storage, high reversible capacity and good cycling performance were demonstrated with a current density of 500 mA g−1 over 200 cycles. Even when tested at relatively high current densities of 1000, 2000 and 3000 mA g−1, the average reversible capacities were also achieved at about 1441, 1213 and 966 mAh g−1, respectively. The achieved electrochemical characteristics of MnCo2O4.5 anodes were proved to be better than many binary transition metal oxides or comparable with high-capacity Si-based anodes. Overall, this study demonstrated micro/nanostructured MnCo2O4.5 as potential high-performance anodes for practical applications of next generation lithium-ion batteries
A novel 3D simulation model for investigating liquid desiccant dehumidification performance based on CFD technology.
No full textPrevious 2D CFD simulation models fail to elaborate the actual simultaneous flow and dehumidification process in liquid desiccant cooling system. Accordingly, the present study successfully developed a novel 3D simulation model for investigating the liquid desiccant dehumidification performance of a falling film dehumidifier. The penetration mass transfer model was implemented in the simulation to account for the interfacial dehumidification process. Experimental system was built for the model validation and the results indicated that the newly developed 3D CFD model could predict the absolute moisture removal accurately with an average deviation of 7%. Parametric study revealed that the dehumidification performance was closely related with air humidity, velocity, solution temperature, centration, temperature and contact angle but seldom affected by air temperature. The simulation results also indicated that falling film of liquid desiccant shrank gradually along the flow direction, leading to an inhomogeneous water vapor absorption process in the dehumidifier. Intense water vapor absorption occurred at the phase interface, resulting in large solution concentration gradient and humidity content in the zone near the air/liquid contact interface. However, minor mass transfer occurred in other zones mainly in the form of diffusion. Accordingly, several heat/mass transfer enhancement approaches, i.e. structural modifications and surface modification, were proposed to improve the flow turbulence and to enlarge the falling film wettability. The newly proposed 3D simulation model and dehumidification enhancement approaches are meaningful for the design and operation of liquid desiccant cooling system
Performance of desiccant enhanced evaporative cooling system based on high-low control
Get PDFDesiccant enhanced evaporative cooling system is a sustainable air-conditioning (A/C) system which deals the latent load and sensible load separately by a dehumidifier and an evaporative cooler. A LDD-RIEC system consists of a liquid desiccant dehumidifier (LDD) and a regenerative indirect evaporative cooler (RIEC) were investigated. The LDD-RIEC system is characterized by low energy consumption compared with conventional mechanical cooling system, but the main shortcoming is the high dependency on ambient air conditions. To maintain stable indoor temperature, a control scheme is essential. However, very limited research work regarding control strategy can be found in open literatures. In this paper, a novel controller named high-low (H-L) control is proposed. Multi-speed technology is utilized for primary air fan and secondary air fan operating either at high speed or at low speed. The annual performance of a LDD-RIEC system is simulated in Hong Kong, a typical hot and humid region. The results indicate that H-L control is effective in maintaining stable indoor thermal comfort with temperature fluctuation from 24 °C to 27 °C for 99% of time
Shaking it up 搖出不一樣的精采
Get PDFMeet the beverage professionals who are mixing things up behind the bar and bringing creative contemporary cocktails - and mocktails - to the table
才華橫溢的調酒大師分享他們的創作之道
Plat Du Jour 名菜解構
Get PDFSignature showcase
示範作
Finnish chef Jaakko Sorsa imbues his creations with a sense of his culinary culture
芬蘭大廚Jaakko Sorsa喜歡在菜式裡融入自己的烹調文
