This paper presents the development of a thermodynamic model to determine the extended operating window of an aluminum cell to enable power modulation. The integration of renewable energy to aluminum production needs to overcome the challenge of narrow operating windows of aluminum cells. The proposed model takes an industrial aluminum cell as a case study to demonstrate how to build the operating window, constrained by the cell design technical limitations. The extended operating window can also be used to estimate the heat exchanger heat rate requirements to enable an aluminum cell to operate under a wide power modulation.
The article illustrates the fluid-dynamic and mechanical analysis of some forms of small-power vertical axis wind turbines, resistant type, whose blades are made of wood and easily workable in a joinery. In particular, a classical-shaped Savonius, a modified two blades Savonius, a three-bladed Savonius and, again, a rotor with three straight blades having a crescentmoon section, were studied. A result of the study, worthy of note, concerns the possibility of greatly reducing the mechanical stresses on the support relatively to the rotor having the last shape. This is very important for its installation near inhabited buildings or even integrated into roofs. Furthermore, the crescent-moon section prototype is able to provide 1 kW power at the nominal wind condition of 12.5 m/s and an annual energy production of 1200-1500 kWh/year, considering a typical urbane site having an average wind speed between 4.5 and 5 m/s.
Experiments are conducted under typical humid ambient conditions of Singapore on an advanced airconditioning system wherein desiccant coated fin-tube heat exchangers (DCFTHX) are retro-fitted within the ducting of a conventional HVAC system with a watercooled condenser. The desiccant is regenerated using room-return air (specific humidity of 0.0109 kg/kg d.a.) and the low-grade heat (warm water at 35.5oC) from the condenser unit. During dehumidification, water from the cooling tower helps in maintaining low air temperature, thereby improving the adsorption performance of the DCFTHX. It is found that DCFTHX managed 39% of the cooling load thereby reducing the compressor load by the same percentage. The experiments prove the efficacy of such internally cooled/heated desiccant systems for practical applications.
Power industry is the most important basic energy industry of national economy development, and it is also a big carbon emitter. With the continuous and rapid growth of renewable energy (RE) capacity, the contradiction between the scale development of renewable energy and the lack of market capacity is becoming more and more obvious. To achieve lowcarbon development and build a low-carbon society, we must develop low-carbon electricity and construct a feasible low carbon electricity price mechanism. In this paper, based on the efficient RE consumption, we introduce carbon cost to construct dynamic and variable low carbon real time electricity price mechanism, including the spot market pricing, grid fees and RE surcharge. Then the paper gives the electricity price strategy and its realization algorithm and verifies the beneficial effect of the proposed pricing mechanism by the example analysis. The proposed low carbon price mechanism is of great practical significance for the development and consumption of large-scale renewable energy.
The exploration of efficient utilization of lignin is very important and necessary for the applied biomass energy and sustainable development. In this work, hydrolyzed lignin residue, contenting more than 70% lignin, obtained from acid hydrolysis of sorghum straw was reused to synthesized ultrahigh surface area and hierarchical porous activated carbon for the first time. As-prepared nanomaterial (HLAC-1) presented unusual features such as unique interconnected porous structure, ultrahigh surface area (ca.2927 m2 /g), large total volume (ca.1.65 cm3 /g) and a high graphitization degree. Furthermore, as the electrode material for supercapacitor, HLAC-1 also exhibited remarkably high capacitance (400 F/g at 0.5 A/g) and superior cycling stability (99.1％ capacity retention after 20,000 cycles at 5 A/g) in 6M KOH aqueous electrolyte. A high energy density of 9.53 Wh/kg at a powder density of 53.22 W/kg (6.96 Wh/kg at a powder density of 2532.39 Wh/kg) have been achieved in KOH aqueous supercapacitors, indicating that the conversion of hydrolyzed lignin residue from activated carbon is very attractive and promising for the application in supercapacitor.
High temperature heat transfer, mass transfer, and thermochemical storage performances of the solar driven CO2 reforming of methane are numerically investigated along reactor length. A pseudo-homogeneous mathematical model is developed to simulate the heat and mass transfer processes coupled with thermochemical reaction kinetics in photo-thermochemical reactor with radiative heat loss. Thus, the temperature profile at the surface of the solid phase and the temperature profile in the gas phase are obtained. In addition, the conversions of reactants of CH4 and CO2 are studied under different operating temperatures. On the other hand, the DFR of H2 and QChem are also evaluated at the operating temperature.
Power-to-Fuel technologies are important for reducing fossil fuel consumption in the transport sector. Carbon dioxide (CO2) from biogas and hydrogen (H2) production from wind electrolysis provide convenient components for the synthesis of methanol. This study evaluates the environmental performance of a novel Power-to-Fuel (PTF) system, in which methanol is produced at a biogas production plant. A Life Cycle Assessment is carried out considering five feasible process routes in order to identify the one that delivers greater environmental benefits. The proposed system is also compared to a system of conventional methanol production. Results show improvements in most impact categories, which make it interesting from the environmental point of view.
This paper reports a synthesis strategy to develop Ni@yolk-meso-SiO2 by adopting the leaching and re-deposition of silica in mild alkaline solution with CTAB as stabilizer. It was compared to Ni@SiO2 core-shell catalyst and point out their difference in catalytic performance. The catalyst shows stable and near equilibrium conversion of methane and carbon dioxide for 50 hours. The increased in surface area and total pore volume contributed its high activity and stability.
In order to solve the problems of high heat loss, low fermentation temperature and low gas production in biogas engineering in winter. In this paper, the annual thermal energy loss of biogas project is systematically analyzed, and a regenerative mass recovery device with solid-liquid separation is developed. Finally, the heating effect of the device at different temperatures is tested through experiments. The results showed that under the condition of good heat preservation measures, the heat loss of the fermentation tank accounted for 89.3% 93.2% of the total heat loss of the anaerobicfermentation system. Under the ambient temperatureof 18 ℃, the feed at 16.2 ℃can be heated to 26.6 ℃by regeneration and mass recovery. The waste heat ofthe biogas slurry recovered accounted for 51.9% of theheat required for constant temperature fermentation.At ambient temperature of 0 ℃, the feed at 2.5 ℃can be heated to 18.9 ℃ by regeneration and massrecovery. The waste heat of the biogas slurry recoveredaccounted for 47.2% of the heat required for constanttemperature fermentation. The remaining heat issupplied by a collector array consisting of 14 groups ofsolar collectors, which can ensure the constanttemperature fermentation of biogas engineering at37 ℃ in winter. And the system has good economicand environmental benefits.
A well‐parameterized battery model is prerequisite of the model‐based estimation and control methods. This paper focuses on the unbiased model parameter identification when noises corrupt the measurements. The parameter identification problem within the noise corruption scenario is reformulated as a nonlinear least squares (NLS) problem. A novel offline two‐step method combining least squares (LS) regression and variable projection algorithm (VPA) is then proposed to coestimate the noise variances and unbiased model parameters. The proposed LSVPA is further extended to the online recursive version by using the Gauss‐Newton (GN) method. Simulation and experimental results show that the proposed method can well compensate for the noise effect and improve the accuracy of model parameterization.