Abstract

Aimed at solving the problem of DC bus voltage sudden drop in medium-voltage DC system, caused by the input of pulse power load such as high-energy weapon, the transient voltage changes of rectifier generator with sudden-added load is given by PSCAD simulation. The input of the pulse power load is equivalent to a small resistance load, and the input of the energy storage device is equivalent to a DC/DC converter in parallel with a DC voltage source to compensate the power required by the load. The simulation results show the relationship between the size of the pulse power load and the compensation power of the ES device.

Abstract

The integration of an additional regenerative turbine is an effective method to decrease the irreversibility of regenerative heaters for ultra-supercritical coal-fired power plants. However, the regenerative turbine belongs to the backpressure turbine and its steam pressure is influenced greatly by the steam mass flow. The purpose of this study is to investigate the dynamic characteristics of regenerative turbine system. Dynamic models were developed and the turbine power and heat consumption rate were calculated during processes of loading down and regenerative heater shutting down. The results indicated that the heat storage in the metal and working medium leads to the delay of the load and the delay increases more at the load-down rate 4%TMCR min−1 compared to 2%TMCR min−1. The load increases greatly in the moment that the regenerative heater shuts down . The respond speed of the high-pressure heater shutting down decreases obviously compared to that of the low-pressure heater shutting down. Moreover, the energy efficiency reduces ultimately with the regenerative heater shutting down.

Abstract

The low-speed electric vehicle (LSEV), a product similar to the neighborhood electric vehicle in California, has experienced explosive growth in China’s third- and fourth-tier cities and villages. The number of ownership has reached 4 million, but there is still no national standard regulation for it. The choice of battery type is one of the core controversies during the process of product legislation, since most LSEVs use lead-acid batteries for cost reduction nowadays, while many experts believe this would be harmful to the environment and not conducive to technical progress. This paper focuses on the battery choice issue and establishes a consumer-centric total cost of ownership model, which is composed by initial purchasing cost and operating cost, to compare the life-cycle cost of LSEVs using three different kinds of batteries including lead-acid, lithium-iron phosphate and ternary lithium-ion batteries. The results suggest that the vehicles using lead-acid batteries aren’t superior to those using other types of batteries in terms of life-cycle cost, and even the superiority in initial purchasing cost will gradually weaken over time, which provides a reference for product design and regulation development.

Abstract

In the wind-photovoltaic-storage hybrid power system based on gravity energy storage, a capacity optimization configuration method is proposed. Firstly, the capacity optimization configuration model of wind-photovoltaic-storage hybrid power system is established. Secondly, under the condition of different gravity energy storage capacity, the cat swarm optimization is used to optimize the capacity configuration of wind farm and photovoltaic power station. The optimal configuration meets the following indicators: utilize the complementary features of wind and photovoltaic, reduce the loss rate of power supply, increase the contribution rate of wind and photovoltaic, and ensure the minimum total cost of the system. Thirdly, the simulation analysis is carried out with data from a certain area of Gansu Province, China. The simulation results show that the proposed capacity optimization configuration method is reasonable and effective.

Abstract

In this research, dried cabbage, chicken and rice were pre-treated by hydrothermal or pyrolytic carbonizations (HTC or PC). Non-isothermal gasification by thermal gravimetric analyzer (TGA) was conducted to explore gasification behavior of the chars. The maximum gasification rate temperature (Tmax) was used to explain the comparison of the reactivity and higher Tmax means lower reactivity. For cabbage and chicken, higher alkaline index of their PC200 char, with Tmax of 795°C and 910°C respectively, led to higher reactivity compared to their HTC200 chars, with Tmax of 925°C and 992°C respectively. However, the catalytic effect by alkaline was minimized in the case of rice feedstock and the rice PC200 (Tmax of 986°C) showed slightly higher reactivity than HC200 (Tmax of 990°C). Therefore, the higher reactivity of PC chars may not only be correlated with the alkaline index but also with development of the pore structure. Increasing the HTC temperature resulted in a lower alkaline index and thereby lowered the reactivity. However, morphology of the char would be the dominant factor for PC char. Increasing the PC temperature will enhance the stable structure like graphite in the chars, leading to lower reactivity.

Abstract

Valve-regulated lead-acid (VRLA) battery, owning the huge market, plays an important role in all aspects of industries. A VRLA battery sometimes called sealed leadacid (SLA) or maintenance-free battery, however, the safety of VRLA has been a wide concern since it is prone to self-heating problems which generate extra cost or even cause accidents when the internal temperature (IT) of VRLA is out of range. To prevent potential hazards, effective internal VRLA temperature monitoring methods are in need of further management. In this paper, a narrowband (NB) Internet of thing (IoT) connected VRLA battery internal temperature prediction (VBITP) algorithm is developed to provide early warning of battery temperature. In VBITP, the internal temperature is estimated by ambient temperature (AT) and input current (IC) through a pre-trained prediction model. The measured temperature data will be sent to the backend server using NB-IoT. A kind of recurrent neural network, nonlinear autoregressive exogenous (NARX) is applied to find the potential relationship between the input AT, IC and the output IT and train this model. The experimental results show that VBITP could estimate the IT of VRLA battery with an error rate of 0.04.

Abstract

With severe environmental pollution pressures growing, research on fuel cell vehicles is increasing. Compared to electric vehicles, fuel cell vehicles do not have the constraints of driving distances. Meanwhile, the emissions of fuel cell vehicles are cleaner than the traditional vehicles. This paper takes a fuel cell bus as the research object. Based on the characteristics of fuel cell vehicles，the Dynamic Programming algorithm is used to calculate the global optimal process for typical urban conditions. The drawback of the global optimal process is that the operating conditions must be known before.As a result, it is not reasonable to use dynamic programming in real driving condition. Therefore, we propose to use an adapted power management method to deal with the actual driving conditions.

Abstract

The highly energy requirement of rich amine solvent regeneration process is the biggest obstacle for the industrial application of amine-based CO2 capture technology. In this work, to reduce the heat duty of absorbent regeneration, the zeolite Beta/SBA-15 (BS) with different zeolite Beta (β) content synthesized by the hydrothermal method with zeolite Beta (β) as the silicon source were utilized to prepare the novel Zr@BS and FeZr@BS catalysts for amine regeneration. Experiments for CO2 stripping were performed under the temperature of 370.15 K using amine solvent (monoethanolamine (MEA)) with an initial CO2 loading of 0.5 mol CO2/mol amine. Additionally, various techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption–desorption experiment, ammonia temperature programmed desorption (NH3-TPD), and pyridine-adsorption infrared spectroscopy (Py-IR) were adopted to characterize and estimate the prepared catalysts. Also, the catalytic CO2 desorption performances of seven different catalysts (β, SBA-15, three BS catalysts, Zr@BS and Fe-Zr@BS) were investigated and evaluated in terms of the cyclic capacity, desorption rate and energy consumption. The experimental results showed that the Fe-Zr@BS catalysts exhibited best catalytic performance than other catalysts studied in this work, enhancing the desorption factor by 212% and reducing the energy consumption by 33% compared to the blank run. Furthermore, the Fe-Zr@BS catalysts have no influence on the amine absorption performance in terms of the absorption rate and have the advantages of good stability and easy regeneration. Based on the results of characterization and experiments, the possible catalytic mechanism for the Fe-Zr@BS catalysts catalyzed amine regeneration for CO2 stripping were proposed and the reusability of the catalysts were also investigated.

Abstract

The development of CO2 capture became great of importance in recent years. Apart from reducing the emissions from power generation sector, capturing CO2 from industrial flue gas has not been a popular topic, especially in the cement industries which is quite energy intensive and a main resource of anthropogenic CO2 emission in industries. The main purpose of this work was to systematically conduct techno-economic analysis of CO2 capture based on MEA technology, in which the impactors such as the flue gas flow rate, flue gas CO2 concentration and CO2 recovery rate were studied with the commercialized software Aspen Plus. Meanwhile, the concentration of MEA solutions was studied. The results indicate that 20% MEA is more suitable for practical application. The CAPEX is more sensitive to these selected impactors than OPEX, but still OPEX dominates the major change in the overall cost. In addition, the gas flowrate and CO2 concentration are the major impactors affect the cost rather than the CO2 recovery rate.

Abstract

Making the heavier components of coal tar into lighter components, which are the raw material for fuel and the chemicals, will improve the economy of pyrolysis. To promote the hydrogenation of heavy components, the co-hydrogenation of heavy components and pine sawdust (PS) was extensively studied in this work. The addition of PS significantly promoted the hydrogenation of heavy components which improved the yield of n-hexane soluble matter from 66.63 wt% to 75.46 wt%. The results of synchronous fluorescence showed that the product has a significant degree of lightening. Addition of biomass increased the aliphatic hydrogen content as evidenced by Fourier transform infrared spectroscopy.