Performance Analysis of an Efficient Integration System of Coal-Fired Power Plant,Solar Thermal Energy and CO_(2)Capture

Coal-fired power plant is a major contributor to greenhouse gas emissions.The post-combustion capture is a promising method for CO_(2)emission reduction but the high thermal demand is unbearable.To address this issue,solar thermal energy and CO_(2)capture are jointly integrated into the coal-fired power plant in this study.The solar thermal energy is employed to meet the heat requirement of the CO_(2)capture process,thereby avoiding the electricity loss caused by self-driven CO_(2)capture.Furthermore,the heat released from the carbonation reaction of MgO adsorbent is integrated into the steam Rankine cycle.By partially substituting the extracted steam for feedwater heating,the electricity output of the power plant is further increased.According to the results from the developed model,the system could achieve a CO_(2)capture rate of 86.5%and an electricity output enhancement of 9.8%compared to the reference system,which consists of a self-driven CO_(2)capture coal-fired power plant and PV generation unit.The operational strategy is also optimized and the amount of CO_(2)emission reduction on a typical day is increased by 11.06%.This work shows a way to combine fossil fuels and renewable energy for low carbon emissions and efficient power generation.

Analysis on optimal working fluid flowrate and unstable power generation for miniaturized ORC systems

For efficient utilization of a limited geothermal resource in practical projects,the cycle parameters were comprehensively analyzed by combining with the heat transfer performance of the plate heat exchanger,with a variation of flowrate of R245 fa.The influence of working fluid flowrate on a 500 W ORC system was investigated.Adjusting the working fluid flowrate to an optimal value results in the most efficient heat transfer and hence the optimal heat transfer parameters of the plate heat exchanger can be determined.Therefore,for the ORC systems,optimal working fluid flowrate should be controlled.Using different temperature hot water as the heat source,it is found that the optimal flowrate increases by 6-10 L/h with 5 ℃ increment of hot water inlet temperature.During experiment,lower degree of superheat of the working fluid at the outlet the plate heat exchanger may lead to unstable power generation.It is considered that the plate heat exchanger has a compact construction which makes its bulk so small that liquid mixture causes the unstable power generation.To avoid this phenomenon,the flow area of plate heat exchanger should be larger than the designed one.Alternatively,installing a small shell and tube heat exchanger between the outlet of plate heat exchanger and the inlet of expander can be another solution.

Discussion on the Mechanism of Source Integration between Solar Energy and Biomass Energy with Similar Grades

The clean transformation of the China’s energy structure is related to the establishment of China as an energy power in the new world pattern.The multi-energy systems based on renewable energy,especially solar energy and biomass energy,have become a popular energy supply mode.However,there is no clear theoretical guidance for the quantitative source integration of these two types of clean energy.Concretely,whether the source grades of solar energy and biomass energy are similar in different solar energy modes has not been considered yet.Aiming at this problem,based on the theory of space-time unity of the special theory of relativity,a new principle of source integration is proposed,and the corresponding mathematical model is established.The theoretical calculation of the combination of solar energy and different types of biomass energy is carried out.Under the premise of the similarity between the source grades of different biomass energy and solar energy,the specific solar energy concentration ratio is obtained.According to this principle,the matching efficiency of the multi-energy integration for rice and corn plants can be increased by 39.2%and 36.2%,respectively.

Effect of Nanobubble Evolution on Hydrate Process: A Review

As a huge reserve for potential energy, natural gas hydrates(NGHs) are attracting increasingly extra attentions, and a series of researches on gas recovery from NGHs sediments have been carried out. But the slow formation and dissociation kinetics of NGHs is a major bottleneck in the applications of NGHs technology. Previous studies have shown that nanobubbles, which formed from melt hydrates, have significant promotion effects on dissociation and reformation dynamics of gas hydrates. Nanobubbles can persist for a long time in liquids, disaccording with the standpoint of classical thermodynamic theories, thus they can participate in the hydrate process. Based on different types of hydrate systems(gas + water, gas +water +inhibitors/promoters, gas + water + hydrophilic/hydrophobic surface), the effects of nanobubble evolution on nucleation, dissociation, reformation process and "memory effect" of gas hydrates are discussed in this paper. Researches on the nanobubbles in hydrate process are also summarized and prospected in this study.

Overview on artificial intelligence in design of Organic Rankine Cycle

Converting thermal energy into mechanical work by means of Organic Rankine Cycle is a validated technology to exploit low-grade waste heat.The typical design process of Organic Rankine Cycle system,which commonly in-volves working fluid selection,cycle configuration selection,operating parameters optimization,and component selection and sizing,is time-consuming and highly dependent on engineer’s experience.Thus,it is difficult to achieve the optimal design in most cases.In recent decades,artificial intelligence has been gradually introduced into the design of energy system to overcome above shortcomings.In order to clarify the research field of arti-ficial intelligence technique in Organic Rankine Cycle design and guide artificial intelligence technique to assist Organic Rankine Cycle design better,this study presents a preliminary literature summary on recent progresses of artificial intelligence technique in organic Rankine cycle systems design.First,this study analyzes four main procedures which constitute a typical design process of Organic Rankine Cycle systems and finds that design problems encountered during design process can be divided into three categories:decision making,parameter optimization and parameter prediction.In the second section,a detailed literature review on each design proce-dures using artificial intelligence algorithms is presented.At last,the state of art in this field and the prospects for the future work are provided.

An Improved Treatment on the Apparent Contact Angle of a Single-Bubble in Consideration of Microlayer for Simulations of Nucleate Pool Boiling

Numerical simulation of single-bubble growth behavior during nucleate pool boiling was developed based on the volume of fluid method considering the thin liquid layer under the bubble(microlayer).However,the experimental values of apparent contact angle(the small region connecting the microlayer and bulk liquid)are crucial for the simulations.Reliance on experimental results limited the further application of such numerical method.In this study,a new method calculating the force balance,used to determine the interface shape near the apparent contact angle,was proposed instead of using the experimental values of the apparent contact angle.As a result,the good agreement was shown between the simulation results obtained based on the new and previous numerical methods.The simulation results were also in consistent with the experimental results.It can be concluded that the single-bubble behavior,including the heat transfer characteristics,during nucleate pool boiling can be simulated based on the proposed method.

碳捕集能耗分析模型的对比研究（英文）

目的:碳捕集能耗较高的技术瓶颈,亟待热力学理论在交叉研究中解决。热力学理论工具在碳捕集技术能耗水平评估方面的准确性、有效性和局限性都尚未明确,且碳捕集能耗研究的共性规律仍未被把握。本文对现有能耗分析模型进行对比以揭示碳捕集技术能耗的实质,并提出普适性和针对性恰当的能耗分析模型,以明确碳捕集能耗水平的"天花板"。创新点:1.提出热力学碳泵模型,分析碳捕集技术理想能耗;2.对比不同碳捕集能耗分析模型,通过案例分析说明其不同特点和理想化程度的差异。方法:1.通过概念比拟,类比热泵概念,提出热力学碳泵概念,并阐述碳捕集过程是通过热或功驱动的二氧化碳从低浓度向高浓度逆向富集的非自发过程(图2和3),实现碳捕集技术实质的理想化概括;2.通过热力学理论推导,获得基于热力学碳泵模型的碳捕集最小理想能耗(公式(13));3.通过案例分析,论证热力学碳泵模型相对混合气体分离模型和碳泵模型的理想化程度是否更高(图9),以及其中碳源、汇的无限质容假设是否更接近理想状态。结论:1.通过碳泵模型可以得到碳捕集技术的理想能耗,并且碳泵模型相对混合气体分离模型在使用时更便捷。2.热力学碳泵模型相对碳泵模型的理想化程度更高;因为忽略碳源、汇由传质引起的不可逆性,热力学碳泵模型计算所得最小理想能耗比碳泵模型计算所得理想能耗更小。3.通过热力学碳泵模型分析直接空气碳捕集技术表明,其最小理想能耗是相同反应条件下烟气处理技术的4.916倍。