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The use of heat pump technology to recover the waste heat of circulating water from the power plant instead of steam extraction for heating can not only improve the thermal efficiency of the unit and reduce the loss of cold source, but also has great advantages in energy saving. This paper uses absorption and compression heat pumps to recover the waste heat of circulating water in the power plant to study its energy-saving benefits. Under the same heating load, the economics of the two heat pumps are calculated and analyzed. The results show that the energy-saving benefits of absorption heat pump units are far greater than compression units. But in terms of water saving, the water saving capacity of the compression heat pump unit is higher than that of the absorption heat pump.

Regarded as brand-new porous material, metal organic framework(MOF) has a certain ability to remove pollutants due to its high porosity, high specific surface area, adjustable micropore size and easy functionalization. Compared with other metal organic framework materials, MIL-53 has a relatively higher specific surface area and stronger hydrothermal stability, which leads to excellent performance and application prospects in the removal of pollutants. In this paper, synthesis methods of metal-organic framework material MIL-53 are introduced, and the influencing factors in the synthesis process using hydrothermal method are discussed, including the component ratio, type of organic solvent and pH value. Due to less dependence on residence time and organic solvent, mechanical method can reduce energy consumption and has latent value for future application. Among different influencing factors, reducing the pH of solution when synthesizing MIL-53 using hydrothermal method seems to save time and achieve rapid formation.

Peeling is regarded as a main technique barrier for the application of coating. Many factors affects the peeling of coating. Among them, the interfacial properties between coating and substrate plays a vital role. In this work, the β-Si3N4/diamond interface is conducted as the sample to study the changes in atomic structure and potential energy in the process of detachment by the first-principles calculations. The β-Si3N4/diamond (2 × 2) crystal unit is used as the calculated model. The detachment is simulated by moving up β-Si3N4 far from diamond by the 0.1 A of each step. The results show that in the beginning of detachment, the bonds in the interface keep a constant length, rather than extension like spring. When the distance between β-Si3N4 and diamond reaches a certain distance, the interfacial bonds would suddenly break, and the elongated β-Si3N4 resumes its original statues indicating that the interface between two surfaces may exist a threshold value to control the peeling. When the external force is less than this threshold value, the peeling of coating would not occur. However, once the external force is greater than this one, the peeling would immediately present. The interface presents the brittle failure in the process of detachment, which is in good agreement with the experimental observation. Meanwhile, the different physical properties between van der Waals and quantum effects lead to the transient status in the process of detachment, where although the interfacial bonds are broken, the adhesive strength is still strong due to its low negative adsorption energy.

When planning a neighborhood-scale distributed energy system (NDES), enough attention should be paid to the urban spatial structure, which may affect not only the system configuration on the supply side but also the load profiles on the demand side as well as their interactions. In this study, a novel nonlinear optimization model is developed for the determination of neighborhood design and NDES arrangement in terms of energy-saving aspect. By executing the optimization model, besides the configuration of energy supply technology, optimal building mix within the neighborhood can be also deduced. As an illustrative example, a mixed-use neighborhood located in Shanghai, China has been assumed for analysis. According to the simulation results, the introduction of NDES may achieve satisfied energy-saving benefits. Although additional energy consumption including heat loss and pump power may be encountered in the NDES, it can be offset through rational plan of the urban spatial structure and its cooperation with the supply side. For a fixed building mix, the reduction of supply radius may lead to better energy performance. Moreover, there exists the maximum supply radius over which, the NDES will not be recommended from the energy-saving viewpoint.

The utilization of organic Rankine cycle (ORC) technology is increasing rapidly due to its adaptability to various low-grade heat sources. This paper examines the economic and environmental performances of different trigeneration systems integrated with ORC unit based on different low/medium-temperature heat sources. By coupling the ORC unit to combined cooling, heating and power (CCHP) plant, solar collector and biomass boiler, three systems, namely, CCHP-ORC, Solar-ORC as well as Biomass-ORC are proposed. In order to realize the best performance of each integrated system, a mixed integer linear programming (MILP) model is developed to deduce the optimal system combination and corresponding operation strategies, from different preferences. As an illustrative example, the above three integrated systems have been assumed to cover the energy demands of two typical commercial buildings: hotel and office for a calendar year. Comparative analysis among the proposed three systems is implemented considering both economic and environmental objectives. The simulation results indicate that the Solar-ORC system has the best economic performance, whereas the Biomass-ORC system enjoys the best environmental benefit. In addition, the potential environmental benefits of the ORC unit are recognized be higher than the economic ones.

Exploring low-cost and earth-abundant photocatalysts to efficiently release H2 from wastewater is an appealing solution for global energy and environmental issues. Here, we successfully prepared flower-like 1T/2H-MoS2-decorated g-C3N4 (thiourea)/g-C3N4 (urea) (denoted as CNT/CNU) isotype heterojunction photocatalysts via a facile ultrasonic dispersion method and researched the photocatalytic H2 generation and pollutant degradation performance in oxalic acid (OA) simulated wastewater. The results displayed that 20% 1T/2H-MoS2@CNT/CNU sample exhibited the highest photoreactivity, and the H2 release rate was 1563.32 μmolg-1h−1, which was about 96 times higher than the CNT/CNU. Meanwhile, it also showed the highest total organic carbon (TOC) removal rate of 67.5%. The increased photoreactivity of nanocomposites can be ascribed to the double-interface system to effectually improve the separation of photoinduced charges. Additionally, the experimental results further confirmed that the loading of flower-like 1T/2H-MoS2 could provide abundant active sites as well as expand the visible-light absorption range. Significantly, photoelectrochemistry measurements and density functional theory (DFT) calculations also confirmed that 1T/2H-MoS2 cocatalysts accelerated the charge migration. On this basis, the mechanism of 1T/2H-MoS2@CNT/CNU promoting hydrogen production and synergistic OA degradation was proposed. This research presents a prospective idea for the utilization of waste water and the simultaneous production of clean energy.

Titanium dioxide (TiO2) is regarded as the best known semiconductor photocatalysts, but its large band gap and low rate of photogenerated charge separation impede the application to solve the environmental contaminations and energy crisis. Reducing band gap and improving electron-hole separation and migration have remained a longstanding challenge. While creating the junctions between different crystal phases and substance is an effective method. In this work, we prepared the V2O5/rutile-anatase photocatalyst system with homo-hetero junctions via a facile incipient wet impregnation method. In this system, the synergetic effects of homo- and hetero-junctions are beneficial to separate the generated electron-hole pairs, facilitate interfacial charge-transfer rate, and reduce band gap, which greatly promote photocatalytic activities. Furthermore, it exhibits an enhanced activity on photocatalytic oxidation of elemental mercury (Hg0), which shows the highest Hg0 oxidation efficiency of 93.58% under visible light. The result suggests that combination of both homo- and hetero- junctions in one photocatalyst is a promising method to improve the photocatalytic activities for solving the environmental contaminations and energy crisis. We believe that the preparation of this new photocatalyst system may be a great assist in the design and preparation of efficient photocatalyst. Meanwhile, this method is sought-after for large-scale industrial applications of photocatalysis.

Bismuth-based nanomaterials exhibiting unique structures, which endow them with fascinating physicochemical properties, have received more and more interests as promising photocatalysts. Fabrication of BiOIO 3 photocatalysts by calcination method was investigated for the first time. XRD patterns showed that the crystallinity of BiOIO 3 photocatalysts could be controlled by calcination temperature. TGA demonstrated that calcining the precursor at a specific temperature range was appropriate for preparing BiOIO 3 photocatalysts. XPS and FT-IR characterization revealed that the BiOIO 3 photocatalysts prepared by calcination method possessed oxygen vacancies, which acted as the positive charge centers to trap the electron easily, inhibiting the recombination of photo electron-hole pairs. Furthermore, PL spectra confirmed the oxygen vacancies can favor for the separation of the electron-hole pairs and in turn enhance the photocatalytic performance. From the above analysis, the mechanism of preparing BiOIO 3 photocatalysts by calcination method was proposed. Meanwhile, the effect of oxygen vacancies on the photocatalytic activity of BiOIO 3 photocatalysts was investigated. The BiOIO 3 photocatalysts with oxygen vacancies were found to be efficiently photocatalytically remove gaseous Hg 0 and the relative photocatalysis mechanism was investigated.

As the installed capacity of wind power and other renewable energy sources continues to increase, the intermittent and volatility of their output has put tremendous pressure on the safe and stable operation of the power grid. The demand for peak shaving is becoming increasingly urgent. In this paper, the electrolysis hydrogen production system participates in the deep peak shaving of coal-fired generators. Through the participation of load regulation of the electrolysis hydrogen production system, according to the requirements of the power grid on the different loads of the unit, the load of the electrolysis hydrogen production system is adjusted to adjust the load of the unit. In order to realize full-load regulation of coal-fired thermal power plants and improve the power generation efficiency of units.

Intermittent power generation of renewable energy power generation system is the active reason affecting the stability of power grid, and adjusting the load imbalance between power generation and power supply through hydrogen production unit is the main means to reduce the impact of natural conditions and ensure continuous and stable power supply. In this paper, the simulation model of permanent magnet direct drive fan system for hydrogen production load is established, and the permanent magnet direct drive wind power generation unit is used to supply power to hydrogen production load to achieve the effect of stable output power.

In 2012, the Japanese government launched the new Feed-In Tariff Act (FIT), which aimed at promoting the stable, integrated rise of renewable energy in the wake of the Fukushima nuclear accident. Solar photovoltaic (PV) energy on both the residential (installation capacity less than 10 kW) and non-residential side (installation capacity 10 kW and above) has been associated with significant benefits with the passage of the new FIT Act. However, a number of issues have emerged during implementation, including unjust enrichment from delayed PV plant operation and high renewable energy taxes. In this paper, we present an overview of the evolution of the FIT and explore how the relevant issues have been addressed through revised government policy. The paper also examines, the FIT’s effect on PV energy development. An economic analysis was conducted to identify the impact of FIT fixed price changes on the profitability of solar PV plants on both the residential and non-residential side from 2012 to 2019. Furthermore, a sensitivity analysis was conducted based on scenarios of future FIT fixed purchase price reductions and PV initial investment cost reductions. The results show that the FIT can potentially be reduced on the residential side and that the current FIT has reached its feasibility limits in terms of non-residential PV investments.

To explore the effect of surface heterojunction between (0 0 1) and (1 0 1) planes on photocatalytic activity of anatase TiO2, the anatase TiO2 photocatalysts with different ratio of (0 0 1) and (1 0 1) planes were prepared via a facile hydrothermal method. The as-prepared photocatalysts were characterized by XRD, TEM, HRTEM, UV–vis, and PL to explore the optimal ratio of these facets. Meanwhile, the as-prepared samples were used to photocatalytically remove elemental mercury under UV lamp irradiation. The results indicated that the removal efficiency was different and the percentage of (0 0 1) was 32% exhibiting the best photocatalytic activities. It can be attribute to the surface heterojunction between (0 0 1) and (1 0 1) planes and the optimal ratio of these facets, which can suppress the recombination of photoexcited electron-hole pairs.

A dual-mode CO2 heat pump coupled with hot and cold thermal storages was proposed as a high-efficiency smart grid enabling option for supporting higher penetration levels of intermittent renewables in the energy system. However, the optimal control of simultaneous hot and cold thermal storage systems in real time is very delicate. In this study, a novel system-based optimization method is proposed, in which the COP of such system is simplified with empirical correlation, and a solution for the optimal control vector that maximize the transient system COP is determined using genetic algorithm for global optimization. To evaluate the system-based optimization method, experimental tests were conducted, and a real-time near-optimal control strategy for charging of dual-model energy storage systems was developed and implemented. Practical operation results show that the near-optimal control strategy is able to search the near-optimal transient total COP in real time, and optimize the overall COP of such dual-mode coupled systems during energy charging.

Hetero layered BiOI/BiOIO3 composites were fabricated by a simple hydrothermal method. The prepared BiOI/BiOIO3 heterostructures were characterized and evaluated for gas-phase Hg0 oxidation. The photocatalytic activity of the BiOI/BiOIO3 heterostructures was detected under LED light and UV irradiation. Meanwhile, the cycle experiments were carried out to certify the stability of BiOI/BiOIO3 composites. The results showed that BiOI/BiOIO3 photocatalysts were of excellent photocatalyic ability with great efficient in oxidizing Hg0. The Hg0 removal efficiency reached up to 98.53% and 100% under LED light and UV irradiation respectively when the mole ratio of BiOI/BiOIO3 was 3:1. The photocatalytic reaction mechanism was elaborated in detail.

It is the aim of thermal power plants start-up scheduling to minimize the start-up time and limit the turbine rotor stresses, which is a highly nonlinear problem and has multiple local optima. A novel mathematical model of start-up schedule was proposed in this study. Based on the operation regulations of 320 MW subcritical condensing steam turbine at a power plant, different cold start-up optimization schedules were made according to the mathematical model of start-up schedule. The finite element method (FEM) was applied to calculate the temperature field and stress field of the steam turbine rotor under different schedules. Taking the calculation results as the sample data, support vector machines (SVM) was employed to establish the regression model of start-up schedules and the dangerous point stress under the start-up schedule. Combining the regression model, the optimal start-up parameters could be obtained by the particle swarm optimization (PSO) algorithm. The results show that limiting the maximum Von Mises stress, the start-up time of the optimized schedule was reduced by almost 150 min compared with the original schedule. At the same time the optimal start-up schedule was verified by FEM, and the maximum Von Mises stresses at the dangerous points satisfy the stress requirements.

A series of CeO 2 modified and Ce-Mn co-modified activated carbons (AC) were prepared for the gas-phase elemental mercury (Hg 0 ) removal experiment under N 2 atmosphere. The loading of CeO 2 ranged from1 wt.% to 7 wt.%, and the mass ratio of manganese to cerium was 0.7. The BET results indicated that the big surface area and pore volume benefited the physical adsorption of Hg 0 . The XPS results indicated the existence of the Ce 3 + /Ce 4 + redox couple and multiple valence state Mn ions, and Ce 4 + and Mn 4 + species released lattice oxygen to promote the Hg 0 oxidation. The experimental results showed the 3 wt.% CeO 2 -Mn(0.7)/AC was the optimal sample at 120 °C.

Most of the major faults in gas turbines often originate from the rotor shaft. Some of these faults could result to misalignment, imbalance, crack, rub-impact and eccentricity. This study analyzes nonlinear factors such as lube-film surge and thermal-stress. Seal and bearing quality significantly affect the performance of a rotor system. The nonlinear dynamic characteristics of a high-temperature rotor–bearing–seal coupled system are investigated. Dynamic trajectories, Poincaré maps, frequency spectra diagrams are used to analyze the features of the rotor-bearing-seal coupled system in terms of various parameters. Several nonlinear phenomena in the high-temperature rotor–bearing–seal coupled system, such as periodic, double-periodic, multi-periodic, and quasi-periodic motion are investigated. Through these curves and the program, the dynamic characteristics of gas turbine rotors could be easily and accurately calculated. To validate this method, the critical speed of a real rotor of an actual gas turbine was calculated by means of the program and curves. The results are consistent with the measured data and may contribute to further understanding the nonlinear dynamics of the high-temperature rotor-bearing-seal coupled system.

This study develops a mixed-integer linear programming (MILP) model integrating energy system optimization and benefit allocation scheme of the building distributed heating network. Based on the proposed model, the minimized annual total cost, energy generators configuration, optimal operation strategy and heating pipeline lay-out of the distributed energy network can be determined. Moreover, four benefit allocation schemes (Shapely, the Nucleolus, DP equivalent method, Nash-Harsanyi) based on cooperative game theory are employed to deal with the benefit (reduced annual cost) assignment among the building clusters, while considering the stability and fairness of each scheme. As a case study, a local area including three buildings located in Shanghai, China is selected for analysis. The simulation results indicate that the ground coalition in which all buildings cooperate with each other by sharing and interchanging the thermal energy yields the best economic performance for the distributed energy network as a whole. In addition, different allocation schemes may result in diversified outcomes in terms of the fairness and stability, which are measured by the Shapley-Shubik Power Index and the Propensity to Disrupt value, respectively. For the current case study, the Shapely value method is recognized to be the most acceptable allocation scheme from both viewpoints.

To explore the effect of pH on the photocatalytic oxidation activities of BiOCl catalysts, the BiOCl catalysts under different pH values were prepared via a facile hydrothermal method. The as-prepared catalysts were characterized by BET, XRD, HRSEM, SEM and UV–vis to find out the impact of pH values. Photocatalytic ability of BiOCl catalysts were evaluated by oxidation of gaseous elemental mercury under UV light irradiation. It was found that BiOCl catalysts prepared under alkaline condition exhibited the best photocatalytic oxidation activities. The difference of photocatalytic activity among the as-prepared catalysts can be attribute to the growth orientation of the crystal BiOCl catalyst and the adsorption capacity of elemental mercury.

To overcome the supply-demand imbalance problem within a conventional distributed energy system, the distributed energy network (DEN) based on electricity and heat interchanges is proposed. With rational design and operation, the DEN may achieve satisfied economic performance compared with the situation without energy interchange. However, the maximum of overall economic benefits does not necessarily lead to satisfied economic performance for each consumer. Therefore, to promote the consumers' participation in the DEN, an effective and fair allocation mechanism for the additional profit is necessary. In this study, firstly, a mixed-integer linear programming (MILP) model is proposed to deal with the optimal technique selection, lay-out of the energy transmission line and running strategy of the DEN. Then, a mathematical model for fair benefit allocation amongst the participants is presented based on the core method of the cooperative Game-theory. As an illustrative example, three buildings located in Tokyo, Japan have been selected for analysis. According to the simulation results, total annual cost is reduced by 14.5% thanks to the energy interchange within the DEN. Moreover, fair profit allocation mechanism is determined by employing the core method. In this way, a win-win solution is achieved for both group interests and individual interests.

CuO-CeO 2 /Graphene Oxide(GO) nanocomposite photocatalyst was fabricated by a facile dip-molding and ultrasound assisted process, which has a high specific surface area and photo activity. The as-prepared nanocomposites were characterized by N 2 adsorption-desorption, X-ray diffraction, UV–vis diffuse reflectance spectra, HRTEM, and FE-SEM. The nanocomposite showed better catalytic activity than pure CuO and CuO/GO toward the degradation of methyl orange (MO) in the presence of H 2 O 2 under visible light irradiation (λ>400 nm). With the efficient interelectron transfer and superior adsorption capacity which were attributed to the amazing properties of the GO and nanoparticles, it's a promising photocatalyst in managing some chemically stable azo dyes in water.

Based on the self-designed annular combustion chamber of a 300 MW heavy-duty gas turbine, the ANSYS Fluent 15.0 is used to carry out numerical simulation research on the flow process in the combustion chamber. It mainly studies the influence of the swirling strength of the inlet airflow on the velocity fields in non-reacting and reacting flows, temperature field and low pollution emission in the annular combustor. It is found that two central recirculation zones with opposite directions of rotation are formed in the inlet section of the combustion chamber. Two angular recirculation zones are formed at the bosses and rotate around the bosses. The structure of the central recirculation zone is mainly affected by the swirling strength of the premixed flow from outer ring while the angular recirculation zone is affected by the flows from inner hole and outer ring. The average velocity of the reacting flow is about twice that of the non-reacting flow. The temperature on the central axis section of the combustor increases first and then decreases from the central of chamber to the wall. The average temperature of the central recirculation zone in the combustion chamber is around 2223 K. The average temperature in the near-wall region is around 2200 K. Due to the high temperature in the combustion chamber, a certain amount of NOx is generated.

Materials Institute Lavoisier-101-D (MIL-101(Cr)-D) composites were first successfully synthesized by traditional solvent hydrothermal synthesis method. The effect of MIL-101(Cr) which was modified by DEA on CO2 adsorption was studied and characterized by XRD, TGA, FT-IR, N2 adsorption technique, and SEM. In order to compare the CO2 adsorption of MIL-101(Cr) and MIL-101(Cr)-D composites, CO2 fixed-bed adsorption experiment had been performed. The results demonstrated that MIL-101(Cr)-D-0.24 had the best CO2 adsorption performance and was 33.3% higher than the unmodified one. The characterization results also confirmed that MIL-101(Cr)-D-0.24 had the largest specific surface area and specific pore volume. The SEM images showed that with the increase of DEA grafting, the unit cell could not continue to maintain the octahedral structure. The amount of CO2 adsorption of MIL-101(Cr)-D was also reduced which was caused by the collapse of the pore structure. The grafting of DEA did not affect the thermal stability of MIL-101(Cr).

The key to reduce the concentration of CO2 in atmosphere by using the photocatalytic reduction method lies in the development of low-cost, stable, and environmentally friendly photocatalysts. Given that g-C3N4 has the advantages of non-toxic, no metal elements, narrow band gap, good thermal stability and so on, analysis shows that this is a very potential photocatalyst. However, at present, the photocatalytic efficiency of pure g-C3N4 is limited by small specific surface area, low visible-light utilization efficiency and high recombination rate of photogenerated charge carriers. In this review, we report the methods for improving photoactivity of the g-C3N4, for instance, loading precious metal cocatalysts, earth-abundant metal cocatalysts and non-metallic cocatalysts. Finally, the issues that should be paid attention to when further studying the photoreactivity of g-C3N4 and its future research directions are discussed.

The dewatering and drying of sludge are important to achieve volume reduction and resource utilization, while the sticky properties of sludge is one of the main problems in the dewatering and drying process. Therefore, reducing the viscosity of sludge and the amount of sludge adhesion is critical to improving the operating efficiency of drying equipment. In practice, the surface electro-osmosis has been used to reduce the adhesion of soil to a loading shovel, and electro-osmotic pulse is applied to a concrete structure to achieve humidity reduction. In this research, the effect of surface electro-osmosis pulse on reducing the adhesion of sludge is studied by using a periodically changing electric field combined with surface electroosmosis technology. The results showed that with surface electro-osmosis pulse, the sludge adhesion stress is reduced from 1514.7 to 820.5Pa at 45% water content within 10s, which indicates that surface electro-osmosis pulse has application value in dewatering and drying process.

The carbon modified BiOI/BiOIO 3 (CSs-BiOI/BiOIO 3 ) composites with heterostructures have been prepared via a facile hydrothermal method, using carbon spheres, bismuth nitrate and potassium iodate as precursors. Moreover, a new synthesis mechanism has been proposed. The photocatalytic activities of as-prepared catalysts are evaluated by oxidation of gaseous elemental mercury under visible light irradiation. It is found that the CSs-BiOI/BiOIO 3 exhibits highly enhanced visible photocatalytic activity, compared with that of pure BiOIO 3 . The results show that the Hg 0 removal efficiency of CSs-BiOI/BiOIO 3 reach up to 92.9% and 83.0% under LED light irradiation and simulated sunlight irradiation respectively. The improved photocatalytic activity can be ascribed to the increased the absorption of visible light, enhanced charge separation and transfer and the surface properties. This work points to CSs-BiOI/BiOIO 3 nanocomposites as new and efficient visible light photocatalysts for environmental remediation applications.

Interaction potential plays a vital role on the friction. Potential energy of two contacts directly determines on the friction force. However, many mathematic models proposed, always abandon the instantaneous status during sliding to devote to a weighted average over lateral force, which might miss some information about friction behavior. In this work, the relation among potential energies, separation distances of two contracts, and positions in the sliding direction are studied to evaluate the instantaneous friction characteristics. Two hydrogenated diamond surfaces are used as the examined model. The results show that a watershed between positive and negative friction forces locates at the position with the minimum adsorption energy. A rapid decrease in potential energy occurs near the 2.5 nN external force, where the friction coefficient approaches zero at each position in the sliding direction. Therefore, a novel method may be developed to greatly reduce the friction coefficient between two surfaces by adjusting the contract pressure.

A novel creep-fatigue life prediction model was deduced based on an expression of the strain energy density in this study. In order to obtain the expression of the strain energy density, the load-controlled creep-fatigue (CF) tests of P92 steel at 873 K were carried out. Cyclic strain of P92 steel under CF load was divided into elastic strain, applying and unloading plastic strain, creep strain, and anelastic strain. Analysis of cyclic strain indicates that the damage process of P92 steel under CF load consists of three stages, similar to pure creep. According to the characteristics of the strains above, an expression was defined to describe the strain energy density for each cycle. The strain energy density at stable stage is inversely proportional to the total strain energy density dissipated by P92 steel. However, the total strain energy densities under different test conditions are proportional to the fatigue life. Therefore, the expression of the strain energy density at stable stage was chosen to predict the fatigue life. The CF experimental data on P92 steel were employed to verify the rationality of the novel model. The model obtained from the load-controlled CF test of P92 steel with short holding time could predict the fatigue life of P92 steel with long holding time.

In this study, a multi-objective MILP (mixed integer linear programming) model has been developed for the optimization of a distributed energy network integrated with heating interchanges. The model allows to determine the energy generation components among various candidates, the site and size of each selected technology, optimal running schedule, as well as optimal lay-out of heating pipelines. Both economic and environmental aspects have been taken into account in the objective function with relative weighting factors. As an illustrative example, the model is applied to a low carbon community including five buildings (hotel, hospital, office, store and apartment) located in Shanghai, China. According to the simulation results, by introducing the distributed energy network, the total capacity of distributed generations is increased, and the overall performances (both economic and environmental ones) of the local area are enhanced. In addition, the sensitivity analyses indicate that the determination of user preference, as well as the fluctuation of energy loads and fuel prices may have considerable influence on the performances of the distributed energy network. Moreover, according to the results of “8 buildings” cases with different building combinations, the rational selection of end-users is of vital importance for the plan and design of a distributed energy network.

In the present study, to insert the Cu nanoparticles (NPs) into mesoporous carbon aerogels and first applied it to remove H2S efficiently. This desulfurizer was made based on the dimensional policy by inserting the Cu NPs on mesoporous carbon aerogels to overcome the sintering problem and improve the activity, which has potential performance at high-temperature catalysis. The obtained desulfurizer was employed for H2S removal at middle temperature conditions (optimal H2S adsorption at 550 °C). We explored the optimum doping amount of CuOx, optimum temperature conditions, and the influence of textural parameters of carbon aerogels. The desulfurizers were characterized by means of field-emission scanning electron microscopy (FESEM), N2-adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), and Raman spectra techniques. The results confirmed that the presence of H2 was unfavorable for sulfidation and obviously shortened the breakthrough time. However, the existence of CO had little impact on the desulfurization and sulfur capacity. In a nutshell, this work could provide a new synthetic route to prepare Cu NPs deep into the lattice of carbon aerogels structure of desulfurizers and understand the desulfurization mechanism.

As one of the effective measures to cope with the continually increasing energy consumption in the building sector, BCHP (building combined heat and power) systems have been paid great attention in both developed and developing countries. To understand the overall benefits of a BCHP system, comprehensive assessment of system performances is necessary. In this study, a multi-criteria assessment model has been developed by combining the improved GRA (gray relation analysis) approach and the AHP (analytic hierarchy process) method. As an illustrative example, two building categories located in different climate zones in both Japan and China have been selected for analysis. In this way, the influences of climate condition, building type as well as market data on the introduction of BCHP systems have been examined. According to the simulation results, the BCHP systems in Japan achieve more benefits than that in China; and the rank of regions for the same building type may vary in different cases for both countries. In addition, the coldest region always enjoys the best overall performance, followed by the hottest zone and mild climate zones in Japan; on the other hand, the influence of climate condition on the performance of BCHP systems in China is inexplicit.

An experimental study is carried out to examine the simultaneous cooling and heating performances of an ejector expansion CO 2 transcritical system with an adjustable ejector and a variable speed compressor under different operating conditions in detail. Experimental results show that the total capacity and the total COP of an ejector CO 2 system reach their maxima at the ejector throat diameter of 2.0 mm under extreme operating conditions. As compressor frequency decreases from 60 Hz to 35 Hz, the total COP of an ejector cycle can be increased by up to 71.4%, although the total capacity can be decreased by 21.3%. Low outdoor air temperature benefits COPs while high indoor air temperature benefit cooling and heating capacity. The empirical correlations of COPs with ejector internal geometries, compressor efficiency and operating conditions are developed, which can be used for optimization of ejector CO 2 vapor compression systems.

Aiming at improving vibration performance of 1.5 MW wind turbine blades, the theoretical model and the calculation process of vibration problems under geometric nonlinearity and unidirectional fluid-structure interaction (UFSI) were presented. The dynamic stability analysis on a 1.5 MW wind turbine blade was carried out. Both the maximum brandish displacement and the maximum Mises stress increase nonlinearly with the increase of wind speed. The influences of turbulent effect, wind shear effect and their joint effect on displacement and stress increase sequentially. Furthermore, the stability critical curves are calculated and analyzed. As a result, the stability region is established where the wind turbine blade can run safely.

In this study, a mixed integer linear programming model of a distributed energy supply network integrated with electricity and hot water interchanges is presented minimizing the overall annual costs, which include annualized initial investment cost, annual operation and maintenance cost as well as annualized total infrastructure cost while guaranteeing the resilience of energy demands of various consumers. The superstructure of the energy supply system is determined. Furthermore, the system size and operational strategies including energy interchanges are optimized simultaneously. As an illustrative example, a low-carbon community located in Tokyo, Japan, has been selected for study. The robustness of the optimization model as well as the performance of distributed energy supply network have been illustrated through comparative analysis of four scenarios and multiple sensitive analyses of various uncertainty parameters including community scale, energy prices, energy policies as well as energy generation efficiency.

Under the Kyoto Protocol, Japan was supposed to reduce six percent of the Greenhouse Gas (GHG) emission. However, in the year 2012, the statistics suggested that the GHG emission increased 9% compared with the year 1990. Even with the leading energy saving technologies and a lot of experience on handling with environmental issues, Japan still could not meet the target set by Kyoto Protocol. The demonstration area of “smart community” suggests Japanese exploration for low carbon strategies. It is the shift toward the emphasis on the GHG emission control in civil sector. The Japanese version of smart communities also suggests the promotion on the use of renewable and untapped energy resource as well as the collaborative energy to be used in the district level. Much more important than the technology itself, the concept of smart community in Japan makes the community and the city as a whole, setting up a system of cooperation between the industry, government and residents. Taking the city of Kitakyushu as case study, this paper introduces the current development of smart community in Japan, focusing on analyzing its potential and challenges.

TiO2 hollow sphere was synthesized by hydrothermal method using trifluoroacetic acid (TFA) and Ti(SO4)2 as raw materials, and it was applied to photocatalytic oxidization of elemental mercury (Hg0) in the simulated flue gas. The prepared samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (UV-vis DRS) and nitrogen adsorption/desorption. The results showed that only anatase phase TiO2 hollow sphere was obtained. The average diameter of TiO2 hollow spheres was about 800 nm and the shell thickness was about 200–400 nm. When M, the molar ratio of TFA to Ti(SO4)2, was higher than a certain value, the photocatalytic activity of prepared TiO2 hollow spheres began to reduce. When M = 2, addition TFA content was the best quantity, which got the best TiO2 hollow spheres and provided the most appropriate F− decomposed from TFA during the sample preparation, which was helpful to its photocatalytic ability. In the experimental temperature range, the photocatalytic oxidation efficiency decreased with the increasing of reaction temperature, and the intensity of UV irradiation had an important effect on the photocatalytic reaction. When UV irradiation intensity was 303.45 μW cm−2 and reaction temperature was 55 °C, TiO2 hollow sphere sample prepared at M = 2 had the highest photocatalytic ability and the mercury removal efficiency reached up to 82.75%.

Based on the background of SCR denitrification technology widely used in pulverized coal utility boilers, the characteristics of denitrification catalysts used in industry were studied. Microwave radiation was used to prepare 8Mn-8Fe/Al2O3 denitrification catalyst by using microwave as an efficient and fast heating method. The results show that microwave irradiation can make the catalyst heated from inside to outside without temperature gradient, make the molecule oscillate rapidly, change the specific surface area and pore structure of the catalyst, thus improving the catalytic activity of the catalyst.

In order to maintain the balance of desulfurization slurry material circulation system, prevent the soluble part of the chlorine concentration in flue gas to exceed a specified value, and ensure the quality of gypsum, discharge from the system is necessary, including a certain amount of waste water, which is mainly from gypsum dehydration and cleaning system. The impurities in waste water mainly include suspended, supersaturated sulfites, sulfates, and heavy metals, many of which are the primary pollutants required to be strictly controlled by national environmental standards. The photocatalysis showed great superiority on wastewater treatment. Based on the photocatalytic mechanism and the kinetics, the photocatalytic process includes primary reaction process and secondary reaction process, and the wastewater degraded with photocatalysts is studied in this chapter. Through the analysis of traditional method on degrading wastewater, it is a universal view that photocatalysis is a promising method with industrialized value. At last, several future developing views of the application of photocatalysts on wastewater treatment were put forward, which included efficiency priority, combining immobilization, mechanism in microcosmic, and application in macroscopic.

We prepared a series of mole percentage of modified titanium dioxide materials. The crystalline phases of as-prepared nanocomposites were characterized by using the X-ray diffraction (XRD) of Cu Kα radiation (BRUKER D8 ADVANCE Diffractometer, Germany), in which the scanning angle range begins from 10° to 90° (the scanning rate is 2°min−1). In order to further identify the element composition, the AIK alpha X ray (HM = 1486.6 eV) radiation operated under 250 W (PHI5300, USA) was used to carry out the X ray photoelectron spectroscopy (XPS) analysis. In order to observe the surface structure and morphology, scanning electron microscope (SEM, Phillips XL-30 FEG/NEW) was used. Transmission electron microscopy (TEM, Philips Model CM200) confirmed the shape and microstructure. The crystal structures of the prepared samples were characterized by high resolution TEM (HRTEM). Energy dispersive X ray spectroscopy (EDS) was used to confirm the composition of the samples. According to the Brunauer-Emmett-Teller (BET) method (Micromeritics ASAP 2020), the error line of the specific surface area of the sample prepared from the N2 adsorption/desorption data is 1% of the measurement result. Fourier transform infrared (FTIR) spectra were obtained by using Nicolet Nexus spectrometer in the range of 4000–400 cm−1 using potassium bromide. The optical absorption properties of the samples prepared in 350–800 nm range were collected on UV-vis DRS (SHIMADZU UV-3600 Plus). BaSO4 is used as the reflectivity standard in UV-vis DRS experiment. Photoluminescence (PL) measurements of samples were carried out on SHIMADZU RF5301 (Japan), and data recorded in the range of 350–600 nm were recorded. The prepared samples were excited at 310 nm.

A series of zinc-based photocatalyst and bismuth-based photocatalyst were prepared. Several preparation methods and their characteristics of zinc-based photocatalyst are given. BiOIO3 nanosheets are studied systematically, which possess superior photocatalytic properties. The fabricated CSs-BiOI/BiOIO3 composites with heterostructures show the enhanced photocatalytic performance than BiOIO3. The physical and chemical properties of the as-prepared materials are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, high resolution TEM, Brunauer-Emmett-Teller, Fourier transform infrared, UV-vis diffuse reflectance spectra, and Photoluminescence.

Semiconductor photocatalysis technology is a green technology being developed rapidly in recent years by using solar energy for energy conversion and environmental purification, which has important application in both energy and environment. Photocatalysis has gradually been considered as a promising way to solve energy and environmental problems since Fujishima achieved hydrogen production from cracking water using titanium dioxide (titanium dioxide) in 1972. This field is becoming a hot topic and has attracted a lot of scientists’ attention and research. Semiconductor catalyst is driven by light to convert light energy into electrical or chemical energy without additional pollution. Furthermore, it is a technology to produce environmental friendly clean energy only with sunlight and can solve the ever increasing environmental pollution problems. In recent years, the depletion of fossil fuel and requirement of clean environment push the development of renewable energy including solar energy, which provides a good platform for the photocatalytic technology to accomplish the dream of blue sky and white cloud and sustainable developing. This chapter focuses on the development of photocatalytic technology for decades and expounds its development from the advent to the prosperous.

Mercury in the flue gas of coal combustion exists in three chemical forms: elemental mercury (Hg0), particle-bounded mercury (Hgp), and oxidized mercury (Hg2+). Hg2+ is water-soluble, so it can be removed by wet scrubbers and the Hg2+ removal efficiency can reach up to 90%. In addition, Hgp can be easily removed by electrostatic precipitator (ESP) or fabric filter (FF). However, elemental mercury is difficult to remove because of its volatility, insolubility and chemical stability. So the most critical step is to control elemental mercury. There are two main methods for elemental mercury control: adsorption and oxidation. Activated carbon injection has proven to be an effective adsorption method for elemental mercury removal in flue gas. However, its high operation cost and negative effect on fly ash quality may restrict its industrial application. The drawbacks associated with the use of particulate adsorbents make the oxidation method more attractive. In recent years, the progress in the photocatalytic oxidation of elemental mercury has aroused wide interests among researchers. Compared with other methods, photocatalytic oxidation possesses higher oxidation ability and no secondary pollution, therefore it is a promising technology for oxidation of elemental mercury. We set up a chemical reactor system to evaluate the photocatalytic performance on mercury in the simulated flue gas, and studied the mercury oxidation efficiency of different photocatalysts, including morphology controlled photocatalysts, metal or nonmetal modified titanium dioxide photocatalysts and others photocatalysts, such as BiOIO3 and ZnO. The morphology controlled photocatalysts include hollow titanium dioxide photocatalyst and anatase titanium dioxide with co-exposed (001) and (101) facets. The metal modified titanium dioxide photocatalysts include CuO/titanium dioxide and V2O5/titanium dioxide photocatalysts, and the nonmetal modified titanium dioxide photocatalysts include carbon spheres supported CuO/titanium dioxide photocatalysts and carbon decorated In2O3/titanium dioxide photocatalysts. These studies are helpful to observe the characteristics and performance of different kinds of photocatalysts.

NOX and SO2 emission from power plants during the coal burning process has been one of the major problems that result in adverse effect on the environment and human health. In general, ammonia based selective catalytic reduction (NH3-SCR) and calcium-based wet flue gas desulfurization (WFGD-Ca) processes have been applied to flue gas treatment of coal-fired power plants on a large scale, but they have not been able to achieve the comprehensive removal of a variety of pollutants. The combination of NH3-SCR and WFGD-Ca processes is mainly used to remove both simultaneous NOX and SO2, but the high capital operating costs limit its use in developing countries. In recent years, the study on the degradation of wastewater and gaseous pollutants by titanium dioxide has received extensive attention and has obtained good results in basic research and application-oriental research. Fe3O4-titanium dioxide composites were prepared by hydrothermal method, and the titanium dioxide layer was coated on the surface of Fe3O4. Because of the benefits of photocatalytic method, it has been paid attention to control NOx and other pollutant in the flue gas. The main principle of photocatalytically treating NOx is to photocatalytically oxidize NO into NO2, which is soluble and may be captured by WFGD through liquid absorption.