Organic Rankine cycle (ORC) which recovers waste heat in the temperature range of 80°C-140°C was investigated. Exergy efficiencies of various components and ORC system were paid great attention. The working ...
Organic Rankine cycle (ORC) which recovers waste heat in the temperature range of 80°C-140°C was investigated. Exergy efficiencies of various components and ORC system were paid great attention. The working fluids of R245fa and R600a are used. It is found that, for saturated ORCs, the expander inlet temperature has the optimum value, so the system exergy efficiency is maximum. With the increase of heat source temperature, the optimal inlet temperature of the expander is also increased. And also for saturated ORCs, the exergy efficiencies of evaporator and expander are highest efficiency, when evaporator exergy efficiency is increased with increase of heat source temperatures, the expander exergy efficiency is unchanged. The condenser decreased exergy efficiencies by increasing the heat source temperatures.
A tortuous labyrinth passage consists of a series of right angle turns in a disk of high pressure control *** this paper,numerical simulations are made for the velocity and pressure distributions in this *** is shown ...
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A tortuous labyrinth passage consists of a series of right angle turns in a disk of high pressure control *** this paper,numerical simulations are made for the velocity and pressure distributions in this *** is shown that the “series passage” can induce a pressure dropping more *** main function of the “series passage” is to induce a pressure dropping while the “parallel passage” is mainly to regulate the *** a cross sectional area process,a series of reduction and expansion,the pressure will also see dropping and partial recovery,which is called the multistage pressure *** this way,the velocity can be controlled in a reasonable level anywhere in this tortuous labyrinth *** the fluid pressure dropping in a downwards serrated way,the pressure is higher than the local saturate vapor pressure,therefore,no cavitation is induced by the phase transition.
Counter-current gas-solid downer reactors can be used to prepare necessary high solids concentrations for high heat and/or mass transfer processes. However, the downward particle movement is much likely to be prevente...
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Counter-current gas-solid downer reactors can be used to prepare necessary high solids concentrations for high heat and/or mass transfer processes. However, the downward particle movement is much likely to be prevented by an upward gas flow, which can be named as so-called "flooding" phenomenon. The energy-minimization multiscale (EMMS) theory has been shown to be capable of capturing multiscale heterogeneous structures in gas-solid systems, and hence is further utilized to simulate counter-current gas-solid downward flow in this article. The formulated model characterizes well the axial hydrodynamics and its parametric effects in counter-current gas-solid downers. Flooding gas velocity can be further determined from the calculation results, which is consistent with the empirical correlation qualitatively.
In this paper, [email protected] 2 O 4 with a fiber-in-tube mesoporous nanostructure has been fabricated via a one-step single-spinneret electrospinning technique. This unique nanostructure is made of an outer sp...
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In this paper, [email protected] 2 O 4 with a fiber-in-tube mesoporous nanostructure has been fabricated via a one-step single-spinneret electrospinning technique. This unique nanostructure is made of an outer spinel CoFe 2 O 4 tube and a loose inner fiber composed of the residual carbonaceous materials and metal precursors. The nanostructure's properties, such as morphology, components, structures and thermal stability, are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer, Emmett and Teller type specific area (S BET ) determination, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). As an anode material for lithium-ion batteries, the [email protected] 2 O 4 composite (6.25 wt% carbon content) exhibits a high reversible capacity of 740 mA h g −1 after over 200 cycles at the current density of 200 mA g −1 with excellent cycling stability, which is attributed to its one dimensional continuous fiber-in-tube mesoporous morphology, as well as its stable structure benefiting from the existence of carbonaceous yolk. In addition, pure CoFe 2 O 4 nanotubes can also be obtained by sequentially agitating this product in water, which provides more potential applications of CoFe 2 O 4 .
Based on the principle of depth from defocus,a three-dimensional positioning method based on two images with different degrees of blur was proposed for moving *** theoretical analysis,simulation work and experimental ...
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Based on the principle of depth from defocus,a three-dimensional positioning method based on two images with different degrees of blur was proposed for moving *** theoretical analysis,simulation work and experimental study of the 3 D movement measurement for micrometer-sized particles are carried out,respectively.A system was established for measuring experiments of three-dimensional particle movement,using single lens and dual *** distance between the lens and one of the cameras was adjusted by increasing the spacers of different *** the same object distance,two images with different degree of blur were *** image was transformed into gradient image by the adaptive edge detection algorithm based on gradient *** on the theory of moment invariants,the bright area of the image edge compared to the whole image is calculated,and the ratio of the two defocus radius α is *** to the formula of the object distance u,the depth position of the particle can be realized without *** order to verify the feasibility of the system,the simulation studies were conducted based on the calibrated parameters of the system,and images of the standard dots of 45μm to 2000μm were captured and processed for *** results show that during simulation,the error is less than 2% in 15 times depth of field of the imaging system,and the error in experiments is less than 8% in 12 times of depth of *** the results show that the size of particles has little effect on the accuracy of the method.
The ash-related issues due to the high-alkali characteristic are still unresolved during utilization of biomass and Zhundong coal. Here, the correlations of several chemical properties of high-alkali solid fuels were ...
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The ash-related issues due to the high-alkali characteristic are still unresolved during utilization of biomass and Zhundong coal. Here, the correlations of several chemical properties of high-alkali solid fuels were investigated. The distributions of ash compositions in various biomass exhibit obvious diversity, while the distribution of K 2 O content within wheat and corn straws are the most scattered. The ash content in biomass shows a decrease tendency with the increase of carbon content. Zhundong coals generally have medium but close ash fusion points despite of quite different ash compositions sometimes.
Nanostructure-derived interfacial effect plays a great role in enhancing catalytic activities. Herein, a MnO 2 [email protected] nanosheets core-shell hybrid nanostructure was successfully prepared by uniformly d...
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Nanostructure-derived interfacial effect plays a great role in enhancing catalytic activities. Herein, a MnO 2 [email protected] nanosheets core-shell hybrid nanostructure was successfully prepared by uniformly decorating NiO nanosheets on the one-dimensional MnO 2 nanowires. The physi-chemical properties of the MnO 2 and MnO 2 @NiO were characterized by using XRD, BET, SEM, H 2 -TPR and XPS techniques. Compared to the single MnO 2 nanowires, the MnO 2 @NiO nanocomposite with better low-temperature reducibility and more active surface oxygen species exhibited much better performance in complete oxidation of benzene, giving the temperatures for 100% benzene conversion of 320 °C under the conditions of 1000 ppm benzene in air and space velocity of 120,000 mL g −1 h −1 while the value over pure MnO 2 was 380 °C. The novel hetero-interface constructed between MnO 2 and NiO core-shell nanostructures might make a great contribution on this significantly promoting effect.
The influences of operating conditions, such as excess air ratio and SOFA arrangement, on temperature distributions, species distributions, NO x emissions and burnout of a tangentially-fired utility boiler using bitum...
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The influences of operating conditions, such as excess air ratio and SOFA arrangement, on temperature distributions, species distributions, NO x emissions and burnout of a tangentially-fired utility boiler using bituminous and blended coal were investigated by numerical approach in the present study. The simulation results show that the fuel type exhibits certain effect on the temperature distributions and the NO x emissions. Moreover, higher excess air ratio could restrain the CO formation but promote NO x emission. The temperature and the species distributions are highly related to the SOFA arrangement. In addition, SOFA technology is still an effective approach to control the NO x emissions during blended coal combustion, while the disadvantageous effect on char burnout should be considered.
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