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The fractal derivative is adopted to describe the non-linear fractional wave equation in a fractal space. A variational principle is successfully established by the semi-inverse method. The two-scale method and He?s exp-function are used to solve the equation, and a good result is obtained.

Copper-1,3,5-benzoic acid (Cu-BTC) was synthesized by the hydrothermal method, which had regular octahedral morphology. The Cu-BTC particles were used as additives in the polyacrylonitrile (PAN) solution fabricate Cu-BTC/PAN membrane by the electrostatic spinning method, its good filtration performance was witnessed experimentally.

Crude oil is an attractive fuel for energy production, since its use does not require additional processing costs. Existing technologies for burning liquid fuel do not always ensure the achievement of the modern ecological and energy performance when using highly viscous and substandard fuels. This relates to unstable ignition and combustion of such fuels in the combustion chamber, relatively fast coking of the burner surfaces, etc. The work deals with investigation of crude oil burning in a flow of superheated steam as a promising way to reduce NOx and increase the completeness of fuel combustion. The experiments were carried out using an original burner where liquid fuel is sprayed due to interaction with a high-velocity flow of superheated steam. This method of spraying allows the creation of a highly dispersed two-phase flow and prevents nozzle chocking and coking when using sub-standard fuel and waste. At the same time, steam gasification of products of fuel thermal decomposition allows the reduction of toxic emissions, increasing carbon burnout. The regimes of crude oil burning in a modernized burner that provide high completeness of fuel combustion (~44 MJ/kg) with a low content of NOx and CO in the combustion products have been determined. The amount of these toxic components corresponds to class 1 of EN 267. The results obtained confirm the effectiveness of the investigated method of fuel spraying by a superheated steam jet for environmentally friendly crude oil burning, including this process in the low-power burners (~15 kW). Such devices can be used for the cleaner elimination of liquid hydrocarbon waste with the receipt of thermal energy.

Exergy analysis of a vapor-compression refrigeration system with TiO2 nanoadditives in the compressor oil was performed. Two-step method was used for the preparation of nanooil for various solid particle volume fractions between 0% and 1%. Irreversibilities were determined by using the Second law of thermodynamics. It is found that a reduction in total irreversibility is achieved with nano-particle inclusion and it was significant for higher particle volume fraction.

Injection and mixing of cryogenic propellants are very complex at near-critical and supercritical conditions. The concise description and the reliable measurements on such flows are still questionable. In this work, a RANS study is performed for a pure N2 fluid injection at transcritical conditions on a laboratory scale test rig. An in-depth thermodynamical analysis on the real-gas behavior has allowed N2 density prediction over the experimental range of the injection temperature and for several equations of state. A focus was thrown on the prediction of the density evolution on the chamber centerline and across the injector. The calculations were performed using both adiabatic and constant temperature conditions for the injector wall. The inner heat transfer in the injector had a significant effect on the jet density distribution and therefore, on the overall flow dynamics. Numerical results regarding axial profiles of density and dense core lengths agree fairly well with the experimental data provided by the literature.

This paper first analyzes that the waste heat before the flue gas of thermal power company enters the desulfurizationwer can be heated by the low pressure economizer, and then the heated condensate can be incorporated into the regenerative system, so as to recover the waste heat and improve the unit efficiency. In this paper, the possible lay-out scheme of the low pressure economizer in the thermal system is constructed firstly, and then the mathematical model of the equivalent enthalpy drop increment of the unit is established with the water partition coefficient as the independent variable. Particle swarm optimization and co-ordinate rotation are used to optimize the model, and the results show that particle swarm optimization is more effective in solving the problem. After the low pressure economizer is added to the unit, the heat consumption of the whole plant of the unit is reduced by 61.131, the unit efficiency is increased by 0.783%, and the coal consumption of the whole plant is reduced by 2.293. Finally, from the perspective of industrial agglomeration, industrial diversification and economic resilience, this paper analyzes the advantages of diversified agglomeration of thermal power companies.

The motion of non-Newtonian fluid with heat and mass transfer through porous medium past a shrinking plate is discussed. The fluid obeys Casion model, heat generation, viscous dissipation, thermal diffusion and chemical reaction are taken in our considered. The motion is modulated mathematically by a system of non liner partial differential equations which describe the continuity, momentum, heat and mass equations. These system of non linear equations are transformed into ordinary differential equations by using a suitable transformations. These equations are solved numerically by using Mathematica package. The numerical distributions of the velocity, temperature and concentration are obtained as a functions of the physical parameters of the problem. Moreover the effects of these parameters on these solutions are discussed numerically and illustrated graphically through some figures. It is clear that these parameters play an important role to control the velocity, temperature and concentration of the fluid motion. It’s found that the fluid velocity deceases with the increasing of electric parameter while it increases as the magnetic hartman parameter increases, these results is good agreement with the physical situation. Also, the fluid temperature decreases and increases as the Prandtl number and Eckert number increases respectively. At least the fluid concentration decreases with both of soret and schimdt numbers.

With the increase of particulate pollution in the atmosphere, it becomes extremely significant to understand the overall distribution characteristics of particulates and their adsorption of toxic gases for the source analysis and precise controlling of atmospheric particulate matters. The fractal theory was adopted to analyze particle sizes distribution characteristics in Xi?an city, China. Results showed the fractal dimension of particulate matters distribution ranged from 4.32-4.83, with an average fractal dimension of 4.54. A higher fractal dimension predicts a higher concentration of fine particles. Additionally the effects of outdoor temperature, humidity, and wind speed on the fractal dimension were also studied experimentally

In this article, we present an efficient local meshless method for the numerical treatment of 3-D convection-diffusion PDE. The demand of meshless techniques increment because of its meshless nature and simplicity of usage in higher dimensions. This technique approximates the solution on set of uniform and scattered nodes. The space derivatives of the models are discretized by the proposed meshless procedure though the time fractional part is discretized by Liouville-Caputo fractional derivative. Some test problems on regular and irregular computational domains are presented to verify the validity, efficiency, and accuracy of the method.

The understanding of gas sorption mechanism is essential to characterize the original gas-in-place for shale gas reservoirs. In this study, experimental data of five shale samples have been used to estimate the shale gas-in-place with new sights. Langmuir model is commonly used to measure the amount of adsorbed gas but this model does not include the amount of absorbed gas and its behavior. However, such gas usually contributes about 22% in respect to total gas storage even though its input remains undefined. Sorption model used in this study includes adsorbed and absorbed gas. Good results are obtained from sorption model as compared to Langmuir model. Variable range of total gas storage is observed using different approaches in all shale samples. Initially at low pressure, total gas storage is observed to be higher because of gas absorption contribution in new proposed approach when compared to approach-2. When pressure increases, total gas storage is altered in keeping with characteristics of adsorption and absorption of gas. Adsorbed and sorbed porosity is estimated at two different approaches and where total gas storages capacity is affected due to adsorbed or sorbed porosity. Further, the contribution of absorbed gas amount is found at about 19-22% in respect to total gas storage in all shale samples and that is in same range as mentioned in literature. The sorption model and new proposed approach includes adsorption and absorption of gases and provides new insights to understand the gas storage mechanisms and estimation of shale gas-in-place.

This paper presents a numerical study of a double diffusive convection in an inclined square porous cavity filled with an electrically conducting binary mixture. The upper and bottom walls are maintained at a constant temperatures and concentrations whereas the left and right walls are assumed to be adiabatic and impermeable. A uniform and tilted magnetic field is applied at an angle, γ, about the horizontal, it is obvious that this is related to the orientation of the magnetic force that can help or oppose the buoyant force. The Dupuit-Darcy flow model, which includes effects of the inertial parameter, with the Boussinesq approximation, energy and species transport equations are solved numerically using the classical finite difference method. Governing parameters of the problem under study are the thermal Rayleigh number, Rt, Hartmann number, Ha, Lewis number, Le, the buoyancy ratio, φ,inclination angle, Φ and tilting angle of the magnetic field, γ,. The numerical results are reported on the contours of streamline, temperature, and concentration and for the average Nusselt and Sherwood numbers for various parametric conditions. It is demonstrated that both the inertial effect parameter and the magnetic field, have a strong influence on the strength of the natural convection heat and mass transfer within the porous layer.

Nanofluids have high thermal conductivity and can be used as vehicle engine coolant. In this article, the effects of Al2O3 nanoparticles to an engine coolant were experimentally investigated and the results were compared with the results of the original coolant including 50% ethylene glycol and 50% water mixture. The nanofluid was prepared by adding 0.5% Al2O3 nanoparticles by volume. The inlet temperature of the coolant was held constant at 95?C. The tests were carried out at the air inlet temperatures between 23.4-28.6?C, the air velocity be-tween 1.7-4.3 m/s, the cooling power between 2.5-15 kW and the cooling fluid flow rates between 10-25 Lpm. The results show that nanoparticles increase the cooling performance of the engine radiator. By using Al2O3 nanoparticles, cooling power of the radiator has increased up to 17.46% compared to original case.

A fractal modification of the reaction-diffusion process is proposed with fractal derivatives, and a fractal variational principle is established in a fractal space. The concentration of the substrate can be determined according to the minimal value of the variational formulation. The solution process is illustrated step by step for ease applications in engineering, and the effect of fractal dimensions on solution morphology is elucidated graphically.

A space spectral interpolation collocation method is proposed to study non-linear reaction-diffusion systems with complex dynamics characters. A detailed solution process is elucidated, and some pattern formations are given. The numerical results have a good agreement with theoretical ones. The method can be extended to fractional calculus and fractal calculus.

Mixed convection has been one of the most interesting subjects of study in the area of heat transfer for many years. The entropy generation due to MHD mixed convection heat transfer in L-shaped enclosure being filled with Cu-water nanofluid and having an internal heating generation is explored in this investigation by the finite volume technique. Lid-motion is presented by both right and top parts of walls to induce forced convection and the cavity is under an inclined uniform magnetic field along the positive horizontal direction. The statistics concentrated specifically on the impacts of several key parameters like as the aspect ratio of the enclosure, Hartmann number, nanoparticle volume fraction, and heat source length/location on the heat transfer inside the L-shaped enclosure. Outcomes have been manifested in terms of isotherm lines, streamlines, local and average Nusselt numbers. The obtained results show that addition of nanoparticles into pure fluid leads to increase of heat transfer. The maximum value of local Nusselt pertaining to the heat source occurs when L = 0.1. Impacts of heat source size and location, internal heat generation absorption, angle of magnetic field on heat transfer and entropy generation are completely analyzed and discussed. The best configuration and values of important parameters are also presented using thermal performance criteria.

Based on one planned arctic natural gas pipeline engineering which will cross continuous, discontinuous, sporadic and non-permafrost areas from north to south, with different pipeline temperatures set, a thermal model of the interaction between pipeline and permafrost is established to investigate the influence of pipelines on the freezing and thawing of frozen soil around pipeline and thermal stability of permafrost. The results show that different pipeline temperatures influence the permafrost table greatly. Especially in discontinuous permafrost areas the permafrost table is influenced in both positive temperature and negative temperature. The warm gas pipeline of 5oC could decrease the value of permafrost table about 1 to 3 times pipe diameter and aggravate the degradation of permafrost around pipeline; -1oC and -5oC chilled gas pipeline can effectively improve the permafrost table and maintain the temperature stability of frozen soil , but the temperature of soils below pipeline of -5oC decreases obviously, which may lead to frost heave hazards. In terms of thermal stability around pipeline, it is advised that transporting temperature of -1oC is adopted in continuous permafrost area; in discontinuous permafrost area pipeline could operate above freezing in the summer months with the station discharge temperature trending the ambient air temperature, but the discharge temperature must be maintained as -1oC throughout the winter months; in seasonal freezing soil area chilled pipeline may cause frost heave, therefore pipeline should run in positive temperature without extra temperature cooling control.

The differential model for electrochemical capacitors under dynamical cycling results in discontinuity of the electric current. This paradox makes theoretical analysis of the electrochemical capacitors much difficult, and there is not universal approach to treatment of the problem. This paper finds that the fractal calculus can be powerfully applied to the problem, and a continuous electric current can be obtained as it should be.

A kind of anomalous diffusion and heat transfer on a comb structure with anisotropic relaxation are studied, which can be used to model many problems in bio-logic and nature in fractal porous media. The Hausdorff derivative is introduced and new governing equations is formulated in view of fractal dimension. Numerical solutions are obtained and the Fox H-function analytical solutions is given for special cases. The particles spatial-temporal evolution and the mean square displacement vs. time are presented. The effects of backbone and finger relaxation parameters, and the time fractal parameter are discussed. Results show that the mean square displacement decreases with the increase of backbone parameter or the decrease of finger relaxation parameter in a short of time, but they have little effect on mean square displacement in a long period. Particularly, the mean square displacement has time dependence in the form of t?/2 (0 < ? ? 1)when t>?, which indicates that the diffusion is an anomalous sub-diffusion and heat transfer.

Many factors have an influence on the development of compartment fire notably on its heat release rate as well as on its capability to propagate and become a flashover situation. The main element which rapidly conveys fire from a compartment to another is hot smoke flowing out through openings of the compartment source of fire. The present work aims to experiment the impact of the variation of heat release rate of the source on the behaviour of fire. So, five fire tests with different heat release rates were thus carried out in a reduced scale room. Temperature of burned gases inside the room, were measured during tests by sensors connected to a data acquisition system. Results revealed that temperature of burned gases as well as its content in carbon monoxide, evolves differently according to two ranges of the incoming air/outgoing gases ratio. The first range of which the ratio is lower than 2, corresponds to the case where both parameters decrease rapidly. The second range of which the ratio is higher than 2, corresponds to the case where both parameters decrease moderately. The transition from the first to the second range, points out the passing from the ventilation-controlled fire to the fuel-controlled fire. A relation expressing the variation of the mass flow rate of outgoing burned gases according to the heat release rate of the fire source has been given.

Accurately obtaining the temperature distribution of the medium in the shutdown pipe-line of waxy crude-oil has important guiding significance for making maintenance plan and restart plan. The phase transition process of waxy crude-oil involves complex problems such as natural-convection heat transfer, latent heat release, and difficulty in tracing liquid-solid interface. In this paper, the concept and significance of breaking point were proposed. Taking the breaking point and the freezing point as dividing point, a new zonal partition model was established based on the influence of phase change of crude-oil wax crystal on heat transfer mode, with the corresponding governing equations being established for different regions. With the proposed model, the effects of natural-convection on heat transfer, latent heat release, location change of condensate reservoir, heat transfer mechanism, and other key issues in the process of oil phase transition were analyzed.

Temperature is one of the important reasons causing the cracks on the bridge structure during the construction and operation. In this paper, the temperature field produced by hydration heat and early thermal stress of a 64 m simply supported channel-box girder are simulated during casting process, considering the time-varying characteristics of concrete shrinkage and creep, elastic modulus, and tensile strength. Then, various parameters influencing the temperature field are analyzed, and the corresponding measures of controlling temperature cracks are proposed.

We consider a heat transfer augmentation problem to minimize the entropy generation by assuming boundary-layer flow of nanofluid over a moving wavy surface. The nanofluid demonstrates great potential in enhancing the heat transfer process due to its high thermal conductivity. The famous Tiwari and Das model has been used in the present article. Two types of water based nanofluids containing Cu and Fe3O4 nanoparticles are considered. Moreover, the surface texture is taken to be sinusoidal wavy to improve the thermal contact. The governing equations are transformed into a system of non-similar PDE by using suitable dimensionless variables and solved by the Keller-Box method. The effects of involved parameters like amplitude wavelength ratio, group parameters, and volume fraction on the total entropy number and the Bejan number are analyzed graphically. It is showed Fe3O4 base nanofluid is more effective to lessen the entropy production as compared to Cu base nanofluid.

Smaller fibers are welcome in many applications due to larger surface area, but there is a threshold for smallest fibers for a fixed spinning system. In order to further improve surface area, hierarchical structure is considered in this paper using electrospinning. A bi-solvent system is used in our experiment for fast solvent evaporation. Unsmooth nanofibers are obtained, and the formation mechanism is elucidated.

An isotropic structure modelled as a Timoshenko beam is considered for the optimal vibration control problem. The beam model to be controlled is described by a distributed parameter system with the selection of Timoshenko?s shear correction factor. Control of the vibrations is achieved through a function placed on the boundary conditions. The performance index which seeks to be minimized indicates that the goal is to minimize the magnitude of performance measure without consuming control effort in large quantities. It is shown how to derive the optimal control function using Pontryagin?s principle that turns the control problem into solving optimality system of PDE with terminal values. Wellposedness of the optimal solution on the control set is presented and controllability of the problem is analyzed. Numerical simulations are given in terms of computer codes produced in MATLAB? in the forms of graphical and tables in order to show the applicability and effectiveness of the control acting on the boundary conditions.

In this work we study numerically the turbulent natural convection of nanofluids (water + Al2O3/NTC/Cu) in rectangular cavities differentially heated. The objective is to compare the effect of the macro-structural aspect of the rectangular cavity and the effect of the types of nanofluids studied on the thermal exchange by turbulent natural convection in this type of geometry. Therefore, we have numerically treated the cases of these three nanofluids, for different particles volume fractions (0 ? ? ? 0.06) and for different form ratios of the rectangular cavity. The standard k-? turbulence model is used to take into account the effects of turbulence. The governing equations are discretized by the finite volume method using the power law scheme which offers a good stability characteristic in this type of flow. The results are presented in the form of streamlines and isothermal lines. The variation of the average Nusselt number is calculated as a function of the types of nanoparticles, of theirs particles volume fractions, for different form ratios of the cavity, and for different Rayleigh numbers. The results show that the average Nusselt number is greater as the form ratio is large and that the effect of the use of CNT in suspension in a water prevails for voluminal fractions and large Rayleigh numbers.

This paper establishes a mathematical analysis for describing the homogeneous and heterogeneous chemical reactions in the nearness of stagnation region of a sphere immersed in a single-phase nanofluid due to a Newtonian heating. The flow is resulted by an impulsively rotating sphere, and the nanofluid involves nanoparticles of Copper and Ferro. The available unsteady-states of the considered system are given in the case when the diffusion coefficients of both reactant and auto catalyst have the same size. The resulting non-linear dimensionless coupled partial differential equations in which governing the mixed convection flow have been tackled numerically via an implicit finite difference technique in combination with the quasi-linearization scheme. The similarities and differences in the behavior of physical pertinent fluid parameters have been elaborated and discussed graphically. It has been clarified that the nanofluid velocity and temperature profiles grow gradually by adding nanoparticles in the base fluid. Again it is noticed from present contribution that concentration of the nanofluid is decreases function by rising the strength of homogeneous and heterogeneous chemical reactions. Finally, numerical computations of the skin friction and heat transfer factors are presented.

Although the increment the performance of photovoltaic thermal (PVT) systems by using the nanofluids as working fluids have gained the attention of researchers during the last two decades, there is still, a lack in the literature study associated to this application. This study contributes to the investigations and researches of applying the nanofluids to increase the performance of PVT collectors. A flat non-concentrating PVT collector has been designed, constructed and, outdoor tested in Karabuk University, Turkey. The considered working fluids in this study are multiwall carbon nanotubes (MWCNT), and graphene nanoplatelets dispersed in water as a base fluid with a concentration of 0.5 wt.%. The experiments were run with a volume flow rate of 0.5 L per minute for the aforementioned nanofluids and distilled water (as a reference fluid). The study results have shown and revealed that the MWCNT-water nanofluid presented a better performance in terms of eletrical energetic efficiency compared to graphene nanoplatelets-water nanofluid and distilled water, while graphene nanoplatelets-water nanofluid revealed the highest thermal energetic efficiency. Moreover adding thermal unit to photovoltaic module enhanced the total energetic efficiency by 53.4% for distilled water, 57.2% for MWCNT-water, and 63.1% for graphene-water.

This work is about studying the natural convection of two-dimensional steady state non-Newtonian power law fluid numerically. The inner cylinder was put eccentrically into the outer one. The cylinders are held at constant temperatures with the inner one heated isothermally at temperature Th and the outer one cooled isothermally at temperature Tc (Th>Tc). The simulations have been taken for the parameters 103?Ra?105, 10?Pr?103, 0.6?n?1.4, 0???0.9 and an inclination angle ? from 0? up to 90?. The average Nusselt numbers for the previous parameters are obtained and discussed numerically. The results revealed that the average Nusselt number has the highest values when n=0.6, Ra=105 at ?=0 which is a signal for the large transfer herein and has the lowest values for n=1.4, Ra=103 at ?=90? which is a signal that the transfer is by conduction more than convection. Furthermore, the increasing of eccentricity causes an increase in the Nusselt number for all the cases. Finally, the best case where we can get the best heat transfer is at ? = 0, ?=0.9 among them all. The results have compared with some precedent works and showed good agreement.

The linear and non-linear Klein-Gordon equations are considered. The fractional complex transform is used to convert the equations on a continuous space/time to fractals ones on Cantor sets, the resultant equations are solved by local fractional reduced differential transform method. Three examples are given to show the effectiveness of the technology.

In this study, HKUST-1 prepared under solvothermal conditions and tested in desulphurization of model gasoline. The prepared HKUST-1 samples were characterized using surface area and pore volume analysis (BET), powder X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR). The prepared HKUST-1 was used for desulphurization of model gasoline (thiophene with iso-octane), and the influence of the thiophene concentration, HKUST-1 dose, temperature, and contact time. The experimental results revealed that the sulfur content in model fuel was reduced from 1500-148.2 ppm (90.12% removal efficiency) for four hours contact time at 30 ?C. In addition, an isotherm adsorption and kinetics study were performed for a batch process to understand the system equilibrium (i. e., the best fitting Langmuir isotherm or Freundlich isotherm). The kinetics study proved that the contained sulfur removal was best fitted by pseudo-second-order kinetics. Regeneration results show that the HKUST-1 has a reversible nature as an adsorbent. Therefore, HKUST-1 might be used as a promising adsorbent for removing thiophene compounds from gasoline.

This paper proposes a novel exponential rational function method, a modification of the well-known exp-function method, to find exact solutions of the time fractional Cahn-Allen equation and the time fractional Phi-4 equation. The solution procedure is reduced to solve a system of algebraic equations, which is then solved by Wu?s method. The results show that the present method is effective, and can be applied to other fractional differential equations.

Higher temperature and humidity will adversely affect the thermal comfort of helmet users. In order to improve the comfort level of the helmet and obtain an optimal cooling helmet model, four kinds of helmet models were established by using phase change material, heat-absorbing cooling technology, and fan cooling technology. Through the air conditioning system, the working states of four kinds of helmet models in the thermal environment of 30 ? were simulated, and the thermal comfort of four kinds of helmet models was evaluated. The results show that: high temperature environment is an important factor affecting the cooling effect of fan helmet fan, Under high temperature environment, the helmet with fan cooling technology has a certain cooling effect in the early stage, but after 30 minutes, the cooling effect becomes worse and worse. Under high temperature environment, phase change materials safety helmet has a good cooling effect, but poor ventilation results in the excreted sweat clinging to the scalp and hair, resulting in a poor user experience. There are defects in using phase change material heat absorption cooling technology or fan cooling technology alone. The helmet combines phase change material heat absorption cooling technology with fan cooling technology, so that the cooling effect and internal thermal environment stability of the helmet are the best, and the thermal sensation of human body is the best. Therefore, the helmet is an optimal design model.

The mechanical properties of certain flexible core materials of ship structure sandwich panels, having skins made of metallic or composite laminates maybe significantly influenced by the temperature variations that may occur during the operational loading. At the same time, the improving knowledge of the behaviour of these panels in terms of bending strength and other stress/strain related aspects in various harsh conditions increases their superiority in terms of weight-to-strength ratio, high stiffness, easy to manufacture, acoustic, and thermal insulation. In the paper, the behaviour of the ship structural rectangular sandwich panels to the mechanical and thermal loading are presented. The sandwiches have a special core of 20 mm and skins made out of different materials (glass fiber reinforced polyester, steel and aluminum) with a thickness of 3 mm. Analysis consists of the behaviour of the composite sandwich panels in the bending test at constant speed by the three-point method, for three distances between different supports, by measuring the maximum displacement and force applied to the specimens under various thermal fields. The sandwich structures are also thermally analysed, determining their thermal conductivity by the heat flow measurement method. The experimental results are compared with the results obtained by finite element analysis in numerical simulation of all modelling cases.

An extended variational iteration method within the local fractional derivative is introduced for the first time, where two Lagrange multipliers are adopted. Moreover, the sufficient conditions for convergence of the new variational iteration method are also established.

Lead acid batteries have been widely used in different fields, so abundant waste lead acid battery was generated. Waste lead acid battery is regarded as a toxic material due to the metallic lead and the lead paste compounds. Once lead and its compounds enter the human body and the environment, which will cause serious threats. At present, the waste lead acid batteries are mainly recovered in the form of metal lead, which has many problems. Thus, this paper put forward a novel technology to recycle waste lead acid battery. Vacuum thermal decomposition was employed to treat recycled lead carbonate from waste lead acid battery. Thermodynamics analysis and experiments were finished from the reaction free energy of lead carbonate decomposition and vacuum furnace. The results showed that the recycled lead carbonate began to be decomposed when the temperature reached 250°C. Above 340°C, most of intermediate PbCO3•2PbO were converted to red α-PbO and then transformed to yellow β-PbO when the temperature was raised further to 460°C. Furthermore, the study provided the fundamental data for the preparation of α-PbO and β-PbO in vacuum, which also demonstrated a new way for the reuse of spent lead acid battery resource and an outlook of sustainable production.

Dry hot rock power generation is an important part of geothermal energy application, and condenser has become an important part of the system because it can provide a lower outlet back pressure for steam turbine, and improve the power generation of the system. Engineering equation solver is applied to assess the performance of cooling towers for ORC power generation systems. In the present study, two models with different cooling towers are considered. In the first model, the predicted performance of the opening cooling tower for ORC systems is studied and compared with the experimental measurement for a 500 kW system and in the second model, because of the high mass-flow of the cooling water and high energy consumption of the cooling water pump for the opening cooling tower, the predicted performance of the closed wet cooling tower to replace the opening cooling tower for ORC systems is studied. The models are capable of predicting the variation of evaporation and condensation temperatures, the pressure loss of heat ex-changers. The R123, R227ea, R245fa, R600, and R600a are tested as working flu-ids. The results show that the second model reduces the energy consumption of the cooling water pump, and it also improves the net power generation and net generation efficiency for using R227ea, R600, and R600a. However, with the increase of the closed wet cooling tower pressure loss, both the net power generation and net generation efficiency decrease. Therefore, different working fluids are suitable for different pressure loss.

Fractal calculus is an excellent tool to explaining natural phenomena in porous media. In this paper, we first give a simple introduction on He?s fractal derivative, and then it is used to establish a model for thermal conduction of silkworm cocoon reveal its biomechanism. The theoretical results obtained in this paper are helpful for the biomimetic design.

An experimental study was carried out to investigate the effect of intake air pre-heating, exhaust gas re-circulation, and hydrogen enrichment on performance, combustion, and emission characteristics of CH4/waste cooking oil biodiesel fuelled compression ignition engine in dual fuel mode. Methyl ester derived from waste cooking oil was used as a pilot fuel which was directly injected into the combustion chamber at the end of the compression stroke. The CH4/hydrogen-enriched methane was injected as the main fuel in the intake port during the suction stroke using a low pressure electronic port fuel injector which is controlled by an electronic control unit. The experiments were conducted at a constant speed and at the maximum load. Experimental results indicated that the increase in energy share of gaseous fuel extends the ignition delay. With air preheating the thermal efficiency increased to 49% and 55% of CH4 and hydrogen-enriched CH4 energy share, respectively. The CO and HC emissions were higher in CH4 combustion with biodiesel when compared to the conventional diesel operation at full load and a reduction in CO and HC was observed with air preheating. Lower NOx were observed with gaseous fuel combustion and it further reduced with exhaust gas re-circulation but NOx increased by preheating the intake air. Improvement in thermal efficiency with a reduction in HC and CO was observed with hydrogen-enriched CH4.

In this work, the condensation heat transfer and pressure drop characteristics of plate heat exchangers were simulated, and the 3-D temperature, pressure, and velocity fields were obtained. From the flow field, we can see that the velocity of vapor is higher than that of condensate. From the pressure field, we can see that the pressure shows a downward trend along the flow direction, and there is, the more pressure drop in the first half of the plate. From the temperature field, we can see that the temperature gradient increases with the increase of velocity and pressure gradient. Meanwhile, the effect of vapor mass-flow, dryness and super-heat on condensation heat transfer coefficients and pressure drops were investigated. The results show that the pressure drop and heat transfer coefficient both increase with the increase of dryness, degree of superheat and mass-flow. In addition, the correlation equations developed to predict the condensation heat transfer and friction factor perfectly agree with the experimental results.

Reasonable capacity configurations of distributed energy system are issues which need to be discussed. Determinate design without considering variations in energy load and energy prices can result in non-achievement of project targets during its service life. Therefore, a design method that takes into account uncertain factors takes precedence over other methods. In this paper, a three-stage optimization method is proposed to provide theoretical guidance on the optimization of combined cooling, heating, and power system configurations. The first two stages link the optimization of the operation strategy and equipment capacities simultaneously under current load and energy prices. The Monte-Carlo simulation is applied in the third stage to fully consider the effects of various possible scenarios, and the Tabu search algorithm was introduced for system optimization. The comprehensive benefits include energy consumption, economy, and emission level. These were taken into consideration in the objective function. Moreover, a detailed design process was presented to illustrate the application of the proposed method. In conclusion, the proposed method is not only suitable for the design of combined cooling, heating, and power system, but could easily extend to other energy system easily.

In order to maintain the cryogenic environment of cryogenic wind tunnel in service, heat transfer of insulation structure is investigated in this work. Firstly, the design and material selection of insulation structure is conducted. Afterwards, theoretical calculation on heat transfer of insulation structure is carried out based on 1-D heat conduction model. Subsequently, the finite element model of insulation structure is established, on this basis, involving the actual work condition of cryogenic wind tunnel, heat transfer of the insulation structure is numerically calculated. Finally, the testing platform able to simulate the work environment of cryogenic wind tunnel is built and the temperature measurement experiments at the cryogenic condition and at the cryogenic pressure condition are carried out, respectively. The obtained results show that the designed insulation structure is in possession of great insulation characteristics to ensure the cryogenic environment of cryogenic wind tunnel. Additionally, the established testing platform can provide a testing method to investigate the heat transfer character of other materials or structures in cryogenic environment.

A fabric?s moisture/air permeability is a main factor for the fabric design for advanced applications, and no theoretical model was available in literature for an optimal permeability. In this paper, we use the capillary-like effect to elucidate the permeability property, and the effect of nano/micro particles on the fabric?s surface on the permeability is studied by the geometric potential theory. Our theoretical analysis shows that an unclean surface gives a negative impact on the permeability. A superhydrophobic surface is needed to design a good and lasting moisture/air permeability.

The special active agent content of herbs makes them suitable for healing and health preservation. The key element in the processing of herbs and spices is drying. Before drying, the medicinal plants should be stored under appropriate conditions to avoid deterioration of quality where one of the possible methods is pre-drying with ambient air. This work defines the determination of main operational parameters at forced convection drying with ambient air like drying rate, volume decrease, maximum drying air velocity, and porosity for various medicinal plants (common yarrow ? Achillea collina, giant goldenrod ? Solidago gigantea, wormwood ? Artemisia, walnut leaf ? Juglandis folium, wild carrot ? Daucus carota). To determine the drying rate, a convective dryer was used where the average drying rate of common yarrow and wild carrot were the highest followed by giant goldenrod, walnut leaf and wormwood. Measurements were made on a pilot plant fluidized bed dryer to determine the volume decrease and the maximum drying air velocity. The volume decrease was determined as a function of time and moisture content. It was found that the maximum drying air velocity for each medicinal plant was between 1.8 and 2.2 m/s. In addition, for each herb the porosity was measured by an air pycnometer.

High speed rail vehicles need to start the emergency traction battery system in an emergency. In order to ensure that the emergency traction battery system can be quickly started in cold conditions and ensure that the high speed railway has sufficient mileage, this paper proposes a multi-stage heating method based on flat heat pipes. The thermodynamic parameters of the power battery are obtained by simulation analysis and experimental verification. According to the thermodynamic model, the heat generation model and coupled heat transfer model of the battery are established. Different heating powers are assigned to different heating points and the total heating power is kept constant. Through the analysis results, the multi-stage heating device of the emergency traction battery system can effectively reduce the heating time under cold conditions and the temperature difference between the battery system Modules. This paper can provide reference to the design of the battery pack and the matching of the heating system.

Investigating the pool boiling process in the absorption chiller generator by studying the valid parameters may enhance the chiller?s COP. In the present study, the transient 2-D numerical modelling of LiBr/H2O solution pool boiling in the generator of the absorption chiller was carried out using the two-phase Eulerian-Eulerian approach, extended Rensselaer Polytechnic Institute boiling model and renormalization group k-? turbulence model. The numerical model was applied on three types of the bare, notched fin, and low fin tubes to investigate the effect of using fin on the boiling heat transfer rate in the generator of the absorption chiller and comparing it with the bare tube. Moreover, the numerical results were compared with the data obtained from the previous experimental studies to validate numerical modelling. A good agreement was achieved between numerical and experimental results. The results showed the evaporation mechanisms in the microlayer, evaporation in the three-phase (liquid-vapor-solid) contact line, and transient conduction the superheat layer for constant thermal heat flux and the three surfaces of the copper tube within a specific period from the boiling point of LiBr/H2O solution. The results also showed that the use of a notched fin-tube and low fin tube increases the non-homogeneous nucleation rate, causes the solution boil earlier than the bare tube, and reduces the required thermal energy in the generator of an absorption chiller.

The present numerical investigation aims to analysis the enhancement heat transfer in the nanofluid filled-complex geometries saturated with a partially layered porous medium. The vertical walls of the cavity are taken as complex wavy geometries. The horizontal walls of the cavity are flat with insulated temperature. The complex wavy cavity is filled with a nanofluid and the upper half of the wavy cavity is saturated with the porous medium. In the analysis, the governing equations are formulated for natural convection under the Boussinesq approximation in various environments including pure-fluid, nanofluid, and porous medium. In this investigation, the effects of the Rayleigh number (103 ? Ra ? 105), Darcy parameter (10?6 ? Da ? 10?3), thermophoresis parameter (0.1 ? Nt ? 0.5), nanofluid buoyancy ratio (0.1 ? Nr ? 0.5), Brownian motion parameter (0.1 ? Nb ? 0.5), inclination angle (0? ? ? ? 90?), and geometry parameters ?1 and R have been studied on the streamlines, temperature, nanoparticles volume fraction, local Nusselt number, and the local Sherwood number. It is found that, the performance of the heat transfer can be improved by adjusting the geometry parameters of the wavy surface. Overall, the results showed that the nanofluid parameters enhance the convection heat transfer and the obtained results provide a useful insight for enhancing heat transfer in two separate layers of nanofluid and porous medium inside complex-wavy cavity.

In this study, the flow as well as heat transfer of a classical Newtonian fluid of constant density and viscosity in a porous medium between two radially stretching disks is explored. The role of the porosity of the medium, the stretching of the disks, the viscous dissipation, and radiation on the flow and temperature fields is taken into account. The flow and heat equations are transformed into non-linear ODE by invoking the classical similarity transformations. These non-linear differential equations were linearized using Quasi linearization method. Further the linearized equations were discretized by employing the finite differences which were then solved numerically using the successive over relaxation parameter method. Some features of the flow and temperature are discussed in detail in the form of tables and graphs. The present study may be beneficial in lubricants and computational storage devices as well as fluid-flows and heat transmission in rotor-stator systems.

The evaporation-capillary pumping flow of the capillary wick and the working fluid system was experimentally studied in this paper. The capillary wick used in the experiment was fiber, and the working fluid contained water, ethanol and ethanol aqueous solution with water content of 25, 50, and 75 wt.%. The results show that the capillary pumping rate with ethanol as working fluid is in range 210.0-1812.5 kg/m2s when there is no heat load added. When the heating flux is 10616, 15924, 21231, and 26539 W/m2, the evaporation-capillary pumping rate is 102.5, 247.5, 390.0, and 530.0 kg/m2s, respectively. The higher the heat load power, the greater the evaporation-capillary pumping rate and the higher the final stable temperature. With the increase of heat load power, the time required to reach temperature balance becomes shorter and the temperature fluctuations after reaching temperature equilibrium become larger. The obvious temperature fluctuation has occurred when the heat flux is 26539 W/m2. The evaporation capillary pumping rate corresponding to the four different concentrations of ethanol solution in the experiment gradually decreases with the increase of water content. The temperature change processes and the final equilibrium temperatures of the four working fluids are nearly the same. The differences in boiling point of the working fluids do not have much influence here.

Buried pipe leakage can lead to poor heat transfer performance and even system failure. Leakage analysis of buried tube greatly affects the operation condition diagnosis for the heat exchange in buried tube. In this study, the simulation software was applied in analyzing heat transfer process and efficiency of the buried pipes under different leakage conditions. Moreover, changes in outlet temperature, water pressure and flow rate were simulated at different positions and diverse sizes of the leakage port. According to our results, the size of leakage port greatly affected the parameter variation of the outlet port when the system started and stopped, thus affecting the cooling effect. In addition, position of the leakage port also had obvious influence on the physical state of the outlet water.

In this paper, we present the fractional motion equations and fractional non-Noether symmetries of Lagrangian systems with the conformable fractional derivatives. The exchanging relationship between isochronous variation and fractional derivative, and the fractional Hamilton?s principle of the holonomic conservative and non-conservative systems under the conformable fractional derivative are proposed. Then the fractional motion equations of these systems based on the Hamil?ton?s principle are established. The fractional Euler operator, the definition of fractional non-Noether symmetries, non-Noether theorem, and Hojman?s conserved quantities for the Lagrangian systems are obtained with conformable fractional derivative. An example is given to illustrate the results.