结构在无限流体域中振动时附连水质量的数值计算方法

通过对结构与理想流体耦合问题的分析 ,利用有限元法对流固耦合问题的附连水质量解耦的方法进行了研究 .对一些规则的结构进行了计算 ,同时与解析解及 Morison公式进行比较 .在对计算结果分析的基础上 ,提出了有限元法计算附连水质量时流体范围的划取方法 ,使实际工程计算能够有所依据地选定所要计算的流体范围 ,从而节省了计算工作量 .

Indirect heat integration across plants using hot water circles

Total site heat integration(TSHI) provides more opportunities for energy saving in industry clusters. Some design methods including direct integration using process streams and indirect integration using intermediate-fluid circuits, i.e., steam, dowtherms and hot water, have been proposed during last few decades. Indirect heat integration is preferred when the heat sources and sinks are separated in independent plants with rather long distance. This improves energy efficiency by adaption of intermediate fluid circle which acts as a utility provider for plants in a symbiotic network. However, there are some significant factors ignored in conventional TSHI, i.e. the investment of pipeline, cost of pumping and heat loss. These factors simultaneously determine the possibility and performance of heat integration. This work presents a new methodology for indirect heat integration in low temperature range using hot water circuit as intermediate-fluid medium. The new methodology enables the targeting of indirect heat integration across plants considering the factors mentioned earlier. An MINLP model with economic objective is established and solved. The optimization results give the mass flow rate of intermediate-fluid, diameter of pipeline, the temperature of the circuits and the matches of heat exchanger networks(HENS) automatically. Finally, the application of this proposed methodology is illustrated with a case study.

Modulating the mean residence time difference of wide-size particles in a fluidized bed

For non-catalytic gas-solid reaction, it is desirable to match the mean residence time （MRT） of particles and complete conversion time （tc） in a fluidized bed. In this study, the MRT differences （MRT ratios） between the coarse particles and the fine particles were investigated in a continuous fluidized bed with a side exit by varying the superficial gas velocity, feed composition and particle size ratio, The results show that the MRT ratio increases firstly and then decreases with increasing the gas velocity. By controlling the gas velocity and the feed composi tion of coarse particles, the MRT ratio can be modulated from 1.8 to 10.5 at the gas velocity of 1.0 m-s -1 for the binary mixture with the size ratio of 2.2. The MRT ratio can reach to - 12 at the gas velocity of 1.2 m. s for the particle size ratio of 3.3. The present study has endeavored to obtain fundamental data for an effective plant operation to meet the need of synchronously complete conversion of particles with different sizes during the film diffusion controlling reaction.

A Group Contribution Method for the Correlation of Static Dielectric Constant of Ionic Liquids

Static dielectric constant is a key parameter to estimate the electro-viscous effect which plays important roles in the flow and convective heat transfer of fluids with ions in microfluidic devices such as micro reactors and heat exchangers.A group contribution method based on 27 groups is developed for the correlation of static dielectric constant of ionic liquids in this paper.The ionic liquids considered include imidazolium,pyridinium,pyrrolidinium,alkylammonium,alkylsulfonium,morpholinium and piperidinium cations and various anions.The data collected cover the temperature ranges of 278.15-343.15 K and static dielectric constant ranges of 9.4-85.6.The results of the method show a satisfactory agreement with the literature data with an average absolute relative deviation of 7.41%,which is generally of the same order of the experimental data accuracy.The method proposed in this paper provides a simple but reliable approach for the prediction of static dielectric constant of ionic liquids at different temperatures.

Electricity Generation from Low Temperature Waste Heat with Application to Hydrogen Production from Water

This paper presents an extensive study of the heat pump cycle and associated working fluids to generate electricity from low temperature industrial waste heat. An Aspen Plus simulation has been developed to evaluate the effect of various working fluids on the net heat pump efficiency over a wide range of turbine inlet temperatures between 50℃ and 250℃. One hundred eight （108） refi＇igerants were investigated from the environmental classifications of Hydrochlorofluorocarbons （HCFC）, Hydrofluorocarbons （HFC）, Chlorofluorocarbons （CFC） and Hydrocarbons （HC） with boiling points between -88.65 ℃ and 110.65℃. Net efficiency, which ranged from 0.1% to 25.8% in this work tends to increases with the temperature of the waste heat. Results of the present study demonstrate that working fluid R41 （with source temperature of 44 ℃） provides the maximum efficiency among those evaluated. Refrigerants R13B1 and R32 provide the best efficiency for waste heat source temperatures ranges 60 - 67 ℃ and 68 - 78℃ respectively. Ammonia shows the highest efficiency from 79℃ to 132 ℃. Refrigerants R31, R21, 17,30 and benzene perform well in the temperature ranges 133-151 ℃, 152-178 ℃, 179-236℃ and 237-250 ℃respectively. The optimal heat pump systems are applied to the hybrid copper sulfate-copper oxide thermochemical cycle for hydrogen production from water. 100.8 MW of electrical energy is produced, which increased the efficiency from 24.1% to 25.9%.

Experimental Study and Analysis on Heat Transfer Coefficient of Radial Heat Pipe

The experimental study was performed on five eccentric radial heat pipes with two outer-tube diameters.The test range can be given as follows,working fluid filling ratio Ω=44%～83%,heat flux q=10000W/m2～32000W/m2,and working temperature tv=50 ℃～120 ℃.The correlations between radial heat pipe heat transfer performance and filling ratio,heat flux,working temperature were studied in the experiment.Based on linear regression of experimental data,the relationship between heat pipe equivalent heat resistance R and working temperature tv,heat flux q and filling ratio Ω was obtained.

An aerodynamic design and numerical investigation of transonic centrifugal compressor stage

In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described.Firstly the CFD program was validated by an experimental case.Then the preliminary aerodynamic design of stage completed through in-house one-dimensional code.Three types of impellers and two sets of stages were computed and analyzed.It can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow range.Similarly,the performance of the stage with swept impeller is better than others.The total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% respectively.The vane diffuser with same airfoils along span increases attack angle at higher span,and the local flow structure and performance is deteriorated.

Multi-point Optimization of Recirculation Flow Type Casing Treatment in Centrifugal Compressors

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. R is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.