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With the aim of reducing fan performance failure, an effective method of fan reliability analysis based on a hybrid uncertainty model was investigated using a combination of orthogonal test design, an approximation model, and computational fluid dynamics (CFD) simulation and analysis technology. By introducing interval uncertainty, this method can effectively solve the problem of quantifying model uncertainty owing to the lack of experimental samples and can greatly expand the applicability of reliability analysis technology in fluid machinery research. Random and interval uncertainty parameters were introduced to describe the fan system and a mixed random-interval reliability analysis model of fan performance was established based on the traditional first-order reliability analysis method. Using CFD analysis of the renormalization group (RNG) model, the flow, pressure, shaft power, efficiency, and other fan performance parameters were calculated, and the performance function was obtained. Owing to the low efficiency of the CFD calculation, the effective iterative algorithm of response surface to solve hybrid reliability model was studied, and the failure probability interval of fan performance was calculated. The method was used to study the fan performance of a rail transit train, and the failure probability, reliability index, and performance parameter sensitivity and uncertainty were analyzed. The influence of parameter uncertainty on system reliability was determined, and the engineering measures necessary to improve the fan’s performance reliability were proposed.

A kind of modified epoxy resin sheet molding compounds of the impeller has been designed. Through the test, the non-metal impeller has a better environmental aging performance, but must do the waterproof processing design. In order to improve the stability of the impeller vibration design, the influence of uncertainty factors is considered, and a multi-objective robust optimization method is proposed to reduce the weight of the impeller. Firstly, based on the fluid-structure interaction, the analysis model of the impeller vibration is constructed. Secondly, the optimal approximate model of the impeller is constructed by using the Latin hypercube and radial basis function, and the fitting and optimization accuracy of the approximate model is improved by increasing the sample points. Finally, the micro multi-objective genetic algorithm is applied to the robust optimization of approximate model, and the Monte Carlo simulation and Sobol sampling techniques are used for reliability analysis. By comparing the results of the deterministic, different sigma levels and different materials, the multi-objective optimization of the SMC molding impeller can meet the requirements of engineering stability and lightweight. And the effectiveness of the proposed multi-objective robust optimization method is verified by the error analysis. After the SMC molding and the robust optimization of the impeller, the optimized rate reached 42.5%, which greatly improved the economic benefit, and greatly reduce the vibration of the ventilation system.

Configurational-bias Monte Carlo simulations in the isobaric-isothermal ensemble using the TraPPE-UA force field were performed to study the microscopic structures and molecular interactions of mixtures containing supercritical carbon dioxide (scCO(2)) and ethanol (EtOH). The binary vapor-liquid coexisting curves were calculated at 298.17, 333.2, and 353.2 K and are in excellent agreement with experimental results. For the first time, three important interactions, i.e., EtOH-EtOH hydrogen bonding, EtOH-CO(2) hydrogen bonding, and EtOH-CO(2) electron donor-acceptor (EDA) bonding, in the mixtures were fully analyzed and compared. The EtOH mole fraction, temperature, and pressure effect on the three interactions was investigated and then explained by the competition of interactions between EtOH and CO(2) molecules. Analysis of the microscopic structures indicates a strong preference for the formation of EtOH-CO(2) hydrogen-bonded tetramers and pentamers at higher EtOH compositions. The distribution of aggregation sizes and types shows that a very large EtOH-EtOH hydrogen-bonded network exists in the mixtures, while only linear EtOH-CO(2) hydrogen-bonded and EDA-bonded dimers and trimers are present. Further analysis shows that EtOH-CO(2) EDA complex is more stable than the hydrogen-bonded one.

A millisecond mixing process for liquids was implemented using a new mixer design, i.e., a jet nozzle connected with a trumpet -shaped module. The jet nozzle can facilitate two or three liquid channels, performing an initial impingement mixing of liquid sheets in the thickness at millimeters. Then, the joint liquids sheet out of the jet nozzle was stretched thinner and thinner on the expanded solid surface of the trumpet -shaped module, which significantly intensified the liquid mixing process. Accordingly, dual controls on the liquid mixing can be accomplished flexibly by optimizing the operating conditions and the module configuration. Experiments were carried out to investigate the influencing factors on the mixing performance, where the planar laser induced fluorescence (PLIF) technique was used to measure the mass transport of fluorescent dye between the liquids. The intensity of segregation ( IOS ) and 95% mixing time ( τ 9 5 ) were employed to characterize the mixing performance. The results showed that the module with a greater curvature surface possessed a better mixing performance owing to the rapid reduction of the liquid sheet thickness, which strengthened the mixing process in the lateral direction along the flow development. The mixing behaviors are greatly influenced by the flow rate ratio between the liquids. An optimum mixing state could be achieved when Q S 1 /Q S 2 is 1:1. An increase of Q T under the same flow rate ratio does not affect the mixing pattern in space, but the corresponding τ 95 is almost linearly shortened. By splitting one liquid stream into two surrounding streams, the so called Sandwich operation brought further improved mixing performance compared with the two liquids mixing process. Using the novel jet nozzle design, millisecond(s) mixing of liquids can be easily achieved with flexible control.

d -Hydantoinase and d -carbamoylase genes from Agrobacterium radiobacter TH572 were cloned by polymerase chain reaction (PCR). The plasmid pUCCH3 with a polycistronic structure that is controlled by the native hydantoinase promoter was constructed to co-express the two genes and transformed into Escherichia coli strain JM105. To obtain the highest level of expression of the d -carbamoylase and avoid intermediate accumulation, the d -carbamoylase gene was cloned closer to the promoter and the RBS region in the upstream of it was optimized. This resulted in high active expression of soluble d -hydantoinase and d -carbamoylase that is obtained without any inducer. Thus, by the constitutive recombinant JM105/pUCCH3, d - p -hydroxyphenylglycine ( d -HPG) was obtained directly with 95.2% production yield and 96.3% conversion yield.

A modified free-volume model was developed to predict solvent diffusion coefficients in amorphous rubbery polymers, with the introduction of the Sanchez-Lacombe equation-of-state (EOS) into the free-volume theory. The characteristic parameters of the EOS are the only introduced parameters, and they can be determined with the knowledge of polymer structural units. Since all of the parameters with respect to the polymer can be determined by the group contribution method, this model provides feasibility to correlate the solvent diffusivities with polymer structures, without the knowledge of any diffusion or viscoelastic data. The calculations of infinite dilution diffusion coefficients and solvent self-diffusion coefficients for seven kinds of organic solvents in seven kinds of polymers were generally consistent with the published experimental results.

A modified free-volume model was proposed to predict the solvent diffusion coefficient in rubbery polymers without knowledge of any diffusion data. With the introduction of the Sanchez–Lacombe (SL) equation-of-state (EOS) into the Vrentas–Duda model, this model is an attempt to bridge the gap between the thermodynamic and transport properties of polymer solutions. The free volume provided by polymers for solvent diffusion can be estimated solely using the parameters of the SL EOS characteristics and the polymer glass transition temperature; thus the proposed model avoids the need to use polymer viscoelastic data in determination of polymer free-volume parameters. The other parameters in the Vrentas–Duda model remain applicable. Calculated results of solvent self- and mutual-diffusion coefficients of four common solvents in two polymers indicated that the modified model can give reliable predictions. In addition, it can reflect the effect of pressure on solvent diffusivity for concentrated polymer solutions.

The effect of hydrogen-bond cooperativity on self- and cross-aggregation of multiple polar species in supercritical carbon dioxide was investigated using both ab initio calculations and Monte Carlo simulations. Ab initio calculations indicate that hydrogen-bond cooperativity has a significant impact on the cluster size, but does not greatly influence the composition of clusters. The microscopic structures in the ethanol + CO(2) and acetic acid + CO(2) binary mixtures were first studied using Monte Carlo simulations with a strict set of criteria for hydrogen bonding, and a satisfactory agreement with experimental data was achieved. The state of microscopic phase separation in the ethanol + water + CO(2) and acetic acid + water + CO(2) ternary mixtures was then extensively investigated, indicating that the size and composition of aggregates are strongly dependent on the mixing ratio. Moreover, hydrogen-bond cooperativity must be considered to acquire more thorough understanding of the hydration process. On the basis of the detailed distributions of aggregate size and structure, a new two-staged hydration mechanism was finally proposed for the ternary solutions.