Investigation on Gas Storage in Methane Hydrate

The effect of additives (anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant alkyl polysaccharide glycoside (APG), and liquid hydrocarbon cyclopentane (CP)) on hydrate induction time and formation rate, and storage capacity was studied in this work. Micelle surfactant solutions were found to reduce hydrate induction time, increase methane hydrate formation rate and improve methane storage capacity in hydrates. In the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation were reduced. The critical micelle concentrations of SDS and APG water solutions were found to be 300×10-6 and 500×10-6 for methane hydrate formation system respectively. The effect of anionic surfactant (SDS) on methane storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduced hydrate induction time and improved hydrate formation rate, but could not improve methane storage in hydrates.

Application of the state space model to the system of wave energy conversion Analytical method for wave forces on singleoscillating rectangular buoy

A new analytical method is proposed to analyze the force acting on a rectangular oscillating buoy due to linear waves.In the method a new analytical expression for the diffraction velocity potential is obtained first by use of theeigenfunction expansion method and then the wave excitation force is calculated by use of the known incident wavepotential and the diffraction potential. Compared with the classical analytical method, it can be seen that the presentmethod is simpler for a two-dimensional problem due to the comparable effort needed for the computation ofdiffraction potential and for that of radiated potential. To verify the correctness of the method, a classical example inthe reference is recomputed and the obtained results are in good accordance with those by use of other methods,which shows that the present method is correct.

THE PREPARATION AND CHARACTERISTICS STUDY OF TiN_xO_y SPECTRAL SELECTIVE ABSORBING FILM BY MAGNETRON SPUTTERING

Spectral selective absorbent film is a crucial factor for the solar heating devi ce. There are many kinds of spectral selective absorbing film made by different ways. TiNxOy thin film with excellent spectral selecting absobent property were successfully prepared by DC magnetron sputtering with Ar as working gas, N2 and O2 as reactive gas, 99.9% titanium as the target and is copper slice as the subs trate. In this article, the optical characteristics and microstructure of TiNxO y thin film were studied. Inputing O2 can decrease the reflection of the visible lights, and double layer film can get good absorption for solar energy.

PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells. In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film, is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6.05% without anti-reflection coating.

Experimental study on pollutant movement in surf zone

The experiments on pollutant movement in surf zone were conducted on the two gentle beaches(with slope of 1:100 and 1:40, respectively), for diverse wave cases. The movement contours and direction of pollutants, under the action of regular and random waves with diverse wave amplitudes, were provided and studied in this paper. It was shown that, due to complicated hydrodynamics in surf zone, the pollutant movement state is quite complicated and different from that in pure current zone.

COMPARISON OF MATERIAL FOR ENCAPSULATING MINIMODULES

The main characteristics of glass, polymethyl methacrylate (PMMA) and polycarbon ate (PC) were presented. The transmittance of glass, PMMA and PC was measured by the UV-VIS spectroscopy analysis. PMMA and PC have the advantages of higher tra nsparency, higher resistance and lower density. It is indicated that both PMMA a nd PC are suitable for encapsulating solar minimodules.

Numerical model of flow and pollutant transportation in non-orthogonal curvilinear coordinates

The planar 2D k-ε double equations' turbulence model was adopted and transformed into non-orthogonal curvilinear coordinates. The concentration convection-diffusion was introduced to planar 2D SIMPLEC algorithm of flow in non-orthogonal curvilinear coordinates. The numerical model of pollutant transportation in non-orthogonal curvilinear coordinates was constructed. The model was applied to simulate the flow and pollutant concentration fields. In the testing concentration field, two optimal operations of contamination discharging both along bank and in the centerline at the first bend of the meandering channel were adopted. Comparison with available data showed the model developed was successful, was valuable to engineering application.

ISOTROPIC TEXTURING OF POLYCRYSTALLINE SILICON WAFERS

An isotropic etching technique of texturing silicon solar cells has been applied to polycrystalline silicon wafers with different acid concentrations. Optimal e tching conditions have been determined by etching rate calculation, scanning ele ctron microscope (SEM) image and reflectance measurement. The surface morphology of the textured wafers varies in accordance with the different etchant concentr ation which in turn leads to the dissimilarity of etching speed. Textured polycr ystalline silicon wafer surfaces display randomly located etched pits which can reduce the surface reflection and enhance the light absorption. The special rela tionship between reflectivity and etching rate was studied. Reflectance measurem ents show that isotropic texturing is one of the suitable techniques for texturi ng polycrystalline silicon wafers and benefits solar cells performances.

OBSERVATION ON DEFECTS IN POLYCRYSTALLINE SILICON THIN FILMS

Polycrystalline silicon thin films were prepared by RTCVD (rapid thermal chemica l vapor deposition) method on several substrates such as SSP (silicon sheet from powder) ribbon, poly-Si wafer and mono-Si wafer. Intra-granular defects such as stacking faults, twins and microstructure defects were investigated on thin fil ms by scan electron microscopy (SEM) technique.

SUBSTRATE MATERIALS FOR POLY-CSiTF SOLAR CELLS: OPTIMIZATION OF SILICON SHEET FROM POWDER

The optimization of silicon sheet from powder (SSP) technology as polycrystalli ne silicon thin film (poly-CSiTF) solar cells' substrate materials is studied by orthogonal design experimental method. Based on technological optimization of S SP prepared from electronic grade silicon powder, SSP solar cell devices with si mple structure are prepared and the effect of SSP substrate is discussed. Up to now, the conversion efficiency of the prepared solar cells on low purity SSP sub strate with fundamental structure has reached 8.25% (with area of 1cm×1cm).

Finite Element Analysis for Effects of Incident Wave Angle and Seabed on Hydrodynamic Characteristics of Buoy

Effects of incident wave angle and seabed on hydrodynamic characteristics of a buoy are studied using the Finite Element Method (FEM). The hydrodynamic coefficients of different conditions are obtained after the numeric method is validated through the comparisons between the numeric results and the analytic results of simple cases. The Biconjugate Gradient Stabilized (BiCGStab) algorithm, considered to be among the most powerful algorithm in solving linear systems, is employed to improve the efficiency of the analysis. The results presented here shed some new light on the behaviors of ocean structures in complex sea areas.

Prediction of Refrigerant Gas Hydrates Formation Conditions

A fugacity model was developed for prediction of mixed refrigerant gas hydrates formation conditions based on the molecule congregation and solution theories. In this model, gas hydrates were regarded as non-ideal solid solution composed of water groups and guest molecules, and the expressions of fugacity of guest molecules in hydrate phase was proposed accordingly. It has been shown that the developed model can indicate successfully the effect of guest-guest molecule interaction. The results showed that the model can describe better the characteristics of phase equilibrium of mixed refrigerant gas hydrates and predictions are in good agreement with experimental data.

PARALLEL SIMULATION OF THE ELLIPTIC MILD SLOPE EQUATION WITH A PERSONAL COMPUTER CLUSTER

With the massage passing interface, a parallel solution method was proposedfor the simulation of the elliptic mild slope equation, and implemented numerically on a parallelsystem based on a personal computer cluster, which was constructed by the authors. The wavetransformations over two typical topographies with mild slopes were simulated. Numerical resultsshow that the parallel solution method presented in this paper can not only increase thecomputational efficiency, but also decrease very much the memory storage on a single computer, sothe parallel system based on a PCC can be used to simulate wave transformations over much largerareas.

CALCULATION OF THERMAL AND SALINE TURBULENT FLOW BY k-ε MODEL

Based on the N-S equation, taking the character of thermal and salinestratified flow into account, and considering the effects of buoyancy on turbulence, the k-ε modelof thermal and saline stratified flow is established. Density stratified flow with both the verticaltemperature gradient and the vertical salinity gradient is simulated numerically, in whichturbulent terms are calculated by the k-ε turbulent model. The distributions of velocity,temperature and salinity are given in this paper. The feature of stratification and turbulence isdescribed correctly by the model. The computational results agree well with the experimental data.

Calculation of NARM's Equilibrium with Peng-Robinson Equation of State

The liquid molar volumes of nonazeotropic refrigerant mixtures(NARM), calculated with Peng Robinson (PR) equation, were compared with vapor-liquid equilibrium experimental data in this paper.Provided with coreaction coefficient kij, the discrepancies of liquid molar volume data for R22+R142b and R22+R142b using PR equation are 7.7% and 8.1%, respectively. When HBT (Hankinson-Brobst-Tholnson) equation was joined with PR equation, the deviations are reduced to less than 1.5% for both R22+R114 and R22+R142b.