Research on Temperature Field and Thermal Stress of Liquefied Natural Gas Carrier with Incomplete Insulation

The insulation of membrane type liquefied natural gas(LNG) carrier is composed of plywood boxes filled with perlite.Within the service period,considering of the effects of load conditions,such as sloshing,wave load,it is possible to have some damage of the plywood box,leakage of perlite,and failure of the insulation box.LNG carrier without whole protection of effective insulation is dangerous.Hull structure is extremely fragile when exposed to ultra-low temperature.In order to solve these problems,firstly a study on insulation boxes' character and work condition is carried out and some presuppositions of partial disabled insulation are put forward.Secondly the thermal system of LNG carrier is analyzed to find out an effective way to simulate the thermal action of close air between outer and inner hull.Then a calculation about temperature field and thermal stress is done by MSC/PATRAN&NASTRAN.At the end it is concluded that LNG carrier with incomplete insulation is dangerous and needs to be avoided.

Influence of Carrier Gas on Analysis of MgO Powders by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） has been widely adopted for the direct multi-elemental analysis with high sensitivity. Especially analysis of fine ceramics by LA-ICP-MS without time-consuming sample decomposition process has been one of the most expecting application field. Small additive elements in MgO powders were analyzed by LA-ICP-MS. For precise and accurate analysis influence of carrier gas （Ar or He） was presented by the signal intensities of ICP-MS, relative standard deviation of signal intensities and ablated particle size distribution. Ablated particles were collected and analyzed by scanning electron microscopy （SEM） to investigate the particle size distribution, and the ablated sample surface was examined by camscope. In He gas atmosphere, the signal was more stable than in Ar gas atmosphere. The signal intensity was higher in Ar than in He. Examination of ablated particles and sample surface reveals that more particles were generated in Ar atmosphere and the distribution of particle size was larger.

A Study on the Effects of Carrier Gases on the Structure and Morphology of Carbon Nanotubes Prepared by Pyrolysis of Ferrocene and C_2H_2 Mixture

Carbon nanotubes （CNTs） were prepared using different carrier gases, with ferrocene as the catalyst precusor and acetylene as the carbon source. The effects of ammonia and nitrogen as carrier gases on the structure and morphology of CNTs were investigated. Transmission electron microscope （TEM）, high-resolution electron microscope （HRTEM）, scanning electron microscope （SEM） and X-ray diffraction （XRD） were employed to characterize the products and the catalyst. Experiment results show that the CNTs grown in N2 gas exhibited cylindrical and tubular structure, while a bamboo-like structure was observed for the CNTs grown in NH3 gas. Moreover, vertically aligned CNTs were obtained on an A12O3 disk when NH3 was used as the carrier gas. The carrier gas also exerted influence on the shape of the catalyst. Based on the theory of active centers of catalysis and combined with the particle shape of the catalyst, a growth model for the vertically aligned CNTs on the substrate is given.

Effect of carrier gas pressure on vapor condensation and mass flow-rate in sonic nozzle

Non-equilibrium vapor condensation of moist gas through a sonic nozzle is a very complicated phenomenon and is related to the measurement accuracy of sonic nozzle.A gas-liquid two-phase model for the moist gas condensation flow was built and validated by moist nitrogen experiment of homogeneous nucleation through a transonic nozzle.The effects of carrier gas pressure on position and status of condensation onset in sonic nozzle were investigated in detail.The results show that condensation process is not easy to occur at lower carrier pressure and throat diameter.The main factors influencing condensation onset are boundary layer thickness,heat capacity of carrier gas and expansion rate.All of results can be used to further analyze the effect of condensation on mass flow-rate of sonic nozzle.

Research on the navigational risk of liquefied natural gas carriers in an inland river based on entropy:A cloud evaluation model

Due to the flammability and explosive nature of liquefied natural gas(LNG),an extremely strict process is followed for the transporta-tion of LNG carriers in China.Particularly,no LNG carriers are operating in inland rivers within the country.Therefore,to ensure the future navigation safety of LNG carriers entering the Yangtze River,the risk sources of LNG carriers’navigation safety must be identi-fied and evaluated.Based on the Delphi and expert experience method,this paper analyses and discusses the navigation risk factors of LNG carriers in the lower reaches of the Yangtze River from four aspects(human,ship,environment and management),identifies 12 risk indicators affecting the navigation of LNG carriers and establishes a risk evaluation index system.Further,an entropy weight fuzzy model is utilized to reduce the influence of subjective judgement on the index weight as well as to conduct a segmented and overall evaluation of LNG navigation risks in the Baimaosha Channel.Finally,the cloud model is applied to validate the consistent feasibility of the entropy weight fuzzy model.The research results indicate that the method provides effective technical support for further study on the navigation security of LNG carriers in inland rivers.

Photographic Analysis and Optical Diagnosis of Kilowatt Microwave Plasma Torch with Air Carrier Gas

The spatiotemporal motion characteristics of the kilowatt argon microwave plasma torch with the air carrier gas(kW-AC-ArMPT)and the behavior of the plasma filaments are investigated with a digital single-lens reflex(SLR)camera and a high-speed camera.Along with the introduction of the air,both the volume of the central channel and the rotational frequency of the plasma filament are increased.Besides,the excitation temperature(Texc),rotational temperature(Trot),and density of electron number(ne)of the kW-AC-ArMPT are measured with optical diagnosis.It is clearly shown that the introduction of air contributed to the rise of Trot and ne of the plasma,which is beneficial to improving the analytical performance of the plasma.Then the detection limits of some heavy metal elements are measured by kW-AC-ArMPT,which are in the ppb range.The experimental results show that the kW-ArMPT has a high tolerance to air injection at least 1.0 L/min,which allows the direct extraction of air from the environment for analysis and therefore has the potential for online and in-situ detection of ambient air quality and industrial exhaust gases.

废热热化学回收对气体运输船能效的影响分析

Enlarging the fleet of gas carriers would make it possible to respond to the growing demand for hydrocarbon gases,but it will increase carbon dioxide emissions.The International Maritime Organization(IMO)has developed the energy efficiency design index(EEDI)with the objective of carbon emission reduction for new ships.In this paper,thirty gas carriers transporting liquefied natural gas(LNG)and liquefied petroleum gas(LPG)and equipped with various types of main engines are considered.As shown by the calculation of the attained EEDI,2 of the 13 LPG carriers and 6 of the 17 LNG carriers under study do not comply with the EEDI requirements.To meet the stringent EEDI requirements,applying thermochemical regenerators(TCRs)fed by main engine exhaust gases is suggested.Mathematical modeling is applied to analyze the characteristics of the combined gas-turbine-electric and diesel-electric power plant with thermochemical recuperation of the exhaust gas heat.Utilizing TCR on gas carriers with engines fueled by syngas produced from boil-off gas(BOG)reduces the carbon content by 35%and provides the energy efficiency required by IMO without the use of other technologies.

Effect of carrier gas species on the microstructure and compressive deformation behaviors of ultra-strong pure copper manufactured by cold spray additive manufacturing

Cold spray(CS)which has recently become a promising additive manufacturing(AM)technology,was used to fabricate ultra-strong pure copper.In addition,the effects of carrier gas species on the microstructural characteristics,mechanical properties and deformation mechanisms were systemically explored.The CSAM copper manufactured with N_(2) carrier gas reveals a heterogeneous bimodal microstructure consisting of ultra-fine grains at the particle interface and relatively coarse grains in inner particles.With He carrier gas,a homogeneous grain structure consisting of ultra-fine grains in most areas was obtained.Compressive tests showed that N_(2) and He carrier gasses enabled ultra-high yield strengths of 340 and415 MPa,respectively.These values are comparable to severely plastic deformed copper,which has extremely low ductility and shape fidelity.On the other hand,both samples showed a strain-softening phenomenon that does not commonly occur at room temperature.The deformation microstructures revealed that dynamic recovery(DRV)and dynamic recrystallization(DRX)phenomena were generated despite being deformed at room temperature.Based on the above findings,the overall deformation mechanisms according to the carrier gas species in the CSAM copper manufacturing process were discussed.Furthermore,the work hardening and softening behaviors of CSAM Cu are predicted by using a constitutive equation.

Production of ammonia from plasma-catalytic decomposition of urea: Effects of carrier gas composition

Effects of carrier gas composition（N2/air） on NH3 production, energy efficiency regarding NH3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al2 O3-packed dielectric barrier discharge（DBD） reactor at room temperature. Results show that the presence of O2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH3. The final yield of NH3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23 kV, respectively when air was used as the carrier gas instead of N2.From the viewpoint of energy savings, however, air carrier gas is better than N2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al2 O3 catalyst to give NH3 and CO2 as the main products. Compared to a small amount of N2 O formed with N2 as the carrier gas, however,more byproducts including N2O and NO2 in the gas phase and NH4 NO3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH3, the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma.

Determination of Vapor Pressure of Liquid Copper by Carrier Gas Method

The relationship between the vapor pressure of liquid copper and the flow rate of carrier gas argon was discussed, when the carrier gas method was used to determine the vapor pressure of liquid copper at 1892 K. The proper argon flow rate range obtained was 150-500 mL/min and enough evidence was provided to verify the vapor pressure-flow rate of carrier gas relationship at the target temperature. Based on the proper flow rate range, the vapor pressure of liquid copper was measured at 1609-1892 K. The relationship of vapor pressure-temperature obtained by the method of regression analysis can be expressed as： In（p/Pa） = （25.470 -I- 0.903） - （39099.8 -4- 1574.5）/T, Further, the thermodynamic properties including the heat of vaporization and the Gibbs free energy of the Cu （I） = Cu （g） reaction were calculated by the vapor pressiJre obtained over the temperature range covered.

Numerical and Experimental Investigation on the In-Flight Melting Behaviour of Granulated Powders in Induction Thermal Plasmas

An innovative in-flight glass melting technology with thermal plasmas was developed for the purpose of energy conservation and environment protection. In this study, modelling and experiments of argon-oxygen induction thermal plasmas were conducted to investigate the melting behaviour of granulated soda-lime glass powders injected into the plasma. A two-dimensional local thermodynamic equilibrium （LTE） model was performed to simulate the heat and momentum transfer between plasma and particle. Results showed that the particle temperature was strongly affected by the flow rate of carrier gas and the particle size of raw material. A higher flow rate of carrier gas led to lower particle temperature and less energy transferred to particles which resulted in lower vitrification. The incomplete melting of large particles was attributed to the lower central temperature of the particle caused by a larger heat capacity. The numerical analysis explained well the experimental results, which can provide valuable practical guidelines for the process control in the melting process for the glass industry.

A modified simplex method for multifactor optimization of selectivity in gas chromatography

A computer-assisted advanced simplex method is presented for the simultaneous optimization of multifactor (stationary phase loading, carrier gas dow rate and column temperature) for separation of ten compounds in gas chromatography. A three factors factorial design was used. The method was based on a special polynomial established from fifteen preliminary runs, using resolution as the selection criterion, with connection to a general simplex method. Excellent agreement is found between the predicted data and the experimental results, and most of experiments required in the general simplex method can be omitted.