行波型热声发动机与脉冲管配合的实验研究

采用热声发动机驱动脉冲管制冷机 ,使彻底消除低温制冷机中的运动部件成为可能。作者研制了行波型热声发动机驱动脉冲管制冷机实验台。进行三个脉冲管与行波型热声发动机的配合实验 ,着重研究了热端气体温度。

康熙宫廷里的一缕机械论科学之光 在华耶稣会士介绍温度计的另一著作

1669年,南怀仁制作了一架空气温度计进献给大清皇帝,并于1671年出版了《验气图说》一文,专门对该仪器的结构、用法和工作原理进行了简要说明。然而,在梵蒂冈教廷图书馆的入华耶稣会士档案中,却可以找到另外一部介绍温度计的手稿,题为《验气寒暑表说》。其中同时详细介绍了空气温度计和1657年之后发明的液体温度计的制作方法和工作原理,并且明确指出了空气温度计的缺陷。更重要的是,手稿中还系统引入伽利略到波义尔之间发展起来的气体静力学理论,完全是在新机械论物理学的基础上对温度计进行理论性讨论,与南怀仁借助于亚里士多德物理学,利用"自然厌恶真空"的概念来解释温度计工作原理的做法绝然不同。

影响回转烘干机技术性能的因素及技术改造

回转烘干机广泛应用于建材工业、化学工业及矿物烘干,分析了影响回转烘干机技术性能的两类因素,一类为由转筒烘干机本身引起的因素,另一类为烘干工艺方面的因素。同时提出技术改造措施。

Control of combustion area using electrical resistivity method for underground coal gasification

Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.

Study on the comparison of the pyrolysis gas release of lignite and its briquette

In this experiment, lignite was refined and processed through binderless briquette preparation process from low-rank coal and became briquette. Then, lignite and its briquette were pyrolysed as materials to compare the nature of their pyrolysis. In this study, the experiment was carried out through a lab tube furnace, at a heating rate of 10 ~C/min, and the gas was analyzed and compared, which was collected at different temperatures. The results show that： in the pyrolysis temperature of 550-850 ℃, the semi-coke yield of briquette is 2%-6% higher than lignite, the tar yield of briquette is 2%-3% higher than lignite and the gas yield of briquette is 4%-9% less than lignite. The time required for complete release of the briquette is about 20 min less than lignite. The components in the pyrolysis gas of lignite and its briquette are the same, and their variation with the pyrolysis temperature is similar.

Effect of thermal stimulation on gas production from hydrate deposits in Shenhu area of the South China Sea

The Shenhu area on the northern continental slope of the South China Sea （SCS） is one of the promising fields for gas hydrate exploitation. The hydrate-bearing layer at drilling site SH2 is overlain and underlain by permeable zones of mobile water. In this study a vertical well was configured with a perforated Interval I for producing gas and a coiled Interval II for heating sed- iment, The hydrate is dissociated by a small depressurization at Interval Ⅰ and a thermal stimulation at Interval Ⅱ. The numeri- cal simulations indicate that the thermal stimulation has a significant effect on gas release from the hydrates in the production duration and improves the gas production in the late period. The gas released by thermal stimulation cannot be produced as quickly as the production gets operated because of the hard pathway for fluids to flow in the sediments. The gas production is enhanced due to the heating for 7242 m3 in the whole production. Increasing heating temperature at Interval Ⅱcan improve gas production and restrain water output, and advance the arrival time of the gas flow from the zone at Interval Ⅱ. The absolute criterion and relative criterion suggest that the thermal stimulation in the production schemes is pronounced for releasing gas from the hydrate deposit, but the production efficiency of gas is limited by the sediment of low permeability. The study pro- vides an insight into the production potential of the hydrate accumulations by thermal stimulation with depressurization in two wells, and a basis for analyzing economic feasibility of gas production from the area.

Molecular dynamics simulations of the mechanisms of thermal conduction in methane hydrates

The thermal conductivity of methane hydrate is an important physical parameter affecting the processes of methane hydrate exploration,mining,gas hydrate storage and transportation as well as other applications.Equilibrium molecular dynamics simulations and the Green-Kubo method have been employed for systems from fully occupied to vacant occupied sI methane hydrate in order to estimate their thermal conductivity.The estimations were carried out at temperatures from 203.15 to 263.15 K and at pressures from 3 to 100 MPa.Potential models selected for water were TIP4P,TIP4P-Ew,TIP4P/2005,TIP4P-FQ and TIP4P/Ice.The effects of varying the ratio of the host and guest molecules and the external thermobaric conditions on the thermal conductivity of methane hydrate were studied.The results indicated that the thermal conductivity of methane hydrate is essentially determined by the cage framework which constitutes the hydrate lattice and the cage framework has only slightly higher thermal conductivity in the presence of the guest molecules.Inclusion of more guest molecules in the cage improves the thermal conductivity of methane hydrate.It is also revealed that the thermal conductivity of the sI hydrate shows a similar variation with temperature.Pressure also has an effect on the thermal conductivity,particularly at higher pressures.As the pressure increases,slightly higher thermal conductivities result.Changes in density have little impact on the thermal conductivity of methane hydrate.