Study On The Properties And Gas Hydrate Of Dry Water

Dry water (DW) or dry liquid has good dispersion and mobility, in which the main ingredient is water or liquid covered by hydrophobic materials. These DW is very different from the traditional concept of vapor, liquid and solid, whose special structure causes great concern to the future application from the scientists.Natural gas hydrate (NGH) is a new efficient, clean energy and a plenty of potential resources. Gas hydrate technology was developed in many countries and wide appliced in chemical, biological, energy, environmental protection. Because of its safe, efficient, energy saving, flexible performance characteristics, natural gas hydrate storage and transportation technology accepted by scientists.Thanks to the special and stability structure, good dispersion and mobility, high specific area etc, dry material has unique advantages in cosmetics, fire fighting materials, paint additives, and was used to dramatically enhance methane uptake rates in methane gas hydrate in recently.The special properties of dry waer has the direct relationship with the formation structure. This paper study the method of preparation of dry water by hydrophobic fumed SiO2 HB-630, and observe the appearance of water by micro-optical microscope. The results show that: The optimum condition is mSiO2:mH2O=1:20, 90s mixing time by high intensity mixing method with the material of fumed SiO2 HB-630 and water. Prearation of the dry water in 5 ~ 20μm particle size out of uniform particle size, and good mobility dispersion. And the dry salt water(DSW), copper powder dry water(CDW) can be successfully prepare by dry water modification experiments but tetrabutyl ammonium bromide(TBAB), tetrahydrofuran(THF), polyvinylpyrrolidone(PVP), ethanol, pure ethanol and the hydrophilic SiO2 (Hydrophilic silica and water mixture,HSWM) will not work. The key to the formation of dry water is the hydrophobicity of SiO2.Combination of engineering calculation and storage gas apprication, the physical properties and thermodynamic properties of dry water was detected in various methods. We kown that the apparent density of dry water is about 0.6 g·mL-1, and the tap density is 0.78 g·mL-1 by centrifugation. The mSiO2:mH2O=1:20 of dry water is minimum undercooling and the shortest induction time when observed freezing characteristics of dry water emplyed freezing schedule during the temperature changes. The order of the undercooling and induction time of Various dry waten and modified dry water were H2O < HSWM < DW(1:20)< DSW < CDW and H2O < HSWM < DW(1:20)< DSW < CDW. Dissociation heat of frozen dry water is 312.86 kJ·kg-1 by mixed heating measurement with Dewar under atmospheric pressure. The average thermal conductivity of dry water is 0.37 W·m-1·K-1 measure by HotDisk thermal constant analyzer (at 30℃). The evaporation rate of dry water testing by static placement method is 8.74g·h-1·m-2 (at 23.5～26.5℃, relative humidity 46%～66% ).A gas storage apparatus by DW hydrate was set up for studying the storage of propane, carbon dioxide and methane by Steady-state constant-volume cooling method. The experiment results indicated that the maximum propone, carbon dioxide and methane uptake in DW is 70.7 V/V, 158.1 V/V, and 159 V/V. Repectively, the maxium methane storage capacity of DSW and CDW is 157 V/V, 182.3 V/V. This study indicates that dry water can greatly increased the storage rate and capacity; methane can also be storage in DSW effectively; CDW can enhance the heat transfer greatly, short the reaction time and increase the gas storage capacity, which is better than DW.