Chong-Bo Kim

Study on gas hydrates for the solid transportation of natural gas

Natural gas hydrate typically contains 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. When referred to standard conditions, 1 m3 solid hydrate contains up to 200 m3 of natural gas depending on pressure and temperature. Such the large volume of natural gas hydrate can be utilized to store and transport a large quantity of natural gas in a stable condition. In the present investigation, experiments were carried out for the formation of natural gas hydrate governed by pressure, temperature, gas compositions, etc. The results show that the equilibrium pressure of structure II is approximately 65% lower and the solubility is approximately 3 times higher than structure I. It is also found that for the sub-cooling of structure I and II of more than 9 and 11 K respectively, the hydrates are rapidly being formed. It is noted that utilizing nozzles for spraying water in the form of droplets into the natural gas dramatically reduces the hydrate formation time and increases its solubility at the same time.

Combined convection and radiation in a tube with circumferential fins and circular disks

Combined convection and radiation heat transfer in a circular tube with circumferential fins and circular disks is investigated for various operating conditions. Using a finite volume technique for steady laminar flow, the governing equations are solved in order to study the flow and temperature fields. TheP- 1 approximation and the weighted sum of gray gases model (WSGGM) are used for solving the radiation transport equation. The results show that the total Nusselt number of combined convection and radiation is higher than that of pure convection. If the temperatures of the combustion gas and the wall in a tube are high, radiation becomes dominant. Therefore, it is necessary to evaluate the effect of radiation on the total heat transfer. Key Words: Convection, Radiation, Nongray Radiation,P- 1 Approximation, Weighted Sum of Gray Gases Model

Dissolution behavior and hydrate effect on CO2 ocean sequestration

CO₂ocean sequestration is one of the promising options to reduce CO₂ concentration in the atmosphere because the ocean has vast capacity for CO₂ absorption. Therefore. in the present investigation. calculations for solubility and dissolution behavior of liquid CO₂ droplets released at 1000 m and 1500 m deep in the ocean from a moving ship and a fixed pipeline have been carried out in order 10 estimate the CO₂ dissolution characteristics in the ocean. The results show liquid CO₂ becomes CO₂ bubble at around 500 m in depth. and the solubility of seawater is about 5% less than of pure water. Also. it is shown that the injection of liquid CO₂ from a moving ship is a more effective method for dissolution than from a fixed pipeline. and the presence of hydrate on liquid CO₂ acts as a resistant layer in dissolving liquid CO₂.CO2 ocean sequestration is one of the promising options to reduce CO2 concentration in the atmosphere because the ocean has vast capacity for CO2 absorption. Therefore, in the present investigation, calculations for solubility and dissolution behavior of liquid CO2 droplets released at 1000 m and 1500 m deep in the ocean from a moving ship and a fixed pipeline have been carried out in order to estimate the CO2 dissolution characteristics in the ocean. The results show liquid CO2 becomes CO2 bubble at around 500 m in depth, and the solubility of seawater is about5% less than of pure water. Also, it is shown that the injection of liquid CO2 from a moving ship is a more effective method for dissolution than from a fixed pipeline, and the presence of hydrate on liquid CO2 acts as a resistant layer in dissolving liquid CO2.

Experimental Study on the Structural Characteristics of Gas Hydrates for the Transportation of Natural Gas

Natural gas hydrates typically contain 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. When referred to standard conditions, 1㎥ solid hydrates contain up to 172N㎥ of methane gas, depending on the pressure and temperature of production. Such large volumes make natural gas hydrates can be used to store and transport natural gas. So, the tests were performed on the formation of natural gas hydrate is governed by the pressure, temperature, gas composition etc. The results show that the formation pressure of structure II is lower about 65% and the solubility is higher about 3 times than that of structure I.