• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.211-216
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• 2022

Since liquefied natural gas (LNG) is imported in a liquid state of about -162℃ to increase transportation efficiency in Korea, it must be vaporized in a gaseous state to supply it to consumers. Among them, ambient air vaporizer (AAV) has caught attention due to eco-friendly and low costs characteristics. However, there is a disadvantage that the performance of the heat exchanger is deteriorated due to frost due to mist and icing when used for a long time. In this paper, frost generation model in AAV vaporizer was investigated with numerically to examine utilizing the vaporizer performance with the frost generation behavior. The frost generation behavior of AAV vaporizers was examined with humidity, fin characteristic, and temperature effects. As for the LNG discharge temperature, the 12 fin vaporizer showed the highest discharge temperature when the atmospheric temperature was 25℃, and the 8 fin vaporizer had the lowest LNG discharge temperature when the atmospheric temperature was 0℃. In the case of frost formation, in the case of the 12 fin vaporizer, it was formed the most at the atmospheric temperature of 25℃, and the least was formed in the vaporizer at the 0℃ condition of the atmospheric temperature of 8 fins.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.679-688
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• 2008

Air-heating vaporizer usually is used to regasify LNG at satellite areas because of the small demand of natural gas there. The common type of air heating vaporizer which exists in the market is the longitudinally finned type with 8 fins, 55 mm fin length and 2mm fin thickness. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50mm(fin length) with 2 mm(fin thickness) which exist in the market and 4 fins, 75 mm(fin length) with 2 mm(fin thickness), which is proposed, were conducted. Then, both types of vaporizers are compared. The experiments were conducted in one hour by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same temperature, humidity and air velocity with air condition in every season available and the length was varied 4000 mm, 6000 mm and 8000 mm for each type of vaporizer. Additional experiment with longer duration, i.e. In this experiment, the main aspects in analyzing the characteristics of the air heating vaporizer the inlet-outlet enthalpy difference and the outlet temperature of the working fluid. $LN_2$ is used to substitute LNG because of safety reason. The results show that the characteristics of the finned type 4fin75le vaporizer are comparable to finned type 8fin50le vaporizer.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2321-2326
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• 2007

To return LNG to a gaseous state, it is fed into a regasification plant. For inland area, where pipelines do not exist or difficult to construct, the LNG is delivered to the inland-receiving terminal available at that area, regasified and delivered to consumers. At inland-receiving terminal, air-heating vaporizer type is usually used. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50 mm fin length (8fin50le) and 4 fins, 75 mm fin length (4fin75le) were conducted. The experiments were conducted by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same condition with air condition in every season available. $LN_2$ is used to substitute LNG because of safety reason. The results show that characteristics of the finned type 4fin75le vaporizer are comparable to finned type 8fin50le vaporizer at all season.

• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.5-10
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• 2017

This paper analyzed the heat transfer characteristics on the outer surface of the ambient air vaporizer which received the heat from the air through natural convection by using numerical and experimental methods. The working fluid was a liquid nitrogen. The experimental variables were the length (2,000 mm, 1,800 mm, 1,600 mm) and width of the vaporizer fin and the fluid flow ($6.7m^3/h$, $7.1m^3/h$, $7.5m^3/h$). Based on the temperature data from the experiments, the heat transfer coefficient was calculated. Numerical analyses were also conducted in order to find the heat transfer coefficient for the range of Nusselt number which was difficult to get the data from experiments. The correlation equation between Nusselt number and Rayleigh number were suggested using both the experimental and numerical data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.85-92
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• 2021

Ambient Air Vaporizer (AAV) is an essential facility in the process of generating natural gas that uses air in the atmosphere as a medium for heat exchange to vaporize liquid natural gas into gas-state gas. AAV is more economical and eco-friendly in that it uses less energy compared to the previously used Submerged vaporizer (SMV) and Open-rack vaporizer (ORV). However, AAV is not often applied to actual processes because it is heavily affected by external environments such as atmospheric temperature and humidity. With insufficient operational experience and facility operations that rely on the intuition of the operator, the actual operation of AAV is very inefficient. To address these challenges, this paper proposes an artificial intelligence-based model that can intelligent AAV operations based on operational big data. The proposed artificial intelligence model is used deep neural networks, and the superiority of the artificial intelligence model is verified through multiple regression analysis and comparison. In this paper, the proposed model simulates based on data collected from real-world processes and compared to existing data, showing a 48.8% decrease in power usage compared to previous data. The techniques proposed in this paper can be used to improve the energy efficiency of the current natural gas generation process, and can be applied to other processes in the future.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.116-119
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• 2017

In this paper, natural convection around the ambient evaporator was numerically studied using commercial computational fluid dynamics software. From the simulations, temperature and velocity fields around the evaporator were found as a function of evaporator size and liquefied gas flow rate. The heat transfer coefficient at the external surface of the evaporator was also calculated from the simulation results. In order to give the heat transfer coefficient for various conditions, correlation between Rayleigh number and Nusselt number was proposed.