Journal of Mechanical Science and Technology 22 (2008) 981~990 www.springerlink.com/content/1738-494x Journal of Mechanical Science and Technology Experimental study on the characteristics of longitudinal fin air-heating vaporizers in different seasons Hyo Min Jeong 1 , Han Shik Chung 1,* , Eldwin Djajadiwinata 2 , Pil Hwan Kim 2 and Yong Hun Lee 3 1 School of Mechanical and Aerospace Engineering, the Institute of Marine Industry, Gyeongsang National University, 445 Inpyeong-dong, Gyeongsang-namdo 650-160, Korea. 2 Graduate School, Department of Mechanical and Precision Engineering, Gyeongsang National University, 445 Inpyeong-dong, Gyeongsang-namdo 650-160, Korea. 3 Department of Mechanical and Precision Engineering, Gyeongsang National University, 445 Inpyeong-dong, Gyeongsang-namdo 650-160, Korea (Manuscript Received March 2, 2007; Revised December 13, 2007; Accepted December 23, 2007) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Abstract Air-heating vaporizers are usually used to regasify LNG at satellite areas because of the small demand for natural gas there. The common type of air heating vaporizer which exists in the market is the longitudinally finned type with 8 fins, 50mm 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 2mm fin thickness (8fin50le) -which exist in the market- and 4 fins, 75mm fin length with 2mm fin thickness (4fin75le), 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 condition (same temperature, humid- ity and air velocity) with air condition in every season available and the length was varied 4000mm, 6000mm and 8000mm for each type of vaporizer. Additional experiment with longer duration, i.e., 4 hours and in a single room condition was conducted to validate the previous result. In this experiment, the main aspects in analyzing the character- istics of the air heating vaporizer are the inlet-outlet enthalpy difference and the outlet temperature of the working fluid. LN 2 is used to substitute LNG for safety reasons. The results show that the characteristics of the finned type 4fin75le vaporizer are comparable to the finned type 8fin50le vaporizer. Keywords: LNG (Liquefied Natural Gas); LN 2 (Liquid Nitrogen); Vaporizer; Fin; Super low temperature -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1. Introduction Liquefied natural gas (LNG) is natural gas (NG) that has been cooled to the point that it condenses to a liquid, which occurs at a temperature of approxi- mately –161 and at atmospheric pressure. Lique- faction reduces the volume by approximately 600 times, thus making it more economical to transport between continents in specially designed ocean ves- sels. Hence, LNG technology makes natural gas available throughout the world. At the present time, world demand for LNG is increasing. This can be seen in Fig. 1 [1]. To return LNG to a gaseous state, it is fed into a re- gasification plant. The LNG is warmed by passing it through pipes heated by direct-fired heaters, seawater or through pipes that are in heated water. These de- vices are known as ‘vaporizers’. The vaporized gas is then regulated for pressure and enters the pipeline system as natural gas. Finally, residential and com- mercial consumers receive natural gas for daily use from local gas utilities or in the form of electricity. But for inland areas, where pipelines do not exist or * Corresponding author. Tel.: +82 55 640 3185 Fax.: +82 55 640 3188 E-mail address: hschung@gnu.ac.kr DOI 10.1007/s12206-007-1216-1