A numerical investigation on LNG flow and heat transfer characteristic in heat exchanger Handry Afrianto a , Md. Riyad Tanshen a , B. Munkhbayar a,b , U. Tony Suryo c , Hanshik Chung a , Hyomin Jeong a,⇑ a Department of Energy and Mechanical Engineering, Gyeongsang National University, 445 Inpyeongdong, Tongyeong 650-160, Gyeongnam, Republic of Korea b School of Chemical Engineering, The University of Adelaide, SA 5005, Australia c Department of Mechanical Engineering, Diponegoro University, Semarang, Indonesia article info Article history: Received 20 December 2012 Received in revised form 15 September 2013 Accepted 16 September 2013 Keywords: CFD LNG heat transfer 1–2 Shell and tube exchanger Buoyancy effect abstract The current article reports a numerical study on liquid natural gas (LNG) flow and heat transfer charac- teristic in heat exchanger at 0.6 MPa pressure condition. The computational fluid dynamics (CFD) code FLUENT was used to simulate the fluids flow and heat transfer characteristic in heat exchanger. The three-dimensional model of 1–2 heat exchangers was used to perform the numerical simulation. The numerical simulation of the current study was validated and compared with a reference data, indicating effectiveness-NTU and LMTD method. Therefore, the properties of LNG were calculated from NIST stan- dard database 4 (SUPERTRAPP) versions 3.2. The variation effects of mass flow rate and heat transfer characteristic of the fluids were investigated. The numerical results show that the heat transfer coeffi- cient increases with increasing the mass flow rate. Furthermore, the optimization of mass flow rate of fluids for vaporization process was reported in this study. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The liquid natural gas (LNG) is one of the clean energy resources that useful in industry fields, such as power production, district heating; and pipeline gas for households, automotive and maritime industries. Natural gas is converted to LNG by cooling into 111 K at atmospheric pressure. Therefore, the volume reduces until 600 times, which allows keeping natural gas in storage tank. Recently, the new technology has been developing to use LNG as a maritime fuel to diminish emission effect, followed by global warming issue because of the LNG has a low emission when used as ship fuel. The LNG has been saved in fuel storage tank in liquid condition. There- fore, LNG converts to natural gas before its use as ship engine fuel using vaporization devices (heat exchangers). In the heat exchan- ger, the LNG adsorbs of heat and it changes to gas due to passing through the pipe, as shown in Fig. 1. Pipe is heated by hot water from the heat transport between the electric heaters in reserve tank. However, LNG reduces the heat transfer efficiency of the system due to cryogenic condition of LNG, vaporization occurs in frost formation. The other problems are non-uniformity thermal proper- ties, buoyancy force resulting from non-uniform density distribu- tion over the cross section of the channel, and acceleration or deceleration of the flow. These are due to expansion or contraction of the fluid as a result of significant axial variations of bulk temper- ature under heating or cooling, as reported in He et al. [1]. There- fore, in respect of effective design of vaporization device, flow and heat transfer characteristic are very important to investigate. To design the heat exchanger device, there are many parameters need to be considered according to internal structure and mechanism of heat transfer complicatedly related to design parameters, as reported by Kara and Guaras et al. [2]. Noie et al. [3] was employed the experimental and theoretical solution to investigate the ther- mal performance of air-to-air thermo-syphon heat exchanger. A computer simulation program is based on the effectiveness-NTU method, which was developed to estimate the outlet temperature and the experimental result was close to those obtained from com- puter simulation and became better as the velocity increases. Thantrung et al. [4] was compared numerical simulation and experimental tests were to study the fluid flow and heat transfer characteristics for a rectangular shaped heat exchanger using e-NTU method. The result obtained from numerical analyses was a good agreement with that obtained from experimental data of the heat transfer coefficient estimated to be less than 9%. Hasan et al. [5] evaluated the effect of channel geometry on heat transfer and fluid flow behaviors of counter-flow heat exchanger using numerical simulation. The effectiveness and performance indexes were expressed in terms of relative size of channel; Reynolds num- ber and thermal conductivity ratio of the solid wall to that of the 0017-9310/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.09.036 ⇑ Corresponding author. Tel.: +82 55 640 3184. E-mail address: hmjeong@gnu.ac.kr (H. Jeong). International Journal of Heat and Mass Transfer 68 (2014) 110–118 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt