Thermal design and performance evaluation of a shell-and-tube heat exchanger using LNG cold energy in LNG fuelled ship. (5th May 2020)

• Record Type: Journal Article
• Authors: Lim, Tae-Woo; Choi, Yong-Seok
• Is Part Of: Applied thermal engineering. Volume 171(2020)
• Publication Date: 2020-05-05
• Subjects: Cold energy -- LNG -- Organic Rankine cycle -- Organic fluid -- Shell-and-tube heat exchanger; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2020.115120
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Integrated LNG cold energy-ORC exhibited the thermal efficiency of about 23%. R227ea and R123 exhibited the largest output; output of R134a was the smallest. Exergy efficiency of R227ea and R134a is the highest and lowest, respectively. Heat transfer surface area of evaporator and condenser is 36 m 2 and 73 m 2, respectively. Abstract: This study focuses on integrating the cold energy of liquid natural gas (LNG) fuelled ships with the ORC and the thermal design of the heat exchanger in the organic Rankine cycle (ORC) system. An ORC system is constructed to utilise the cold energy of the LNG and the jacket cooling water of the main engine as a low and high-temperature heat source, respectively, to exploit the large amount of energy consumed in the process of raising the temperature of the LNG to a constant value to allow its use as a fuel. Five kinds of working fluids are applied to analyse the performance of the cycle according to the change in the condensation temperature. The results of the cycle performance analysis indicate that the R123 and R227ea have the highest and lowest thermal efficiency of about 17–23% and about 15–21%, respectively. The R123 and R134a exhibit the highest and lowest exergy efficiency of about 25–31% and about 23–29%, respectively. The condensation temperature at which the maximum output is obtained is about 223 [K]. In addition, since the efficiency of the ORC system can be improved through the optimal design of the heat exchanger, the thermal design of the heat exchanger, which is a primary part of the ORC system, is performed. As the working fluid, three kinds of organic fluids, which are the most widely used among the five considered types, are selected to simulate the evaporator, condenser, and preheater. The simulation result shows that the condenser and preheater have the largest and smallest heat transfer surface area of 73 m 2 and 34 m 2 for R134a, respectively. For the condenser, it is found that the R134a and R152a have the largest and smallest heat transfer surface areas of 73 m 2 and 59 m 2, respectively. In contrast, in the case of the evaporator, the R245fa and R134a have the largest and smallest heat transfer surface areas of 42 m 2 and 36 m 2, respectively.