Fabrication and Study on the Performance Characteristics ofPlate Heat Exchanger Condenser for marine ORC systems
Cheol Oh*, Dae-jung Hwang*, Sang-kyun Park*, Jae-hoon Jee**, Eun-shin Bang**The Republic of Korea, Korea Maritime & Ocean University727, Taejong-ro, Yeongdo-gu, Busan, Republic of Korea
E-mail: ohcheol@kmou.ac.kr**Department of Mechanical Engineering, Mokpo National Maritime University91, Haeyangdaehak-ro, Mokpo-si, Jeollanam-do, Republic of Korea

AbstractResearch to improve the energy efficiency of ships is being conducted in various fields. Accordingly, the applicationof an Organic Rankine Cycle (ORC) power generation system for ships using exhaust gas waste heat generated from themain engine is being considered. The heat exchanger constituting the ORC system should be designed and manufactured
to be suitable for stable operation and suitable for the system. In this study, in order to fabricate a plate type condenser
that can be used in a marine ORC system, Computational Fluid Dynamics (CFD) modeling and Aspen Exchanger Designand Rating (EDR) modeling of a condenser made based on a given single heat transfer plate shape were compared andreviewed. As a result, similar heat transfer performance of CFD modeling and EDR modeling was confirmed. EDR
condenser modeling was applied and a basic marine ORC system was constructed and simulated using R245FA
refrigerant as the working fluid. As a result of the simulation, it was confirmed that the ORC system efficiency improved
as the cooling water temperature increased, but the heat transfer rate of the condenser decreased. It was confirmed thatthe turbine output and ORC system efficiency were improved as the turbine inlet pressure increased. In particular, it wasconfirmed that the ORC system efficiency improved significantly in the range of 10 bar to 20 bar, which is a relatively
low-pressure region than in the high-pressure region. In addition, the ORC system efficiency and heat transfer rate of thecondenser increased as the flow rate of the working fluid of the ORC system increased. In particular, it was confirmedthat the liquid fraction in the condenser decreased from a specific flow rate of working fluid through the change in theheat transfer rate distribution occupied by sensible and latent heat load inside the condenser.
Keywords : Organic Rankine Cycle, Condenser, Plate Heat Exchanger, Efficiency, Heat Transfer Rate

1. Introduction
The International Maritime Organization (IMO) is enacting and revising various international conventions such as
MARPOL Convention to reduce greenhouse gas emissions from international shipping. As the main contents of such
regulations, energy efficiency management and increase of ships, such as the Energy Efficiency Design Index (EEDI) for
new ships and the Ship Energy Efficiency Management Plan (SEEMP), occupies a large part. In order to improve theenergy efficiency of a ship, research related to the development of an ORC system for ships using waste heat from exhaustgas generated from the ship's main engine is being conducted. As a representative study, Moon et al. (2021) examined
the appropriate operating pressure representing the maximum net power by simulating ORC performance using waste
heat generated from ships and seawater used as cooling water. Song et al. (2012) confirmed the power generation outputof 2,400 kW through a simulation using various eco-friendly organic refrigerants to optimize the marine ORC power
generation system using the seawater temperature difference. Ibrahim et al. (2017) simulated a combine ORC systemusing waste heat generated from the 1,000kW power generation engine of a Naval ship and confirmed the effect of saving
67.2 tons of carbon dioxide and the economic effect of fuel saving. The above study is focused on identifying the optimal
operating conditions applicable to ships in terms of overall efficiency of the system rather than the characteristics ofindividual elements constituting the ORC system. Therefore, for the stable operation of the power generation system, it
is necessary to study the performance analysis of individual components such as the heat exchanger reflecting thecharacteristics of the marine ORC system. Sotirios et al. (2011) reviewed the changes in heat transfer coefficient and heatexchanger efficiency by analyzing the effect of major variables of ORC systems operating in the supercritical region, notfor ships, on the heat exchanger performance. The final purpose of this study is to manufacture a 110kW brazed plate
heat exchanger type condenser that can be applied to an ORC power system for ships. For this purpose, research anddevelopment was carried out in the following orders. First, CFD modeling is produced using ANSYS CFX (v.18.1), acommercial numerical analysis program, based on a single heat transfer plate to be used for manufacturing plate heatexchangers. Through simulation through the CFD modeling, the condenser design requirement conditions for stable
operation are confirmed. Based on these design requirements, the ORC power generation system including the condenser
to which this requirement has been applied was simulated by using Aspen Exchanger Design and Rating (EDR, v.12.1),
a program dedicated to heat exchanger design, and Aspen Plus (v.12.1), a process simulation program. Through thesimulation results, the performance characteristics of condenser analysis according to the major factors of ORC power
generation system was reviewed. In this paper, the heat transfer performance of the CFD modeling and the EDR modelingof the condenser was compared and reviewed, and the heat transfer performance characteristics of the condenser
according to the turbine inlet pressure, cooling water temperature, and flow rate of working fluid in the ORC systemwere reviewed.

2. Figure and Table

3. Conclusion
In this study, CFD modeling and EDR modeling of the condenser constituting the marine ORC system were madeand the heat transfer performance was compared. A marine ORC system using R245FA as the working fluid was designed,
and the condenser performance characteristics were mainly reviewed through process simulation Aspen Plus (v.12.1). As
a result, the following conclusions were drawn within the scope of this analysis and calculation conditions.
(1) When the superheat condition of 5 ℃ of the heater was applied, the ORC thermal efficiency increased as thecooling water temperature of the condenser increased.
(2) As the inlet pressure of the turbine increases, the turbine output and system efficiency are improved. In particular,
the system efficiency improved significantly in the pressure range of 10 bar to 20 bar, which is a relatively low-pressure
region than in the high-pressure range.
(3) As the flow rate of the working fluid increased, the ORC system efficiency and heat exchanger heat transfer rateincreased. In particular, a decrease in the liquid fraction in the condenser was confirmed under a specific flow rate 1.1kg/s
condition through the analysis of the heat transfer rate distribution occupied by sensible and latent heat inside thecondenser. Therefore, appropriate working fluid flow rate should be selected for a stable condenser operation.

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