Thermo-Economic Study of a Regenerative Dual-Loop ORC System Coupled to the Main Diesel Engines of a General Support Vessel

Athanasios G Vallis,Efthimios G Pariotis,John S Katsanis,Theodoros C Zannis,Elias A Yfantis,Konstantina D Asimakopoulou

doi:10.3390/en13112991

Athanasios G Vallis, Efthimios G Pariotis + Show 4 more

Open Access

https://doi.org/10.3390/en13112991

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Journal: Energies	Publication Date: Jun 10, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Hellenic Naval Academy, University of Nicosia

Abstract

A thermo-economic analysis of a regenerative dual-loop organic Rankine cycle (ORC) is conducted, which will be coupled with the main diesel engines of a general support vessel. An energy and exergy analysis of the regenerative dual-loop ORC is conducted. The energy and exergy analysis results of the regenerative dual-loop ORC are compared with pertinent results for a simple dual-loop ORC without regeneration. A mission analysis that was based on a vessel speed profile with the proposed ORC was conducted. A heat transfer analysis was performed for dimensioning the heat exchangers of both ORC loops. Finally, an economic analysis is conducted to calculate the total capital cost and the payback period of the proposed ORC. The results showed that the proposed ORC is thermodynamically superior in both energetic and exergetic terms compared to the simple dual-loop ORC. The total fuel cost saving is 337,493 Euros, the total CO2 emission saving is 1,153,416.4 kg, and the SO2 emission saving is 36,044.3 kg. The total capital cost of the proposed ORC is 2,546,000 Euros. Finally, the installation of the proposed ORC in the examined vessel is economically feasible because it results in a reasonable payback period, which is less than nine years.

Highlights

Contemporary marine diesel engines that are currently used in naval vessels as main engines or auxiliary engines are characterized by high efficiency, which is higher when compared to marine gas turbines and marine steam turbines [1]
The geometrical dimensions of all heat exchangers were derived based on the heat transfer analysis of the fin-and-tube heat exchanger of the evaporator 1 of the high temperature (HT) loop that was described in Section 5.1 and the heat transfer analysis of the plate heat exchangers of the intercooler, the preheater, the evaporator 2 of the low temperature (LT) loop, and the condenser that was described in Section 5.2 and the vessel speed profile of the mission analysis
The regenerative dual-loop organic Rankine cycle (ORC) was comprised of two loops: one high temperature (HT) loop equipped with an evaporator for recovering waste heat from exhaust gases and an open feed organic heater (OFOH), which was fed with a high temperature organic fluid that was depreciated from the expander of the HT loop at intermediate pressure and used to preheat the low temperature organic fluid before it entered the evaporator of the HT loop

Summary

Introduction

Contemporary marine diesel engines that are currently used in naval vessels as main engines or auxiliary engines are characterized by high efficiency, which is higher when compared to marine gas turbines and marine steam turbines [1]. The remaining fuel heating power, which is not converted to useful brake power and exhaust gas heating power, is rejected to the engine coolant, to the cooling medium of the intercooler, and to the lubricant oil cooler, whereas a small percentage of the fuel heating power is rejected to the ambient through radiative heat transfer thermal losses [3]. Singh and Pedersen [4] have analyzed the specifications and the advantages and disadvantages of a water steam Rankine cycle, a subcritical Rankine cycle, and a supercritical organic Rankine cycle. They have examined the use of a secondary Kalina cycle with the ammonia–water mixture as working medium as an alternative thermodynamic cycle for the waste

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