###### Abstract
[9] presented a novel concept for an ORC system consisting of three loops. This innovative design involves the integration of two loops that overlap, utilizing the high-temperature flue gas from the host as the primary heat source. Additionally, a separate subsystem is formed, utilizing the host cylinder liner cooling water as another heat source. The condensers in these two subsystems operate in series and employ flash natural gas as the cooling medium. In their research, [PERSON] et al. [10] introduced an innovative approach that combines the steam Rankine cycle and the organic Rankine cycle to enable simultaneous recovery of waste heat from the ship's main engine and the cylinder liner cooling water. Furthermore, they utilized the cylinder liner cooling water to preheat the mass in the exhaust heat recovery circuit. This integration resulted in a remarkable improvement of 4.42% in overall efficiency. In their study, [PERSON] et al. [11] implemented a strategy in the ORC system where the working fluid is preheated using waste heat from the main engine's jacket cooling water. Following the preheating process, the working fluid is directed to the evaporator to facilitate direct heat exchange with the high-temperature exhaust gas. This approach enables the effective cascade utilization of waste heat energy. [PERSON] and [PERSON] [12] analyzed the possibility of using an ORC system to simultaneously recovers three forms of waste heat from a Two-stroke diesel engine exhaust, charge air and cylinder liner cooling water, and calculated and analyzed that the system could reduce the ship's carbon emissions by 6.9%. [PERSON] et al. [13] built two separate ORC systems to recover two forms of wasted energy from a maritime vessel's medium-speed diesel engine. They succeeded in increasing the diesel engine's thermal efficiency by 10.2%, and the net output power of the two systems reached 101.1 kW. [PERSON] et al. [14] improved the central cooling system of an LNG vessel with electric propulsion and built various types of ORC systems with a maximum net output of 820 kW for recovering waste heat from charge air cooling, cylinder liner cooling water, and lube oil cooling. [PERSON] et al. [15] used an ORC system driven by exhaust gas, cylinder liner cooling water, and booster air waste heat from the main engine of an oil tanker for power generation. [PERSON] and [PERSON] [16] used exhaust gas and cylinder liner cooling water as the ORC system heat source to recover waste heat from a dual-fuel main engine of an LNG vessel at the same time, and the net output power of the ORC system could reach 5.17% of the power of the main engine. [PERSON] et al. [17] built three types of ORC systems to collect waste heat from a ship's medium-speed diesel engine's exhaust gas and jacket cooling water. There are few studies to investigate BORC and RORC systems in terms of actual operating parameters of specific types of marine main engines, and no specific calculations have been made to analyze the fuel savings and carbon emissions during the whole year. In this work, the MAN 8865 ME-C8.6 HL model with complete operating parameters under standard operating conditions (sweep gas temperature 25 \({}^{\circ}\)C, ambient temperature 25 \({}^{\circ}\)C) is selected based on the operating parameters of each model provided in the CEAS database for the low-speed two-stroke diesel fuel that is currently in common use, and the type and distribution of waste heat generated by this type of diesel engine under various operating loads is first investigated. Two ORC models are constructed with reference to the actual operating parameters of the main engine of a type of ship, using exhaust gas and cylinder liner cooling water waste heat, analyzing the effects of seawater temperature and load changes on system performance during the voyage of the main engine.