## 1 Introduction  
Internal combustion (IC) engines have been the primary power source for automobiles, long-haul trucks, locomotives, and ships over the past century [1]. Over this time, periods of high fuel costs and concerns about foreign oil dependence have resulted in increasingly complex engine designs to reduce fuel consumption [2]. Although the most efficient mode of the modern large diesel engines is about 48-51% efficient in utilising the fuel energy [3], the remainder is still lost as waste to the environment through exhaust gas and jacket water. It appears that developing concepts for utilising the waste heat is important in the area of IC engine application. Current interest in reducing emissions and engine operating costs has led to the use of efficient waste heat recovery (WHR). For marine engines, the waste heat was originally used for direct heating services, including space heating in winter [4], heavy fuel oil (HFO) heating [5], ballast water heating [6], and hot water supply. However, the heating loads needed for shipboard service on a conventional vessel are usually much less than the available waste heat, resulting in a large amount of heat being unused. WHR technology for power production was then proposed to be coupled with the power propulsion plants or to meet the demand for auxiliary services without additional fuel costs and zero associated CO\({}_{2}\) emissions. Steam-based WHR systems for both four- and two-stroke marine engines are available commercially, among others by MAN, ABB, Wartsila, Mitsubishi heavy industries, and Cummins [3]. Some work on marine WHRs has been reported in the past few years. The work conducted by [PERSON] and [PERSON] analysed a single pressure steam Rankine cycle (SRC) for a marine engine WHR [7], finding that the WHR is more attractive to combine with two-stroke IC engine than four-stroke IC engine from an economic perspective [8]. [PERSON] et al. [9] compared SRC-WHRs of a new design with a retrofitting one on board a passenger ship equipped with diesel-electric propulsion. [PERSON] et al. [10] studied a dual pressure SRC as a WHR system of a two-stroke diesel engine used for the propulsion of a tanker. As the exhaust gas temperature of marine engines is usually lower than 370 \({}^{\circ}\)C, it is economically unviable to operate a steam Rankine cycle system [11]. Organic Rankine cycle (ORC) has since been proposed as an alternative solution for two-stroke engines because of their low exhaust temperatures. [PERSON] [12] conducted a review of different waste heat recovery systems for power generation, including Rankine cycle, Kalina cycle, exhaust gas turbine system, thermoelectric generation system, and the combination of these technologies, focusing on the utilisation of WHR for the supply of mechanical/electrical power to the ship. [PERSON] and [PERSON] [13] made comparisons between SRC, ORC, and Kalina cycle for marine WHR, and indicated that ORC produced about 7% additional power and that the SRC and Kalina cycles produced about 5% additional power. A comparison between ORC and conventional steam Rankine cycle was conducted by [PERSON] et al. [14], which showed that ORC has better performance, as higher turbine efficiencies can be achieved for the ORC compared with the steam Rankine cycle system. These studies aimed to explore the ORC system's potential as an alternative to SRC and demonstrated its potential to improve fuel efficiency at relatively low engine exhaust temperatures. Apart from heating and electricity, cooling is also required for food preservation and air conditioning, especially for cruise ships. Thermally powered cooling technologies have gained considerable interest. [PERSON] et al. [15; 16; 17] proposed an electricity-cooling combined system (ECCS) for waste heat recovery of marine engines, in which the condensation heat of SRC is used to heat the generator of the absorption refrigeration cycle. Some scholars proposed to integrate power with cooling cycles, in which the ammonia mixture is used as the working medium [18; 19; 20].