## 1 Introduction
R-141b is a dichlorofluomethane compound and used to be one of the older types of refrigerants [26]. However, it has generally been replaced by environmentally friendly alternatives and was previously used in commercial refrigeration systems and some industrial applications. The usage of specific chemicals in various industries, including those utilized as working fluids in ORC systems, has been increasingly impacted by PFAS (Per- and Polyfluoroalkyl Substances) regulations. PFAS production, usage, and disposal are subject to stricter regulations from regulatory agencies such as the European Chemicals Agency (ECHA) and the U.S. Environmental Protection Agency (EPA). This includes restricting the amount of PFAS in products and outright outlawing specific PFAS compounds. The detailed descriptions of each fluid's characteristics and applications are provided in Table 1.  
The International Maritime Organization (IMO) amended MARPOL Annex VI in 2011 to require operational and technological energy efficiency measures to lower the quantity of CO2 emissions from international vessels. On 1 January 2013, the Ship Energy Efficiency Management Plan (SEEMP) and the Energy Efficiency Design Index (EEDI) were enacted. In 2021, IMO member states enacted additional energy efficiency measures to lower international shipping's carbon intensity by a minimum of 40% by 2030 compared to 2008. Additionally, within the scope of this study, the effect of adding a recuperator to the designed RC system on efficiency has been investigated. These calculations were performed separately for each working fluid used in the RC design, and the results were compared. Recuperators can be employed to enhance efficiency in specific thermodynamic cycles. In the RC, a recuperator can heat the feedwater by using the heat of the water leaving the condenser. This ensures the vapor has higher temperatures and more energy [1]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Fluid Type** & \multicolumn{2}{c}{**Characteristics**} & \multicolumn{2}{c}{**Typical Applications**} & \multicolumn{2}{c}{**Examples of Use**} \\ \hline Dry Fluids & - & Do not exhibit & & - & Air in gas turbines \\  & significant condensation & - & Gas turbines & - & Dry refrigerants in \\  & - & Remain in the superheated & - & Refrigeration systems & cooling systems \\  & vapor region & & & - & Idealized air cycles \\  & - & Undergo processes with & & - & in engines \\ Isentropic Fluids & - & constant entropy & - & Ideal gas processes & - \\  & - & Assume no heat transfer & - & Steam engines & - \\  & - & with surroundings & & & turbine models \\  & - & Enter the two-phase & - & Steam power plants & - \\ Wet Fluids & & (liquid-vapor) region & - & Cryogenic applications & - \\  & - & Partially condense during expansion & - & Cryogenic applications & cryogenic systems \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Descriptions of fluids’ characteristics and applications. Recuperators are particularly useful in systems with reduced heat emissions to the environment, facilities where energy recovery occurs, and continuously operating industrial applications [27]. This enhances system efficiency, reduces energy consumption, and minimizes environmental impacts. Recuperators recover waste heat from a system and convert this heat into usable energy for beneficial purposes. This results in energy savings and increases the overall efficiency of the system. Recuperators enable the system to operate more efficiently by recovering the energy of hot gases or liquids within the system instead of losing it as waste heat. This translates to reduced energy consumption. The recovery of waste heat can help reduce energy costs, significantly saving long-term operating expenses. By promoting energy savings, recuperators contribute to a decrease in fossil fuel consumption, subsequently reducing environmental impacts. Lower energy consumption can contribute to reducing greenhouse gas emissions and environmental pollution.