Brayton Cycle System Research Articles

Effect of H2S on the corrosion behavior of austenitic and martensitic steels in supercritical CO2 at 550 °C and 20 MPa for Brayton cycle system

Corrosion of alloy materials significantly influences the stability and efficiency of the supercritical carbon dioxide (S-CO2) Brayton cycle. In this study, we investigated the corrosion behavior of the austenitic alloy SP2215 and the martensitic alloy X19CrMoNbVN11-19 (X19) in S-CO2 at 550°C and 20 MPa. The effect of impurities, H2S, on corrosion behavior was studied. After 900 hours, SP2215 formed a 1.1 μm thick oxide layer (Cr2O3). X19 formed a loose and porous double oxide layer of 4.1 μm (outer: Fe3O4, inner: FeCr2O4). After H2S doping, SP2215 had an oxide layer of 6.2 μm (FeS, SiO2, and Cr2O3), while X19 was 9.8 μm (outer: Fe3O4, SiO2, FexSy and Fe2O3, inner: FeCr2O4, Fe2SiO4 and Cr2S3). Metal sulfides formed and the corrosion layer thickened. This indicates that H2S not only changes the corrosion mechanism but also aggravates the corrosion. However, the corrosion of CO2 is dominant. SP2215 has better corrosion resistance than X19.

Investigation on heat transfer of supercritical CO2/Xe mixture crossing pseudo-critical temperature cooled in a horizontal circular tube

Supercritical CO2/Xe mixture has a potential application prospect in the Brayton cycle system from the perspective of thermodynamic. Supercritical cooler is one of the key components there. However, the cooling heat transfer characteristics and mechanism of supercritical CO2/Xe mixture is still unclear, which restricts the development and design of supercritical cooler. The heat transfer of supercritical CO2/Xe mixture crossing Tpc cooled in a horizontal tube with inner diameter 8 mm is numerically explored in this study. The influences of operating parameters on supercritical mixture heat transfer are thoroughly examined. Buoyancy effect is evaluated through the buoyancy criterion Gr/Re2. Further, the mechanism of supercritical CO2/Xe mixture cooling heat transfer is revealed. It is found that heat transfer enhancement may occur during supercritical CO2/Xe cooled process, and heat transfer is weakened when mass fraction of Xe increases. Considering the bulk specific heat and buoyancy dominating jointly the behavior of supercritical cooling heat transfer, a modified Dittus-Boelter correlation is newly developed to predict heat transfer coefficient of supercritical CO2 and its mixture with Xe. The correlation matches well with the experimental and numerical data, and the average relative deviations of the new correlation are 18.27 % and 14.14 %, respectively. The investigation provides insight into the characteristics and mechanism of supercritical CO2/Xe mixture cooling heat transfer. The correlation can provide significant theoretical guidance for accurate design and optimization of supercritical cooler.

Investigation of the thermal-hydraulic characteristics of SCO2 in a modified hybrid airfoil channel

The performance of printed circuit heat exchangers (PCHE) is critical to ensuring the efficiency and compactness of supercritical carbon dioxide (SCO2) Brayton cycle systems used in advanced nuclear energy. In order to improve the performance of the airfoil fin channel PCHE, the effect of the airfoil fin size on the channel performance is investigated and the effect of the airfoil fin arrangement parameters on the channel performance is analyzed by the Taguchi method. Particularly, a modified hybrid airfoil fin channel adapted to the changes in thermophysical properties of SCO2 is proposed. The results show that the heat transfer characteristics of the PCHE channel are enhanced and the flow characteristics are weakened with the reduction of the airfoil fin size, and the comprehensive performance firstly increases and then decreases. Taking the comprehensive performance of the channel as the optimization objective, the best combination of airfoil fin arrangement parameters is 2 mm for transverse spacing, 10 mm for longitudinal spacing, and 4 mm for staggered spacing. Compared with the traditional airfoil finned channel, the modified hybrid airfoil fin channel has significantly improved the comprehensive performance by 2.8%–13.2 %.

Impact of pipe resistance on performance of supercritical carbon dioxide Brayton cycle system

This study develops a system simulation model based on the megawatt-class supercritical carbon dioxide Brayton cycle unit in Hengshui, China, to examine the effect of pipe section resistance on system performance. The results indicate that increased pressure loss in pipe sections significantly reduces power generation efficiency and power supply efficiency. Specifically, a 100 % increase in pressure loss results in 3.290 % and 4.377 % decreases in power generation efficiency and power supply efficiency, respectively. Moreover, higher pressure loss leads to increased CO2 mass flow rate at design power generation load. When the pressure loss is doubled, it requires a 17.593 % increase in CO2 mass flow rate to achieve the design power. Pressure loss in high-pressure section has minimal impact on system performance, while resistance in low-pressure section significantly affects it. For instance, a 100 % increase in pressure loss from the compressor outlet to the low temperature regenerator inlet causes a 0.37 % decrease in system power supply efficiency, and a similar increase from the high temperature regenerator outlet to the low temperature regenerator inlet leads to a 0.76 % decrease. These findings provide meaningful guidance for component design and piping layout optimization for similar systems.

Thermal safety characteristics analysis of helium xenon gas cooled small reactor system under LOCA accidents

The thermal safety characteristics of the system after a small break loss of coolant accident (SB-LOCA) in a helium xenon gas-cooled small reactor will determine whether the reactor will experience a meltdown and the duration of the meltdown. At present, research on SB-LOCA both domestically and internationally is mostly focused on water-cooled reactors, lacking relevant research on helium xenon gas-cooled reactors (He-Xe GCR). Therefore, it is of great significance to research the thermal safety characteristics of He-Xe GCR after a breach loss of coolant accident. This article improves the gas turbine model based on the original SB-LOCA analysis program for pressurized water reactors. And added a calculation model for the characteristics of helium xenon mixed gas, a heat transfer model for helium xenon mixed airflow, and a compressor model. Finally, a Brayton Cycle Reactor System Analysis program (BRESA) was developed for SB-LOCA analysis of He-Xe GCR. Explore the impact of the size and location of fractures on the thermal safety characteristics of the system using BRESA. Research has found that as the size of the rupture gradually increases, the decrease in reactor core power is greater, and the reactor power is shut down earlier. Comparative analysis of the impact of different breach positions on the residual heat removal characteristics reveals that a breach accident on the high-pressure side of the system poses a greater threat to system safety. Therefore, when setting the safety threshold for the Brayton cycle system, the focus should be on the hazards of high-voltage side breaches. This research achievement assists with the safe operation strategy of He-Xe GCR in the future.

An integrated system based on liquid air energy storage, closed Brayton cycle and solar power: Energy, exergy and economic (3E) analysis

In pursuing net zero emissions amid increasing energy consumption, renewable energy sources offer a path towards environmental sustainability. However, they are plagued by instability and intermittency. Energy storage systems have emerged as a solution to address these challenges, ensuring a stable power supply despite the fluctuations of renewables. Liquid air energy storage (LAES) has advantages over compressed air energy storage (CAES) and Pumped Hydro Storage (PHS) in geographical flexibility and lower environmental impact for large-scale energy storage, making it a versatile and sustainable large-scale energy storage option. However, research on integrated closed Brayton cycle (CBC) systems with LAES is still in infancy. A novel integrated system is proposed, incorporating LAES, CBC and solar power. Steady-state models for LAES and CBC were developed and validated in Aspen Plus® V12. A comprehensive and systematic evaluation of the proposed LAES-CBC system was performed. The optimal round-trip efficiency (RTE) reaches up to 68.82 %, improving 11.70 % compared to the base LAES-CBC system. Parametric analysis reveals that higher compressor outlet pressures enhance both exergy efficiency and RTE. Compressors contribute significantly to exergy destruction, particularly in the charging process. The optimal outlet pressure for PUMP1 is found to be 80 bar. Economic analysis shows a reasonable payback period of 8.60 years and 0.307 $/kWh of LCOS, confirming the system's financial viability.

Investigation of cross-wavy primary surface structures for heat exchangers of Brayton cycle system using argon

In order to investigate the performance of the Cross-Wavy (CW) primary surface heat exchanger in Brayton cycle system using argon, a three-dimensional numerical model is established in this paper, and the influence of the structural characteristics of the flow channel on heat transfer and flow is analyzed in depth based on numerical simulation results. Effects of amplitude (A), height (H) and thermal channel radius (R1) on pressure loss, heat transfer and overall performance are further investigated. The results indicate that the increase in A leads to a significant rise in heat transfer performance and energy loss. Compared with the maximum and minimum amplitude simulation results, the increase in the f coefficient can reach 140%, and the increase in Nu is 31.94%. With the increase of H from 1.7 mm to 3.2 mm, f decreases by 18.75% and Nu decreases by 8.07%. Whereas, the change brought about by R1 is very small, less than 2.5%. By comparing the f coefficients with the experimental results of the biconvex stamped plate heat exchanger, the feasibility of the CW primary surface heat exchanger for application in a micro nuclear power system is verified.

Design and cooling of permanent magnet generator in MW-class space closed Brayton cycle system

The closed Brayton cycle (CBC) system is a prime energy conversion technology to convert heat from the reactor to electric power for space missions due to its light weight, compact and stable operation. The CBC system incorporates a permanent magnet generator (PMG) mounted on the CBC shaft with the turbine and compressor. To ensure safe operation of the CBC system, a small fraction of the working fluid is used to provide the required cooling. In this study, four different cooling schemes used in CBC system are concluded and the key dimensions of the PMG are obtained through mechanical design theory and electromagnetic theory. Comprehensive research on the electromagnetic field and loss calculation is then performed. Furthermore, the cooling paths of the PMG are designed and the resulting temperature profiles are calculated. Finally, different cooling schemes are compared and the appropriate cooling advice is proposed.

Thermoeconomic analysis for hybrid solar Brayton cycles operating with different working fluids

A Brayton cycle analysis with regeneration fed by heat input from a central concentration solar energy tower and a combustion chamber that uses natural gas is presented. The thermodynamic model includes the irreversibility of the different components of a conventional Brayton cycle system and a solar concentration system through energy and exergy considerations. The environmental conditions of Barranquilla are used for the plant analysis using different working fluids throughout the day, where the carbon dioxide cycle presents an overall efficiency of 28.8 %, the cycle with air efficiency is 26.6 %, and the Helium cycle is 20.2 %. The model considers the energy flows within the plant and the exergy destruction. In this sense, the solar concentration system contributes an energy fraction of 0.209 when operating with air, while the exergy destruction fraction is 0.189 when operating with carbon dioxide when solar radiation is maximum. Finally, an estimation of the Levelized Cost of Energy is presented.

Thermodynamic performance of an innovative space nuclear Brayton cycle with S–N2O

The supercritical Brayton cycle system is renowned for its characteristics of elevated high-power density, compact structure, lightweight design, and extended operational lifespan, rendering it as a preeminent energy conversion approach for space nuclear power systems. Using nitrous oxide (N2O) as the working fluid in a supercritical Brayton cycle system enables heightened efficiencies at comparatively lower cycle temperatures. This study examined four distinct layout configurations, culminating in an in-depth analysis of their respective thermodynamic performances. Among the configurations analyzed, the newly proposed recompression Brayton cycle with partial cooling and heat recovery (RBC-PCHR) layout exhibited the best thermodynamic performance compared to other cycle configurations. This superiority can be principally attributed to augmented heat recovery procedures and reduced compression workloads. A detailed multi-objective optimization strategy is subsequently embarked upon, building upon the insights gained from the sensitivity analysis pertaining to the key operating parameters. The optimization outcomes show significant enhancements, with an increase of 1.37% in ηth and 32.18% in MBRU, along with a marginal decrease of 0.70% in ηex.

Structural optimization of S-CO2 Brayton cycle compressor impeller based on evolutionary algorithm

As the critical components for marine low-speed diesel engine flue gas waste heat recovery (WHR) supercritical carbon dioxide (S-CO2) Brayton cycle system, the structure of the compressor impeller is optimized by the evolutionary algorithm (EA) based on the co-simulation of the CAESES, ANSYS CFX and Opti Slang. The law of impeller pressure ratio, efficiency and power consumption in S-CO2 Brayton cycle (SCBC) as a function of rotational speed, inlet temperature, pressure and impeller structural parameters are revealed, and the method of improving SCBC efficiency for marine low-speed diesel engine flue gas waste heat recovery is studied. The optimized impeller structure is greatly enhanced in aerodynamic performance and safety, and the isentropic efficiency is increased by 2.54%, the pressure ratio is increased by 35.64%, and the temperature rise is increased by only 4.6%. A 100kW S-CO2 compression cycle test bench was set up to verify the simulation-optimized impeller results. The final results show that the optimized impeller structure, aerodynamic performance and safety are greatly improved. It provides theoretical support for selecting and optimising compressor impellers for marine low-speed diesel engine flue gas waste heat recovery S-CO2 Brayton cycle.

Research on the enhanced heat transfer performance of SCO2 caused by vortex generators with different geometric dimensions in novel airfoil channels

The performance of printed circuit heat exchangers (PCHEs) has a significant impact on the heat transfer efficiency and compactness of the supercritical carbon dioxide (SCO2) Brayton cycle system suitable for the fourth-generation nuclear energy system. Compared to PCHEs with other types of channels, the airfoil fin PCHEs have superior flow heat transfer performance. The installation of vortex generators (VGs) in the heat transfer channels can enhance heat transfer efficiently, but the application of them to PCHEs is very limited. In order to improve the performance of PCHE with airfoil fin channels, a novel channel structure combining airfoil fin channels with rectangular VGs is proposed, and the effect of geometric parameters of VGs on the thermal-hydraulic performance of the channels is also investigated. The results show that the VG improves the synergistic effect of velocity field and temperature gradient field, leading to the increase of turbulent kinetic energy and decrease of heat transfer entropy production in the channel, which finally promotes the enhancement of heat transfer. The comprehensive performance of the airfoil fin channel with VGs is 5.95%–19.47% higher than that of the conventional airfoil fin channel. The increase in the height and length of the VGs improves the heat transfer performance of the channel, and the increase in the width of the VGs weakens the heat transfer performance of the channel, and both increase the flow resistance of the channel. By comparing the comprehensive performance, it is found that the VGs have the best height of 0.2 mm, the best length of 0.8 mm and the best width of 0.04 mm. In addition, according to the noise performance statistics (NPS), the height of the VG contributes more to the Nu and Fanning friction coefficients of the airfoil fin channels.

Study on coupled heat transfer model and enhanced heat transfer law of liquid metals and supercritical fluids

ABSTRACT The supercritical carbon dioxide Brayton cycle system is being considered for application in the power conversion system of advanced liquid metal fast reactors. One important research topic is the coupled heat transfer characteristics and enhanced heat transfer laws between liquid metals and supercritical fluids. However, the traditional Reynolds analogy hypothesis with a constant turbulent Prandtl number is difficult to satisfy the numerical conjugate heat transfer research of liquid metals and supercritical fluids. Therefore, based on the open-source computational fluid dynamics program OpenFOAM, a numerical method suitable for the coupled heat transfer calculation of liquid metals and supercritical fluids was developed, which can achieve precise conjugate heat transfer solutions by applying different turbulence models and heat flux models to liquid metals and supercritical fluids. Subsequently, based on this method, the coupled heat transfer behavior of liquid metals and supercritical fluids in the straight channel of a typically printed circuit heat exchanger was studied. The focus was investigating the conjugate heat transfer characteristics of liquid heavy metal lead-bismuth eutectic and liquid metal sodium with supercritical carbon dioxide. Some sensitive results, including the inlet temperature and Reynolds number of liquid metals and supercritical fluids, were qualitatively and quantitatively analyzed.

Proposal and evaluation of a combined refrigeration system for engine waste heat recovery based on a supercritical CO2 Brayton cycle

Abstract In recent years, engine waste heat utilization technology has become one of the essential directions for green energy-saving development. In this study, the design of a combined refrigeration system for engine waste heat recovery under a two-stage supercritical carbon dioxide Brayton cycle is carried out, and based on the engine top-cycle energy flow and reactive flow characteristics, combined with thermodynamic and economic analysis models, the thermal and reactive efficiencies of the S-CO_2 Brayton cycle system are investigated. The multi-objective optimization model for waste heat recovery was created with hydropower efficiency and investment return as its objectives. The results showed that the minimum values of annual operating cost and initial investment cost of the combined system under the optimized conditions were 104.8 and 505.2 thousand RMB, respectively, and the total system energy loss was 7.25%. By further analyzing the top cycle parameters of the combined system, it is concluded that the combined system has better thermo-economic performance, and the results can provide some references for the combined refrigeration with engine waste heat recovery.

Energy system and resource utilization in space: A state-of-the-art review

<p>Deep space exploration expands our understanding about the evolution history of solar system, while the future development heavily relies on the construction of energy systems and utilization of resources on the planet. This paper systematically reviewed the progress in the environmental control and construction technologies of space bases, extraterrestrial in situ resource utilization technology, energy systems, key technologies for planetary transportation platforms, and geological explorations. The current status, pros and cons of these technologies and systems are introduced and discussed. As an important artificial microenvironment in the space base, the environmental control and life support system (ECLSS) provides necessary resources for human. Sintering and additive manufacturing technologies demonstrate the potential to construct a space base with lunar regolith or simulants. The extraction and in situ utilization of resources on the Moon, including water ice, oxygen, and helium-3, are crucial to maintain life support for lunar exploration. Typical energy systems that can be used on the Moon include photovoltaic cell, Stirling power generation technology, closed Brayton cycle (CBC) system, Rankine cycle system, heat storage system, and integrated energy system. The CBC system has the highest thermal efficiency (39%) among them, making it suitable for late-period energy supply. The performance of various planetary rovers, the most important transportation platforms, are summarized. Through geological explorations, the resource distribution, content, and occurrence can be obtained. Perspectives on the future, promotions of environment adaptation, resource recovery, energy efficiency, and intelligence of the existing technologies are still needed to move forward on space explorations.</p>

Thermoeconomic performance of supercritical carbon dioxide Brayton cycle systems for CNG engine waste heat recovery

The supercritical carbon dioxide (S–CO2) Brayton cycle is a potential technology for recovering waste heat from compressed natural gas (CNG) engines. To choose suitable cycle configurations is important considering the complex operating characteristics of CNG engines. The traditional evaluation models of the S–CO2 cycles configuration are relatively one-sided without the comprehensive considerations of evaluation metrics. On the basis of the analytic hierarchy process and information entropy theory, this paper proposes a multi-dimensional comprehensive evaluation method for S–CO2 cycles from three perspectives: thermodynamic, economic, and environmental performance. A thermoeconomic performance optimization is conducted using a non-dominated genetic algorithm Ⅱ. Unlike most of the existing researches that use a single stable operating condition, this paper considers the full operating conditions of engines. Results show that the recompression cycle has the best overall performance among the investigated cycles with an exergy efficiency and electricity production cost of 67.20 % and 0.45 $/kWh, respectively. The efficiency improvement of the CNG engine coupled with the WHR system can reach up to 6.31 %. This study can provide a new reference for the comprehensive multidimensional evaluation and performance characteristics and optimal performance acquisition under full engine operating conditions of the S–CO2 cycle.

High-Temperature Flow Behavior and Energy Consumption of Supercritical CO2 Sealing Film Influenced by Different Surface Grooves.

The Brayton cycle system, as a closed cycle working under high-temperature, high-pressure and high-speed conditions, presents significant prospects in many fields. However, the flow behavior and energy efficiency of supercritical CO2 is severely influenced by the structures of face seals and the sealing temperature, especially when the sealing gas experiment is the supercritical transformation process. Therefore, a numerical model was established to investigate the high-temperature flow behavior and energy consumption of face seals with different surface grooves. The effects of the operation parameters and groove structure on the temperature distribution and sealing performance are further studied. The obtained results show that the supercritical effect of the gas film has a more obvious influence on the flow velocity uθ than ur. Moreover, it can be found that the temperature distribution, heat dissipation and leakage rate of the gas face seals present a dramatic change when the working condition exceeds the supercritical point. For the spiral groove, the change rate of heat dissipation becomes larger, from 3.6% to 8.1%, with the increase in sealing pressure from 15 to 50 MPa, when the temperature grows from 300 to 320 K. Meanwhile, the open force maintains a stable state with the increasing temperature and pressure even at the supercritical point. The proposed model could provide a theoretical basis for seal design with different grooves on the supercritical change range in the future.

A new channel structure for strengthening heat transfer of SCO2 printed circuit heat exchanger (PCHE): variable sectional semicircular channel

In this paper, a mathematical and physical model is established to study the convective heat transfer performance of supercritical carbon dioxide (SCO2) in three kinds of horizontal semicircular channels (uniform cross-sectional channel, diverging and converging channels). The accuracy of the numerical model is verified by comparing with the experimental data. The computational results demonstrate that the converging channel can strengthen heat transfer effectively compared with the uniform cross-sectional channel under the same heat transfer area. In the range of calculated working conditions, the use of a converging channel resulted in a maximum improvement of 42.26% in the heat transfer performance of SCO2. However, the diverging channel deteriorates the heat transfer. It is discovered that the improvement of the field coordination of SCO2 in the converging channel is one of the main reasons for its enhanced heat transfer. In addition, the different distribution of turbulent kinetic energy and thermal conductivity are also an important factor affecting the heat transfer performance of SCO2 in different channels. Finally, we propose a new heat transfer correlation of the SCO2 cooling process in the horizontal semicircular converging channel. Compared with the five selected correlations, the new correlation has the best prediction accuracy, and its mean absolute relative error (MARE) and root mean square error (RMSE) are 9.49% and 10.6%, respectively. Our work will provide new insights and theoretical guidance for the design and optimization of coolers in SCO2 Brayton cycle system.

Analysis on the flow and heat transfer performance of SCO2 in airfoil channels with different structural parameters

As an important component of the system, the performance of the printed circuit heat exchanger (PCHE) has a significant impact on the efficiency and compactness of the supercritical carbon dioxide (SCO2) Brayton cycle system. Optimization of the structural parameters of airfoil fins can improve the performance of PCHE flow channels, but it has not received enough attention. Therefore, it is of great significance to investigate the effects of structural parameters such as the maximum thickness (Wf), the distance from the position where the maximum thickness is located to the leading-edge (Df), and the radius of the leading-edge (Rf) of the airfoil fins on the flow heat transfer performance of SCO2 in the channel of PCHE. A three-dimensional numerical model is developed and validated for performance analysis of the PCHE, meanwhile the thermal-hydraulic performance of channels with different structural parameters of the airfoil fins is compared. The results show that with the increase of the Wf of the airfoil fins, the heat transfer characteristics of the PCHE channel are gradually enhanced, and the flow characteristics are gradually weakened. When the maximum thickness of the airfoil fins is in the front, the heat transfer and flow characteristics of the PCHE channel are better. As the Rf of the airfoil fins increases, the heat transfer characteristics and flow characteristics of the PCHE channel fluctuate. The change of the turbulent kinetic energy, the boundary layer thickness, the synergistic effect of the velocity field and the temperature gradient field, and the local entropy production in the channel can well explain the mechanism of the flow and heat transfer of the SCO2 in the airfoil fin channel. In addition, among the channels with different structural parameters of the airfoil fins, the Fin-5 airfoil fin channel with Wf of 1.5 mm, the Fin-6 airfoil fin channel with Df of 0.6 mm and the Fin-13 airfoil fin channel with Rf of 1.46 mm are recommended. Their comprehensive performance is 2.0–6.3%, 0.9–5.6% and 0.13–1.81% higher than that of the Fin-3 airfoil fin channel, respectively.

Characteristics of the S-CO2 Brayton cycle for full-scale multi-condition diesel engines

With the diesel engine test data of the flue gas as the initial conditions and the boundaries, the arrangement of the S-CO2 recompression Brayton cycle (SCRBC) was established and the optimization of the S-CO2 Brayton cycle (SCBC) system for 6EX340EF, 6L16/24, and CHD622V20 diesel engine were studied. Additionally, the model accuracy was validated with the test data from Sandia National Laboratories (SNL). Meanwhile, the parameter optimization determined the optimal system operating conditions via a multi-objective genetic algorithm (MOGA). Finally, the feasibility of the SCBC applied in flue gas waste heat recovery (WHR) for marine engines was comprehensively assessed from the efficiency, net output power, fuel consumption rate, and exergy. The results showed that with the recompression Brayton cycle layout in the optimal configuration, the low-speed marine diesel engine could reach 1.68% of the maximum total efficiency improvement and 6.43 g/kWh of the fuel consumption rate reduction at 100% load, the maximum net output power increased to 178.14 kW; the medium-speed marine diesel engine could reach 2.37% of the maximum total efficiency improvement and 11.60 g/kWh of the fuel consumption rate reduction at 100% load, the maximum net output power increased to 31.69 kW; the high-speed marine diesel engine could reach 1.00% of the maximum total efficiency improvement and 5.58 g/kWh of the fuel consumption rate reduction at 25% load, the maximum net output power increased to 21.54 kW. By comparing the SCRBC of the marine diesel engine, the high-speed engine has the highest efficiency of flue gas WHR, followed by the medium-speed engine and finally, the low-speed engine. The cooler, flue gas heat exchanger, and high-temperature recuperator (HTR) modules were the weak points of the SCRBC system through the exergy analysis, and further optimization of the SCRBC system can be extended to other engines to improve efficiency and emission.