Thermoeconomic optimization of a hybrid power and cooling facility using waste heat recovery from a marine diesel engine

Abstract

Improving energy efficiency and reducing environmental impacts have become essential goals in today’s world. Finding ways to utilize waste heat for generating both power and cooling is a meaningful step toward more sustainable energy use and better resource management. In this research, the aim is to enhance the basic efficiency of diesel engines by harnessing the waste heat. By merging the diesel engine cycle with the ORC and the ejector-heat pipe cooling process, we can simultaneously generate power and cooling. This study focuses on tapping into the unused heat from a specific marine diesel engine to produce both power and cooling. The primary motivation is to cut down on fossil fuel usage due to its adverse environmental impact. To put it another way, this research focuses on increasing the base efficiency of diesel engines by recycling waste heat. By systematically integrating the diesel engine cycle with the organic Rankine cycle and the ejector-heat pipe cooling system, we can produce both power and cooling. Ultimately, 2-archive multi-objective cuckoo search algorithm-based optimization (MOCS2arc algorithm) establishes the optimized conceptual design. The system offers an electrical output of 72.01 kW and cooling capabilities of 56.83 kW, achieving an exergy efficiency of 60.4%. Moreover, economic metrics, including the facility’s unit cost of the product ($1259/GJ) and annual exergy destruction costs ($386,670), were ascertained. Under the optimization, exergy efficacy and SUCP of 64.9% and $902.21/GJ are achievable.

Introduction

Today, energy stands as humanity’s most strategic need, and its provision has evolved into an ongoing concern for nations^1–3. With the dwindling fossil fuel resources on one hand, and the adverse environmental effects they cause on the other, the importance and necessity of optimizing fossil fuel usage methods and energy production becomes increasingly evident^4,5. The rising consumption of fossil fuels, their limited availability, the steadily increasing cost of energy, and the environmental contamination emitted from the release of carbon dioxide and greenhouse gases, all strongly advocate for the efficient use of available energy and energy conservation⁶. Considering that the energy crisis is among the most fundamental challenges facing human societies, finding efficient energy production methods is a primary objective. Electricity production in thermal power plants is accompanied by significant losses^7,8. Even under optimal production conditions, like those in a combined cycle, more than 50% of the input thermal energy does not get converted into electricity^9,10. Instead, it is wasted as heat through plant smokestacks, plant condensers, and other equipment. Thus, the utilization of cogeneration systems emerges as a solution to reduce these losses and enhance the system’s efficiency¹¹.

Cogeneration systems for simultaneous power, heat, and cooling serve as a solution to energy wastage and environmental challenges. By harnessing the maximum work, heat, and cooling produced from a single fuel source, these systems have attracted the attention of researchers. Such units employ a heat source and, by minimizing wasted energy, bring the system’s waste heat source temperature closer to ambient temperature, thereby increasing the system’s thermal efficiency^12,13. It is here that cogeneration systems for power, heat, and cooling operate as an alternative system, satisfying diverse energy needs, ranging from cooling and heating to power. Given the significance of energy conversion topics in global advancement, effective utilization of energy resources and incorporating the industry of waste heat recovery can serve as suitable strategies for enhancing the efficiency and performance of cogeneration energy systems^14,15.

Newly, there has been a heightened interest in recovering wasted heat, and researchers have proposed novel methods for power generation through high and medium-temperature heat sources. Among the methods proposed for power cycles, diesel engines owing to their features such as lower environmental pollution, economic feasibility^16,17, high power, and elevated exhaust stream temperature can serve as an apt heat source in conjunction with other systems. Although, utilizing the marine engine waste heat potential that can be considered as a primary energy source for running power plan, very limited investigations have concentrated on the recovery of potential energy from the exhaust streams of internal combustion in mentioned type of engines¹⁸.

Agarwal et al.¹⁹ conducted an experimental research on agricultural machinery engines and power generators used the EGR method to study the pollution and performance of these engines. They concluded that with this method, the amount of NO_X and the temperature of the exhaust gases decreased, but the levels of HC, CO, and particulate matter increased. In another investigation, researchers²⁰, coupled two organic Rankine cycles (ORCs), one high-temperature and one low-temperature, using a heat exchanger, aiming to utilize the waste heat of engines. A waste heat recovery system for diesel engines was introduces by Song et al.²¹. In that study, two separate ORCs were used; one harnessed waste heat from the water chamber, and the other from exhaust gas emissions. For the appropriate fluid selection for each cycle and for optimizing system parameters, the highest power output generated by the system was set as the primary criterion. Moreover, by examining the results from the economic analysis and system design, they demonstrated that the system can be operational in real world. Zhao et al.²² conducted research on a co-generation power and heat system with a 70 kW gas-powered internal combustion engine in an office building in China. Scholars in another investigation²³, conducted a detailed assessment and optimization of the ORC system to harness waste heat from ship engine exhausts. The researchers mentioned that utilizing R141b in the optimized ORC setup offers a promising and cost-effective method for marine waste heat recovery.

Aghdoudchaboki et al.²⁴ developed an integrated system for eco-friendly ships to harness waste heat from marine engines and produce both power and fresh water. Through a dual-objective optimization focused on exergy efficiency and total cost rate, an optimal condition was identified, boasting 35.96% exergy efficiency at a cost of $2.54/hr. To address the energy crisis and environmental pollution, Ouyang et al.²⁵ focused on waste heat recovery from natural gas engines, given their environmental edge over diesel engines. A new system had been introduced that merges the supercritical CO₂ Brayton cycle, a dual-effect cooling system using absorption, and the Kalina cycle for waste heat recovery. This system enhances power output by 15.33% and shortens the return on investment time by 25.6%. This makes it a viable method for capturing unused heat from natural gas motors.

Boodaghi et al.²⁶ introduced a dual-loop Organic Rankine Cycle system aimed at recovering waste heat from a 12-cylinder stationary heavy-duty Diesel engine. A one-dimensional numerical model of the 1000 kW diesel engine was developed and subsequently validated against experimental data. The sensitivity analysis indicated that the total power output increases with higher values of the SOI, N, and elevated pressure in the high-temperature loop. Notably, the engine parameters did not influence the thermal efficiency or the rate of exergy destruction. In reference²⁷, both normal and advanced exergy analyses of a waste heat recovery system were conducted. The proposed system features a dual-loop organic Rankine cycle designed to capture the waste heat available from the intake air. The total exergy destruction that could be avoided in the low-temperature loop was quantified at 46.62 kW, suggesting that it warrants greater focus compared to the high-temperature loop, which had a lower exergy destruction of 12.42 kW. Furthermore, Etghani and Boodaghi²⁸ proposed a hybrid energy system that utilizes solar energy, incorporating a parabolic trough collector, a supercritical CO₂ Brayton cycle, a recuperative organic Rankine cycle, a proton exchange membrane electrolyzer, and a two-tank direct thermal energy storage system. This system is capable of delivering a dependable and sustainable supply of electricity, hydrogen, and hot water, showcasing a promising and feasible poly-generation technology suitable for both grid-connected and off-grid scenarios.

Avazpour et al.²⁹ conducted a thorough study on a parallel ORC system designed to recover waste heat from diesel engines used in off-road applications. Their approach integrated both transcritical and subcritical operational modes. For optimization, they employed a multi-objective genetic algorithm, targeting both exergy efficiency and specific investment cost. Through this bi-objective optimization, they attained a peak exergy efficiency of 45.92%, paired with a specific investment cost of $3350/kW. In a related development, Lebedevas and Čepaitis³⁰ numerically examined the practical considerations of ORC implementation with common marine medium-speed diesel engines, specifically citing the Wartsila 12V46F model. Their findings indicated that comprehensive waste heat recovery from all auxiliary heat sources within an ORC system could potentially boost the main engine’s energy efficiency by 13.5–21%. This efficiency gain was observed across a load range from 100% down to 25% of the engine’s nominal power. Mahmoud et al.³¹ explored the use of a ground-cooled ORC system for recovering waste heat generated by a diesel generator. Their study utilized real-time experimental data for ambient and ground temperatures. The ORC system, when operating at a design temperature of 300 °C, resulted in a 7.98% increase in overall output power compared to operating the diesel generator in isolation.

In our research, we aim to enhance the basic efficiency of diesel engines by harnessing the waste heat. By merging the diesel engine cycle with the ORC and the ejector-heat pipe cooling process, we can simultaneously generate power and cooling. This study focuses on tapping into the unused heat from a specific marine diesel engine to produce both power and cooling. Our primary motivation is to cut down on fossil fuel usage due to its adverse environmental impact. To put it another way, this research focuses on increasing the base efficiency of diesel engines by recycling waste heat. By systematically integrating the diesel engine cycle with the organic Rankine cycle and the ejector-heat pipe cooling system, we can produce both power and cooling. Ultimately, 2-archive multi-objective cuckoo search algorithm-based optimization (MOCS2arc algorithm) establishes the optimized conceptual design. The key differences and contributions of our study are now clearly articulated as follows:

• i.While many existing studies focus on dual ORC loops or single-mode heat recovery, our work proposes a unique integration of an ORC with an ejector-heat pipe cooling subsystem, powered entirely by marine diesel exhaust. The use of a heat pipe allows passive circulation, eliminating the need for a mechanical pump, which reduces auxiliary energy consumption and improves reliability.
• ii.Unlike most prior studies that focus on stationary engines or land-based systems, our research specifically targets marine diesel engines, which are underexplored despite their high thermal potential and continuous operation profiles.
• iii.Our study applies the 2-Archive Multi-Objective Cuckoo Search (MOCS2arc) algorithm, which, compared to traditional multi-objective optimizers (e.g., NSGA-II, MOPSO), offers better convergence and diversity handling through its dual-archive approach. This ensures a more comprehensive and balanced trade-off between exergy efficiency and cost.
• iv.Many previous works focus on either thermodynamic or simple economic assessments. We provide a detailed exergoeconomic breakdown, including cost of exergy destruction, component-level cost analysis, and sensitivity to key parameters, which is lacking in much of the existing literature.

Description of the proposed facility

In Fig. 1, we see a diagram showcasing the combined power and cooling system powered by a marine diesel engine. Table 1. provides the technical and functional details of this marine diesel engine. As illustrated, the heat produced from the engine’s exit first powers the ORC. After this, its remaining heat gets channelled to the ejector-heat pipe cooling system. In this setup, the ORC, equipped with an inbuilt heat exchanger, is primarily designed for waste heat capture and boosting overall efficiency. Within the ORC, the organic fluid initially heads towards the internal heat exchanger. Here, by soaking up heat from the boiler sourced from the exhaust gas, it transforms into saturated steam. This heated fluid, due to its high temperature and pressure, propels the turbine, thereby generating power. Following this, the temperature of the stream that departs from the boiler drops as it releases its heat in the boiler, and then it advances to the cooling cycle’s generator. The cooling system consists of various components: a generator, ejector, a mock pump mimicking oscillatory movements inside the heat pipe, an expansion valve, a condenser, and lastly, an evaporator.

Fig. 1.

scheme of the proposed combined cooling and power generation system.

Table 1.

 Technical features of the studied marine engine.

Parameter	Value
Engine type	ZLC-6210-5
Number and arrangement of cylinders	six-line
Cylinder diameter (mm)	210
The volume of a cylinder (litres)	10
Stroke (mm)	290
Maximum fuel pressure (MPa)	5/13
Engine power (kilowatt)	662
Fuel consumption rate (g/kWh)	202

The fluid inside the generator gets heated from the exhaust gases and merges with the fluid coming from the evaporator before making its way to the ejector. Owing to the pressure disparity, the high-pressure and low-pressure streams combine in the ejector, resulting in a mid-level pressure. The outflow from the ejector then turns into a liquid. A fraction of this liquid utilizes the heat pipe’s oscillatory characteristic, simulating a pump to move into the generator. Concurrently, another segment experiences a drop in both pressure and temperature in the expansion valve, which consequently generates cooling in the evaporator.

Thermodynamic modelling

Energy analysis

The total energy can be expressed as the sum of internal energy, kinetic energy, and potential gravitational energy as follows:

1

2

Exergy analysis

The exergy balance for a control volume is calculated from relation (3):

 

3

For steady-state, steady-flow processes, relation (3) converts to Eq. (4):

4

Unlike exergy destruction, the exergy loss exits the system and enters the environment, which can be in the form of fluid flow or heat transfer to the surroundings. The exergy balance for a control volume is determined according to relation (5):

5

The exergy efficiency is also determined according to relation (6):Table 2. gives the exergy balance equations, based on the exergy of fuel and product.

Table 2.

 Exergy balance equations, based on the exergy of fuel and product.

Element	Exergy balance based on fuel	Exergy balance based on the product
Boiler
Turbine
Heat exchanger (ORC)
Condenser (ORC)
Pump
Steam generator
Ejector
Condenser (ejector)
Expansion valve
Evaporator

6

Exergoeconomic analysis

Exergy is a basis for costing in a thermal system. In fact, thermoeconomic, or exergoeconomic, is based on the notion that exergy is the only logical source for allocating expenditures related to the financial exchanges with its environment and its inefficiencies. Essentially, exergy, which is a thermodynamic concept, is converted into money, which is an economic concept. Therefore, the cost balance equations for system components are summarized by³²:

7

The exergy balance equation in its general form, by expanding relation (7), becomes relation (8):

8

Herein, the cost balance and auxiliary equations for each of the system components are addressed, and the resulting equations are presented in Table 3..

Table 3.

 Cost balance equations.

Element	Cost balance equation	Auxiliary equation	Cost of element
Boiler
Turbine
Heat exchanger (ORC)
Condenser (ORC)
Pump
Steam generator
Ejector
Condenser (ejector)
Expansion valve
Evaporator

Performance evaluation of proposed system

To reach a better insight into the proposed combined plant, an assessment of the overall performance of the proposed system is essential. To this end, the performance criterion has been expanded under the thermodynamics laws. Furthermore, the relationship for system’s unit cost of product (SUCP) for the proposed combined facility has been developed and calculated. Thus, denotes the net power output of the proposed system that can be calculated by:

9

Additionally, the energy and exergy efficiencies of the overall facility are defined by relations (10) and (11):

10

11

Additionally, SUCP factor can be measured for the proposed combined system by:

12

here,  shows the net price of generated power that is calculated by:

13

The 2-archive multi-objective cuckoo search algorithm

The MOCS2arc algorithm is an advanced optimization technique designed to address complex multi-objective problems by integrating the Cuckoo Search (CS) algorithm with a dual-archive strategy. The CS algorithm, inspired via the brood parasitism behavior of cuckoos, has been recognized for its effectiveness in global optimization tasks. The CS algorithm follows Lévy flight-based random walks to explore the search space efficiently. Mathematically, the position of a cuckoo is updated using:

14

where, α is the step size scaling factor and L(λ) represents a Lévy flight distribution given by:

15

The Lévy flight enables a balance between exploration and exploitation, which is crucial for avoiding local optima. The two-archive mechanism in MOCS2arc maintains two separate archives:

Convergence Archive: Stores high-quality solutions guiding the search towards Pareto front.

Diversity Archive: Preserves solution diversity by maintaining a diverse set of solutions.

The MOCS2arc algorithm is comprised of the following steps

Initialization

The algorithm starts via initializing a set of solutions randomly distributed in the search space. The initial population is evaluated, and non-dominated solutions are stored in the two archives.

Solution generation via Lévy flights

New solutions are generated using Lévy flights:

16

Fitness evaluation and archive update

The fitness of each solution is computed using objective functions. Solutions are stored based on their dominance in either CA or DA. With probability (), poor solutions are discarded, and new solutions are introduced to maintain diversity. Steps 2 to 4 are repeated iteratively until a stopping criterion, such as a predefined number of iterations, is met³³. Figure 2 demonstrates the flowchart of the MOCS2arc algorithm.

Fig. 2.

The structure of the MOCS2arc technique.

Results and discussion

Results of thermodynamic and exergoeconomic modelling

To analyse the proposed system from thermodynamic and thermoeconomic approaches, the simulations were used along with the Engineering software. The results obtained from the energy, exergy, and thermoeconomic analysis of the system are mentioned in Table 4..

Table 4.

Results of thermodynamic and thermoeconomic modelling of proposed system.

Indicator	Value
Generated power by turbine	74.81 kW
Net power generation	72.01 kW
Inlet heat flux	409.8 kW
Condenser heating load (ORC subsystem)	222 kW
Condenser heating load (Ejector subsystem)	168.1 kW
Cooling load generation	56.83 kW
Mass ratio of ejector	0.5228
Energy efficiency (whole plant)	31.44%
Exergy efficiency (whole plant)	60.39%
SUCP index	1259 $/GJ
The exergy destruction cost	386,670 $/year

As shown in Table 4., the system designed in this research is capable of supplying electrical power of 72.01 kW and cooling capacity of 56.83 kW. The energy efficiency of the combined system is 31.44%, which has increased by approximately 28% compared to the basic organic Rankine cycle. Moreover, the unit cost of the total exergy and the cost of the total exergy destruction are respectively 1259 dollars per gigajoule and 386,670 dollars per year. Figure 3 shows the destroyed exergy of the components that have the highest irreversibility. As observed, Condenser 1, due to its heat exchange with the external environment for cooling the turbine outlet flow, has the largest share of exergy destruction.

Fig. 3.

Rates of exergy destruction in plant components.

Results of thermoeconomic assessment

Table 5. indicates the outcomes of the thermoeconomic investigation of the combined facility. In this table, from right to left, the order is destruction cost, price, relative cost difference, and thermoeconomic factor.

Table 5.

Results of thermoeconomic assessment for proposed plant.

Component		, $/yr	, $/yr	, $/yr	, $/yr
Boiler	45.2	0.50	621.8	613	764
Turbine	90.0	10.60	101,503	90307.5	11,196
Pump	69.85	0.98	3656.5	2552	1104
Condenser (ORC)	1.0	157.51	70,863	794	70,854
Steam Generator	38.30	0.87	628.0	240.2	388
Heat Exchanger (ORC)	13.18	0.43	2100.3	322.72	2093
Evaporator	77.40	27.40	1304.4	1303	381.5
Condenser (Ejector)	37.72	4.60	4716	1776	2940
Ejector	0.0	5.72	5876	0.0	5876
Expansion valve	73.65	1.07	1.9	0.6	1.4
Whole plant	20.18	26.07	484,577	97,907	386,672

Parametric study

Impact of combustion product temperature

Figure 4 demonstrates that as the temperature of the combustion products rises, both the basic cycle’s energy efficiency and the system’s overall energy efficiency improve. For instance, at 635 K, their efficiencies stand at 26.91% and 35.72% respectively. By analysing these results and the graphic representation, it’s evident that the system’s overall energy efficiency sees an enhancement of roughly 30% when compared to the base ORC’s energy efficiency. However, the exergy efficiency sees a reduction as the temperature increases. In line with the observed trend in energy efficiency, as combustion product temperatures rise, the power produced by the turbine and the heat supplied to the boiler also surge. Figure 4 depicts that with rising combustion product temperatures, the per-unit cost diminishes, while the total system exergy destruction rate amplifies. With elevated temperatures, there’s a boost in both the turbine power and the cooling capacity of the system, thereby incurring higher costs. However, the aggregate per-unit cost of the entire system trends downwards. This drop can be attributed to the fact that factors raising the cost don’t escalate as sharply as other influential parameters.

Fig. 4.

Impact of combustion product temperature on performance of proposed system.

Impact of condenser temperature

The condenser, known for its significant exergy destruction and high ratio of exergy wastage, is the focus of this section. Figure 5 showcases that, at a condenser temperature of 303.7 K, the entire system achieves its peak energy efficiency, registering at 33.44%. However, this efficiency drops as the temperature ascends. Concurrently, the system’s exergy efficiency bottoms out at 49.3% when the condenser temperature hits 307.2 K. Transitioning to Fig. 5, we observe a financial implication. As the condenser temperature elevates from 303.2 K to 310.2 K, the system’s unit cost climbs from 1259 to 1269 $/GJ. The rationale behind this uptick stems from the system’s cost dynamics. Based on the unit cost equation for the entire setup, both the net power output’s associated costs and those of the cooling capacity have swelled. This, in turn, prompts an upswing in the system’s cumulative per-unit cost.

Fig. 5.

Impact of condenser temperature on facility’s operation.

Impact of evaporator temperature

The temperature of the evaporator has a pivotal role in the ejector refrigeration cycle. Figure 6 presents the effects of variations in evaporator temperature on the operational characteristics of the system. According to Fig. 6, when there’s an uptick in the evaporator temperature, the net output power of the entire system maintains a steady trend without any discernible change. A rise in the evaporator temperature boosts the mass flow rate in the ejector refrigeration cycle, which, in turn, amplifies the cooling capacity. Continuing with Fig. 6, increasing the evaporator temperature sees both the energy and exergy efficiencies of the whole system trending upwards, displaying parallel trajectories. Specifically, as the evaporator temperature climbs, the energy efficiency jumps from 29.99 to 33.14%, while the exergy efficiency sees a more subtle increment, from 60.4 to 60.7%. Turning our attention to Fig. 6, it is observed that the system’s unit cost initially descends with rising evaporator temperature, hitting a nadir of 1259 $/GJ when the temperature reaches 283.2 K.

Fig. 6.

Impact of evaporator temperature on the facility’s performance.

Impact of steam generator temperature

The generator temperature is a key factor in the ejector refrigeration cycle. Its influence on the facility overall operation is the primary focus of this section. Figure 7 elucidates the effects of generator temperature changes on various performance indicators. According to Fig. 7, a hike in the generator temperature correlates with increases in both the thermodynamics efficiencies of the whole system, and these efficiencies move in tandem. As the generator temperature escalates, both the unit cost and the destructed exergy trend downwards. This decline can be attributed to the heightened generator temperature, which brings about reductions in the costs associated with the cooling capacity and the net power output. Consequently, this leads to a decrement in the overall per-unit cost for the system. Furthermore, as illustrated in the figure, there’s a decline in the system’s rate of exergy destruction.

Fig. 7.

Impact of generator temperature on facility’s operation.

The performance of the baseline ORC was simulated under identical inlet heat flux conditions (409.8 kW), and the results were as tabulated in Table 6..

Table 6.

Performance comparison between baseline ORC and proposed hybrid system.

Parameter	Baseline ORC system	Proposed hybrid system
Input heat flux (kW)	409.8	409.8
Net power output (kW)	57.5	72.01
Cooling output (kW)	–	56.83
Energy efficiency (%)	24.5	31.44
Exergy efficiency (%)	51.3	60.39
SUCP ($/GJ)	1478.2	1259

This comparison clearly illustrates the 28% relative improvement in energy efficiency and a notable reduction in SUCP. The hybrid system not only produces more power but also introduces a cooling benefit, which the baseline ORC lacks.

Optimization results

The generated Pareto front effectively demonstrates the trade-off between exergy efficiency (η_exergy) and SUCP in an energy system optimization scenario. As observed in the scatter plot (see Fig. 8), increasing η_exergy corresponds to a gradual reduction in SUCP, following an exponential decay trend. This behavior aligns with fundamental thermodynamic principles, where improvements in system efficiency lead to better utilization of energy inputs and cost reductions associated with energy losses. The knee point, marked in the Pareto front, represents the optimal compromise between cost and efficiency. It is identified at and . This point is where the rate of cost reduction per unit efficiency gain diminishes, making it the most cost-effective operating condition. Beyond this point, additional efficiency gains come at a significantly higher cost, indicating diminishing returns. The Pareto front reveals a high-density region of optimal points around the knee, highlighting the stability of the cost-efficiency trade-off in this range. The broad spread of points indicates variability in cost and efficiency due to different parameter combinations. This suggests that multiple configurations exist that can yield near-optimal performance, allowing for operational flexibility in selecting design parameters.

Fig. 8.

The Pareto front for the trade-off between exergy efficiency and SUCP in the energy system under MOCS2arc algorithm-based optimization scenario.

The exponential decay observed in the Pareto front suggests that initial improvements in efficiency yield substantial cost reductions, but as the system reaches higher efficiency values, the rate of cost savings decreases. This trend is crucial for economic decision-making. From an engineering perspective, the Pareto front confirms that higher exergy efficiency correlates with lower exergy destruction costs.

Conclusion

This investigation undertook an intricate energy, exergy, and economic exploration of a unique cycle aimed at concurrent power and cooling generation by fusing the ORC, ejector-based cooling, and a heat pipe. Grounded in the principles of the first and second laws of thermodynamics, this assessment employed the exhaust heat from a marine diesel engine. The layered cycle, articulated through thermodynamic laws, revealed a surge in energy efficiency with augmented heat input to the boiler and elevated combustion product temperatures. While significant exergy losses were pinpointed in the ORC’s condenser and boiler, minor losses were attributed to the expansion valve and pump. This innovatively designed system promises an electrical output of approximately 72.01 kW alongside a cooling provision of 56.83 kW. Demonstrating an impressive 31.44% energy efficiency, it trumps the basic ORC’s efficiency by nearly 28%. Integral to its design, the system’s heightened efficiency owes much to the negated need for a pump, courtesy of the heat pipe’s capillary action. Economic evaluations spotlighted a unit exergy cost of 1259 $/GJ and an annual exergy destruction cost of 386,670$. Furthermore, a meticulous investigation illuminated the repercussions of varied system parameters on overall performance. The key findings of this investigation are as follows:

1. With an elevate in the exit temperature of combustion products entering the system, the overall energy efficiency has increased by ~ 30% compared to the energy efficiency of the basic ORC. Also, the exergetic efficacy has a decreasing trend with the increase in temperature.

2. With an increase in condenser temperature within the specified range, the net output power reaches its minimum value of 71.81 kW at 307.1 K and then follows an upward trend. Also, the maximum cooling capacity of the entire system at the condenser temperature is 56.94 kW at 305.2 K.

3. The unit cost increases by ~ 0.8% via increasing the condenser temperature from 303.2 K to 310.2 K. The exergy destruction rate also decreases.

4. Under the optimization, exergy efficacy and SUCP of 64.9% and $902.21/GJ are achievable.

Author contributions

Author Statement: Mohamed Bechir Ben Hamida: Investigation, Software, Methodology, Writing – original draft, Formal analysis, Waqid Al-Mussawi: Investigation, Software, Validation, Writing – original draft, Visualization.Mohamed Shaban: Formal analysis, Investigation, Writing – review & editing.Mohammad Marefati: Methodology, Investigation, Formal analysis, Validation, Conceptualization, Project administration, Writing – original draft, Software, Methodology.

Funding

This work was supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University (IMSIU) (grant number IMSIU-DDRSP2503).

Data availability

Data availabilityAll data generated or analysed during this study are included in this published article.

Declarations

Competing interests

The authors declare no competing interests.