Exergetic Sustainability Index Research Articles

Waste to hydrogen: Investigation of different loads of diesel engine exhaust gas

In this study, green hydrogen production by utilizing diesel engine exhaust gas waste heat in steam and organic Rankine with internal heat exchanger with two thermoelectric generators and proton exchange membrane electrolyzer combined system under different load conditions is investigated. Thermo-economic, enviro-economic and exergo-environmental analyses of the maximum hydrogen production point determined for different waste heat conditions are carried out. Total and specific investment cost and levelized cost of hydrogen determined under different loads are compared. Simple and dynamic payback period, profit ratio of investment and net present value of the combined system at different selling prices of hydrogen are determined and their feasibility is analyzed. Carbon reduction and carbon credit gain amount due to green hydrogen produced in line with zero emission targets are compared under different waste heat conditions. Exergetic sustainability index of the system were determined within the scope of exergo-environmental analysis. In terms of economic and environmental performance, a hydrogen cost of 2.04 $/kg was obtained under 100% load and a carbon saving of 7211 $ was achieved depending on the hydrogen produced. Dynamic payback period and net present value were found to be 4.467 years and 404,696 $, respectively, if the hydrogen selling price was 5 $/kg under 100% load. It is found that a 50% load reduction leads to an increase in dynamic payback period and levelized cost of hydrogen by 18.6% and 13.72%, respectively, and a decrease in net present value and profit ratio of investment by 54.39% and 12.39%, respectively. On the other hand, since the exergy destruction decreases with the decrease in the load, exergo-environmental index is found to decrease by 2.03%.

Thermodynamic and environmental performance of a Kalina-based multigeneration cycle with biomass ancillary firing for power, water and hydrogen production

The performance of a Kalina-based multigeneration cycle for power, water, and hydrogen production is investigated from thermo-environmental, sustainability, and thermo-economic perspectives. The plant comprises a gas turbine (GT), Kalina cycle (KC), and vapor absorption system (VAS) as the bottoming cycle and an integrated domestic water heater and proton-electron membrane (PEM) electrolyzer for hydrogen production. The system's models were simulated with Engineering Equation Solver (EES) codes. The results indicate a net energy efficiency of 53.48% and exergy efficiencies of 50.05 %, with an additional 30,178 kW of products from the bottoming cycles. The GT contributed approximately 85.81 % of the overall exergy destruction. The system's exergo-thermal index (ETI) stood at 1.713, with the GT only having an ETI of 2.106. Similarly, the exergetic sustainability index (ESI) of the multigeneration plant was not greater than 2.04. The exergoeconomic analysis shows a low average energy cost from the GT, estimated at 0.836 $/GJ, compared to the Kalina subsystem, which stood at 6.53 $/GJ. The thermodynamic and cost evaluation of the system demonstrates substantial benefits from the plant, which kept the hydrogen production rate at 0.1524 kg/hr.

Exergy analysis and Exergetic sustainability index of package boiler

Energy is one of the basic human needs. Economic growth and population growth in a country which continues to increase is directly proportional to the growth in energy needs required by society. Indonesia is the largest energy user in Southeast Asia, namely more than 36% of Southeast Asia's primary energy use. Utilization of the energy used will reduce the increase in production costs for an industry. The use of energy is better known as energy conservation. Energy and exergy analysis based on the first and second laws of thermodynamics is used to analyze the thermal system of industrial units. This can be applied to equipment units in the fertilizer industry to identify sources of inefficiency, determine their location and the amount of exergy destruction that occur. To reduce exergy destruction, this can be done by modifying the operating conditions of the package boiler. The results show that 94.3% of the total exergy destruction from the boiler package is obtained from the evaporator component with a value of 2.7 x 108 kJ/hr Modification of the operating conditions of the evaporator is carried out by reducing Boiler Feed Water (BFW) inlet temperature with T 100C (196 – 116 oC). The decrease BFW temperature will increase the amount of required latent heat and reduce the convection heat that will be carried by the flue gas to generate superheated steam. Optimization of the BFW temperature is performed be calculating the flue gas temperature and exergoeconomic analysis. Exergoeconomic analysis is performed by calculating the cost rate of exergy destruction (ĊD,k) and exergoeconomic factor (fk). The results obtained were that the temperature was optimum of BFW is at 161°C which resulted the reduction of exergy destruction of 6,2x106 kJ/hr and resulting difference cost losses based on actual data (196 oC) of Rp 1,370,354,743/hr. Exergetic Sustainability Index (ESI) used to demonstrate how reducing a system's environmental impact can be achieved by reducing its exergy consumption (destruction and losses) or increasing its exergetic efficiency. In this research, ESI Value was achieved at 0.918.

Exergy analysis and exergetic sustainability index of package boiler

Exergy analysis and exergetic sustainability index of package boiler

Exergy analysis and exergetic sustainability index of package boiler

Exergy analysis and exergetic sustainability index of package boiler

Thermodynamic Analysis of the Integrated System that Produces Energy by Gradual Expansion from the Waste Heat of the Solid Waste Facility

The rapid increase in consumer societies leads to a rise in waste facilities. Especially when considering the amount of power used in waste plants and the corresponding waste heat generated, an approach to recover waste heat from these facilities has been proposed. Initially, the waste heat from the solid waste facility was assessed using the Rankine cycle. Subsequently, an Organic Rankine Cycle (ORC) system was integrated into the lower cycle of the steam Rankine cycle. The integrated system was completed by harnessing waste heat from the Rankine steam cycle in the carbon dioxide cycle. These power generation systems are designed with two turbines, each with gradual expansion. Using sub-cycles, 1 kg/s of air at 873.2 K was obtained by evaluating the waste heat. In terms of energy efficiency, it can be observed that the R744 gradual expansion cycle exhibits the highest energy and exergy efficiency. Cooling with water in heat exchangers reduces exhaust efficiency. The highest mass flow requirement is found in the ORC system when the R123 fluid is used. The energy efficiency for the entire system was calculated as 22,4%, and the exergy efficiency for the entire system was calculated as 60.7%. When Exergo Environment Analysis was made, exergy stability factor was found to be %60.7, exergetic sustainability index was found to be 2.66. There is also 370K waste heat available, which is recommended for use in drying units. These calculations were performed using the Engineering Equation Solver (EES) program.

Sustainability evaluation of a heavy-duty diesel engine used in railways

Heavy-duty diesel engines are essential power units for the Rail and Maritime transportation of people and goods. They are inevitable and consume large amounts of petroleum base fuel, producing substantial emissions. Since they are very bulky and costly to run and maintain, their performance, efficiency, and sustainability data are scarce, also. They are stationary constant-speed engines. Their efficiency values are relatively higher than conventional diesel engines. However, with newer pre and post-injections and fumigation techniques, those engines have significant room for improvement. This study thermodynamically examined a 16-cylinder, 4-stroke, and 90lt heavy-duty diesel engine with 1700 kW rated power output at 1500 rpm. Analyzes were performed on four different same-type engines archive data, obtained by permission, including different speeds and load conditions. Mean energetic and exergetic efficiency values were 12.84% and 11.92% at idling speeds of 650 rpm, 32.00%, and 29.70% at 1000 rpm, 31.35% and 29.10% at 1200 rpm, and 31.35% and 29.09% at the maximum speed of 1500 rpm. The waste-exergy ratio was 71%, the exergy destruction factor 45.5, the environmental effect factor was to be 2.44, and the exergetic sustainability index 0.41.

Exergoeconomic and Exergetic Sustainability Analysis of a Combined Dual-Pressure Organic Rankine Cycle and Vapor Compression Refrigeration Cycle

In this paper, an exergoeconomic and exergetic sustainability analysis of a dual-pressure organic Rankine cycle (ORC) and vapor compression refrigeration cycle (VCRC) driven by waste heat is performed for power generation and cooling production. In addition, the most suitable fluid couple among the thirty-five different fluid pairs was investigated for the proposed combined system. The results indicate that the highest energy utilization factor, exergy efficiency, the system coefficient of performance, and net power are calculated for the R123-R141b fluid pair. In terms of exergetic sustainability indicators, the best performance results are obtained for the R123-R141b fluid combination. The minimum unit electricity generation cost and the shortest payback period are calculated as 0.0664 $/kWh and 2.5 years, respectively, for the R123-R290 fluid pair. The system component with the highest exergy destruction is the boiler, with 21.67%. The result of the parametric analysis showed that the thermodynamic performance parameters increase with the increment of the ORC’s boiling temperature. In addition, with the increasing boiling temperature, the environmental effect factor of the system decreases, while the exergetic sustainability index increases. Additionally, as the boiling temperature increases, the total system cost increases, while the unit electricity production cost and payback period decrease. It is suggested to use a R123-R141b fluid couple among fluid pairs created as a result of thermodynamic, exergoeconomic and sustainability analysis.

Experimental and numerical performance assessment of a hybrid parabolic dish collector with photovoltaic for a distiller

ABSTRACT Environmental pollution has been rising recently, and so clean water needing has also increased. People could have easy access to pure water in all environments and conditions. This study is the solar tracking parabolic dish collector with produced pure water independent of electricity (off-grid). This system is fully renewable and autonomous. This system possesses a receiver, a boiler, a condenser, six 1000 mm diameter parabolic dish collectors, and 1 kW photovoltaic (PV) collectors. Thermal oil uses as the working fluid in the experiments. The experiment measured solar radiation, air temperature, air velocity, oil inlet and outlet temperatures, oil flow rate, receiver side surface temperatures, and instantaneous amount of pure water. Numerical and thermal analysis of the receiver in the experimental setup carry out. ANSYS Fluent 18.1 uses for numerical analysis. Energy and exergy analysis calculates the receiver for pure water production rate. The time interval when the system operates at high performance determines. In this study investigates the behavior of some exergetic indicators on the performance of the experimental setup, the cost of the experimental setup, and the enviro-economic impact of the parabolic dish-type collector. For this purpose, some exergetic factors such as the exergy effect, environmental impact factor, waste exergy rate, improvement potential, and exergetic sustainability index examine. The receiver’s improvement potential is between 1700 and 3000 W. In addition, the sustainability index, waste exergy rate, and environmental impact factor range from 0.32 to 0.36, 0.90 to 0.94, and 2.6 to 3.0, respectively.

Energy efficiency and cost assessment of a residential site with a combined heat and power system optimized with cryptocurrency mining

AbstractCombined heat and power (CHP) systems, an effective way of meeting high energy demand with high efficiency, were adapted to existing large service buildings in most studies. Because of the large daily and seasonal fluctuations in energy and electricity demands of the buildings, optimization problems have come into view and have been studied. This study propounds a holistic design solution for the CHP systems' inadequacy to meet varying consumer energy demands in residential and the excessive electricity demand created by cryptocurrency mining. In addition, the study defines the possible high efficiency and sustainability for residentials producing and consuming heat and electricity by themselves.An energy‐conservative three‐block residential and a CHP system were projected together by a holistic view balancing the residencies' peak thermal demand to the thermal output capacity of the CHP system. The investment return rate of the CHP system was maximized by optimizing the thermodynamic efficiencies and maximizing the electric generation for cryptocurrency mining. The energetic efficiency increased from 40% to an energy utilization factor of 83%, and exergetic efficiency increased from 39% to 42%. The waste‐exergy ratio decreased from 61% to 58%. The engine's environmental effect factor was 1.56 and reduced to 1.38 with the CHP system. The exergetic sustainability index was improved from 0.64 to 0.72. The benefit–cost ratio was estimated as 1.6, with an internal return rate of 79%. Holistic designs considering common values should be considered to improve sustainability.

Energy, exergy, thermoecologic, environmental, enviroeconomic and sustainability analyses and assessments of the aircraft engine fueled with biofuel and jet fuel.

In this study, utilization of a bio-based fuel in a turbojet engine is comprehensively monitored with adapting various useful indicators for the scope of the study based on thermodynamic principles. In this regard, extensive energy and exergy, thermoecologic, environmental, enviroeconomic and sustainability analyses are performed for both the turbojet engines fueled by jet kerosene and fueled by a bio-based fuel. As per the main findings, the mass stream of combustion emissions is measured to be 4.547kgs-1, when the engine is powered by biofuel. The specific fuel consumption and specific thrust are determined as 0.13kgkN-1s-1 and 147.81 kNs kg-1 for jet kerosene-powered case, while they are calculated as 0.15kgkN-1s-1 and 148.23 kNs kg-1 for biofuel-powered case. If biofuel is selected over jet-kerosene fuel, it is observed that the engine has better energy efficiency performance by 18.18%. The engine's environmental effect factor value is found as 4.88 for jet-kerosene usage condition, while it is found to be 4.93 for biofuel utilization case. The overall emitted CO2 emissions is measured as 336,672kg-CO2 year-1 for jet-kerosene usage condition, while it is estimated as 222,012kg-CO2 year-1 for the biofuel utilization case. Also, as far as biofuel is chosen as alternative to jet-kerosene, the environmental damage cost stream, namely the enviroeconomic parameter of the engine, falls from 59,254.27 US$ year-1 to 39,074.11 US$ year-1. It is observed that sustainable efficiency factor and exergetic sustainability index outputs of the components of air compressor are the same for jet-kerosene and biofuel utilization cases, which are 8.31 and 7.31, respectively.

Assessment of Whole Milk Powder Production by a Cumulative Exergy Consumption Approach

The production of food is a sector that consumes a significant amount of energy and encompasses both agricultural and industrial processes. In this study, the energy consumption of whole milk powder production, which is known to be particularly energy-intensive, was examined. The study used a cumulative exergy consumption approach to evaluate the overall production process of whole milk powder, including the dairy farm (raw milk production) and dairy factory (powder production) stages. The results showed that raw milk production dominated energy and exergy consumption and carbon dioxide emissions. An amount of 68.3% of the total net cumulative exergy consumption in the system was calculated for raw milk production. In the dairy factory process, the highest energy/exergy consumption occurred during spray drying, followed by evaporation and pasteurization. In these three processes, 98.3% of the total energy consumption, 94.6% of the total exergy consumption, and 95.7% of the total carbon dioxide emissions in powder production were realized. To investigate the improvement potentials in the system, replacing fossil fuels with renewable energy sources and using pasture feeding in animal husbandry were evaluated. While using alternative energy sources highly influenced powder production, pasture feeding had a high impact on consumption in raw milk production. By using renewable energy and pasture feeding, the exergy efficiency, cumulative degree of perfection, renewability index, and exergetic sustainability index values for the overall process increased from 40.5%, 0.282, −0.22, and 0.68 to 68.9%, 0.433, 0.65, and 2.21, respectively.

Drying Characteristics, Kinetic Modeling, Energy and Exergy Analyses of Water Yam (Dioscorea alata) in a Hot Air Dryer

In this study, drying characteristics, kinetic modelling, energy and exergy analyses of a convective hot air dryer are presented for water yam. The drying experiments were carried out at temperature levels of 50, 60, and 70°C and slice thicknesses of 3, 6, and 9 mm. The effects of drying variables on the drying rate (DR), moisture diffusivity (Deff), activation energy (Ea), energy utilization (EU), energy utilization ratio (EUR), exergy loss (EXL), exergy efficiency (EXeff), improvement potential (IP), and exergetic sustainability index (ESI) were investigated. The results showed that increasing air temperature increased the DR, Deff, EU, EUR, EXL, EXeff, IP, and ESI, while increasing the slice thickness increased Deff and Ea, but decreased the DR. The highest Deff and Ea values were 4.2 × 10−8 m2/s, and 53 KJ/mol, respectively. EU and EUR varied from 10 to 150 J/s and 0.39 to 0.79, respectively. EXL and EXeff varied between 2 and 12.5 J/s and 58 to 75 %, respectively. Midilli’s model had the best performance in predicting the moisture ratio of water yam with coefficient of determination (R2 = 0.9998), root mean square error (RMSE = 0.0049), and sum of square error (SSE = 0.0023).

Optimization of energy and exergy parameters for a conceptual after burning turbojet engine

In this study, parametric cycle analysis of a conceptual turbojet engine with an afterburner (TJEAB) was conducted at sea level conditions-zero Mach. Based on this analysis, exergetic sustainability parameters of TJEAB were scrutinized for military mode (MM) and afterburner mode (ABM). Constitutively, several design parameters of TJEAB were chosen so as to optimize performance and exergetic parameters which consist of specific fuel consumption (SFC), overall efficiency, exergy efficiency, environmental effect factor (EEF) and exergetic sustainability index (ESI). In this context, compressor pressure ratio (CPR), turbine inlet temperature (TIT) were preferred due to high effect of these variables on engine performance. CPR ranges from 4 to 11 whereas TIT varies from 1150 K to 1550 K. According to optimization of performance parameters, minimum SFC was achieved as 28.59 g/kN.s at MM and 43.95 g/kN.s at ABM. On the other hand, maximum overall efficiency is determined as to be 13.07 % at MM and to be 8.5 % at ABM. As for exergetic parameters, exergy efficiency was calculated as maximum with 30.85 % at MM and 23.2 %at ABM. Finally, maximum exergetic sustainability index of TJEAB was computed as 0.446 at MM and 0.269 at ABM. It is thought that energetic and exergetic parameters analyzed in this analysis could guide in designing turbojet engines in terms of lower fuel consumption thereby environmental-benign.

Energy, exergy, economic, environmental, and sustainability assessments of the CFM56-3 series turbofan engine used in the aviation sector

In this study, aviation, energy, exergy, environmental, exergoeconomic, and exergoenvironmental analyses are performed on a CFM56-3 series high by-pass turbofan engine fueled with Jet-A1 fuel. Specific fuel consumption and specific thrust of the engine are found to be 0.01098 kg/kN.s and 0.3178 kN/kg/s, respectively. Engine's energy efficiency is calculated as 35.37%, while waste energy ratio is obtained as 64.63%. Exergy efficiency, waste exergy rate, and fuel exergy waste ratio are forecasted as 33.32%, 33175.03 kW, and 66.68%, respectively. Environmental effect factor and ecological effect factor are computed as 2.001 and 3.001, while ecological objective function and its index are taken into account of −16597.22 kW and −1.001, respectively. Exergetic sustainability index and sustainable efficiency factor are determined as 0.5 and 1.5 for the CFM56-3 engine, respectively. Environmental damage cost rate is determined as 519.753 $/h, while the environmental damage cost index is accounted as 0.0314 $/kWh. Specific exergy cost of the engine production is found as 40.898 $/GJ from exergoeconomic analysis, while specific product exergy cost is expressed as 49.607 $/GJ from exergoenvironmental analysis. From exergoenvironmental economic analysis, specific exergy cost of fuel is computed as 10.103 $/GJ when specific exergy cost of production is determined as 40.898 $/GJ.

Exergetic Sustainability Analysis of a Naphtha-Based Combined Cycle Power Plant (CCPP)

In today’s scenario, ensuring sustainability of energy system particularly in the field of power generation is a major concern, and in this regard, exergy analysis is widely accepted tool. For this purpose, first, a comprehensive performance is carried out between two gas turbine plants, i.e., GT2 (case I) and GT1 (case II) using various exergy performance parameters. Further, a comprehensive performance evaluation is carried out between three cases; GT2 (case I), GT1 (case II) and CCPP (case III) using different sustainability indicators such as exergy efficiency, waste exergy ratio, exergy destruction factor and recoverable exergy ratio. Results demonstrate that exergetic sustainability index of combined cycle power plant (CCPP) is 0.45 when compared with GT2 (0.29) and GT1 (0.28). The increased sustainability index is because of the incorporation of a bottoming cycle, which ultimately decreases waste exergy ratio and leads to an increase in exergy efficiency and sustainability index of CCPP.

Thermodynamic, sustainability, environmental and damage cost analyses of jet fuel starter gas turbine engine

Jet Fuel Starter Gas Turbine Engine (JFS-GTE) used on a military aircraft is explored for on design mode and off design mode configurations at rated capacity cycles employing thermodynamic, environmental, sustainability, emission impact, and environment pollution cost analyzing. The engine generates 157.94 kW-shaft power at on design case whilst it produces 187.05 kW-shaft power at off design case. In this situation, the energy efficiency of JFS-GTE is accounted for 15.81% in an on design case and 17.01% in an off design case while the exergetic efficiency of JFS-GTE is estimated to be 14.89% in on design case and 16.02% at off design case. Using the environmental analyzing method, the enviro-effect factor and ecology-effect factor of JFS-GTE are found as 5.716 and 6.716 at on design case and 5.241 and 6.241 at off design case. Then, exergetic sustainability index and sustainable efficiency factor of JFS-GTE are computed as 0.175 and 1.175 at on design mode and 0.191 and 1.191 at off design mode. Afterward, the specific emission impact (sei) is computed as 6.555 mPts/GJ at on design and 5.621 mPts/GJ at off design mode. Finally, the specific environmental damage cost is determined to be 0.045 $/GJ at on design and 0.041 $/GJ at off design. These results show that JFS-GTE operates more energy and exergy efficiency, is more sustainable engine, has a low environmental impact and less environmental damage cost formation at off design case.

Exergetic sustainability comparison of turquoise hydrogen conversion to low-carbon fuels

Turquoise hydrogen is produced from methane cracking, a cleaner alternative to steam methane reforming. This study evaluates two proposed systems based on solar methane cracking for low-carbon fuel production. The systems employ different pathways to convert the turquoise hydrogen into a suitable form for transportation and utilize the carbon solid by-product. A direct carbon fuel cell is integrated to utilize the carbon and capture the CO2 emissions. The generated CO2 is utilized for fuel production using CO2 hydrogenation or co-electrolysis. An advanced exergetic analysis is conducted on these systems using Aspen plus simulations of the process. The exergetic efficiency, waste exergy ratio, exergy destruction ratio, exergy recoverability ratio, environmental effect factor and the exergetic sustainability index were determined for each system and the subsystems. Solar methane cracking was found to have an environmental effect factor of 0.08 and an exergetic sustainability index of 12.27.

Comparative exergetic sustainability analysis of subcritical and supercritical organic Rankine cycle plants for a waste heat recovery application

This study was aimed at comparing the exergetic sustainability and exergoenvironmental performance of subcritical (SUBORC) and supercritical (SUPERORC) organic Rankine cycle (ORC) plants for waste heat recovery from a marine vessel engine. A liquid-gas shell-and-tube heat exchanger was employed to recover the engine exhaust gases’ thermal energy. The hot exhaust gases flowing through the gas side heat the Therminol 66 heat transfer fluid employed on the liquid side, which in turn heats the ORC working fluid (R600a). Zero-dimensional mass, energy, and exergy balance equations defined by the Laws of Thermodynamics were implemented in MATLAB for the design of the two ORC configurations. Results showed that the evaporator and the preheater are the most sustainable components with exergetic sustainability index (ESI) values of 7.7 and 39.4 for the SUBORC and the SUPERORC, respectively. Additionally, the condenser was obtained in both cases with the worst environmental performance with exergoenvironmental impact of electricity (EIE) values of 12 and 13 eco-indicator points per 1 MW of electricity produced by the SUBORC and the SUPERORC, respectively. Moreover, results showed that a switch from the SUBORC to the SUPERORC would have an insignificant effect on the ESI at the system level; it would reduce the recoverability ratio by about 4%, from about 0.47 in the SUBORC to around 0.45 in the SUPERORC; and it would reduce the EIE by 1.4 Pt/MW. In sum, a supercritical ORC system would exhibit better exergetic environmental sustainability than a subcritical one for waste heat recovery from a marine vessel engine.

Effects of working fluid mixtures on the exergetic sustainability of a solar-biomass organic Rankine cycle power plant

This study assessed the effects of working fluid mixtures on the exergetic sustainability of a solar-biomass organic Rankine cycle (ORC) plant. The design features of a real ORC plant operational at Ottana (Italy) were employed for analyses. Although a lot of studies exist in the literature on thermo-economic implications of mixture working fluids in ORC plants, the aspect of sustainability is often left out. The desire to bridge this gap is the key motivation for this study. Zero-dimensional models were implemented in MATLAB for the design of all the hybrid plant units. The ORC design considered as working fluids the existing pure MM, and mixtures 0.1MM/0.9MDM, 0.8MM/0.2MDM, and 0.9MM/0.1MDMselected actively from the REFPROP database. Furthermore, established off-design models were incorporated into the ORC simulations. The exergetic sustainability index (ESI), the environmental effect factor (EEF), the exergetic improvement potential rate (IP), and the exergetic recoverability ratio (RECR) were adopted as sustainability performance indicators. Additionally, the destruction factor (DF) was used to assess the effects of a working fluid mixture on the sustainability performance of the ORC at the component level. Results showed that under design conditions, the mixture 0.1MM/0.9MDM had worse ESI than pure MM by about 1.5%, while the mixtures 0.8MM/0.2MDM and 0.9MM/0.1MDM improved ESI by about 1.6% and 2%, respectively. At off-design conditions, the optimum HTF mass flow rate with the highest ESI was obtained as about 7 kg/s for all the fluids. For the HTF temperature, 260 o C was obtained as the optimum for the mixture 0.8MM/0.2MDM, and 250 o C for all the other fluids. Also, decreasing the heat sink temperature in all fluids increases linearly the system ESI. Moreover, the ORC condenser showed the highest DF of over 70% for all the fluids, and the use of the best mixture (0.9MM/0.1MDM) as the ORC working fluid would increase the condenser DF by about 2 percentage points relative to pure MM. Future studies should seek to derive a set of general criteria that would aid the selection of cycle and working fluid mixture designs in favor of sustainability.