Comparative Exergy Analysis Research Articles

Exergy and Energy Analysis of Bifacial PV Module Performance on a Cloudy Day in Saudi Arabia

Bifacial solar modules, capable of harvesting sunlight from both sides, present a promising pathway for sustainable energy generation. This study examines the performance of bifacial modules on a cloudy day through comparative exergy and energy analyses. The analysis considers both the quality and quantity of energy produced by bifacial and monofacial modules. Conducted at Qassim University in Buraydah City, Saudi Arabia, the study recorded measurements during two intervals on a cloudy day using a real-time photovoltaic measurement system. Module performance was evaluated concerning energy yield, exergy yield, and solar irradiance, factoring in ambient and module temperatures. The results demonstrate that bifacial modules outperformed monofacial modules in electrical energy and output exergy. In the first period, the bifacial modules showed a 9.5% higher exergy efficiency and a 7% greater energy efficiency compared to the monofacial modules. During the second period, the bifacial modules achieved a 4.5% higher exergy efficiency and a 3.5% increased energy efficiency over the monofacial modules. These findings contribute to global sustainability efforts by reducing fossil fuel dependence and optimizing bifacial PV module design and operation for enhanced energy and exergy efficiency, even in cloudy conditions. The study’s implications for sustainable development and energy policies underscore the essential role of advanced PV technologies in achieving sustainable energy goals.

Comparative exergy and economic analysis of deep in-situ gasification based coal-to-hydrogen with carbon capture and alternative routes

The deep in-situ gasification based coal-to-hydrogen (deep IGCtH) is attracting attention for its unique advantage in utilizing unrecoverable coal seam. In this paper, its improvement scope in energy conversion and utilization is analyzed using advanced exergy analysis, and the efficiency from cumulative exergy consumption (CExC) perspective and economic competitiveness with Lurgi surface gasification based coal-to-hydrogen (Lurgi SGCtH), coke-oven gas-to-hydrogen (COGtH) and natural gas-to-hydrogen (NGtH) are compared. Results indicate 39.9 % and 25.1 % of the exergy destruction of deep IGCtH and Lurgi SGCtH are unavoidable, while steam methane reforming and coal gasification possess the largest improvable potential, with avoidable endogenous/exogenous destruction of 96.63 MW/81.58 MW and 162.52 MW/151.19 MW, suggesting thermodynamic improvement can also be achieved by improving other components or optimizing process structure in addition to increasing its own efficiency. The CExC of deep IGCtH outputting 1 kg hydrogen is only 83.6 % that of Lurgi SGCtH, indicating it is more efficient route with significantly energy consumption reduction and can better demonstrate its efficiency advantage under large production capacity condition. The deep IGCtH shows only 68.7 % that of Lurgi SGCtH in investment and also presents significant advantage in cost. However, its profitability advantage over NGtH loses with hydrogen price increasing and there exists lower limit on capacity of 0.46 billion Nm3 to maintain cost and profitability competitiveness over COGtH. Furthermore, deep IGCtH shows emission reduction cost advantage over Lurgi SGCtH when capture rate exceeds 80 %, and profitability will not be limited by carbon tax and coal seam thickness within the considered range.

Comparative exergy and economic analyses of single slope solar desalination unit combined with concentrator integrated evacuated collectors

This paper deals with the exergy analysis of single slope solar desalination unit combined with N number of compound parabolic concentrator integrated evacuated tubular collectors (NCPCETC-SU) considering New Delhi climate. An exhaustive computation considering each month of year is carried out. The methodology consists of feeding all fundamental equations with relevant data to MATLAB code and presenting the output in the suitable form. Results of NCPCETC-SU are compared with results of SU incorporated with evacuated tubular collectors (NETC-SU). Concludingly, the annual exergy and daily exergy efficiency for NCPCETC-SU are higher by 36.51% and 30.81% than NETC-SU for same mass flow rate, N and water depth under similar climatic situation. The annual freshwater output is higher by 16.81% and freshwater cost is higher by 9.85% at 2% rate of interest for NCPCETC-SU than NETC-SU respectively. Further, the freshwater cost of NCPCETC-SU can be diminished by increasing the concentration ratio.

Comparative exergy and energy analyses of compression–absorption cascade refrigeration cycles with varied configurations and ejector implementations

This study aims to assess the feasibility and performance, as well as the exergy loss, of utilizing ejectors in absorption–compression cascade configurations for low-temperature refrigeration systems. The coefficient of performance (COP) is used to measure system efficiency, including COP.A (COP of the absorption chiller), COP.C (COP of the compression side) and COP.Ca (COP of the cascade configuration). The results highlight the importance of ejector placement on the absorption side for optimal performance. Configuration D1, with an ejector on the absorption side, demonstrates an 85% improvement in COP.A, approximately 10% in COP.C and nearly 100% in COP.Ca compared to configurations without an ejector. However, in certain cases, using an ejector on the compression side is not feasible from a second-law perspective, particularly for higher compression-side evaporator temperatures. Nonetheless, the study suggests that configuration D0, which includes an ejector on the absorption side coupled with a simple compression cycle, is applicable for these conditions and performs similarly to D1 in other temperature ranges. These findings provide valuable insights for optimizing ejector placement in absorption–compression cascade configurations and advancing the development of more energy-efficient refrigeration systems.

Comparative Exergy, Economic and Environmental Analysis of Parabolic Trough Collector and Linear Fresnel Reflector

Comparative Exergy, Economic and Environmental Analysis of Parabolic Trough Collector and Linear Fresnel Reflector

Exergy-efficient sustainable production of diesel additive in infrared energized continuous flow rotating real reactor: Optimization, heterogeneous kinetics, and life cycle analyses

An exploratory expedited synthesis of a diesel additive viz., glycerol monooleate (GMO) was investigated for the first time in a novel energy-efficient infrared-energized continuous flow rotating catalytic fixed bed real reactor (IR-RFBR). Under statistically derived optimum condition maximum 98 ± 0.5 % per pass GMO selectivity was obtained. Using kinetic data from a rotating batch reactor under equivalent conditions, an inclusive non-catalytic and heterogeneous-catalytic kinetic model (R2=0.99) was developed. The IR-RFBR’s performance was evaluated using the derived kinetic model and accounting for axial dispersion (Pećlet Number: 70.15).Comparative exergy and exergo-economic analyses were performed on rotating and non-rotating IR-fixed bed reactors. In terms of lower product exergy cost (4.69 $/kJ), the IR-RFBR outperformed its non-rotating counterpart (11.85$/kJ) due to a 22 % higher GMO yield at reduced residence time (3.2 min). Furthermore, IR-RFBR manifested greater exergoeconomic efficiency (91 %) than conventionally heated RFBR (CRFBR, 69 %, 7.67 $/kJ). Life cycle analyses for IR-RFBR confirmed significant reductions in environmental impact categories such as global warming, fossil depletion, and human toxicity potentials by ∼ 88 %, ∼84.3 %, and ∼ 83 %, respectively, when compared to IR-non-rotating and CRFBR. Thus, the developed process for glycerol based diesel additive synthesis ensures more glycerol utilization in a sustainable and economic pathway.

Comparative exergy analysis of a thermoelectric heat pump and a vapour compression heat pump

The article is performing a comparative exergy analysis of a thermoelectric heat pump and a vapour compression heat pump, operating in the same conditions, from heat source temperature point of view. The COP of vapour compression heat pump was found to be 3.02 compared to 1.349 for the thermoelectric heat pump for 60 ℃ temperature lift. For the same temperature lift, corresponding to the increase in the temperature of the heat source from 5 ℃ to 65 ℃ required for the delivery of heat for household purposes, exergy efficiency of vapour compression heat pump is 59.44% compared to 23.90% for the thermoelectric heat pump, while the energy needed to operate the thermoelectrical heat pump is 20.76 kW compared to 9.29 kW for vapour compression heat pump.

Comparative Exergy Analysis and Environmental Impact of a Dairy Plant Integrated with a Transcritical Heat Pump System: A Feasibility of Throttle Valve, Expander, and an Ejector as Expansion Devices

Comparative Exergy Analysis and Environmental Impact of a Dairy Plant Integrated with a Transcritical Heat Pump System: A Feasibility of Throttle Valve, Expander, and an Ejector as Expansion Devices

Comparative exergy and energy analyses and optimization of different configurations for a laundry purpose

Energy usually plays a critical role in the development of a country. With the gradual decrease of available traditional fuel reserves and air pollutions problems that being followed by using them, the need to replace alternative renewable and sustainable options to decrease our dependence on fossil fuels has drawn attention. Biomass is a kind of reliable renewable energy that is used to derive combined heat and power systems known as the Organic Rankin Cycle (ORC). This paper presents of exergy analysis of three cycles which have been modeled by EES software for a laundry that needs 32 (kW) power and 2500 (kg/h) 65 (Co) hot water which hot water is our main goal in this study. In RC (gas fuel) and ORC (biomass fuel) power which is produced provides part of electricity needed in the laundry but for Boiler Proving Hot Water (BPHW) the whole electricity needed is bought from the grid. R245fa is a friendly environmentally organic fluid that is used in ORC as a working fluid. The result of this analysis shows for the same conditions the most exergy destruction occurs in the boiler and the least in the pump in three cycles. It also shows the most efficiency of second law respectively is belongs to RC, ORC, BPHW with 0.21%, 0.16%, 9% total efficiency respectively. Moreover, by utilizing EES software and genetic algorithm all of the configurations have been optimized and compared.

Experimental based comparative exergy analysis of a spark‐ignition Honda GX270 Genset engine fueled with LPG and syngas

AbstractThe present study investigates three different fuels such as gasoline, liquefied petroleum gas (LPG), and syngas in spark‐ignition Honda GX270 Genset engine under wide‐open throttle position on its performance, combustion characteristic as well as availability analysis. The results showed that when the engine operated with gasoline fuel, the brake thermal efficiency was higher than that of LPG and syngas by 6.2% and 7.4%, respectively, throughout the engine load condition. Brake‐specific fuel consumption of the engine with syngas (660 g/kW h) and LPG fuel (812 g/kW h) was higher than that of the gasoline fuel (510 g/kW h) at the 4.5 kW of engine load. The engine emission results showed syngas operation caused a significant reduction in NOx by 58.4%, CO by 16.5%, HC by 23.2% compared to gasoline fuel at peak load conditions. On the other hand, exergy analysis concludes the exergy efficiency for all the test fuels increases with an increase in engine load due to a high rise in shaft output. At a 4.5 kW power output, the exergy efficiency of the engine was improved to 46.45% from 45.62% and 29.73% with syngas, gasoline, and LPG, respectively. The maximum exhaust gas availability has been observed as 24.51% of availability input for syngas at 100% load condition.

Mixed convective cilia triggered stream of magneto ternary nanofluid through elastic electroosmotic pump: A comparative entropic analysis

Integration of ternary nanofluid with micro-pump heat sink is considered to be the incredible heat exclusion from thermal pumps/channels. The present work intends to present a theoretical thermal analysis of mixed convective transport of radiated magneto ternary fluid through an electroosmotic pump. To achieve efficient mixing and effective pumping, the inner surface of pump is embedded with bio-mimetic cilia. The cilia beat in synchronization to commence a train of metachronal waves along the elastic surface of micropump. The blood based ternary nanofluid is considered as working fluid in the pump by mixing trihybrid nanoparticles of TiO2, SiO2 and Al2O3 in blood. The mixed and forced convection situations are set with the help appropriate governing equations and solved analytically. A comparative exergy analysis between ternary, binary, unary nanofluid and conventional blood is also presented. In comparison the ternary hybrid nanofluid is observed be more thermally efficient then the unary and binary nanofluids and has significant ability to minimize heat losses. The ternary nanofluid shows an effective role in augmenting the heat transfer rate by lifting the rate up to 18.03% at smaller Hartmann number specifically at 0.5. It is further reported that thick EDL and high values of the Hartmann number dampens down the TiO2-SiO2-Al2O3/blood temperature.

Comparative exergy, multi-objective optimization, and extended environmental assessment of geothermal combined power and refrigeration systems

In the present work a comparative exergy analysis, multi-objective optimization, as well as extended environmental analysis of a geothermal-based power and refrigeration system, is carried out. Different arrangements with the ammonia-water refrigeration cycle, organic Rankine cycle (ORC), and thermoelectric generator (TEG) are investigated. The current work novelties are the presentation of a novel power-refrigeration system driven by a geothermal source and the employment of TEG units to recover geothermal energy, besides extended environmental assessment. The results of sensitivity analysis indicate that the highest net output work capacity is for the suggested system (configuration 3). Exergy analysis exhibits that in all cases, the absorber has the highest exergy destruction rate and one of the lowest exergy efficiency because it is the first component, which gains the heat from the geothermal source. The suggested system produces 495.2 kW net output power and the highest energy efficiency of 19.42%, which are 131.7 kW, and 3.84% higher than configuration 1(base system). Optimization results represent that in the optimum point, Ẇnet shows about 33.3% improvement compared with the un-optimized condition. It is found that configuration 3 which consists of cogeneration with two loops of ammonia-water power cycle with refrigeration system along with an additional thermoelectric generator for enhanced waste heat recovery has the highest environmental footprints because of multiple components installed that would occupy more space, electricity, materials, and other resources for its construction, operation, maintenance, and end-of-life.

Thermodynamic assessment of the phenomena of heat and mass transfer for energy-technological systems production of groats concentrates

To assess the thermodynamic excellence of food processing technologies of raw material, it is proposed to use the exergy method based on the second law of thermodynamics. A procedure has been developed for calculating thermal and exergy costs in the moisture-heat treatment of capillary-porous colloidal materials. Thermal and exergy calculations of the production of cooked-dried rice groats were performed. Thermal and exergy analysis of heat and mass transfer processes energy-technological systems (ETS) of various schemes for the production of groats concentrates was carried out. The thermal and exergy estimates of the processes of heat-mass exchange during the moisture-thermal treatment of capillary-porous colloidal materials are obtained using the example of cooked-dried groats. A thermodynamic assessment of the phenomena of heat and mass transfer of ETS for the production of groats concentrates based on the theoretical and experimental studies, which resulted in the development of recommendations on the scientific and practical support for heat and mass transfer processes of moisture- thermal treatment of raw materials. It has been proven that a change in product moisture has a greater effect on exergy than a change in temperature does. It is suggested to use, for an assessment of energy efficiency and a comparative exergy analysis of various ETS for processing raw materials, along with exergy efficiency, specific exergy values characterizing exergy costs per unit of dried finished product, per unit of moisture removal and moisture adsorption

Comparative Exergy Analysis of Units for the Porous Ammonium Nitrate Granulation

The article deals with the study on the efficiency of units for porous ammonium nitrate production. The ways which increase the effective implementation of energy resources are determined by including the ejector recycling module, heat and mass exchangers that utilize principles of regenerative indirect evaporative cooling, and the sub-atmospheric inverse Brayton cycle. Mixed exergy analysis evaluates all flows of the system contour as those of the same value. The target parameter for determining the efficiency of both systems is the ratio of the unit’s productivity to the exergy expenditures to produce the unit mass of the product. As a result, it is found that the mentioned devices and units enable to increase the efficiency of the basic scheme by 87%.

Comparative exergy analysis of the cascade cooling system for alternative refrigerant couples

In this work, a comparative exergy analysis of cascade cooling system working with alternative refrigerant couples has been carried out. In study; R454C and R-744 as low temperature cycle (LTC) refrigerant and R1234ze, R1234yf and R717 as high temperature cycle (HTC) refrigerant were used. The refrigerants used in the study have zero ODP and low GWP values. Exergy analysis was carried out to investigate the effect to exergy efficiency of operation parameters in cascade cooling system. The exergy efficiency values of the cascade cooling system decreases with increasing evaporator temperature for all refrigerant couples. The exergy efficiency values of the cascade cooling system decreases with increasing the condenser temperature. Obtained results show that in all cases, the refrigerant couple R454C/R717 has the highest exergy efficiency.

Comparative exergy analysis between rotary hearth furnace-electric arc furnace and blast furnace-basic oxygen furnace steelmaking routes

Resource fuel used in integrated steelmaking processes are different based on fuel availability consideration. A fuel-based comparative energy utilisation efficiency in integrated steel plants as obtained through exergy analysis for two steelmaking routes, namely, rotary hearth furnace-electric arc furnace (RHF-EAF) and blast furnace-basic oxygen furnace (BF-BOF) is presented with additional consideration of electrical energy input replacing fuel energy in EAF for RHF-EAF route. Initially, exergy flow models of sub-systems (BF, BOF, RHF and EAF) are established separately. These sub-system models are coupled together to analyse the exergy flows, exergy losses and exergy efficiencies of the two integrated steelmaking systems. Gas-based exergy efficiency based on input exergy of RHF-EAF steelmaking process is always found to be better than conventional BF-BOF process as well as BF-Tenova Flexible Modular Furnace system (a modified BF-BOF process having electric arc facility in BOF to increase the scrap percentage in BOF charge). However, BF-BOF processes are found to be superior to RHF-EAF process when metal-based exergy efficiencies are compared. Combined metal plus gas-based exergy efficiencies of RHF-EAF steelmaking process are marginally better than BF-BOF route. Efficiency of scrap reycle for both steelmaking routes has also been analysed through exergy efficiency parameters. It was found that exergy utlisation efficiency of RHF-EAF steelmaking process based on both products steel and total by-product fuel gas for hot charging of direct reduced iron (DRI) above 600°C is superior to BF-BOF steelmaking process for all levels of scrap charging in steel making. For hot charged DRI at 600°C in RHF-EAF steelmaking process, the combined exergetic efficiency based on metal and by-product fuel gas is around 75% compared to 67% of BF-BOF and modified BF-BOF steelmaking systems, indicating more efficient input fuel utlisation than both variants of BF-BOF route.

Comparative exergy analysis of the processes of heating reserve liquid fuel using various coolants at thermal power plants

In this paper the technologies for heating reserve liquid fuel at a thermal power plants are proposed. Provision is made to implement a transition from fuel oil to another reserve fuel that does not require high-temperature heating at thermal power plants. A comparative analysis of the traditional scheme of heating reserve fuel with industrial steam and other coolants was carried out. The analysis was carried out using the exergy method, which allows taking into account different types of power. Exergy flows, exergy losses and exergy coefficient of efficiency are calculated for traditional and proposed technologies of reserve fuel heating.

Comparative exergy and exergoeconomic analysis between liquid fuels production through chemical looping hydrogen generation and methane reforming with CO2

Recently, the concept of carbon utilization has been widely investigated to reduce greenhouse gas emissions and mitigate dependence on fossil fuels. For this purpose, two different carbon capture and utilization processes to produce liquid fuels, carbon looping cyclic reforming (CCR) and carbon dioxide hydrogenation based on chemical looping hydrogen generation (CH-CLHG), are introduced. This article aims to identify which utilization method holds more potential for future technical development. To achieve it, comprehensive thermodynamic, economic and exergoeconomic assessments are implemented. The results indicate that the exergy efficiency of CH-CLHG system is 3.84% more than that of CCR system, and the cost of liquid fuels production is 36.64% less. It is also suggested that CCR system is superior to CH-CLHG system in terms of the liquid fuels output. When the electricity price is below 0.068 $/kWh, the cost of liquid fuels of CCR system is more competitive than that of CH-CLHG system. Since the higher fuel cost and larger exergy destruction, CCR system’s exergy destruction cost is more significant. In addition, the exergy destruction and exergy efficiency as well as exergoeconomic performance of each main component are presented in detail to reveal the cost formation process, and to find out the measure that would improve system efficiency and cost-effectiveness.

Design and comparative exergy and exergo-economic analyses of a novel integrated Kalina cycle improved with fuel cell and thermoelectric module

Combined cooling, heating, and power systems (CCHP) have attracted a lot of attention due to their distinctive advantages of high system and economic efficiencies in addition to less greenhouse gas emissions. The current study investigates the performance of a Kalina cycle-based CCHP system in which geothermal energy is utilized as the low temperature source of prime energy. A thermoelectric generator is used in the system for retrieving wasted heat and producing extra amount of electricity thereby leading to higher overall efficiency. Two types of fluids, i.e. geothermal water and mixture of water-ammonia, are employed for the steam cycle and Kalina cycle, respectively. A comparative performance analysis is carried out on three system configurations, namely; basic Kalina cycle system, Kalina cycle with a thermoelectric generator (TEG), and Kalina cycle integrated with TEG and a Proton Exchange Membrane Fuel Cell (PEMFC). The results demonstrated that employing TEG increases the output power by 25.1 kW and improves cycle efficiency by 1.7%. Moreover, integrating both TEG and PEMFC increases the net output power of the proposed system to 1101 kW, which is 993.2 kW and 971.7 kW higher than the basic Kalina cycle system and the Kalina cycle system coupled with the TEG respectively. In addition, the exergy analysis of each component in the system showed that the condenser has the most exergy destruction. Multi-criteria optimization is applied to seek the optimum operation condition of the proposed system. The net output power and electricity cost were used as two critical optimization targets. An optimum condition of the system is suggested using the concept of ideal point on the Pareto front plot.

Comparative exergy and exergy efficiency analyses of fabricated single and double slope solar still plants at Indore: case study

In this research project two solar still plants have been fabricated; single and double slope still plants. The exergy and exergy efficiency concepts have been applied for the comparative analyses of both solar stills. Experimental readings, i.e. various temperatures, amounts of distilled water and solar radiations have been taken for solar stills at different time intervals in Indore (22° 43′ 4.51″ N and 75° 49′ 59.88″ E). The percentage variations in the different parameters, i.e. increments in temperature, increments in quantity of water, thermal efficiencies, rates of exergy at inlet/outlet and exergy efficiencies have also been calculated for stills at various solar intensities and time intervals. After experimental and comparative analyses, better outputs have been shown at 14:50 PM for double slope and 14:45 PM for single slope plant due to the cumulative effects of solar radiations on the still plants. During this period thermal/exergy efficiencies, i.e. 46.630/1.949% and 47.259/3.389% were found the best. The performance of single slope solar still has been found better, and 14:30 to 14:50 PM time interval has been recorded superior for the distillation of water through still plants where percentage increments of the performance evaluating parameters were enhanced.