Double-effect Absorption Refrigeration Cycle Research Articles

Thermodynamic characteristics of a novel solar single and double effect absorption refrigeration cycle

Solar absorption refrigeration systems provide one of the economical options for air conditioning. In order to reduce the complexity and economic cost, a more advanced solar single-double-effect switching system is proposed. The innovation of this system is that it replaces the single-effect and high-pressure generators in previously developed single-double-effect switching system with a specific generator. The optimal heat source switching temperature of the new system was determined by the genetic algorithm to be 125.5 °C. Compared with the original single-double-effect switching system, the average coefficient of performance of the system is increased by 8.6 %, and the fluctuation of refrigeration capacity during the switching period is reduced by 48 %. The new solar single-double-effect switching system is investigated based on thermodynamic characteristics, energy, exergy, and economy aspects. The results showed that heat exchangers of the system have strong coupling. The cooling water temperature has a greater impact on the performance of the dual-effect mode. In the single-effect mode, the special-pressure generator has the largest exergy destruction (39 %), while in the double-effect mode, the absorber has the largest exergy destruction (41 %). Besides, the economic analysis demonstrated that the new system is economically viable with a payback period of 9.33 years.

Techno-economic analysis and fuel applicability study of a novel gasifier-SOFC distributed energy system with CO2 capture and freshwater production

This study employs the water-gas-shift membrane reactor and multi-effect distillation with thermal vapor compression technologies to facilitate low-energy carbon capture and large-scale freshwater production in gasifier-solid oxide fuel cell (SOFC) systems. The supercritical CO2 Brayton cycle and double-effect absorption refrigeration cycle are introduced to achieve waste heat cascade recovery. This work expands the fuel selection to 12 biomasses to explore the fuel adaptability and application scenarios of the system, and selects four representative cases to reveal their thermodynamic and economic attributes. The base scheme produces 21,635 ton/year freshwater and 1333 ton/year CO2, and achieves energy and exergy efficiencies of 70.68 % and 30.60 % with total cost rate of 23.21 $/h and levelized cost of products of 43.55 $/GJ. The gasifier and SOFC effort contributes to over 60 % of total irreversibility. Larch wood is preferred in resource-rich regions while wood residue, switch grass and wood chip are also prioritized; rice straw, rice husk, cotton stem and algal biomass are suitable for water-scarce areas. As key parameters change, Case-II consistently excels in power output, efficiencies and economic aspects, but lags in cooling capacity compared with other cases. This work provides a reference for low-carbon transition in the energy sector and large-scale freshwater production.

Evaluation of a concentrated solar power-driven system designed for combined production of cooling and hydrogen

The current technique of hydrogen generation and cooling production raises climatic problems, which calls for the investigation of cleaner alternatives. No research has been conducted to propose and analyze a solar thermal power cycle-based water electrolysis for on-site production of hydrogen and the detailed exergy analysis of a series flow double-effect absorption chilling machine employed for large solar cooling. In this regard, a helically coiled tube embedded central receiver is used in the heliostat field for the simultaneous production of solar cooling and green hydrogen to meet the increasing needs of energy and fuel sustainably. The combined system is composed of four sub-systems including a heliostat field, LiBr–H2O operated series-flow double effect absorption refrigeration cycle (DEARC), organic Rankine cycle (ORC), and proton exchange membrane (PEM) electrolyzer. The system was examined from energy and exergy perspectives in the Engineering Equation Solver (EES) using library data of REFPROP for obtaining the thermodynamic properties of working fluids. The results of the thermodynamic model for the combined system are validated. Furthermore, the effect of ambient temperature, solar irradiation, and type of ORC working fluid on the hydrogen and cooling production, and the overall energy and exergy efficiency of the combined system are examined. A computational fluid dynamics simulation applying ANSYS-FLUENT was used to examine how coil curvature ratio and coil torsion affect solar heat transfer fluid (SHTF) pressure and temperature leaving the receiver. The coil curvature ratio affects temperature increase more than coil torsion. Solar heat transfer fluid outlet temperature increases by 36.9 % when the coil curvature ratio increases from 0.063 to 0.095 at direct normal irradiations (DNI) 1200 W/m2, input temperature of 92°C, and coil torsion of 0.032. The response of the cogeneration cycle to varying operating parameters is examined. Application of R141b as the ORC fluid results in a large increase of cooling exergy efficiency from 14.98 % to 63.48 % when the ambient temperature is increased from 15 °C to 45 °C whereas the exergy efficiency of the combined system is marginally improved. The exergy distribution presents for ORC operating on R141b, out of 100 % input solar exergy, 16.42 % is generated as hydrogen exergy and 13.67 % cooling exergy, 66.79 % is the exergy destroyed, and the rest 3.12 % is exergy loss. Exergy analysis is utilized to identify the sources of losses in useful energy within the components of the system considered and provides a more realistic and meaningful assessment than the traditional energy analysis. The results justify a need for the promotion of exergy analysis through policy decisions in the context of the global energy and environment crisis.

Energetic/exergetic study of Kalina and refrigeration bottoming cycles on different solar‐driven organic Rankine cycles

AbstractCombination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature.

Investigation on combining multi-effect distillation and double-effect absorption refrigeration cycle to recover exhaust heat of SOFC-GT system

This study introduces the double-effect absorption refrigeration cycle (D-ARC) and multi-effect distillation with thermal vapor compression unit (MED-TVC) technologies to recover exhaust heat from the SOFC-GT system. This scheme can efficiently utilize waste heat at various temperature levels while enabling large-capacity cooling and freshwater production. The supercritical CO2 Brayton cycle is employed to facilitate the reliable operation of D-ARC and MED-TVC within their preferred temperature zones while enhancing the power output of the entire system. The techno-economic-environmental evaluation, comparative analysis and sensitivity analysis are performed to explore the feasibility of its engineering implementation. The proposed system obtains thermal, exergic and electrical efficiencies of 78.56 %, 65.41 % and 65.77 % with the total cost rate being 18.53 $/h and freshwater production 829.30 ton/year under design conditions, respectively. Exergy analysis indicates that SOFC and afterburner exhibit the highest irreversibility with values of 21.60 kW and 26.02 kW among all the components. Comparative analysis reveals that the system has exceptional thermal efficiency while exhibiting competitive advantages in electrical and exergic efficiencies compared to similar systems. Sensitivity analysis demonstrates that the electrical efficiency and net power output stabilize at their respective maximum values within the SOFC inlet temperature range of 514.3℃-528.6℃. Moreover, it is a promising option by increasing SOFC operating pressure and GT isentropic efficiency to enhance system efficiency and reduce CO2 emission. This work contributes to the development and waste heat recovery of the SOFC-GT system and other prime power units with similar exhaust gas temperature levels.

Performance assessment of PTSC-driven organic Rankine cycle systems integrated with bottoming Kalina and absorption chiller cycles: A parametric study

It is crucial to evaluate the impact of key parameters of multi-generation systems on their performance characteristics in order to develop efficient systems. The present study conducts parametric analysis of a PTSC-driven trigeneration system with a novel energy distribution based on directfed ORC and bottom-cycled arrangement of double-effect absorption refrigeration cycle and Kalina cycle system. Three different ORC structures (simple, regenerative, and ORC integrated with intermediate heat exchanger ? IHE) are proposed. Effect of key ORC parameters namely ORC evaporator pinch point temperature and pump inlet temperature is examined on the thermodynamic performance of systems. Decrease of pinch point temperature enhances overall efficiencies and heating power in all three configurations, and increases (decreases) the net electrical power for ORC and regenerative ORC (RORC) based systems. This also enhances the cooling power of the RORC based system, though it has no impact on the cooling power of the ORC and ORC-IHE based systems. Reduction of the ORC pump inlet temperature increases overall exergy efficiency in all hybrid systems and overall energy efficiency in the ORC and ORC-IHE based systems, whereas it slightly decreases for the RORC based system. Based on a comparative study, performance of the proposed systems is found to be higher than related solar-driven multi-generation systems in the literature.

Advanced power-refrigeration-cycle integrated WHR system for marine natural gas engine base on multi-objective optimization

In the face of huge global energy consumption today, technological implementation of waste heat recovery for electrical generating and refrigeration is of crucial significance for energy conservation. The high-temperature exhaust from marine natural gas engines carries a substantial quantity of thermal energy, making it an attractive option for waste heat recovery. A unique cycle system involving a supercritical CO2 cycle subsystem, a trans-critical CO2 Rankine cycle subsystem, and a double effect absorption refrigeration cycle is developed to utilize the waste energy in the maritime natural gas engine. The parameter variation pattern of each subsystem is investigated, and a total of eight organic working fluids with varying fractions are introduced into the trans-critical CO2 system for further investigation. The thermal-economic outcomes of the suggested integrated system are maximized by implementing the multi-objective optimization process, and it is found that when R32 with a mass fraction of 0.6138 is used as an additive in the trans-critical CO2 system, it has the highest net output power (311.6 kW) and lowest LCOE (0.0298 $/kWh). The results indicate that the novel design is a viable and meaningful strategy for marine natural gas engines' waste heat recovery.

Multi-criteria thermo-economic analysis of solar-driven tri-generation systems equipped with organic Rankine cycle and bottoming absorption refrigeration and Kalina cycles

Optimal thermo-economic integration of renewable energy sources with multi-generation energy systems is a prime research topic today. The present study proposes a multi-criteria evaluation method of such integration, based on combined heating and power (CHP), and combined cooling and power (CCP) scenarios, for three different solar intensities. Three novel solar-driven tri-generation systems are selected. They include different organic Rankine cycle (ORC) architectures and a Kalina cycle system (KCS) and a double-effect absorption refrigeration cycle as bottoming cycles. Evaluation of the tri-generation systems, both with and without the KCS system, indicates a performance improvement of up to 23% in various thermoeconomic characteristics when the KCS system is present. Selection of the suitable tri-generation system for each condition and optimization of the working fluid are carried out based on a multi-attribute decision-making method. P-xylene is found as the optimal organic working fluid for ORC and ORC (ORC integrated with internal heat exchanger) based systems, and benzene for the regenerative ORC-based system in both CHP and CCP scenarios. Multi-criteria analysis shows that ORC-based system outperforms other systems with net outranking flow of 0.44 (0.39) for CHP (CCP) application. The optimal configuration gives 95.6 M$ and 1.99 years for net present value and dynamic payback period, and 83.03% and 34.55% for energy and exergy efficiencies, respectively.

Exergoeconomic evaluation of a novel multigeneration process using solar driven Kalina cycle integrated with gas turbine cycle, double-effect absorption chiller, and liquefied natural gas cold energy recovery

This study is motivated to propose, evaluate, and optimize a solar-based multigeneration system relying on consecutive heat integration. Here, a heliostat field is configured to collect solar power and supply high-temperature air toward a nitrogen-based Brayton cycle. Afterward, the output hot air is subjected to a Kalina cycle suitable for medium-temperature heat resumption. A double-effect absorption refrigeration cycle boosted by a Liquid-based natural gas cold energy recovery unit for power generation and natural gas regasification are the other subsystems. The principal purpose is to protect the energy level of the fluid evacuating the solar field and to minimize the irreversibility of the scheme since solar-based systems lead to major irreversibility. The designed process is apprised from a 3E perspective, including exergy, energy, and exergoeconomic analyses. In addition, a comprehensive sensitivity study is done based on the influence of effective factors on the exergy and energy efficiencies and unit cost of products. Eventually, a multi-objective optimization is performed to set the most suitable condition of decision parameters and reach the optimal unit cost of products and exergy performance (objective functions). To do optimization, a genetic algorithm is applied, and two decision-making approaches, i.e., LINMAP and TOPSIS, are regarded. The optimal objectives are gauged to be 24.76% and 15.90 $/GJ by TOPSIS and 24.47% and 15.73 $/GJ by LINMAP, respectively.

Design and optimization of a novel flash-binary-based hybrid system to produce power, cooling, freshwater, and liquid hydrogen

The current work aims to design and analyze a novel hybrid system that can produce power, cooling, freshwater, and liquid hydrogen from a single energy source. The system consists of a flash-binary system, a double-effect absorption refrigeration cycle, a multi-effect desalination unit, and a hydrogen liquefaction unit. The steam turbine provides the power input for the hydrogen liquefaction unit. The system's performance is evaluated by thermodynamic and economic analyses, and a sensitivity analysis is conducted to investigate the effects of some key parameters on the operation mode. Moreover, the optimal state is determined based on three multi-objective optimization scenarios. The results show that the system consumes 33.93 kW of power and generates 2.106 kg/h of liquid hydrogen. The net present value is mainly influenced by the temperature of the saline feed water, while the fixed capital investment is highly dependent on the cooling load production rate. The optimal state of the system achieves an exergetic efficiency of 25.71% with a payback period of 4.48 years, producing 447.2 kW of cooling load, 1.804 kg/s of freshwater, and 2.107 kg/h of liquid hydrogen.

Thermodynamic analysis of SOFC–CCHP system based on municipal sludge plasma gasification with carbon capture

To solve the environmental problems associated with municipal sludge incineration and landfilling, a combined cooling, heating, and power (CCHP) system integrating plasma gasification, solid oxide fuel cell (SOFC), gas turbine, supercritical carbon dioxide (S-CO2) cycle, and double-effect absorption refrigeration cycle (ARC) is proposed. Additionally, the CO2 generated in the system is captured to reduce the environmental impact. Energy, exergy, and sensitivity analyses of the developed system are conducted. Key parameters such as the SOFC temperature, SOFC pressure, and fuel utilization rate affecting the system performance are studied. The results show that net electrical efficiencies of the SOFC and the system are 41.96 % and 50.00 %, respectively. The exergy efficiency and comprehensive energy utilization rate of the system are 47.04 % and 87.59 %, respectively. The system can generate a power of 175.03 kW, cooling of 45.70 kW, and heating of 85.82 kW under the design conditions, accounting for 67.46 %, 21.23 %, and 11.31 % total energy output of system, respectively. The three main sources of exergy destruction of the system are the plasma gasification, SOFC, and supercritical CO2 cycle subsystems, accounting for 36.8 %, 12.2 %, and 10.7 % exergy destruction, respectively. The system performs the best when the SOFC temperature is 910 °C and the fuel utilization rate is between 0.85 and 0.90. The SOFC pressure has little effect on the system performance. In addition, the carbon capture rate of the system can reach 97.50 %. The CCHP system has high thermodynamic efficiency and hence can convert municipal sludge efficiently into clean energy; therefore, this study provides a new concept for resource treatment of urban sludge.

Performance analysis of a double-effect absorption refrigeration cycle using a low-temperature ethanol solution as the working pair

In this paper, a double-effect absorption refrigeration system using a low-temperature working pair, lithium bromide (LiBr)+1-butyl-3-methylimidazolium bromide ([BMIM]Br)/ethanol (C2H5OH), was proposed to reduce the driving heat source temperature and enlarge the operation range to subzero temperatures. Based on the measured thermal properties, the thermodynamic performance of the double-effect absorption refrigeration cycle under different working conditions was calculated by Matlab and compared with that using LiBr/H2O working pair. Results showed that the generation temperature of the refrigeration system using LiBr-[BMIM]Br/C2H5OH was reduced by about 30 K in comparison to LiBr/H2O under the same operating condition. The temperature in the absorber with LiBr-[BMIM]Br/C2H5OH was 40 K higher than its crystallization temperature, whereas LiBr/H2O was only less than 20 K. Moreover, the system using LiBr-[BMIM]Br/C2H5OH was able to successfully work under 273.15 K without crystallization. At a typical operating condition, the COP of the double-effect absorption refrigeration cycle with LiBr-[BMIM]Br/C2H5OH reached 1.47, which was 0.10 higher than that using LiBr/H2O. As a low-temperature working pair, LiBr-[BMIM]Br/C2H5OH showed a great potential in utilizing solar energy and the low-temperature waste heat under severe operating conditions. Furthermore, compared with LiBr/H2O, the refrigeration system had a better economic performance with LiBr-[BMIM]Br/C2H5OH working pair.

CO2 capture and liquefaction in a novel zero carbon emission co-production scheme for ships by integration of supercritical CO2-based oxy-fuel cycle and ion transport membrane; Energy/exergy/exergoeconomic/exergoenvironmental (4E) and multi-objective optimization

The main goal of this research in the first step is to present a new power generation and cooling system with zero emissions for ships. The presented system is a combination of oxygen separator membrane, Oxy-fuel cycle, lithium bromide-water (LiBr-H2O) double-effect absorption refrigeration cycle, and carbon dioxide (CO2) liquefaction cycle. The fuel of the system is liquefied natural gas(LNG). In the second step, the presented system is evaluated from energy, exergy, exergy-economic and environmental exergy viewpoints. In the third step, multi-objective optimization is used to pinpoint the optimal state of the presented scheme based on economic, performance, and environmental impacts (EI). The results revealed that in the reference state the energetic efficiency is 95% and exergetic efficiency is 38%. The net power per kilogram of produced oxygen and liquefied carbon dioxide is equal to 1194 kW and 47.42 kW, respectively. The levelized cost per exergy unit (LCPEU) of the gross power of the supercritical CO2 (SCO2) cycle turbine, nitrogen turbine, the produced cold water, and total products (cooling and power) are equal to 26.75 $/GJ, 270 $/GJ, and 63.05 $/GJ, respectively. The multi-objective optimization outcomes demonstrated that the exergetic efficiency of the system and the cost per exergy unit (CPEU) of all products can be improved up to 18 % and 13 %, respectively. Moreover, the environmental impact per exergy unit (EIPEU) of all products can be improved by up to 6 %.

Exergy-based weighted optimization and smart decision-making for renewable energy systems considering economics, reliability, risk, and environmental assessments

A holistic analytical and smart management approach is proposed to investigate the performance of renewable-based tri-generation system to generate power, cooling, and domestic hot water with a simultaneous consideration of several operational, design, and system feasibility aspects in a framework. The proposed configuration consisted of a solar driven organic Rankine cycle, and double-effect absorption refrigeration cycle integrated with a Kalina cycle. To analyze environmental implications, life cycle assessments are performed, while further evaluations are conducted utilizing algebraic thermo-mathematical programming. Hazard study and thermal reliability analysis are also performed to analyze the safety and failure rate of the system. Additionally, four critical scenarios are defined: safe urban deployment, economic viability, reliable operation, and sustainable development. In accordance with the four specified scenarios the integrated system is globally optimized using a weighted multi-objective optimization. Following that, a suitable optimum system and fluid allocation is conducted based on hybrid deterministic decision-making technique under smart management. The optimization results showed that the total exergorisk, system reliability, and environmental impact can be simultaneously improved in the range of 4.08–28.3%, 4.14–13.9%, and 1.65–24.6%, in all scenarios employing various working fluids, respectively. Additionally, the system achieves lowest overall cost rate (4.17USD·s−1) with R113, while the highest energetic efficiency (46.3%) and system reliability of (91.2%) was associated with R365mfc. Finally, a comparative analysis indicates a CO2 saving potential of 6646, 4883, and 2878 tons/year in comparison to coal, fuel oil, and natural gas based integrated energy systems.

Performance investigation and collaborative optimization of power, economy and NOx removal for waste heat cascade utilization system in ocean-going vessels

Waste heat recovery technology of ships is meaningful for the enhancement of system efficiency and protection of environment. Compared with conventional diesel engines, the natural gas engines have the advantage of low emission, and its exhaust gas with quite high temperature is very suitable for utilization as the heat source of cascade waste heat system. This study integrates an over-expansion transcritical CO2 cycle with a double effect absorption refrigeration cycle to recover the heat energy from a natural gas engine. At the same time, a post-processing unit is proposed to remove the nitrogen oxide of flue gas. The research results indicate that the higher engine load contributes to improving the equivalent output work and economy of the combined cycle while the post-processing unit can further reduce the payback time under the given conditions. In terms of the parameters analyses, the turbine outlet pressure of transcritical cycle has an optimal value of 2.25 MPa, which can make the output work to reach the maximum value of 305.0 kW, and the performance improvement of refrigeration cycle can be achieved by decreasing the temperature of high pressure generator or increasing the temperature of low pressure generator. After multi-objective optimization, the residual equivalent output work, payback period and amount of NOx reduction of the total system are 150.77 kW, 4.20 years and 8.16 g/kWh, respectively. In addition, the Energy Efficiency Existing Ship Index is further reduced to 8.21 gCO2/ton·nm with the aid of the proposed system.

Exergy and exergoeconomic analyses and multi-objective optimization of a novel cogeneration system for hydrogen and cooling production

Hydrogen production using solar energy can achieve large-scale hydrogen production and solve various energy problems. The concept of hydrogen and cooling cogeneration can realize the cascade and efficient utilization of high-temperature solar energy. In this regard, a novel solar-based combined system is proposed to produce hydrogen and cooling using a methanol-reforming process and double-effect absorption refrigeration cycle. Energy, exergy, exergoeconomic, and economic criteria were defined to evaluate the feasibility of the system for investment and construction. The system was analyzed by developing a precise model in the Engineering Equation Solver. Then, optimal conditions were obtained using multi-objective particle swarm optimization and the LINMAP decision-making approach. The results revealed that the system has an energy efficiency of 75.46% with an exergetic efficiency of 77.24%, a total cost rate of 46.48$/GJ, a cooling production capacity of 346.7kW, and a hydrogen generation rate of 0.01511kg/h. Also, the optimum exergy efficiency and unit cost of products are obtained to be 81.38% and 37.96$/GJ, respectively. Moreover, the total profit of 15.23 $M can be gained at the end of the plant lifetime for the hydrogen cost of 6 $/m3. In this conditions, the payback period is about 1.35years.

An integrated CCHP system based on biomass and natural gas co-firing: Exergetic and thermo-economic assessments in the framework of energy nexus

Agriculture and energy are inextricably connected; many energy systems can be driven by biomass supplied from agricultural waste products. In this study, a combined biomass/natural gas fed multi-generation system, prodcuing cooling, heating, and power is investigated from exergetic and thermo-economic standpoints. The system consists of four susbsystems, encompassing a gasification cycle, a gas cycle, a Rankine steam cycle, and a double effect absorption refrigeration cycle. To increase the lower heating value of the fuel injected into the combustion chamber, natural gas is mixed with syngas. Also, to exploit the exhaust gas from the stack of the gas turbine, the flue gas is divided into two streams by a spliter,providing the required heat for the Rankine steam and absorption refrigeration cycles. The effects of parameters such as the gas turbine inlet temperature , combustion chamber inlet pressure, the amount of natural gas mixed with syngas, and split ratio of the exhaust gas from the gas turbine on the thermodynamic and thermo-economic outputs are studied. The results show that the gas cycle with 61% and the double-effect absorption refrigeration cycle with 6% exergy destruction rates have the largest and lowest shares of the total exergy destruction rate, respectively. By changing the mixing ratio of the natural gas injected into the cycle from 0.5 to 1, the system's net work is seen to increase by 90.77%, while the modified ecological coefficient of the system performance boosts by 9.49%. In addition, such a change leads to 53.45% increase in the net present value of the total cost over the defined economic life, and also an increase of 90.25% in the net present value of the total output of the cycle equivalent to electricity over the economic life. Moreover, it brings about 19.36% decrease in the system's levelized cost of energy.

Thermo-economic evaluation and multi-objective optimization of a waste heat driven combined cooling and power system based on a modified Kalina cycle

Due to the decisive role of combined cooling and power (CCP) systems in improving the overall system efficiency and also the ability of the Kalina cycle to recover waste heat from low-temperature heat sources, an innovative CCP system is investigated in this study. The system consists of a modified Kalina cycle and a double-effect absorption refrigeration cycle driven by the exhaust gases of an internal combustion engine. The merits of the proposed system are demonstrated through the energy and exergy analysis. In addition, using a multi-objective genetic algorithm, the system performance is optimized for maximum exergy efficiency and the minimum total cost rate. Through the exgeoeconomic analysis, the low value of the exergoeconomic factor in the boiler, Recuperator 1 and 2, and the turbine indicates that the cost of exergy destruction in these components is higher than their investment expenditures. The optimization results reveal that under the optimal conditions, the exergy efficiency of the proposed CCP system and its total cost rate are 54.37% (2.22% improvement) and 110.76 $/hr (8.16% reduction), respectively. Consequently, due to the optimal selection of the variables, the products of the proposed system are produced at lower prices. So that, the levelized cost of the generated Power (LCOP) and that of the provided cooling are decreased by 11.73% and 4.15%, respectively.

A novel design of power-cooling cogeneration system driven by solid oxide fuel cell waste heat in ocean-going vessels

Among many global energy and environmental problems, the ocean and air pollution caused by ocean-going vessels cannot be ignored. Cleaner and more efficient power generation systems should be used to replace traditional diesel generators on ships. To this problem, the combination of fuel cell and waste heat recovery technology can become a better choice. In this paper, a novel power-cooling cogeneration system is designed and analyzed, which is mainly composed of solid oxide fuel cell, preheating subsystem, homogeneous charge compression ignition engine and double-effect absorption refrigeration cycle. The study mainly includes mathematical modeling, reliability verification of each subsystem, numerical simulation and results analysis in energy, exergy and economics. The results show that the system thermal efficiency and exergy efficiency can reach 64.01% and 61.83%, respectively, which are 18.76% and 12.62% higher than those of simple cell. Compared with traditional combined system, the payback time of the proposed scheme is about 2.59 years, which not only proves that the cost can be recovered in a short time, but also shortened by about half. By improving energy efficiency and reducing costs, the proposed scheme can ensure the demand of electricity and cold energy in daily life of the crew, and provides a new choice for the marine auxiliary power generation equipment.

Multiobjective Optimization of a Novel Solar Tower-Based Gas Turbine-Driven Multi-Generation Plant With Energy, Exergy, Economic, and Environmental Impact Analysis

AbstractIn this study, a novel solar tower-based gas turbine-driven multi-generation plant is proposed and analyzed in detail with energy, exergy, economic, and environmental impact analysis. A multiobjective optimization is performed by incorporating all performance indicators simultaneously. The proposed plant consists of an intercooling-regenerative-reheat solarized gas turbine cycle as the primary power cycle of a multi-generation plant for the first time. Two organic Rankine cycles are used to utilize waste heat of intercooling section and exhaust of gas turbine. To produce the multi-generation products of power, cooling, industrial process heating, fresh water, floor heating, green hydrogen, domestic hot water, hot air for food drying, and greenhouse heating, power cycles are integrated with a multi-effect desalination, a double-effect absorption refrigeration cycle, an electrolyzer, a drying hot air unit, a greenhouse heater, and an industrial process heater. A rigorous parametric analysis is performed to reveal the effects of variations of decision variables on the plant performance. At the optimum conditions, energy efficiency, exergy efficiency, average unit product exergy cost, and emission savings values are determined as 57.23%, 40.7%, 0.08315 $/kWh, and 948.7 kg CO2/h, respectively. Moreover, proposed plant can produce 1962 kW power and 3.353 kg/h hydrogen in addition to other utilities with a system cost rate of 0.05134 $/s and 3226 kW exergy destruction rate.