Double-effect Absorption Refrigeration Research Articles

Performance analysis and multi-objective optimization of a novel solid oxide fuel cell-based poly-generation and condensation dehumidification system

The application of energy supply systems based on fuel cells contributes to meeting the requirement of sustainable development, and developing high-efficiency, low-pollution, and multifunction poly-generation systems coupled with fuel cells is increasingly attractive. This study proposes a novel combined cooling, heating, power poly-generation and dehumidification system including a solid oxide fuel cell, a gas turbine, a double effect absorption refrigerator, a condensation dehumidification unit, an organic Rankine cycle, and a heat exchanger. Thermodynamic, economic, and environmental analysis models of the entire system are developed to evaluate system comprehensive performance. The effects of system parameters such as the inlet temperature of fuel cell, steam to carbon ratio, air flow rate, and high temperature generator temperature on system performance are analyzed. The analysis findings reveal that the proposed system can provide power, cooling, and heating of 551.904 kW, 20.307 kW, and 193.009 kW, and the dehumidification capacity per unit is 14.516 g/kg when 1.238 kg/s of humid air is treated. The system exergy efficiency is found to be 70.534 %, and the system cost rate is 15.578 $/h with carbon dioxide emission being 0.301 kg/kWh at the design condition. Two groups of multi-objective optimizations of the whole system are further conducted to acquire the optimal system performance and working conditions. The optimization results demonstrate that the optimal exergy efficiency of 72.912 % appears at point C1 in the first group of optimization with the lowest carbon dioxide emission being 0.293 kg/kWh, and the optimal qualities of humid air are found to be 1.606 kg/s at C2 and D2 in the second group of optimization. After optimization, the system carbon dioxide emission is decreased by 0.008 kg/kWh, the exergy efficiency is increased by 2.378 %, and the quality of humid air in dehumidification process is developed by 0.368 kg/s. In summary, the proposed poly-generation and dehumidification system can meet multifunction energy demands and achieve good performance, and the research work could also provide theoretical basis for developing evaluation and optimization technologies of fuel cell-based poly-generation systems.

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.

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.

Exergy-based sustainability analysis of combined cycle gas turbine plant integrated with double-effect vapor absorption refrigeration system

Exergy-based sustainability analysis of combined cycle gas turbine plant integrated with double-effect vapor absorption refrigeration system

Techno-economic-environmental analysis and optimization of biomass-based SOFC poly-generation system

This study presents and investigates a biomass-based SOFC assisted carbon capture poly-generation system, which is integrated with the transcritical CO2 cycle, recompression supercritical CO2 Brayton cycle and double-effect LiBr absorption refrigeration cycle. In addition to supplying cooling, heating and power output, the proposed system can also provide the recovered condensate and the captured CO2. The techno-economic-environmental analysis and four-criteria optimization are performed to comprehensively investigate the system performance. The simulation results show that under the design condition, the overall efficiency, exergy efficiency and total cost rate of the system reach 93.00 %, 29.95 %, and 17.75 $/h. Parametric analysis reveals that the net power output reaches a maximum of 99.66 kW at the SOFC inlet temperature of 550 °C and the current density of 3680 A/m2. Besides, the four-criteria (the thermal efficiency, the exergy efficiency, the total cost rate and the life-cycle CO2 emissions) optimization results demonstrate that the exergy efficiency is increased by 3.19 % and the total cost rate is reduced by 21.18 % in the optimal condition compared with the base case. This work can provide references for the development and exploration of high-efficiency, low-emission, low-cost and multi-functional technologies for the biomass-based SOFC hybrid power system.

Energy and exergy analyses of a recompression supercritical CO2 cycle combined with a double-effect parallel absorption refrigeration cycle

In this study, a new cogeneration system is presented that can make optimal use of the waste heat from the sCO2 power cycle using a double-effect parallel absorption refrigeration cycle (DEARC), generating electricity and refrigeration simultaneously. A comparative study between the proposed (sCO2/DEARC) system and the stand-alone sCO2 power system is conducted to show its advantages and potential. The performances of the sCO2 and sCO2/DEARC systems are evaluated from the energetic and exergetic points of view using an in-house developed thermodynamic simulation platform via Engineering Equation Solver (EES) software. Variables such as pressure ratio, turbine inlet temperature, and evaporator temperature are also used for parametric analysis. The results indicate that the proposed system can generate of 132.72 MW cooling capacity. Also, the results show that the proposed sCO2/DEARC system can achieve a 55.8% and 5.2% improvement in thermal efficiency and exergy efficiency, respectively, with a negligible decrease in net power output (Wnet) compared to the stand-alone sCO2 power plant.

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.

Thermodynamic and economic evaluation of a non-cascaded dual-temperature compression–absorption–resorption refrigeration system

Thermal processes in many industries require simultaneous cooling at multiple temperatures, highlighting the need for an efficient and cost-effective dual-temperature refrigeration system. This study proposes two novel non-cascaded dual-temperature ejector-assisted compression–absorption–resorption refrigeration cycles (ECARC) to deliver simultaneous refrigeration effects at -5°C and 7°C. These cycles are classified based on the compressor staging with an ejector as ECARC-1 and ECARC-2. The performance simulations of the proposed cycles were carried out at the design conditions and a detailed parametric study was performed to determine the influence of the key operating parameters on the first and the second law coefficients of performance. The proposed novel cycles are more efficient and utilise heat more effectively by consuming up to 60 % less electricity than the conventional multi-evaporator compression refrigeration system, for the same operating conditions and refrigeration capacity. These cycles are also more cost effective with a reduction in their unit production cooling cost by up to 50 % and 25.5% as compared with the state-of-the-art double-effect absorption refrigeration system and the multi-evaporator compression refrigeration system, respectively. Thus, the proposed cycles show excellent thermal and economic advantages for a potential dual-temperature refrigeration system, and the development of these systems contribute towards the decarbonisation of the industrial cooling and heating sector.

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.

Performance Evaluation of LiBr-H2O and LiCl-H2O Working Pairs in Compression-Assisted Double-Effect Absorption Refrigeration Systems for Utilization of Low-Temperature Heat Sources

To improve the performance of conventional double-effect absorption refrigeration systems (DEARS), new series parallel (SP) and reverse parallel (RP) configurations using LiCl-H2O and LiBr-H2O as working fluids, combined with two vapor compressors (VC), are proposed and thermodynamically evaluated. The effects of the distribution ratio (D) and compression ratio (CR) on the system performance are discussed. The results reveal that both configurations can extend the operation ranges of DEARS effectively at a higher distribution ratio, and the performance for low-grade heat source utilization is improved substantially by the use of VC. The compressor positioned between the evaporator and absorber is superior to that between the high-pressure generator and low-pressure generator because of the better performance improvement and larger operating ranges. In all the examined cases, LiCl-H2O systems perform better than LiBr-H2O systems in terms of the coefficient of performance (COP) and exergetic efficiency. At the higher CR of approximately 2, the compression-assisted DEARS can be driven by heat sources below 100 °C with high levels of COPs above 1.16 for the LiBr-H2O working pair and 1.29 for the LiCl-H2O working pair. The system can operate at the optimum condition by adjusting the CR values according to the characteristics of the heat sources.

Energy and exergy analysis of a subfreezing evaporator environment ammonia-water absorption refrigeration cycle: Machine learning and parametric optimization

The coefficient of performance (COP) and exergy efficiency of a single and double-effect ammonia-water absorption refrigeration system powered by compound parabolic concentrating collectors were analyzed under various operating situations. A novel method was proposed using support vector machine regression and particle swarm optimization to identify optimal operating parameters. The optimal pressure-temperature conditions, including evaporator pressure (Pe), generator pressure (Pg), and absorber temperature (Ta) that maximize the COP and exergy efficiency while minimizing generator temperature (Tg) and evaporator temperature (Te), were investigated. The generator temperature was the main independent variable, ranging from 370 to 470 K. The findings demonstrated that the gain in COP and exergy efficiency caused by raising the generator temperature to more than 430 K is not cost-effective. The COP increased when the evaporator temperature increased along the investigated range of generator temperatures but yielded lower exergy efficiency in all cases. The exergy destruction rate in condenser, pump, recooler, reheater, and expansion valves is insignificant compared to other components. The generator has the highest exergy destruction rate regardless of operating conditions, making it the most crucial component of the absorption system. The optimization process findings showed that, at Pe = 2.8 bar, Pg = 14.5 bar, and Ta = 303.15 K, the maximum COP and exergy efficiency were 0.8483 and 0.3605, respectively, concerning the minimization of Tg and Te, which were 408 and 267 K, respectively. The model produced an acceptable performance with a high prediction accuracy (coefficient of determination > 0.99 and mean square error < 0.0064).

Design, multi-aspect analyses, and multi-objective optimization of a novel trigeneration system based on geothermal and municipal solid waste energies

The study of multi-source energy systems, due to higher performance and producing various products, is an interesting subject. The current study designs a multi-source system including a gas turbine cycle with CH4 and municipal solid waste digester, a geothermal system with an organic Rankine, organic flash, and a double-effect absorption refrigeration subsystem to produce power, cooling, and heating loads simultaneously. The thermodynamic and economic analyses are utilized to estimate the system’s performance and multi-objective optimization has been applied to define the optimum state of the system concerning two scenarios. The results indicate that the system provides 423.4 kW net power, 384.7 kW heating load, and 106.3 kW cooling load with 39.28% exergetic efficiency and 6.67 years payback period. These values are improved to 664.9 kW net power, 446.5 heating load, 42.01% exergetic efficiency, and 6.05 years payback period at the best optimum scenario. The sensitivity analysis reveals that the air compressor’s pressure ratio mainly impacts the net power, heating load production, and net present value. The cooling load production and exergetic efficiency are mainly affected by the air preheater effectiveness variation.

Modeling and parametric analysis of a new combined geothermal plant with hydrogen generation and compression for multigeneration

Geothermal energy is a promising solution to provide multiple outputs at different temperatures and under different conditions. In this current work, a geothermally powered multigeneration cycle is planned, suggested and studied including a Kalina cycle, an organic Rankine cycle, a thermoelectric generators, a double effect absorption refrigeration system, a dryer, a domestic water heater, a multi-effect desalination processes, a greenhouse, and hydrogen production and storage units. The main objective of this study is to generate power, cooling, heating, hot water, drying, greenhouse heating, hydrogen, oxygen, and freshwater in an environmentally harmless approach. An elaborated thermodynamic analysis of the developed research is calculated by energy and exergy efficiency methods. Furthermore, the parametric modeling is employed to calculate the effect of significant variables on the examined study and subsystems' efficiency. Looking the analysis's findings reveal that the evaluated model's net power generation rate is approximately 298 kW. Additionally, the cooling and heating rates of this integrated combined plant are 1169 kW and 1783 kW, respectively. Moreover, the examined plant produces 0.000392 kg/s of hydrogen and 2.77 kg/s of freshwater. Finally, the examined cycle energy and exergy performance is computed as 0.4248 and 0.3826, 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.

Evaluation of ionic liquids as absorbents for absorption refrigeration systems using hydrofluoro-olefin refrigerant

In this study, we evaluate the use of ILs as absorbents in a double effect absorption refrigeration system using HFO refrigerant. By examining the properties of various refrigerant/absorbent mixtures, we identify the most efficient refrigerant/absorbent pair for the aforementioned absorption refrigeration system. First, we identify a suitable HFO refrigerant for the system. Among the candidates in this study, R1336mzz(Z) and R1234ze(Z) can be used in the absorption refrigeration system because both have low flammability and high critical points. Then, we analyze the characteristics of ILs as absorbents in the absorption refrigeration system. Imidazolium ILs have relatively low viscosities of approximately 20 mPa s at temperatures exceeding 50 °C and high stability. Next, we analyze the characteristics of refrigerant/absorbent pairs. When R1336mzz(Z) and R1234ze(Z) are used as the refrigerant, [OMIM][BF4] have the highest solubilities in oprating conditions. The solubility value of R1234ze(Z) with [OMIM][BF4] is 0.256 at 289.89 kPa and 80 °C, while the solubility value of R1336mzz(Z) with [OMIM][BF4] is 0.154 at 128.02 kPa and 80 °C. Finally, we analyze the performance of the refrigeration system. When the R1234ze(Z)/[OMIM][BF4] is used in the absorption refrigeration system, the COP and cooling capacity of the system exhibit the values of 0.516 and 0.549 kW, respectively.

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.