Net Output Research Articles

Design and multi-objective optimization of combined air separation and ORC system for harnessing LNG cold energy considering variable regasification rates

Regasification of liquefied natural gas (LNG) releases significant cooling potential, but improper usage can easily lead to wastage of resources and environmental pollution. The study developed an integrated air separation system and Organic Rankine Cycle (ORC) power generation system to effectively harness the inherent cold energy within LNG. Two distinct optimization algorithms, the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) and the Particle Swarm Optimization (PSO), were employed to determine the optimal operational parameters. The results showed the superior performance of PSO over NSGA-II, as demonstrated by the exergy efficiency, net output power, and levelized cost of energy at 78.12 %, 2.29*1011 kW, and 0.0665 $/kWh, respectively. Additionally, an assessment of various factors influencing the system's performance was conducted. The performance of both conventional and proposed systems was studied under varying regasification rates. The findings indicated that incorporating the cold recovery and storage unit enhanced the efficient utilization of LNG cold energy, resulting in an increased valley-to-peak ratio of the total power output from 0.03 in the conventional system to 0.5. The proposed system exhibits alignment with the energy consumption demands of users, and this study is anticipated to furnish a theoretical foundation for harnessing the cooling capacity of liquid hydrogen.

Enhancing performance of multi-pressure evaporation organic Rankine Cycle/Supercritical Carbon Dioxide Brayton cycle through genetic algorithm and Machine learning optimization

The Supercritical Carbon Dioxide Brayton combined cycle is one of the most important ways to enhance the performance of the cycle. Since the considerable exergy loss resulting from large temperature differences in the heat exchangers of combined cycles, the multi-pressure evaporation concept was adopted from Organic Rankine cycle research. Two novel multi-pressure evaporation configurations, namely parallel evaporation Brayton combined cycle and series evaporation Brayton combined cycle, are designed with the purpose of enhancing SCO2 Brayton cycle performance. The performance of the two new cycles was compared with that of the baseline cycle. Moreover, Printed Circuit Heat Exchangers were employed to improve the overall compactness of the cycles. The results from model calculations were utilized to train an Artificial intelligence neural network model using machine learning techniques which allowed to simplify the cycle and improves the computational speed. Subsequently, genetic algorithm was employed to conduct multi-objective optimization on the three cycles. Finally, a detailed exploration was conducted from the perspective of thermal and exergy to elucidate the reasons for the advantages and differences between the two new cycles compared to the baseline cycle. The results indicate that the series Brayton combined cycle exhibits the highest performance, and the combined cycle of multi-pressure evaporation helps to improve the performance of the combined cycle. Compared to the baseline cycle, the combined cycle efficiency of both series and parallel combined cycles has increased from 45.54% to 46.18% and 46.29%, respectively, while the bottom cycle efficiency has improved from 3.81% to 4.93% and 5.03%. The ratio of heat exchange area to net output power increased from 0.6051 to 0.6614 and 0.6740 for the parallel and series cycles, respectively. Thermal analysis shows that, the fundamental purpose of changing the layout is to improve the specific power per unit of working medium in the cycle. Exergy analysis shows that, the two new combined cycles improve cycle efficiency by reducing exergy losses in the intermediate heat exchanger. Compared to the parallel version, the series version's staged compression allows for a lower temperature difference in intermediate heat exchanger 1, resulting in smaller exergy losses and higher cycle efficiency. This work will contribute to an enhanced understanding of Supercritical Carbon Dioxide combined cycles within the academic community and the introduction of multi-pressure evaporation will further improve the performance of these important cycles.

Targeting zero energy increment for an onboard CO2 capture system: 4E analyses and multi-objective optimization

In this paper, a novel zero energy increment onboard carbon capture (ZEIOCC) system was proposed. With LNG cold energy and waste heat recovery, the ZEIOCC system integrated organic Rankine cycle (ORC), CO2 liquification, and CO2 capture unit. The ZEIOCC system performances were evaluated via energy, exergy, economic, and environmental (4E) analyses. Parametric studies were performed to investigate the effects of the flue gas mass flow rate (mfg), liquid to gas ratio (L/G), and the pinch point temperature difference at the outlet of the ORC condenser (Tpin) on the system performance indicators. Furthermore, multi-optimization was conducted with the product of energy-exergy efficiencies (ηen,sys*ηex,sys), the total capital investment cost (CI,tot), and the carbon reduction capacity (ξ) as objective functions. Two decision methods TOPSIS and LINMAP were introduced to find the most optimal point from the Pareto front. Under the basic condition, the proposed system proved its advantages of high efficiency, diversified energy output, fast return on investment, and efficient CO2 capture capacity. The results of optimization showed that the system performances meet all the requirement of the design goal. The optimal energy-exergy efficiencies is 10.06 %, the carbon reduction capacity is 28.01 %, and the total capital investment cost is 7.06 × 106 $. Under the optimal condition, the system net output power (Wnet), energy efficiency, and exergy efficiency are 12 kW, 20.53 %, and 49.02 %, respectively. Meanwhile, the payoff period (POP) and the CO2 capture cost (CCC) are 12.0 year and 99.9 $/tonCO2, respectively.

A 3E analysis of a multi‐power generation system employing CO2, LNG, and Organic Rankine cycles

AbstractOne avenue in increasing the energy efficiency of energy systems is through utilizing the thermal energy of flue gases of industrial plants. On this thread, herein, a novel combined cascade cycle for heat recovery of flue gases of an industrial plant is proposed comprising of an organic Rankine cycle (ORC), high‐pressure transcritical CO2 cycle, transcritical CO2 cycle, and a liquefied natural gas (LNG) regasification cycle. System analysis is conducted using energy, exergy, and eco‐exergy equations. The optimization is carried out using the TOPSIS multi‐objective method. Exergy efficiency, net output work, and cost are identified as the optimization objectives. The optimization process focused on fine‐tuning variables including the vapor generator pinch point temperature, ORC turbine inlet pressure, ORC condenser pressure, and ORC condenser pinch point temperature, with optimal values gauged at 19.31°C, 29.59 bar, 1.413 bar, and 14.52°C, respectively. The preheater had the largest exergy destruction share, followed by the heat exchanger unit. The analysis showed that the ORC condenser pressure and temperature difference between two working fluids in the heat exchanger were the most critical parameters in the proposed cycle, significantly affecting the system performance. Accordingly, the exergy efficiency, net output work, and cost values in the optimal state were equal to 15.2%, 6416 kW, and 0.7457 $/s, respectively. The advantages of the proposed system include efficient heat recovery through the coupling of the multiple cycles and enhanced energy conversion pertinent to a wider range of temperatures, maximizing the overall energy extraction from the waste heat.

Numerical study for effect of injection parameters on reservoir: A case study for Lahendong, Indonesia

A single-flash cycle of thermodynamic model coupled with a reservoir of numerical model has been developed through the COMSOL Livelink module to investigate the impact of the geofluid mass flow rate and injection temperature on production temperature and net output power of the power cycle. The geothermal reservoir model was established by using a thermal–hydraulic–mechanical (THM) module in COMSOL Multiphysics. Moreover, the single-flash cycle of the thermodynamics model was constructed in MATLAB. The geothermal reservoir conditions of Lahendong, North Sulawesi, Indonesia was adopted to simulate the geothermal power plants’ actual operation. The results revealed that the variation in geofluid mass flow rate and injection temperature impacted production temperature and net output power. The production temperature considerably decreased with an increase in the geofluid mass flow rate. However, the difference in production temperature between geofluid mass flow rates of 50 kg/s and 250 kg/s at 1st and 30th years were 0.23 K and 0.41 K, respectively. The net output power differences were also 16.204 MW and 15.349 MW, respectively. Finally, increasing the injection temperature correspondingly led to an increase in production temperature and net output power, even though the increment did not exceed 1 K and 0.002 MW, respectively.

The Role of Inflammasome-Associated Innate Immune Receptors in Cancer.

Dysregulated activation of the innate immune system is a critical driver of chronic inflammation that is associated with at least 30% of all cancers. Innate immunity can also exert tumour-promoting effects (e.g. proliferation) directly on cancer cells in an intrinsic manner. Conversely, innate immunity can influence adaptive immunity-based anti-tumour immune responses via Ag-presenting dendritic cells that activate natural killer and cytotoxic T cells to eradicate tumours. While adaptive anti-tumour immunity has underpinned immunotherapy approaches with immune checkpoint inhibitors and chimeric Ag receptor-T cells, the clinical utility of innate immunity in cancer is underexplored. Innate immune responses are governed by pattern recognition receptors, which comprise several families, including Toll-like, nucleotide-binding oligomerization domain-containing (NOD)-like and absent-in-melanoma 2 (AIM2)-like receptors. Notably, a subset of NOD-like and AIM2-like receptors can form large multiprotein "inflammasome" complexes which control maturation of biologically active IL-1β and IL-18 cytokines. Over the last decade, it has emerged that inflammasomes can coordinate contrasting pro- and anti-tumour responses in cancer and non-cancer (e.g. immune, stromal) cells. Considering the importance of inflammasomes to the net output of innate immune responses, here we provide an overview and discuss recent advancements on the diverse role of inflammasomes in cancer that have underpinned their potential targeting in diverse malignancies.

Research on unsteady characteristics of valveless piezoelectric micropump with planar conical tube

The model of valveless piezoelectric micropump with planar conical tube is established in this paper, and dynamic mesh technology is used to simulate the unsteady characteristics of the micropump at different pressure amplitudes and driving frequencies for different diffusion angles. The elements affecting the output performance of the micropump are analyzed. The research indicates that the longer the conical tube, the smaller the flux that flows into the cavity of the micropump during inhalation. While the longer the conical tube, the greater the flux that flows out of the cavity of the micropump during expulsion. The net output flux of the valveless piezoelectric micropump increases with the length of the conical tube. The rectification efficiencies of micropump with tube length of 1mm, 3mm, and 5mm are 8.77%, 14.58%, and 18%, respectively.

Thermodynamic and exergoeconomic assessment of a trigeneration system driven by a biomass energy source for power, cooling, and heating generation

Environmental concerns and the limitations of conventional energy drive the exploration of reliable renewable sources. Herein, a biomass-assisted trigeneration system in conjunction with a methane-fed gas turbine cycle for generating power, cooling, and heating, and an attempt has been made to maximize the energy extraction from the energy source. The proposed system includes a steam Rankine cycle, a gas turbine unit, and a Kalina subsystem, and is investigated from energetic, exergetic, and economic viewpoints. A comprehensive parametric evaluation is carried out, and a multi-objective grey wolf optimization algorithm integrated with the LINMAP decision-maker method is employed to detect the most optimum point through two different scenarios. By conducting a base study, a net output power of 5926 kW, cooling load of 36.56 kW, heating load of 843.4 kW, and an energetic efficiency of 47.41 % can be achieved. The exergetic and economic standpoints bring out an exergy destruction rate of 7697.07 kW, cycle exergetic efficiency of 41.44 %, and a net present value of 12.420 $M that sequels to a payback period of 5.56 years. Biomass proves reliable in multigeneration systems, emphasizing the pivotal role of studies in maximizing energy extraction for diverse product outputs.

Optimal design of a solar-driven Kalina system for combined power and desalination purposes

This research study presents a thermodynamic simulation and exergy analysis of a solar-powered Kalina cycle that is integrated with a reverse osmosis desalination (RO) module and a thermoelectric generator (TEG) system. A parabolic through solar collector (PTSC) provides the required heat to drive designed plant. The thermodynamic simulation and exergy examination of the proposed system are carried out using the Engineering Equation Solver (EES). A parametric study of the presented plant to show the primary parameters impacts on the system operation is conducted. The system in this study generates 212.7 kW of electrical power and 44.46 m3/h. The total energy efficiency of the plant is 24.3 %. The inlet thermal energy from PTSC is 876.5 kW. In addition, the thermoelectric module generates 7.26 kW electrical power. Carried out analyses show that the recuperator has the most significant exergy destruction rate among all system components, with 303.2 kW. The unit responsible for the second major exergy destruction value associated with the RO unit, which accounts for 74.22 kW. To examine the influence of influences of parameters like direct normal irradiance (DNI), turbine inlet pressure, and mass flow rate of the Kalina cycle the system case study is presented. It can be observed that increasing DNI parameter from 750 W/m2 to 1000 W/m2 leads in a net output power increment from 279.1 kW to 372.1 kW and increasing fresh-water production from 41.64 m3/h to 48.09 m3/h. Moreover, the calculation shows that increasing DNI has a positive impact on the TEG unit output power too. Enhancing the inlet turbine pressure increases both net output power and fresh-water production by reverse osmosis unit while this increment diminishes the thermoelectric unit electrical output. It can be observed that increasing turbine inlet pressure from 110 kPa to 200 kPa, increases net output power and fresh-water production by about 6.08 % and 3.5 %, respectively.

Optimization of agricultural planting structure in irrigation areas of Heilongjiang province considering the constraints of water resource system resilience

From the perspective of sustainable development in irrigation areas, imperfect constraints, which have negatively impacted previous agricultural planting structure optimization models, tend to produce unreasonable optimization results. Thus, in this paper, attempts are made to incorporate the resilience of water resource systems into the constraint set and explore the optimal layout of agricultural planting structures in irrigation areas. We selected 12 sample irrigation areas in Heilongjiang Province, China, including Chahayang, Fuyu, and Tailai, as the research areas and considered their actual situations. Then, we established a multiobjective optimization model for an agricultural planting structure with rice, soybean, and corn planting areas as decision variables; socioeconomic benefits, agricultural production benefits, ecological benefits, and water resource benefits as objective functions; and water resource system resilience and net crop output value and other factors as constraints. Fifteen scenarios were assessed through the combination of objective functions, and the nondominated sorting genetic algorithm III (NSGA-III) was used to optimize and analyze the agricultural planting structure of typical irrigation areas in Heilongjiang Province and to determine the optimal planting plan. The research results found that the function values adjusted by planting area have significantly improved compared to those before optimization. The adjustment trend of agricultural planting area is to increase the planting area of rice and soybean and reduce the planting area of corn. The introduction of constraints on water resource system resilience ensures that other benefits remain basically unchanged; thus, the water resource objective function is significantly better with resilience constraints than without them. Therefore, water resource system resilience can act as an effective constraint; this finding enriches and expands the theoretical and methodological system for optimizing the management of agricultural planting structures in irrigation areas and thus provides important technological support for ensuring regional food security, ecological security, and water security, which has substantial practical significance.

A novel geothermal source integrated system to meet the building demands: Exergo-economic and optimization assessment

This study proposes a novel geothermal source integrated system to meet the building demands that combines a solid oxide fuel cell (SOFC), a geothermal source, and a thermoelectric generator (TEG) to achieve enhanced performance. The system is subjected to exergo-economic examination and optimization to determine its thermal performance and cost-effectiveness. Integrating geothermal energy with SOFC can help reduce waste heat and improve overall system performance. Based on the results, it is determined that the cooling system can generate 161.3 kW for building purposes, and the integrated turbine in the cooling system can also produce 891.9 kW of electrical output. The integrated thermoelectric generator modules produce 418.06 kW. Moreover, hybrid systems' energy and exergy efficiencies are 23.29 % and 19.26 %. The case study of the introduced system indicates that by variation of parameters, the systems have different behaviors from thermodynamic and cost points of view. Therefore, multi-criteria optimum finding according to the genetic algorithm is conducted. The optimization results present that in the selected optimal state while using the ideal state, the net output power and overall cost rate are 193307.12 kW and 77.96 $/h.

Experimental performance of a low−grade heat driven hydrogen production system by coupling the reverse electrodialysis and air gap diffusion distillation methods

The reverse electrodialysis (RED) heat engine is an emerging and burgeoning technology used to convert low-grade heat (LGT) to electrical energy. This study designed and built a lab-scale prototype of integrating the RED and air gap diffusion distillation (AGDD) methods to convert LGT (as low as 60℃) to hydrogen, and the performances (the hydrogen production, thermal regeneration characteristic, and system efficiency) of the RED−AGDD integration system were experimentally investigated. The results indicate that the maximum net output power for hydrogen production is determined by the maximum current. The maximum net output power is 0.53 W when the HC−LC feed solution pair is 4−0.05 M. Either the excessively high or low salinity gradient energy is detrimental to the energy conversion efficiency of the RED−AGDD integrated system. In this study, the system efficiency reached its maximum value of 0.014% at the feed solution pair is 5−0.20 M. It is also observed the thermal separation effect of the AGDD unit is improved by increasing the solution temperature and flow rate, but weakened by increasing the concentration of separated solution. The effect mechanisms of the vital operating parameters on system performances are analyzed, providing guidance for the practical application of RED heat engine for hydrogen production.

Multi-criteria assessment and optimization of a biomass-based cascade heat integration toward a novel multigeneration process: Application of a MOPSO method

In this study, a novel biomass-driven cascade heat integration scheme is devised, encompassing combined cooling, heating, and power generation, with a unique focus on the production of a secondary product (freshwater). The process commences with the establishment of a biomass digester, yielding biogas fuel to kickstart the integrated system. Subsequently, the utilization of a gas turbine cycle is introduced, and its waste heat is efficiently harnessed through a supercritical carbon dioxide process, a double-effect refrigeration cycle, and a heating terminal. Additionally, a modified organic Rankine cycle is incorporated to recover heat from the supercritical carbon dioxide process, while reverse osmosis desalination forms an integral part of the equipment lineup. The entire system is rigorously evaluated from both thermodynamic and economic standpoints, undergoing optimization across five distinct scenarios. A multi-objective particle swarm optimization approach, featuring two decision-making algorithms, is deployed in this optimization process. The primary objective is exergetic efficiency, while the secondary objectives encompass net output power, cooling, heating, sum unit cost of products, and net present value, each considered individually. The results of the study reveal that the highest attainable optimal exergy efficiency stands at 38.54 % when the secondary objective is net output power. Furthermore, the optimal values for the secondary objectives are determined to be 41112.59 kW, 1383.75 kW, 28413.97 kW, 18.72 $/GJ, and 75.17 M$, respectively. These findings underscore the potential of the proposed biomass-driven cascade heat integration system in achieving efficient and sustainable energy generation while simultaneously producing valuable secondary products.

Enhanced methanol reforming gas fuel cell system with electrochemical hydrogen pump: Conceptual design, system analysis, and multi-objective optimization

In this work, two methanol-reforming gas fuel cell systems coupled with an electrochemical hydrogen pump (EHP), namely, EHP pre-coupling and post-coupling fuel cell systems were proposed to achieve performance enhancement. A back propagation neural network surrogate model was established for the two systems to accurately describe system behavior, and a second-generation multi-objective non-dominated genetic algorithm was utilized for addressing the multi-objective optimization problem encompassing net output power, carbon mass-specific emission and the levelized cost of electricity. The linear non-weighted multi-attribute preference and technique for order preference by similarity to ideal solution multi-attribute decision-making methods were employed to select the optimal solutions. The optimized EHP pre-coupling fuel cell system exhibited lower carbon emissions (0.69 kgCO2/(kW·h)) and higher net output power (126.02 kW) compared to previous studies. While the EHP post-coupling system achieves a lower levelized cost of electricity (0.36 USD/(kW·h)), and stronger system stability (total efficiency reduction less 1 %). Both EHP-coupling systems offer viable process enhancements for fuel cell systems.

Performance Analysis and Multi-Objective Optimization of a Cooling-Power-Desalination Combined Cycle for Shipboard Diesel Exhaust Heat Recovery

This study presents a novel cooling-power-desalination combined cycle for recovering shipboard diesel exhaust heat, integrating a freezing desalination sub-cycle to regulate the ship’s cooling-load fluctuations. The combined cycle employs ammonia–water as the working fluid and efficiently utilizes excess cooling capacity to pretreat reverse osmosis desalination. By adjusting the mass flow rate of the working fluid in both the air conditioning refrigeration cycle and the freezing desalination sub-cycle, the combined cycle can dynamically meet the cooling-load demand under different working conditions and navigation areas. To analyze the cycle’s performance, a mathematical model is established for energy and exergy analysis, and key parameters including net output work, comprehensive efficiency, and heat exchanger area are optimized using the MOPSO algorithm. The results indicate that the system achieves optimal performance when the generator temperature reaches 249.95 °C, the sea water temperature is 22.29 °C, and 42% ammonia–water is used as the working fluid. Additionally, an economic analysis of frozen seawater desalination as RO seawater desalination pretreatment reveals a substantial cost reduction of 22.69%, showcasing the advantageous features of this proposed cycle. The research in this paper is helpful for waste energy recovery and sustainable development.

Performance and environmental impact evaluations of a novel multigeneration system with sonic hydrogen production and energy storage options

This article designs and develops a unique system integrated with hydrogen production and energy storage effectively to meet the variable energy demands of residential communities by harnessing both solar and geothermal energies. The system features a synergy of technologies, including a steam Rankine cycle, an ammonia-water-based double-effect absorption system, two organic Rankine cycles, a thermal energy storage, battery and hydrogen storage options, and a sonohydrogen production device. In order to develop a new system for producing cooling, electricity, heat and hydrogen, the present study dives deep into an analysis based on energy and exergy approaches using balance equations. The present system has the ability to generate 0.0016 kg/s of hydrogen, creates a net output of 2177 kW, supplies 4337 kW for heating purposes, and offers 903.8 kW of cooling capacity. In addition, the system's performance was rigorously evaluated, revealing an energy efficiency of 83.28 % and an exergy efficiency of 58.71 %, with energetic and exergetic coefficients of performance (COP) of 1.646 and 0.6215, respectively. Additionally, an environmental impact assessment was conducted, focusing on CO2 emissions to gauge the system's sustainability. This assessment further indicates that the system could potentially avoid the release of 3.351 kg of carbon dioxide per kilowatt-hour into the atmosphere which might have come from conventional systems.

A Phenomapping Tool and Clinical Score to Identify Low Diuretic Efficiency in Acute Decompensated Heart Failure

BackgroundIndividuals with acute decompensated heart failure (ADHF) have a varying response to diuretic therapy. Strategies for the early identification of low diuretic efficiency to inform decongestion therapies are lacking. ObjectivesThe authors sought to develop and externally validate a machine learning–based phenomapping approach and integer-based diuresis score to identify patients with low diuretic efficiency. MethodsParticipants with ADHF from ROSE-AHF, CARRESS-HF, and ATHENA-HF were pooled in the derivation cohort (n = 794). Multivariable finite-mixture model-based phenomapping was performed to identify phenogroups based on diuretic efficiency (urine output over the first 72 hours per total intravenous furosemide equivalent loop diuretic dose). Phenogroups were externally validated in other pooled ADHF trials (DOSE/ESCAPE). An integer-based diuresis score (BAN-ADHF score: blood urea nitrogen, creatinine, natriuretic peptide levels, atrial fibrillation, diastolic blood pressure, hypertension and home diuretic, and heart failure hospitalization) was developed and validated based on predictors of the diuretic efficiency phenogroups to estimate the probability of low diuretic efficiency using the pooled ADHF trials described earlier. The associations of the BAN-ADHF score with markers and symptoms of congestion, length of stay, in-hospital mortality, and global well-being were assessed using adjusted regression models. ResultsClustering identified 3 phenogroups based on diuretic efficiency: phenogroup 1 (n = 370; 47%) had lower diuretic efficiency (median: 13.1 mL/mg; Q1-Q3: 7.7-19.4 mL/mg) than phenogroups 2 (n = 290; 37%) and 3 (n = 134; 17%) (median: 17.8 mL/mg; Q1-Q3: 10.8-26.1 mL/mg and median: 35.3 mL/mg; Q1-Q3: 17.5-49.0 mL/mg, respectively) (P < 0.001). The median urine output difference in response to 80 mg intravenous twice-daily furosemide between the lowest and highest diuretic efficiency group (phenogroup 1 vs 3) was 3,520 mL/d. The BAN-ADHF score demonstrated good model performance for predicting the lowest diuretic efficiency phenogroup membership (C-index: 0.92 in DOSE/ESCAPE validation cohort) that was superior to measures of kidney function (creatinine or blood urea nitrogen), natriuretic peptide levels, or home diuretic dose (DeLong P < 0.001 for all). Net urine output in response to 80 mg intravenous twice-daily furosemide among patients with a low vs high (5 vs 20) BAN-ADHF score was 2,650 vs 660 mL per 24 hours, respectively. Participants with higher BAN-ADHF scores had significantly lower global well-being, higher natriuretic peptide levels on discharge, a longer in-hospital stay, and a higher risk of in-hospital mortality in both derivation and validation cohorts. ConclusionsThe authors developed and validated a phenomapping strategy and diuresis score for individuals with ADHF and differential response to diuretic therapy, which was associated with length of stay and mortality.

Thermo-economic-environmental evaluation of an innovative solar-powered system integrated with LNG regasification process for large-scale hydrogen production and liquefaction

In order to achieve a sustainable energy future, it is of utmost importance to harness solar energy for the production of liquid hydrogen. This undertaking is justified by the significant role that liquid hydrogen plays as a clean and highly efficient fuel source, effectively addressing the pressing concerns regarding greenhouse gas emissions and reducing reliance on conventional fossil fuels. An additional advantage lies in the easy storage and transportation capabilities of liquid hydrogen, making it a viable solution for energy storage across diverse sectors. In this regard, the current research presents a novel solar-powered setup consisting of parabolic trough solar collectors (PTSCs), a sequential organic Rankine cycle (ORC), a liquefied natural gas (LNG) regasification unit, and a module dedicated to the production and subsequent liquefaction of hydrogen. A meticulously crafted MATLAB code is utilized to replicate the operations of the proposed system, facilitating a thorough examination of its energy, exergy, environmental, and economic performance. The proposed system exhibits a net output power of 1.13 MW and possesses the capacity to produce hydrogen at a rate of 34.92 kg/h, featuring a levelized cost of hydrogen (LCOH) of 3.59 $/kg. Additionally, the system encompasses a cooling capability of 192 kW. From an environmental perspective, this configuration contributes to a decrease in carbon dioxide emissions by 255.96 kg/h. After conducting a dynamic analysis with meteorological data, it was determined that the system has the potential to generate an annual hydrogen output of 536.84 tons in San Francisco.

Operation characteristic research on organic Rankine cycle-free piston linear generator (ORC-FPLG) based on multi-module combination

Free piston linear generator (FPLG) presents great potential in organic Rankine cycle (ORC) system to replace traditional expanders because of low friction loss, simple structure and good sealing. Drawing on the concept of multi-cylinder engines, ORC-FPLG simulation model coupled with vehicle have been established based on multi-module combination with GT-suite/Simulink. Then, the operation characteristics in parallel mode, series mode and different intake distribution modes are analyzed. And the influence of engine parameters, and the energy-saving potential under road conditions are explored. The results show that: there exists an optimal module number in parallel mode to maximize net output power and thermal efficiency. When the number of modules is 4, the maximum net output power and thermal efficiency are 11.19 kW and 7.73%. The more parallel modules in series mode is, the higher net output power and thermal efficiency is, which is more conducive to improve output performance. Net power output and thermal efficiency gradually increase with engine speed and fuel injection. There exists an optimal injection timing and exhaust timing to maximize net power output and thermal efficiency. Compared to urban road conditions, ORC-FPLG system under suburban conditions achieves better energy recovery results with waste heat recovery efficiency of 2.22%.

Multi-aspect evaluation of a novel double-flash geothermally-powered integrated multigeneration system for generating power, cooling, and liquefied Hydrogen

An integrated renewable geothermal-driven multigeneration system is demonstrated in the present evaluation, consisting of a double-flash geothermal unit, a modified dual-pressure organic Rankine cycle, a Proton exchange membrane electrolyzer, and a Claude Hydrogen liquefication subsystem. The proposed system is examined from various standpoints, and the performance of the system is quantified through the output parameters. Besides, a case study is performed to evaluate the operation of the system in a specified state. Moreover, a sensitivity analysis is conducted to follow the behavior of the system under different conditions. Furthermore, a multi-objective particle swarm optimization algorithm is employed to define the optimum solutions. The results of the study bring out a total generated cooling load of 2.27 MW, a net output power of 10.48 MW, and a liquefied Hydrogen rate of 37.83 kg/h. Also, exergetic efficiency and exergy destruction rate values of 55.89 % and 9.39 MW are obtained, respectively. The exergoeconomic and exergoenvironmental outputs are discussed through a total cost rate of 482.62 $/h, a payback period of 3.27 years, and a product exergy-related environmental impact rate of 9.84 Pts/h.