Iran, Islamic Republic of
Effect of Hydrogen on the Tensile Behavior of Austenitic Stainless Steels 316L Produced by Laser-Powder Bed Fusion
Apr 2021
Publication
Hydrogen was doped in austenitic stainless steel (ASS) 316L tensile samples produced by the laser-powder bed fusion (L-PBF) technique. For this aim an electrochemical method was conducted under a high current density of 100 mA/cm2 for three days to examine its sustainability under extreme hydrogen environments at ambient temperatures. The chemical composition of the starting powders contained a high amount of Ni approximately 12.9 wt.% as a strong austenite stabilizer. The tensile tests disclosed that hydrogen charging caused a minor reduction in the elongation to failure (approximately 3.5% on average) and ultimate tensile strength (UTS; approximately 2.1% on average) of the samples using a low strain rate of 1.2 × 10−4 s−1. It was also found that an increase in the strain rate from 1.2 × 10−4 s−1 o 4.8 ×10−4 s−1 led to a reduction of approximately 3.6% on average for the elongation to failure and 1.7% on average for UTS in the pre-charged samples. No trace of martensite was detected in the X-ray diffraction (XRD) analysis of the fractured samples thanks to the high Ni content which caused a minor reduction in UTS × uniform elongation (UE) (GPa%) after the H charging. Considerable surface tearing was observed for the pre-charged sample after the tensile deformation. Additionally some cracks were observed to be independent of the melt pool boundaries indicating that such boundaries cannot necessarily act as a suitable area for the crack propagation.
Optimization of Geothermal- and Solar-driven Clean Electricity and Hydrogen Production Multi-generation Systems to Address the Energy Nexus
Jan 2022
Publication
Given the limited sources of fossil fuels mankind should find new ways to meet its energy demands. In this regard geothermal and solar energy are acknowledged as reliable safe promising and clean means for this purpose. In this research study a comparative analysis is applied on geothermal and solar-driven multi-generation systems for clean electricity and hydrogen production through energy and exergy assessments. The system consists of an organic Rankine cycle a proton electrolyte membrane electrolyzer and a thermoelectric generator subsystem. The Engineering Equation Solver software has been utilized in order to model the system and obtain the output contours sensitivity analysis and exergy destruction. The results were calculated considering the ambient temperature of Bandar Abbas city as a case study considering the geothermal system due to better performance in comparison to the solar system. According to the sensitivity analysis the turbine efficiency evaporator inlet temperature thermoelectric generator suitability criterion pump efficiency and evaporator inlet mass flow rate are the most influential parameters. Also the exergy analysis showed that the utmost system's exergy destruction is pertinent to the evaporator and the least is related to the pump. In addition the system produces 352816 kWh and 174.913 kg of electrical power and hydrogen during one year.
Simulation of a Multi-Functional Energy System for Cogeneration of Steam, Power and Hydrogen in a Coke Making Plant
Mar 2013
Publication
In this paper a multifunctional energy system (MES) is proposed for recovering energy from the extra of coke oven gas (COG) which is usually flared or vented out as a waste stream in coke making plants. The proposed system consists of a pressure swing adsorption (PSA) unit for extracting some of the hydrogen from COG a gas turbine for producing heat and power from PSA offgas and a heat recovery steam generator (HRSG) for generating the steam required by the plant's processes. o assess the performance of the system practically simulations are carried out on the basis of the design and operational conditions of Zarand Coke Making Plant in Iran. The results indicate that by utilizing about 4.39 tons of COG per hour 6.5 MW of net electric power can be approximately produced by the gas turbine which can supply the coke making plant's total electrical power demand. Furthermore through recovering heat from gas turbine's exhaust close to 57% of the plant's steam demand can be supplied by the HRSG unit. It is also found that around 350 kilograms per hour of nearly pure hydrogen (99.9% purity) at 200 bar can be produced by the PSA unit. According to the sensitivity analysis results if the hydrogen content of the coke oven gas decreases by about 10% the gross power output of the gas turbine also declines by around 5.2% due to the reduction of LHV of the PSA offgas. Moreover economic evaluation of the system shows that the payback period of the investment which is estimated at 36.1 M$ is about 5.5 years. The net present value (NPV) and internal rate of return on investment (ROI) are calculated to be 17.6% and 43.3 M$ respectively.
Progress and Challenges on the Thermal Management of Electrochemical Energy Conversion and Storage Technologies: Fuel Cells, Electrolysers, and Supercapacitors
Oct 2021
Publication
It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result thermal management is an essential consideration during the design and operation of electrochemical equipment and can heavily influence the success of electrochemical energy technologies. Recently significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless the existing reviews on the subject have been primarily focused on battery cooling. Conversely heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques currently employed for temperature control are then exposed and some directions for future studies are provided.
Optimal Scheduling of Multi-energy Type Virtual Energy Storage System in Reconfigurable Distribution Networks for Congestion Management
Jan 2023
Publication
The virtual energy storage system (VESS) is one of the emerging novel concepts among current energy storage systems (ESSs) due to the high effectiveness and reliability. In fact VESS could store surplus energy and inject the energy during the shortages at high power with larger capacities compared to the conventional ESSs in smart grids. This study investigates the optimal operation of a multi-carrier VESS including batteries thermal energy storage (TES) systems power to hydrogen (P2H) and hydrogen to power (H2P) technologies in hydrogen storage systems (HSS) and electric vehicles (EVs) in dynamic ESS. Further demand response program (DRP) for electrical and thermal loads has been considered as a tool of VESS due to the similar behavior of physical ESS. In the market three participants have considered such as electrical thermal and hydrogen markets. In addition the price uncertainties were calculated by means of scenarios as in stochastic programming while the optimization process and the operational constraints were considered to calculate the operational costs in different ESSs. However congestion in the power systems is often occurred due to the extreme load increments. Hence this study proposes a bi-level formulation system where independent system operators (ISO) manage the congestion in the upper level while VESS operators deal with the financial goals in the lower level. Moreover four case studies have considered to observe the effectiveness of each storage system and the simulation was modeled in the IEEE 33-bus system with CPLEX in GAMS.
Optimal Scheduling of a Hydrogen-Based Energy Hub Considering a Stochastic Multi-Attribute Decision-Making Approach
Jan 2023
Publication
Nowadays the integration of multi-energy carriers is one of the most critical matters in smart energy systems with the aim of meeting sustainable energy development indicators. Hydrogen is referred to as one of the main energy carriers in the future energy industry but its integration into the energy system faces different open challenges which have not yet been comprehensively studied. In this paper a novel day-ahead scheduling is presented to reach the optimal operation of a hydrogen-based energy hub based on a stochastic multi-attribute decision-making approach. In this way the energy hub model is first developed by providing a detailed model of Power-to-Hydrogen (P2H) facilities. Then a new multi-objective problem is given by considering the prosumer’s role in the proposed energy hub model as well as the integrated demand response program (IDRP). The proposed model introduces a comprehensive approach from the analysis of the historical data to the final decision-making with the aim of minimizing the system operation cost and carbon emission. Moreover to deal with system uncertainty the scenario-based method is applied to model the renewable energy resources fluctuation. The proposed problem is defined as mixed-integer non-linear programming (MINLP) and to solve this problem a simple augmented e-constrained (SAUGMECON) method is employed. Finally the simulation of the proposed model is performed on a case study and the obtained results show the effectiveness and benefits of the proposed scheme.
Evaluation of a New Combined Energy System Performance to Produce Electricity and Hydrogen with Energy Storage Option
Mar 2021
Publication
According to new findings the use of alternative energy sources such as wind energy is needed to supply the energy demand of future generations. On the other hand combined renewable energy systems can be more efficient than their stand-alone systems. Therefore clean energy-based hybrid energy systems can be a suitable solution for fossil fuels. However for their widespread commercialization more detailed and powerful studies are needed. On the other hand in order to attain sustainable development for the use of renewable energy sources due to their nature energy storage is required. The motivation of this study is introduce and examine a new energy system performance for the production of electricity and hydrogen fuel as well as energy storage. So this paper presents the energy and exergy operation of a hybrid wind turbine water electrolyzer and Pumped-hydro-compressed air system. The electricity produced by the wind turbine is used to produce hydrogen fuel in electrolyzer and the excess energy is stored using the storage system. It was found that the electrolyzer needed 512.6 W of electricity to generate 5 mol/h of hydrogen fuel which was supplied by a 10 kW-wind turbine. In such a context the efficiency of the process was 74.93%. Furthermore on average the isothermal process requires 17.53% less storage capacity than the isentropic process. The effect of key parameters such as rate of hydrogen fuel production operating pressures wind speed and components efficiency on the process operation is also examined.
Exergy and Exergoeconomic Analysis of Hydrogen and Power Cogeneration Using an HTR Plant
Mar 2021
Publication
This paper proposes using sodium-cooled fast reactor technologies for use in hydrogen vapor methane (SMR) modification. Using three independent energy rings in the Russian BN-600 fast reactor steam is generated in one of the steam-generating cycles with a pressure of 13.1 MPa and a temperature of 505 °C. The reactor's second energy cycles can increase the gas-steam mixture's temperature to the required amount for efficient correction. The 620 ton/hr 540 °C steam generated in this cycle is sufficient to supply a high-temperature synthesis current source (700 °C) which raises the steam-gas mixture's temperature in the reactor. The proposed technology provides a high rate of hydrogen production (approximately 144.5 ton/hr of standard H2) also up to 25% of the original natural gas in line with existing SMR technology for preparing and heating steam and gas mixtures will be saved. Also exergy analysis results show that the plant's efficiency reaches 78.5% using HTR heat for combined hydrogen and power generation.
Ranking Locations for Hydrogen Production Using Hybrid Wind-Solar: A Case Study
Apr 2021
Publication
Observing the growing energy demand of modern societies many countries have recognized energy security as a looming problem and renewable energies as a solution to this issue. Renewable hydrogen production is an excellent method for the storage and transfer of energy generated by intermittent renewable sources such as wind and solar so that they can be used at a place and time of our choosing. In this study the suitability of 15 cities in Fars province Iran for renewable hydrogen production was investigated and compared by the use of multiple multi-criteria decision-making methods including ARAS SAW CODAS and TOPSIS. The obtained rankings were aggregated by rank averaging Borda method and Copeland method. Finally the partially ordered set ranking technique was used to reach a general consensus about the ranking. The criteria that affect hydrogen production were found to be solar energy potential wind energy potential population air temperature natural disasters altitude relative humidity land cost skilled labor infrastructure topographic condition and distance from main roads. These criteria were weighted using the best–worst method (BWM) based on the data collected by a questionnaire. Solar energy potential was estimated using the Angstrom model. Wind energy potential was estimated by using the Weibull distribution function for each month independently. The results of the multi-criteria decision-making methods showed Izadkhast to be the most suitable location for renewable hydrogen production in the studied area.
Modeling of a High Temperature Heat Exchanger to Supply Hydrogen Required by Fuel Cells Through Reforming Process
Sep 2021
Publication
Hydrogen as a clean fuel and a new energy source can be produced by various methods. One of these common and economical methods of hydrogen production is hydrocarbon vapor modification. This research studies hydrogen production using a propane steam reforming process inside a high temperature heat exchanger. The application of this high temperature heat exchanger in the path of the power supply line is a fuel cell stack unit to supply the required hydrogen of the device. The heat exchanger consists of a set of cylindrical tubes housed inside a packed-bed called a reformer. The energy required to perform the reaction is supplied through these tubes in which high temperature gas is injected and the heat exchanger is insulated to prevent energy loss. The results show that at maximum temperature and velocity of hot gases (900 K and 1.5 m s−1 ) complete consumption of propane can be observed before the outlet of the reformer. Also in the mentioned conditions the maximum hydrogen production (above 92%) is obtained. The best permeability under which the system can perform best is 1×10−9 m2.
Modeling of Thermal Performance of a Commercial Alkaline Electrolyzer Supplied with Various Electrical Currents
Nov 2021
Publication
Hydrogen produced by solar and other clean energy sources is an essential alternative to fossil fuels. In this study a commercial alkaline electrolyzer with different cell numbers and electrode areas are simulated for different pressure temperature thermal resistance and electrical current. This alkaline electrolyzer is considered unsteady in simulations and different parameters such as temperature are obtained in terms of time. The obtained results are compared with similar results in the literature and good agreement is observed. Various characteristics of this alkaline electrolyzer as thermoneutral voltage faraday efficiency and cell voltage are calculated and displayed. The outlet heat rate and generated heat rate are obtained as well. The pressure and the temperature in the simulations are between 1 and 100 bar and between 300 and 360 Kelvin respectively. The results show that the equilibrium temperature is reached 2-3 hours after the time when the Alkaline electrolyzer starts to work.
Thermal Management System Architecture for Hydrogen-Powered Propulsion Technologies: Practices, Thematic Clusters, System Architectures, Future Challenges, and Opportunities
Jan 2022
Publication
The thermal management system architectures proposed for hydrogen-powered propulsion technologies are critically reviewed and assessed. The objectives of this paper are to determine the system-level shortcomings and to recognise the remaining challenges and research questions that need to be sorted out in order to enable this disruptive technology to be utilised by propulsion system manufacturers. Initially a scientometrics based co-word analysis is conducted to identify the milestones for the literature review as well as to illustrate the connections between relevant ideas by considering the patterns of co-occurrence of words. Then a historical review of the proposed embodiments and concepts dating back to 1995 is followed. Next feasible thermal management system architectures are classified into three distinct classes and its components are discussed. These architectures are further extended and adapted for the application of hydrogen-powered fuel cells in aviation. This climaxes with the assessment of the available evidence to verify the reasons why no hydrogen-powered propulsion thermal management system architecture has yet been approved for commercial production. Finally the remaining research challenges are identified through a systematic examination of the critical areas in thermal management systems for application to hydrogen-powered air vehicles’ engine cooling. The proposed solutions are discussed from weight cost complexity and impact points of view by a system-level assessment of the critical areas in the field.
A Review on Recent Progress in the Integrated Green Hydrogen Production Processes
Feb 2022
Publication
The thermochemical water‐splitting method is a promising technology for efficiently con verting renewable thermal energy sources into green hydrogen. This technique is primarily based on recirculating an active material capable of experiencing multiple reduction‐oxidation (redox) steps through an integrated cycle to convert water into separate streams of hydrogen and oxygen. The thermochemical cycles are divided into two main categories according to their operating temperatures namely low‐temperature cycles (<1100 °C) and high‐temperature cycles (<1100 °C). The copper chlorine cycle offers relatively higher efficiency and lower costs for hydrogen production among the low‐temperature processes. In contrast the zinc oxide and ferrite cycles show great potential for developing large‐scale high‐temperature cycles. Although several challenges such as energy storage capacity durability cost‐effectiveness etc. should be addressed before scaling up these technologies into commercial plants for hydrogen production. This review critically examines various aspects of the most promising thermochemical water‐splitting cycles with a particular focus on their capabilities to produce green hydrogen with high performance redox pairs stability and the technology maturity and readiness for commercial use.
On the Response of a Lean-premixed Hydrogen Combustor to Acoustic and Dissipative-dispersive Entropy Waves
May 2019
Publication
Combustion of hydrogen or hydrogen containing blends in gas turbines and industrial combustors can activate thermoacoustic combustion instabilities. Convective instabilities are an important and yet less investigated class of combustion instability that are caused by the so called “entropy waves”. As a major shortcoming the partial decay of these convective-diffusive waves in the post-flame region of combustors is still largely unexplored. This paper therefore presents an investigation of the annihilating effects due to hydrodynamics heat transfer and flow stretch upon the nozzle response. The classical compact analysis is first extended to include the decay of entropy waves and heat transfer from the nozzle. Amplitudes and phase shifts of the responding acoustical waves are then calculated for subcritical and supercritical nozzles subject to acoustic and entropic forcing. A relation for the stretch of entropy wave in the nozzle is subsequently developed. It is shown that heat transfer and hydrodynamic decay can impart considerable effects on the entropic response of the nozzle. It is further shown that the flow stretching effects are strongly frequency dependent. The results indicate that dissipation and dispersion of entropy waves can significantly influence their conversion to sound and therefore should be included in the entropy wave models.
New Integrated Process for the Efficient Production of Methanol, Electrical Power, and Heating
Jan 2022
Publication
In this paper a novel process is developed to cogenerate 4741 kg/h of methanol 297.7 kW of electricity and 35.73 ton/h of hot water including a hydrogen purification system an absorption– compression refrigeration cycle (ACRC) a regenerative Organic Rankine Cycle (ORC) and parabolic solar troughs. The heat produced in the methanol reactor is recovered in the ORC and ACRC. Parabolic solar troughs provide thermal power to the methanol distillation tower. Thermal efficiencies of the integrated structure and the liquid methanol production cycle are 78.14% and 60.91% respectively. The process’s total exergy efficiency and irreversibility are 89.45% and 16.89 MW. The solar thermal collectors take the largest share of exergy destruction (34%) followed by heat exchangers (30%) and mixers (19%). Based on the sensitivity analysis D17 (mixture of H2 and low-pressure fuel gas before separation) was the most influential stream affecting the performance of the process. With the temperature decline of stream D17 from −139 to −149 °C the methanol production rate and the total thermal efficiency rose to 4741.2 kg/h and 61.02% respectively. Moreover the growth in the hydrogen content from 55% to 80% molar of the feed gas the flow rate of liquid methanol and the total exergy efficiency declined to 4487 kg/h and 86.05%.
A Novel Exergy-based Assessment on a Multi-production Plant of Power, Heat and Hydrogen: Integration of Solid Oxide Fuel Cell, Solid Oxide Electrolyzer Cell and Rankine Steam Cycle
Feb 2021
Publication
Multi-production plant is an idea highlighting cost- and energy-saving purposes. However just integrating different sub-systems is not desired and the output and performance based on evaluation criteria must be assessed. In this study an integrated energy conversion system composed of solid oxide fuel cell (SOFC) solid oxide electrolyzer cell (SOEC) and Rankine steam cycle is proposed to develop a multi-production system of power heat and hydrogen to alleviate energy dissipation and to preserve the environment by utilizing and extracting the most possible products from the available energy source. With this regard natural gas and water are used to drive the SOEC and the Rankine steam cycle respectively. The required heat and power demand of the electrolyzer are designed to be provided by the fuel cell and the Rankine cycle. The feasibility of the designed integrated system is evaluated through comprehensive exergy-based analysis. The technical performance of the system is evaluated through exergy assessment and it is obtained that the SOFC and the SOEC can achieve to the high exergy efficiency of 84.8% and 63.7% respectively. The designed system provides 1.79 kg/h of hydrogen at 125 kPa. In addition the effective designed variables on the performance of the designed integrated system are monitored to optimize the system’s performance in terms of technical efficiency cost-effectivity and environmental considerations. This assessment shows that 59.4 kW of the available exergy is destructed in the combustion chamber. Besides the techno-economic analysis and exergoenvironmental assessment demonstrate the selected compressors should be re-designed to improve the cost-effectivity and decline the negative environmental impact of the designed integrated energy conversion system. In addition it is calculated that the SOEC has the highest total cost and also the highest negative impact on the environment compared to other designed units in the proposed integrated energy conversion system.
An Investigation into the Volumetric Flow Rate Requirement of Hydrogen Transportation in Existing Natural Gas Pipelines and Its Safety Implications
Oct 2021
Publication
As an alternative to the construction of new infrastructure repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that a 342 km 3600 natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the proportions of hydrogen and natural gas in the blends changed signifying disparate flow behaviours and consequent varying flow challenges. The velocity profiles showed that hydrogen can be transported in natural gas pipelines via blending with natural gas by up to 40% of hydrogen in the blend without exceeding the erosional velocity limits of the pipeline. However when the proportion of hydrogen reached 60% the erosional velocity limit was reached at 290 km so that beyond this distance the pipeline would be subject to internal erosion. The use of compressor stations was shown to be effective in remedying this challenge. This study provides more insights into the volumetric and safety considerations of adopting existing natural gas pipelines for the transportation of hydrogen and blends of hydrogen and natural gas.
Comprehensive Study on Hydrogen Production via Propane Steam Reforming Inside a Reactor
Feb 2021
Publication
In the proton exchange membrane fuel cells the required hydrogen must be produced in some way. The power generators in the path of these fuel cells generally include a steam reactor that through other fuels provides the needed energy to produce hydrogen. This study investigates a steam reactor powered by propane fuel consisting of a shell and tube heat exchanger. The shell contains a catalyst that receives the mixture of propane and steam and the tubes embedded inside the reformer contain hot gases that provide a suitable substrate for the reaction. Velocity and temperature fields inside the reformer species concentration control and reaction rate are studied. The conversion of reactants and yield of products are investigated according to the reaction rate. The results show that the hydrogen production yield can vary from 77.5 % to 92.2 %. The reaction rate can be controlled by the velocity and temperatures of the hot gases. However for the T=900 K full propane consumption is achieved at the reformer outlet.
Improving Hydrogen Production Using Co-cultivation of Bacteria with Chlamydomonas Reinhardtii Microalga
Sep 2018
Publication
Hydrogen production by microalgae is a promising technology to achieve sustainable and clean energy. Among various photosynthetic microalgae able to produce hydrogen Chlamydomonas reinhardtii is a model organism widely used to study hydrogen production. Oxygen produced by photosynthesis activity of microalgae has an inhibitory effect on both expression and activity of hydrogenases which are responsible for hydrogen production. Chlamydomonas can reach anoxia and produce hydrogen at low light intensity. Here the effect of bacteria co-cultivation on hydrogen produced by Chlamydomonas at low light intensity was studied. Results indicated that however co-culturing Escherichia coli Pseudomonas stutzeri and Pseudomonas putida reduced the growth of Chlamydomonas it enhanced hydrogen production up to 24% 46% and 32% respectively due to higher respiration rate in the bioreactors at low light intensity. Chlamydomonas could grow properly in presence of an unknown bacterial consortium and hydrogen evolution improved up to 56% in these co-cultures.
A Thorough Economic Evaluation by Implementing Solar/Wind Energies for Hydrogen Production: A Case Study
Jan 2022
Publication
A technical–economic assessment was carried out in this study to determine the possibilities for wind and solar power generation in Afghanistan’s Helmand province. The results showed that most of the province has a solar irradiance of over 400 W/m2 and also showed that wind and solar power generated in the province can be up to twice as cheap as the official price of renewable power in Afghanistan. The most suitable site for solar and hydrogen production was found to be Laškar Gah where solar and hydrogen can be produced at a cost of 0.066 $/kWh and 2.1496 $/kg-H ¯ 2 respectively. In terms of wind power production and hydrogen production from wind the most suitable site was Sang¯ın where wind power and hydrogen could be produced at costs of 0.057 $/kWh and 1.4527 $/kg-H2 respectively. Despite the high potential of wind and solar energy in the Helmand province the most suitable place in this region to produce hydrogen from wind/solar energy was evaluated from technical economic and environmental perspectives with the Multi-Criteria DecisionMaking (MCDM) method. The Stepwise Weight Assessment Ratio Analysis (SWARA) method was used for weighting criteria and the Weighted Aggregated Sum Product Assessment (WASPAS) method was used to prioritize locations. The results show that Sang¯ın is the most suitable place for the construction of a wind hydrogen power plant and Laškar Gah is the most suitable place for the ¯ construction of a solar hydrogen power plant.
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