Recent developments in fuel‐processing and proton‐exchange membranes for fuel cells

In recent years, great progress has been made in the development of proton‐exchange membrane fuel cells (PEMFCs) for both mobile and stationary applications. This review covers two types of new membranes: (1) carbon dioxide‐selective membranes for hydrogen purification and (2) proton‐exchange membranes; both of these are crucial to the widespread application of PEMFCs. On hydrogen purification for fuel cells, the new facilitated transport membranes synthesized from incorporating amino groups in polymer networks have shown high CO₂ permeability and selectivity versus H₂. The membranes can be used in fuel processing to produce high‐purity hydrogen (with less than 10 ppm CO and 10 ppb H₂S) for fuel cells. On proton‐exchange membranes, the new sulfonated polybenzimidazole copolymer‐based membranes can outperform Nafion^® under various conditions, particularly at high temperatures and low relative humidities. Copyright © 2010 Society of Chemical Industry     

氢气中杂质对车用燃料电池性能影响的研究进展

车用质子交换膜燃料电池（proton exchange membrane fuel cells,PEMFCs）的耐久性是制约氢能在交通领域商业化应用的关键因素之一。阳极燃料气中含有的微量H₂S、CO和NH₃等杂质是影响PEMFCs耐久性的最主要因素之一。本文综述了PEMFCs阳极氢气中存在的三种关键杂质,即H₂S、CO和NH₃对PEMFCs阳极性能影响的研究进展,包括杂质毒化机制、动力学、燃料电池操作条件影响以及缓解策略,讨论了氢气杂质容限值规定的理论和实验基础。最后,指出了目前氢气杂质对车用PEMFCs影响研究存在的技术问题及未来发展方向,重点指出了根据我国PEMFCs技术发展水平精准推定满足我国车用燃料电池耐久性的氢气杂质容限值的必要性和紧迫性,从而为优化和完善我国车用燃料电池用氢质量标准提供基础数据,促进车用燃料电池寿命的提升。     

Modification of absorbent poly(glycerol‐glutaric acid) films by the addition of monoglycerides

Monoglycerides (MGs) have been incorporated into the matrix of poly(glycerol‐co‐glutaric acid) films to investigate their effect on the thermal, mechanical, and solvent absorption properties of the resultant films. Solvent absorption studies revealed that poly(glycerol‐co‐glutaric acid‐co‐MG) films were able to absorb and resorb solvents better than poly(glycerol‐co‐glutaric acid) films, albeit they had higher erosion levels. Thermogravimetric analysis showed that the incorporated MGs did not affect the thermal stability of the glycerol‐based films. The MG‐incorporated films were observed to be much softer than the poly(glycerol‐co‐glycerol) films which was further proven by a 39‐fold reduction in Young's Modulus and 17‐fold reduction in fracture energy when compared to the poly(glycerol‐co‐glycerol). Mechanical property studies also revealed that the incorporation of MGs increased the elongation % and reduced the tensile strength of poly(glycerol‐co‐glutaric acid) films. Correlation analysis revealed a strong linear relationship between Young's Modulus and fracture energy (R² = 0.9962), and between Young's Modulus and tensile strength (R² = 0.9972). Our study proved that MGs can be successfully incorporated in the polymer matrix of poly(glycerol‐co‐glutaric acid) films to produce softer films with increased elongation and increased solvent absorption capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45381.     

煤化工装置燃料气系统优化探讨

根据燃料气系统运行现状,提出了两个燃料气系统优化方案,以解决目前燃料气系统无法完全满足下游生产装置需要、排放量过大的问题,达到减少燃料气排放、提高能源利用率、降低企业运行成本的目的。并对两个优化方案进行物料衡算和经济效益核算,分别验证两个方案的可行性和经济性。通过对比两种方案,得出方案一（对现有燃料气管网进行改造,将含烯烃、甲醇较多的燃料气单独送至动力装置,并对现有PSA氢回收装置进行扩能改造,使回收气量达23778.4m3/h）优于方案二（维持PSA氢回收装置目前运行状态,增加一套尾气回收装置回收甲醇弛放气中的CO、H2,使燃料气系统达到物料平衡）。方案一具有可行性高、投资小、操作维护方便、经济效益高的优点,是两种优化方案中的最佳选择。     

Targeting climate-neutral hydrogen production: Integrating brown and blue pathways with green hydrogen infrastructure via a novel superstructure and simulation-based life cycle optimization

This article addresses the sustainable design of hydrogen (H₂) production systems that integrate brown and blue pathways with green hydrogen infrastructure. We develop a systematic framework to simultaneously optimize the process superstructure and operating conditions of steam methane reforming (SMR)-based hydrogen production systems. A comprehensive superstructure that integrates SMR with multiple carbon dioxide capture technologies, electrolyzers, fuel cells, and working fluids in the organic rankine cycle is proposed under varying operating conditions. A life cycle optimization model is then developed by integrating superstructure optimization, life cycle assessment approach, techno-economic assessment, and process optimization using extensive process simulation models and formulated as a mixed-integer nonlinear program. We find that the optimal unit-levelized cost of hydrogen ranges from $1.49 to $3.18 per kg H₂. Moreover, the most environmentally friendly process attains net-zero life cycle greenhouse gas emissions compared to 10.55 kg CO₂-eq per kg H₂ for the most economically competitive process design.     

Application of Gas Permeation in Fuel Cell Powered Vehicles

Main motivation for the use of a polymer electrolyte membrane fuel cell (PEMFC) in traffic applications is its significant higher vehicle efficiency compared to internal combustion engines (ICE) especially under low‐load operation. Hydrogen is the ideal fuel for PEMFCs as it yields the highest level of fuel cell performance. Three different applications for gas permeation inside a fuel cell system have been investigated: water recovery, hydrogen purification, and oxygen enrichment. The focus was on the analysis of the technical feasibility and the availability of capable membranes on the pilot‐scale size for each application.     

Impact of Fuel Cell Power Plants on Multi‐objective Optimal Operation Management of Distribution Network

This paper presents an interactive fuzzy satisfying method based on hybrid modified honey bee mating optimization and differential evolution (MHBMO‐DE) to solve the multi‐objective optimal operation management (MOOM) problem, which can be affected by fuel cell power plants (FCPPs). The objective functions are to minimize total electrical energy losses, total electrical energy cost, total pollutant emission produced by sources, and deviation of bus voltages. A new interactive fuzzy satisfying method is presented to solve the multi‐objective problem by assuming that the decision‐maker (DM) has fuzzy goals for each of the objective functions. Through the interaction with the DM, the fuzzy goals of the DM are quantified by eliciting the corresponding membership functions. Then, by considering the current solution, the DM acts on this solution by updating the reference membership values until the satisfying solution for the DM can be obtained. The MOOM problem is modeled as a mixed integer nonlinear programming problem. Evolutionary methods are used to solve this problem because of their independence from type of the objective function and constraints. Recently researchers have presented a new evolutionary method called honey bee mating optimization (HBMO) algorithm. Original HBMO often converges to local optima, in order to overcome this shortcoming, we propose a new method that improves the mating process and also, combines the modified HBMO with DE algorithm. Numerical results for a distribution test system have been presented to illustrate the performance and applicability of the proposed method.     

pH sensitive interpenetrating network microgels of sodium alginate‐acrylic acid for the controlled release of ibuprofen

pH‐Sensitive interpenetrating network (IPN) microgels (MGs) of sodium alginate (NaAlg) and acrylic acid have been prepared by using water‐in‐oil (W/O) emulsion technique. The MGs were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X‐ray diffractometer (X‐RD). The release of ibuprofen (IB), an anti‐inflammatory drug, from these MGs was studied in pH 1.2 and 7.4 media. MG network consists of NaAlg, which disintegrates in the intestinal fluid, while poly(acrylic acid) provides pH‐sensitivity to the microgel network. The system developed in this study showed a pH‐sensitivity for the release of IB, which was attributed to the diffusion controlled release of the drug through the surfaces of MGs that undergo disintegration after swelling, depending upon the chemical composition of MGs and pH of the medium. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

集成轻烃回收单元代理模型的氢气网络多目标优化

当前炼油企业氢气需求持续增长,导致炼厂成本及生产过程温室气体排放增加,炼油企业通过增设轻烃回收单元对氢气和轻烃组分进行回收利用,能有效缓解这一现状。因此,在氢气网络优化中有必要考虑轻烃回收单元。本研究提出了一种集成轻烃回收单元的氢气网络多目标数学规划模型,对轻烃回收单元采用代理模型建模方法,解决了直接嵌入严格机理模型可能导致的高计算成本问题,以总年度费用最小为优化目标,同时将系统的环境影响也纳入优化目标。实例计算表明,所提出的方法能够有效降低氢气网络的年度费用及温室气体排放,并揭示了集成轻烃回收单元的氢气网络经济性能与环境影响之间的权衡关系,为工业应用提供了一定的理论基础。     

Life cycle assessment of ISPRA Mark 9 thermochemical cycle for nuclear hydrogen production

The nuclear energy driven thermochemical cycle is one of the potential water‐splitting processes for producing hydrogen, presumed to be the transportation fuel of the future. A life cycle assessment (LCA) of one such system, which utilizes nuclear energy to drive the ISPRA Mark 9 thermochemical cycle, is presented in this paper. The results of the LCA are presented in terms of the emissions of greenhouse gases (CO₂‐equivalent) and acid gases (SO₂‐equivalent). The contributions of the thermochemical plant to the emissions were determined through the estimation of material and energy requirements for chemical inventory, raw materials consumption and plant fabrication/installation. The greenhouse gas emissions from the system are 2515 g CO₂‐equivalent kg^?1 H₂ produced and acid gas emissions 11.252 g SO₂‐equivalent kg^?1 H₂ produced. A comparison of this hydrogen production route with other routes, including steam reforming of methane and high‐temperature electrolysis, is also presented in the paper. Copyright © 2006 Society of Chemical Industry     

Exergetic,economic and environmental analyses and multi-objective optimization of an SOFC-gas turbine hybrid cycle coupled with an MSF desalination system

The present study presents thermodynamic, economic and environmental (emissions cost) modeling of a solid oxide fuel cell–gas turbine (SOFC–GT) hybrid system integrated with a multi stage flash (MSF) desalination unit. A heuristic optimization method, namely, multi-objective genetic algorithm (MOGA) is employed afterwards to obtain the optimal design parameters of the plant. The exergetic efficiency and the total cost rate of the system are considered as the objective functions of the optimization procedure; where, the total cost rate of the system (including the cost rate of environmental impact) is minimized while the exergetic efficiency is maximized. Applying the optimization method, a set of optimal solutions is achieved and the final selected optimal design leads to an exergetic efficiency of 46.7%, and a total cost of 3.76 million USD/year. The payback time of the selected design is also determined to be about 9 years. Although the determined value for the payback period seems to be relatively high for the proposed plant (due to the high capital cost of the SOFC system), this integrated technology is expected to be promising in the near future as the capital costs of SOFCs are decreasing and their operational lifetimes are increasing.     

Novel Natural Gas to Liquids Processes: Process Synthesis and Global Optimization Strategies

An optimization‐based process synthesis framework is proposed for the conversion of natural gas to liquid transportation fuels. Natural gas conversion technologies including steam reforming, autothermal reforming, partial oxidation to methanol, and oxidative coupling to olefins are compared to determine the most economic processing pathway. Hydrocarbons are produced from Fischer–Tropsch (FT) conversion of syngas, ZSM‐5 catalytic conversion of methanol, or direct natural gas conversion. Multiple FT units with different temperatures, catalyst types, and hydrocarbon effluent compositions are investigated. Gasoline, diesel, and kerosene are generated through upgrading units involving carbon‐number fractionation or ZSM‐5 catalytic conversion. A powerful deterministic global optimization method is introduced to solve the mixed‐integer nonlinear optimization model that includes simultaneous heat, power, and water integration. Twenty‐four case studies are analyzed to determine the effect of refinery capacity, liquid fuel composition, and natural gas conversion technology on the overall system cost, the process material/energy balances, and the life cycle greenhouse gas emissions. © 2013 American Institute of Chemical Engineers AIChE J, 59: 505–531, 2013     

Magnetic Resonance Imaging of Water in Operating Polymer Electrolyte Membrane Fuel Cells

Water management in polymer electrolyte membrane fuel cells (PEMFCs) is extremely important for the high performance and durable operation of fuel cells. Therefore, fundamental understanding of water transport involved in operating PEMFCs is necessary. This article presents a review of in situ magnetic resonance imaging (MRI) visualisation of water in operating PEMFCs, which is recognised as a powerful diagnostic tool for probing water behaviours, both in flow fields and in the membrane electrode assembly (MEA). The basic principles and hardware related to MRI visualisation are described with emphasis on the design, construction and material selection of a PEMFC for MRI experiments. The MRI results reported by several groups are outlined to illustrate the versatility and potential usefulness of in situ visualisation of water in operating PEMFCs using MRI.     

Synthesis of polyacrylonitrile/polystyrene latex particles that contain platinum

Studies on the incorporation of highly dispersed platinum (Pt) nanoparticles into proton‐exchange membrane fuel cells (PEMFC) as a possible catalyst have gained tremendous attention in the past decade. The major obstacle to fully commercialize PEMFCs is the high cost of Pt as the catalyst. In this study, the incorporation of highly dispersed platinum molecules into poly(acrylonitrile) (PAN) or polystyrene (PS)/PAN latex particles was carried out to form a possible a catalyst precursor for fuel‐cell applications. Pt‐containing PAN/PS particles were prepared using miniemulsion polymerization. Both transmission electron microscopy (TEM) and induction coupled plasma (ICP) measurements indicated that Pt salt was encapsulated into PAN/PS copolymer latex particles. In addition, the encapsulation percentages of Pt salt are all above 90% for different PAN/PS ratios. Additional experiments have been carried out to convert these Pt molecules into nanoparticles and will be elaborated upon subsequent studies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41933     

Integration strategies of hydrogen network in a refinery based on operational optimization of hydrotreating units

Inferior crude oil and fuel oil upgrading lead to escalating increase of hydrogen consumption in refineries. It is imperative to reduce the hydrogen consumption for energy-saving operations of refineries. An integration strategy of hydrogen network and an operational optimization model of hydrotreating (HDT) units are proposed based on the characteristics of reaction kinetics of HDT units. By solving the proposed model, the operating conditions of HDT units are optimized, and the parameters of hydrogen sinks are determined by coupling hydrodesulfurization (HDS), hydrodenitrification (HDN) and aromatic hydrogenation (HDA) kinetics. An example case of a refinery with annual processing capacity of eight million tons is adopted to demonstrate the feasibility of the proposed optimization strategies and the model. Results show that HDS, HDN and HDA reactions are the major source of hydrogen consumption in the refinery. The total hydrogen consumption can be reduced by 18.9% by applying conventional hydrogen network optimization model. When the hydrogen network is optimized after the operational optimization of HDT units is performed, the hydrogen consumption is reduced by 28.2%. When the benefit of the fuel gas recovery is further considered, the total annual cost of hydrogen network can be reduced by 3.21×10₇ CNY·a_-1, decreased by 11.9%. Therefore, the operational optimization of the HDT units in refineries should be imposed to determine the parameters of hydrogen sinks base on the characteristics of reaction kinetics of the hydrogenation processes before the optimization of the hydrogen network is performed through the source-sink matching methods.     

Equation‐oriented flowsheet simulation and optimization using pseudo‐transient models

Tight integration through material and energy recycling is essential to the energy efficiency and economic viability of process and energy systems. Equation‐oriented (EO) steady‐state process simulation and optimization are key enablers in the optimal design of integrated processes. A new process modeling and simulation concept based on pseudo‐transient continuation is introduced. An algorithm for reformulating the steady‐state models of process unit operations as differential‐algebraic equation systems that are statically equivalent with the original model is presented. These pseudo‐transient models improve the convergence of EO process flowsheet simulations by expanding the convergence basin. This concept is used to build a library of pseudo‐transient models for common process unit operations, and this modeling concept seamlessly integrates with a previously developed time‐relaxation optimization algorithm. Two design case studies are presented to validate the proposed framework. © 2014 American Institute of Chemical Engineers AIChE J 60: 4104–4123, 2014     

Nafion‐115/aromatic poly(etherimide) with isopropylidene groups/imidazole membranes for polymer fuel cells

Proton exchange membrane fuel cells (PEMFCs) with Pt/C gas diffusion electrodes and graphite single‐serpentine monopolar plates were constructed based on an aromatic poly(etherimide) with isopropylidene groups (PI)/imidazole (Im) and a popular Nafion‐115 matrix. The electrochemical properties of PEMFCs were tested at 25 and 60°C. The maximum power density of 171 mW/cm² and the maximum current density of 484 mA/cm² were detected for Nafion‐115/PI membrane. For both constructed PEMFCs the efficiency at 0.6 V was found about 41%. Immersion of Nafion‐115 in PI or PI/Im increased the thermal stability and mechanical properties of membranes. Thermal, mechanical properties and morphology of membranes were characterized by TGA, and AFM techniques including force spectroscopy. Interactions between the components in composite membranes were established by FT‐IR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42436.     

Behavioral and Electrophysiological Responses of <Emphasis Type="BoldItalic">Triatoma brasiliensis</Emphasis> Males to Volatiles Produced in the Metasternal Glands of Females

In many insects, mate finding is mediated by volatile sex pheromones, but evidence for this phenomenon in triatomines (Heteroptera: Reduviidae) is still fragmentary. Recently, it was shown that metasternal glands (MGs) are involved in producing signals related to the sexual communication of Triatoma infestans and Rhodnius prolixus. Based on this, we tested whether MG volatiles could be involved in the sexual communication of Triatoma brasiliensis. Odor-mediated orientation responses were studied by using a T-tube olfactometer. These tests showed that males exhibit positive anemotaxis when confronted with adult odor-laden air currents. Moreover, females that had their metasternal glands occluded did not elicit significant orientation by males. Compounds produced by the MGs of T. brasiliensis females were identified by means of SPME, GC-FID, and GC-MS, with achiral and chiral columns. All substances identified were ketones and alcohols, and similar compound profiles were found in the secretions produced by both sexes. The most abundant compounds identified were 3-pentanone, followed by (4R)-methyl-1-heptanol, 3-pentanol, and (2S)-methyl-1-butanol. In addition, GC-EAD recordings showed that the antennae of males responded to several of the main components of female MG secretions. Our results showed that compounds produced by the MGs of T. brasiliensis females are involved in the sexual communication of this species.     

Optimization of a High Temperature PEMFC micro‐CHP System by Formulation and Application of a Process Integration Methodology

A 1 kWe micro combined heat and power (CHP) system based on high temperature proton exchange membrane fuel cell (PEMFC) technology is modeled and optimized by formulation and application of a process integration methodology. The system can provide heat and electricity for a single‐family household. It consists of a fuel cell stack, a fuel processing subsystem, heat exchangers, and balance‐of‐plant components. The optimization methodology involves system optimization attempting to maximize the net electrical efficiency, and then by use of a mixed integer nonlinear programming (MINLP) problem formulation, the heat exchange network (HEN) annual cost is minimized. The results show the high potential of the proposed model since high efficiencies are accomplished. The net electrical efficiency and total system efficiency, based on lower heating value (LHV), are 35.2% and 91.1%, respectively. The minimized total annual cost of the HEN is $8,147 year^–1.     

Conceptual design of ammonia‐based energy storage system: System design and time‐invariant performance

Chemicals‐based energy storage is promising for integrating intermittent renewables on the utility scale. High round‐trip efficiency, low cost, and considerable flexibility are desirable. To this end, an ammonia‐based energy storage system is proposed. It utilizes a pressurized reversible solid‐oxide fuel cell for power conversion, coupled with external ammonia synthesis and decomposition processes and a steam power cycle. A coupled refrigeration cycle is utilized to recycle nitrogen completely. Pure oxygen, produced as a side‐product in electrochemical water splitting, is used to drive the fuel cell. A first‐principle process model extended by detailed cost calculation is used for process optimization. In this work, the performance of a 100 MW system under time‐invariant operation is studied. The system can achieve a round‐trip efficiency as high as 72%. The lowest levelized cost of delivered energy is obtained at 0.24 $/kWh, which is comparable to that of pumped hydro and compressed air energy storage systems. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1620–1637, 2017