High-calorific bio-hydrogen production under self-generated high-pressure condition

Lee, Mo-Kwon,Sivagurunathan, Periyasamy,Yun, Yeo-Myeong,Kang, Seoktae,Na, Jeong-Geol,Kim, Dong-Hoon Elsevier 2018 Bioresource technology Vol.264 No.-

<P><B>Abstract</B></P> <P>For the use of biologically produced H<SUB>2</SUB>, removal of CO<SUB>2</SUB> is an indispensable process. Unlike conventional CO<SUB>2</SUB> removal methods, this study proposed a self-generated high-pressure dark fermentation (HPDF) process as a novel strategy for directly producing high-calorific bio-H<SUB>2</SUB>. The pressure was automatically increased by self-generated gas, while the maximum pressure inside fermenter was restricted to 1, 3, 5, 7, and 10 bar in a batch operation. As the pressure increased from 1 to 10 bar, the H<SUB>2</SUB> content increased from 55% to 80%, whereas the H<SUB>2</SUB> yield decreased from 1.5 to 0.9 mol H<SUB>2</SUB>/mol hexose<SUB>added</SUB>. The highest H<SUB>2</SUB> content of 80% was obtained at both of 7 and 10 bars. Increased lactate production with increased abundance of lactic acid bacteria was observed at high-pressure. Despite the lower H<SUB>2</SUB> yields at high-pressure conditions, HPDF was found to be economically beneficial for obtaining high-calorific bio-H<SUB>2</SUB> owing to the low CO<SUB>2</SUB> removal cost.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel approach for bio-H<SUB>2</SUB> upgrading under high-pressure dark fermentation. </LI> <LI> High H<SUB>2</SUB> content up to 80% was achieved at 7 and 10 bar. </LI> <LI> H<SUB>2</SUB> yield was decreased as pressure increased. </LI> <LI> Increased abundance of lactate producers but decreased abundance of <I>Clostridium</I> sp. </LI> <LI> The benefit for obtaining high-calorific bio-H<SUB>2</SUB> was increased by high-pressure. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Materials Safety for High-Pressure Hydrogen Storage for Fuel Cell Vehicles

Toshio Ogata,Kiyoshi Yokogawa 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

Current situation of fuel cell vehicles (FCVs) and their infrastructure is described. High-pressure hydrogen storage at 70 MPa is developed for FCVs, thus the drafts of the standard for the compressed hydrogen storage system on board has been proposed by SAE and discussed worldwide. The high-pressure equipments for hydrogen stations and the pipelines of the infrastructure of FCVs are controlled by the governmental rule, and then ASME has been discussing and/or has proposed the codes for the hydrogen stations and the pipelines. The materials testing equipments in high-pressure hydrogen to evaluate hydrogen embrittlement (HE) in gaseous hydrogen (hydrogen gas embrittlement (HGE)) in the world are introduced. HGE behaviors of the metals are classified into four categories with HGE characteristics in the AIST HGE data. HE behavior in nano-scale is described by nano-indentation and analyzed by the theoretical calculation. The materials safety, in particular for HGE, is essentially important for the standards or codes for public safety.

고압 수소 가스 하 인장 시험을 이용한 두 오스테나이트계 고망간강의 수소취화 특성 평가

이승용,백운봉,남승훈,황병철,Lee, Seung-Yong,Baek, Un-Bong,Nam, Seung Hoon,Hwang, Byoungchul 한국재료학회 2016 한국재료학회지 Vol.26 No.7

The hydrogen embrittlement of two austenitic high-manganese steels was investigated using tensile testing under high-pressure gaseous hydrogen. The test results were compared with those of different kinds of austenitic alloys containing Ni, Mn, and N in terms of stress and ductility. It was found that the ultimate tensile stress and ductility were more remarkably decreased under high-pressure gaseous hydrogen than under high-pressure gaseous argon, unlike the yield stress. In the specimens tested under high-pressure gaseous hydrogen, transgranular fractures were usually observed together with intergranular cracking near the fracture surface, whereas in those samples tested under high-pressure gaseous argon, ductile fractures mostly occurred. The austenitic high-manganese steels showed a relatively lower resistance to hydrogen embrittlement than did those with larger amounts of Ni because the formation of deformation twins or microbands in austenitic high-manganese steels probably promoted planar slip, which is associated with localized deformation due to gaseous hydrogen.

고압 충전 시 수소 저장 탱크의 온도 변화 및 충전량에 관한 해석

이길강,이길초,명노석,박경우,장선준,권정태 한국수소및신에너지학회 2021 한국수소 및 신에너지학회논문집 Vol.32 No.3

Securing energy sources is a key element essential to economic and industrial development in modern society, and research on renewable energy and hydrogen energy is now actively carried out. This research was conducted through experiments and analytical methods on the hydrogen filling process in the hydrogen storage tank of the hydrogen charging station. When low-temperature, high-pressure hydrogen was injected into a high-pressure tanks where hydrogen is charged, the theoretical method was used to analyze the changes in temperature and pressure inside the high-pressure tanks, the amount of hydrogen charge, and the charging time. The analysis was conducted in the initial vacuum state, called the First Cycle, and when the residual pressure was present inside the tanks, called the Second Cycle. As a result of the analysis, the highest temperature inside the tanks in the First Cycle of the high-pressure tank increased to 442.11 K, the temperature measured through the experiment was 441.77 K, the Second Cycle increased to 397.12 K, and the temperature measured through the experiment was 398 K. The results obtained through experimentation and analysis differ within ±1%. The results of this study will be useful for future hydrogen energy research and hydrogen charging station.

전기화학적 및 고압 수소 분위기하 템퍼드 마르텐사이트강의 수소취화 특성 비교

Sang-Gyu Kim,Jae-Yun Kim,Hyun-Joo Seo,Hwan-Gyo Jung,Jaeyoung Park,Un-Bong Baek,황병철 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.11

The effect of hydrogen charging methods on the hydrogen embrittlement characteristics of tempered martensitic steels were discussed in terms of hydrogen diffusion behavior. Two tempered martensitic steels with different Si content were fabricated by quenching and tempering. The steel with high Si content had a lower cementite fraction because the addition of Si changed the morphology of cementite from a long film-like shape to a short-rod shape by suppressing the precipitation and growth of the cementite. To evaluate the hydrogen embrittlement resistance of the two tempered martensitic steels with different Si content, slow strain-rate tensile testing was employed after introducing hydrogen using three types of hydrogen charging methods (ex-situ electrochemical hydrogen charging, in-situ electrochemical hydrogen charging, and in-situ high-pressure gaseous hydrogen environment). For the hydrogen pre-charged tensile specimens using the ex-situ electrochemical charging method, the steel with high Si content had a better hydrogen embrittlement resistance, with a higher relative reduction in area. On the other hand, there was no significant difference in the relative notch tensile strength of the two tempered martensitic steels with different Si content, regardless of the hydrogen charging methods. In addition, the ex-situ hydrogen charging method exhibited higher relative notch tensile strength compared to the in-situ hydrogen charging method due to the release of hydrogen during the tensile test, after exsitu hydrogen charging. This implies that hydrogen embrittlement resistance can be differently estimated depending on the kind of hydrogen charging methods.

Composite Layer Design Using Classical Laminate Theory for High Pressure Hydrogen Vessel (Type 4)

Gunyoung Park,Chul Kim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4

As air pollution becomes more severe, the use of clean energy in vehicles is an inevitable requirement and it is leading the development of automotive industries. Especially, hydrogen-fueled vehicles require safe and lightweight high pressure storage vessels to carry enough amounts of hydrogen gas. To develop mechanically robust and lightweight high pressure vessel, it is of significance to establish design and manufacturing process for liners and carbon fiber reinforced plastics layers. In this study, to design a composite layer in a high pressure hydrogen vessel (Type 4), a calculation method of stress generated in each ply by applying the CLT (Classical Laminate Theory) is proposed. And based on the calculation method, we carried out the composite layer design in the hydrogen high pressure vessel (Type 4) that can satisfy the requirement for lightweightness and designed the thickness and the pattern of the composite layer with more accuracy than the netting theory and with more rapid than FEA.

50 MPa급 대용량 수소압축기 사이클 해석

송병희,명노석,장선준,권정태 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.2

In the hydrogen compression cycle, which is currently being developed, hydrogen is compressed to a very high pressure using a compressor, and then stored and used in a high-pressure vessel. This shows that an increase in the temperature of hydrogen in the vessel due to a pressure rise during the filling process and the pressure fatigue due to the repeated cycle may cause problems in the reliability of the vessel. In this paper, for the entire processes in a 50 MPa hydrogen compression system, theoretical and numerical methods were conducted to analyze the following: the temperature increase of hydrogen in the vessel and the time required to reach thermal equilibrium with the surroundings, the change in temperature of hydrogen passing through the pressure reducing valve, and the required capacity of the heat exchanger for cooling the vessel. The results will be useful for the design and construction of hydrogen compression systems, such as hydrogen charging stations. 현재 개발되고 있는 수소 압축 사이클에서는 압축기를 통해 초고압으로 압축된 수소를 고압용기 내에 저장하여 사용한다. 이러한 충전과정 중 용기내의 수소의 압력 및 온도 상승으로 인하여 고압용기에서 열응력이 발생할 수 있다. 고압용기의 신뢰성을 확보하기 위해서는 용기내의 수소의 온도를 예측하고 제어하는 것이 중요하다. 본 논문에서는 이러한 고압용기의 신뢰성 해석을 위하여 50 MPa급 수소압축시스템에서 고압용기를 충전하는 과정에서의 압력상승에 따른 용기 내의 수소온도 변화 및 외부와의 열평형까지 걸리는 시간, 감압밸브를 지날 때의 수소온도 변화, 고압용기 냉각을 위한 열교환기의 요구능력 등에 대하여 이론적인 방법과 수치적인 방법으로 해석을 수행하였다. 이론해석 결과, 고압용기의 내부 온도는 충전하기 전에 40 ℃에서 충전 후 1st cycle, 2nd cycle에서 평균적으로 126.675 ℃, 62.1 ℃가 증가하였다. 또한, 고압용기의 충전량은 1st cycle, 2nd cycle에서 각각 7.9 kg, 8.9 kg으로 계산되었다. 본 연구의 결과는 수소충전소와 같이 수소압축시스템이 필요한 현장의 인프라 설계 및 구축 등에 유용하게 활용 될 것이다.

고압수소용 레귤레이터 시스템 모델링

안지윤(Ji Yun An),안중환(Jung Hwan Ahn),김화영(Hwa Young Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

As the modern hydrogen industry develops, storage vessels require high capacity and stability. In general, high-pressure hydrogen gas is used to increase storage properties. However, in the case of this high-pressure hydrogen, it is necessary to reduce the pressure to match the pressure used in the product. Therefore, a pressure reduction process using a regulator is required, and the regulator must always maintain a constant flow rate and pressure even if a change in inlet pressure changes. Therefore, due to the characteristics of the regulator in which the outlet flow rate and pressure must be constant, a robust design must be made. In this study, the design variables of the regulator were defined, the control volume and the piston behavior were obtained, and the outlet pressure and flow rate were simulated through system modeling and compared through experiments.

A Study on the Hydrogen Economic Law for the Realization of Hydrogen Society in Korea

김민철,윤순욱,김현민 숭실대학교 법학연구소 2020 法學論叢 Vol.46 No.-

The South Korean government aims for a hydrogen economy society focusing on hydrogen-powered cars and fuel cells. The purpose of this study is to provide directions for better legislation to support the hydrogen economy roadmap. South Korea's hydrogen industry, which has strengths in hydrogen car and fuel cell technology, draws the attention of the world. Korean legislative trends are also important to other countries for international cooperation, including export, investment, and joint research of related industrial groups. A roadmap to revitalize the hydrogen economy was announced in January 2019. The Act on the Hydrogen Economy, the Act on the Promotion of Hydrogen Industries, and the Act on the Safety of Hydrogen are all pending in the National Assembly. It was difficult to take a systematic response because projects for hydrogen car supply and charging infrastructure were distributed among several agencies. The purpose of legislation is desirable for a systematic response to the hydrogen economy society by enacting the Integrated Hydrogen Economic Act. The Korean government includes hydrogen in the category of climate change technologies. Therefore, the Act on Development of Hydrogen Industries should also be linked to the 'Basic Plan for Climate Change Response'. In other words, the basic energy plan and climate change plan should be considered together in order to foster the hydrogen industry, which is currently one of the key national policies. The Hydrogen Safety Management and Business Act is the most important law in the hydrogen economy. There should also be safety standards regarding hydrogen. The current bills do not contain all hydrogen-related facilities. Facilities that manufacture, charge, and store hydrogen at high pressure are required to comply with standards in accordance with the “High Pressure Gas Safety Management Act.” Safety standards are insufficient for facilities that manufacture, charge, store, sell, or use hydrogen at low pressure. In addition, safety standards were not provided for fuel cells which use hydrogen directly. The Safety Management and Business Act of Hydrogen Fuel was designed to promote the supply and utilization of hydrogen by securing public safety. In addition, systematic support for R&D is also needed for the continuation of the hydrogen economy. Of the hydrogen R&D projects, it is also necessary for South Korea to draw out technical areas that can be effective through investment and to foster them intensively. It will also need technological exchanges and cooperation in safety management know-how with the United States. In particular, research and benchmarking on the hydrogen and fuel cell-related acts of the US will also be needed.

수소 충전소용 초고압 릴리프 밸브 구조설계에 관한 연구

류현종,한승훈 한국기계기술학회 2022 한국기계기술학회지 Vol.24 No.5

In order to cope with climate change, the UN Climate Summit announced a policy to reduce carbon emissions to 0% by 2050. As a result, hydrogen energy is attracting attention as a new energy. Hydrogen energy is one of the future clean energy sources and is the most abundant and ideal fuel on Earth that does not emit pollutants. On the other hand, there is a risk of wide explosion range, easy ignition, and fast flame speed. As a result, There is limited use of hydrogen gases, and research is being conducted to safely use hydrogen gases. However, the localization rate of hydrogen-related equipment parts is low and dependence on foreign countries is high. In order to reduce dependence on foreign countries, this study designed and analysis a model of ultra-high pressure relief valve, which is a safety device for hydrogen charging stations. In order to evaluate the structural stability, a spring, a valve disk, a valve guide, and a valve spindle, which are components of an ultra high pressure relief valve, were applied with pressure resistance test and water pressure test criteria according to KS B ISO 19880-3, and analyzed using an Ansys workbench 2021 R1. Through the analysis results, the structural stability of the relief valve under the water pressure test and the pressure resistance test conditions confirmed.