Performance increase for an open-cathode PEM fuel cell with humidity and temperature control

Ou, Kai,Yuan, Wei-Wei,Choi, Mihwa,Yang, Seugran,Kim, Young-Bae Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.50

<P><B>Abstract</B></P> <P>Water and thermal management of an open-cathode proton electrolyte membrane (PEM) fuel cell is developed in this study. A bubble humidifier, which is one of the balance of plant (BOP) systems, is newly installed to control the humidity of the fuel cell. A multiple-input-multiple-output (MIMO) fuzzy controller is developed, and proven to be superior in controlling a strong non-linear dynamical fuel cell system in real-time. According to the fuzzy control stratagem, the two main control objectives are the axial fan speed control for regulating temperature and the solenoid valve on/off control of the bubble humidifier for humidity variation. First, the axial fan speed is controlled to keep the fuel cell temperature within the desired point. Second, the bubble humidifier is utilized to humidify the inlet hydrogen to manage the water content of a membrane. After simulating the electrochemical and thermal fuel cell models, the optimal operating conditions are determined. A fuzzy logic controller with five inputs and two outputs is constructed and utilized to regulate the temperature and relative humidity of an open cathode fuel cell in real time. Results show that the proposed fuzzy controller effectively increased the output power of PEM fuel cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An advanced control is developed for controlling fuel cell temperature and humidity. </LI> <LI> An open-type fuel cell model is developed to find optimal operating points. </LI> <LI> About 10% of power increase is achieved using our method. </LI> </UL> </P>

A Power Control Scheme of a Fuel Cell Hybrid Power Source

Yujin Song(송유진),S. B. Han(한수빈),S. I. Park(박석인),H. G. Jeong(정학근),B. M. Jung(정봉만),G. D. Kim(김규덕),S. W. Yu(유승원) 한국조명·전기설비학회 2008 한국조명·전기설비학회 학술대회논문집 Vol.2008 No.10월

This paper describes a power control scheme to improve the performance of a fuel cell-battery hybrid power source for residential application. The proposed power control scheme includes a power control strategy to control the power flow of the fuel cell hybrid power system and a digital control technique for a front-end dc-dc converter of the fuel cell. The power control strategy enables the fuel cell to operate within the high efficiency region defined by the polarization curve and efficiency curve of the fuel cell. A dual boost converter with digital control is applied as a front-end ed-ed converter to control the fuel cell output power. The digital control technique of the converter employs a moving-average digital filter into its voltage feedback loop to cancel the low frequency harmonic current drawn from the fuel cell and then limits the fuel cell output current to a current limit using a predictive current limiter to keep the fuel cell operation within the high efficiency region as well as to minimize the fuel cell oxygen starvation.

A Glucose-inducible Gene in Schizosaccharomyces pombe, rrg1+, Is Involved in Negative Regulation of G2/M Progression

Min Ji Kim,Eun Jung Park,Sang Dai Park 한국분자세포생물학회 2002 Molecules and cells Vol.14 No.2

A glucose-inducible gene in S. pombe is rrg1+. Its mRNA level is rapidly decreased and increased by glu-cose-depletion and readdition, respectively. The previous study revealed that the rrg1+ expression was regulated by glucose-dependent mRNA stability con-trol. To understand the significance of the glucose-dependent expression of rrg1+, the cellular function of rrg1+ was explored. Deletion of the rrg1+ gene from the haploid chromosome of S. pombe cells did not lead to cell lethality but brought about cell size reduction, which was accompanied by fast cell proliferation. In accordance with this result, the overexpression of the Rrg1 protein under the control of the nmt1 promoter produced elongated cells of G2 delay, and consequently resulted in the slowing-down of cell proliferation. In addition, the rrg1+ mRNA level showed cell-cycle de-pendent changes, peaking at G2/M. These results dem-onstrate that Rrg1 might be involved in the negative regulation of cell proliferation and G2/M progression for cell size control.

2 kW급 개방 캐소드형 연료전지 출력 향상을 위한 온습도 제어

원위위,최미화,양석란,김영배 한국수소및신에너지학회 2017 한국수소 및 신에너지학회논문집 Vol.28 No.4

Temperature and humidity regulations of an open-cathode PEM fuel cell with balance of plant (BOP) are developed in this study. The axial fan, a bubble humidifier, set of solenoid valves and a controller are used to perform temperature and humidity control simultaneously. A fuzzy controller is designed, and it shows its superiority in real-time controlling for strong non-linear dynamical fuel cell system. The axial fan speed is used for temperature control and solenoid valve on/off signal of the bubble humidifier is used for humidity control. The axial fan speed is controlled to keep the fuel cell temperature within the desired point. Meanwhile, the bubble humidifier is utilized to moisture hydrogen to manage the water content of membrane. The results show that the proposed fuzzy controller effectively increases the output power of 10% for a PEM fuel cell.

Noninvasive Quality Estimation of Adherent Mammalian Cells for Transplantation

Mutsumi Takagi 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.1

The noninvasive quality estimation of adherent mammalian cells for transplantation is reviewed. The quality and heterogeneity of cells should be estimated before transplantation because cultured cells are not homogeneous but heterogeneous. The estimation of cell quality should be performed noninvasively because most protocols of regenerative medicine are autologous cell system. The differentiation level and contamination of other cell lineage could be estimated by two-dimensional cell morphology analysis and tracking using a conventional phase contrast microscope. The noninvasive determination of the laser phase shift of a cell using a phase-shifting laser microscope, which might be more noninvasive, and more useful than the atomic force microscope and digital holographic microscope, was carried out to determine the three-dimensional cell morphology, and the estimation of the cell cycle phase of each adhesive cell and the mean proliferation activity of a cell population. Chemical analysis of the culture supernatant by conventional analytical methods such as ELISA was also useful to estimate the differentiation level of a cell population. Chemical analysis of cell membrane and intracellular components using a probe beam, an infrared beam, and Raman spectroscopy was useful for diagnosing the viability, apoptosis, and differentiation of each adhesive cell.

세포성 면역 알고리즘을 이용한 AGV의 조향 제어기 설계에 관한 연구

이영진,이진우,이권순,Lee, Yeong-Jin,Lee, Jin-U,Lee, Gwon-Sun 제어로봇시스템학회 2001 제어·로봇·시스템학회 논문지 Vol.7 No.10

The PID controller has been widely applied to the most control systems because of its simple structure and east designing. One of the important points to design the PID control system is to tune the approximate control parameters for the given target system. To find the PID parameters using Ziegler Nichols(ZN) method needs a lot of experience and experiments to ensure the optimal performance. In this paper, CMIA(Cell Mediated Immune Algorithm) controller is proposed to drive the autonomous guided vehicle (AGV) more effectively. The proposed controller is based on specific immune responses of the biological immune system which is the cell mediated immunity. To verify the performance of the proposed CMIA controller, some experiments for the control of steering and speed of that AGV are performed. The tracking error of the AGV is mainly investigated for this purpose. As a result, the capability of realization and reliableness are proved by comparing the response characteristics of the proposed CMIA controllers with those of the conventional PID and NNPID(Neural Network PID) controller.

Advanced thermal management of automotive fuel cells using a model reference adaptive control algorithm

Han, Jaeyoung,Yu, Sangseok,Yi, Sun Elsevier 2017 International journal of hydrogen energy Vol.42 No.7

<P><B>Abstract</B></P> <P>Temperature control is a critical issue to ensuring the reliable performance of fuel cell systems. However, nominal feedback controllers currently used to regulate system temperature have limitations, due to the high inherent nonlinearity in the systems, and uncertainty in the parameters of the models, especially in the presence of dynamic load variations. In this study, a feedback controller was designed including Model Reference Adaptive Control (MRAC) to address uncertainties and robustly control the stack and the coolant inlet temperature in a proton exchange membrane fuel cell (PEMFC). The proposed controller was then evaluated by comparison with a nominal feedback controller. It was shown that if the parameters vary in the system the MRAC algorithm yields improved transient performances in terms of recovery speed and deviation in comparison to the nominal feedback control algorithm. The MRAC provides enhanced robustness.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A thermal management module is designed to predict the cooling performance. </LI> <LI> An MRAC algorithm is designed to control the fuel system temperature. </LI> <LI> Simulation is carried out to confirm feasibility of MRAC under dynamic load. </LI> <LI> By algorithm comparison, MRAC is proven to be more feasible for controlling the system temperature. </LI> <LI> MRAC comes to be more reliable under nominal dynamic operating schedules. </LI> </UL> </P>

HCV-Specific Interleukin-21+CD4+ T Cells Responses Associated with Viral Control through the Modulation of HCV-Specific CD8+ T Cells Function in Chronic Hepatitis C Patients

Guo-Hua Feng,Fu-Sheng Wang,Ji-Yuan Zhang,Qing-Lei Zeng,Lei Jin,Junliang Fu,Bin Yang,Ying Sun,Tianjun Jiang,Xiangsheng Xu,Zheng Zhang,Jinhong Yuan,Liyuan Wu 한국분자세포생물학회 2013 Molecules and cells Vol.36 No.4

Interleukin-21 (IL-21)+CD4+ T cells are involved in the immune response against hepatitis B virus (HBV) by secreting IL-21. However, the role of IL-21+CD4+ T cells in the immune response against chronic hepatitis C (CHC) virus infection is poorly understood. This study aimed to investigate the role of IL-21+CD4+ T cells in CHC patients and the potential mechanisms. The study subjects in-cluded nineteen CHC patients who were grouped by viral load (low, < 106 RNA copies/ml, n = 8; high, > 106 RNA copies/ml, n = 11). The peripheral frequency of HCV-specific IL-21+CD4+ T cells was higher in the low viral load group and was negatively correlated with the serum HCV RNA viral load in all CHC patients. Meanwhile, IL-21+ cells accumulated in the liver in the low viral load group. In vitro, IL-21 treatment increased the expression of proliferation markers and cytolytic molecules on HCV-specific CD8+ T cells. In summary, these findings suggest that HCV-specific IL-21+CD4+ T cells might contribute to HCV control by rescuing HCV-specific CD8+ T cells in CHC patients.

미세유체장치 내 박테리아 세포 배양을 위한 저비용 항온·항습 배양기 개발

박우현,김재환,김민석 한국정밀공학회 2023 한국정밀공학회지 Vol.40 No.6

Advances in cell culture technology have improved the understanding of the physiological principles of cells. Recently, the development of microfluidic chips has made it possible to observe single cells in a massively parallelized and accurate manner. However, in order to maximize the availability of the microfluidic cell chip, it is essential to use an incubator that can isolate the cell culture chip from the outside while minimizing contamination and maintaining the temperature and humidity required for cell culture for a long time period. Here, we developed a thermo-hygrostat incubator consisting of an Arduino-based feedback control module for controlling a temperature and humidity complex sensor, a humidifier, and a heater. The temperature and humidity of the incubator could be actively changed according to the needs and application by simple editing control variables of Arduino coding. To demonstrate the efficiency of the device, we conducted an experiment comparing the growth of bacterial cells and obtained optimal conditions necessary for culture. In conclusion, it is expected hat the newly developed thermo-hygrostat incubator can be used for a variety of purposes that require active control of emperature and humidity, as well as for long-term cultivation of bacterial cells inside a microfluidic chip.

Effect of cell senescence on the impedance measurement of adipose tissue-derived stem cells

Jun, H.S.,Dao, L.T.M.,Pyun, J.C.,Cho, S. IPC Science and Technology Press ; Elsevier Scienc 2013 Enzyme and microbial technology Vol.53 No.5

Label-free and real-time monitoring of stem cells based on electrical impedance measurement is increasingly utilized for the quality control of the isolated stem cells to be used in stem cell-based tissue therapy or regenerative medicine. In spite of that the proliferative capacity and multipotency of stem cells are dependent on the type and age of the source tissue, however, the effect of the cell senescence on the impedance measurement of stem cells has not yet been studied. We investigated whether the senescence of adipose tissue-derived stem cells (ADSCs) can be detected by electrical impedance spectroscopy. For this, ADSCs at passage 9 and 31 were prepared and those genetic characteristics and growth kinetics were evaluated by quantitative polymerase chain reaction and cell counting. While the identified ADSCs were grown on the indium tin oxide electrodes, the impedance spectra were measured and interpreted by fitting analysis with an equivalent circuit model. ADSCs at passage 9 adhered on the electrode were small and spindle-shaped whereas the cells at passage 31 were flattened and larger than younger cells. At the beginning of culture time when the cell adhesion occurred, the resistance at 4.6kHz of passage 31 cells was higher than passage 9 due to the larger size of older cells. Afterwards, the value of passage 9 cells increased higher than passage 31, since younger cells proliferated more than old cells. Therefore, the impedance measurement could characterize the proliferative capacity of ADSCs during expanded culture.