Ahmad Arif, Rifdarmon, Milana et al.

Journal of Physics: Conference Series • 2020

Abstract Gasoline engines with electronic fuel injection systems are recommended to use Pertalite type unleaded gasoline to produce a perfect combustion process so as to improve engine performance. However, the majority of vehicle owners prefer to use Premium type fuel and sometimes also mix it with other fuels, resulting in decreased engine performance. This is due to the low price of Premium and consumers do not understand the effect on engine performance. This research was conducted on a Toyota Avanza K3-VE 1,298 cc with an experimental method that aims to determine the performance of a gasoline engine with an electronic fuel injection system using several types of fuel. To find out the optimal engine performance, the test is carried out at maximum engine speed using a dynamometer bench. The results showed that the right fuel used in gasoline engines with electronic fuel injection systems is Pertamax type because it has optimal engine performance, which produces an maximum torque of 176.23 Nm and an maximum power of 105.83 Kw.

Ireneusz Pielecha, Filip Szwajca, Kinga Skobiej

Energies • 2023

This article investigates the impact of loading on the hybrid powertrain of the FCAT-30 model, equipped with a proton-exchange-membrane fuel cell (PEMFC) and a nickel–metal hydride (NiMH) battery. This study involves analyzing structural component performance based on voltage and current measurements of the fuel cell, battery, and powertrain. Tests conducted under different load conditions reveal significant differences in battery current and fuel-cell voltage, highlighting the crucial role of the battery in the powertrain. External loading induces cyclic operation of the fuel cell, generating peak power. The energy balance analysis demonstrates that, under no-load conditions, the vehicle consumes 37.3% of its energy from the fuel cell, with a total energy consumption of 3597 J. Under load, the energy from the battery is significantly utilized, resulting in a constant fuel-cell share of approximately 19%, regardless of the vehicle’s load. This study concludes that the battery predominantly drives the powertrain, with the fuel cell acting as a secondary energy source. These findings provide valuable insights into the power distribution and energy balance in the hybrid powertrain. Using a load driving profile reduced the fuel-cell-stack energy contribution by 6.85% relative to driving without an external load.

Tobias Kistler

ECS Meeting Abstracts • 2023

Solar-driven electrochemical devices, such as PV-electrolyzers and photoelectrochemical (PEC) devices, contain multiple components which can make it difficult to pinpoint the failing piece when overall device performance is degrading. The current-voltage analysis tool for solar fuel production (CATS) is a free app that analyzes current-voltage data collected during operation, parameters that are easily accessible for many devices of interest. The program captures the time-dependence of loss mechanisms at play during PEC device operation and opens the door for real-time optimizations of operational parameters like the feed humidity to minimize performance losses. Aside from the possibility of deconvoluting loss mechanisms, this software can also reveal possible performance benefits, such as by convective PV cooling when the photoabsorber is integrated into the electrolysis cell.

Steven T. Barber, Josh M. Dranoff, Thomas A. Trabold

Volume 1: Advances in Solar Buildings and Conservation; Climate Control and the Environment; Alternate Fuels and Infrastructure; ARPA-E; Combined Energy Cycles, CHP, CCHP, and Smart Grids; Concentrating Solar Power; Economic, Environmental, and Policy Aspects of Alternate Energy; Geothermal Energy, Harvesting, Ocean Energy and Other Emerging Technologies; Hydrogen Energy Technologies; Low/Zero Emission Power Plants and Carbon Sequestration; Micro and Nano Technology Applications and Materials • 2015

Due to ever increasing industrial organic material wastewater regulations, there is growing interest in the food production industry for technologies to mitigate soluble waste discharges. Currently, food manufacturers in NYS with wastewaters that have high concentrations of soluble organic material, indicated by its chemical oxygen demand (COD), are charged substantial premiums by publicly owned treatment works (POTWs) to dispose of their high COD wastewaters. As a result, these producers are keen on pursuing more economical and sustainable alternatives. One novel option is a microbial fuel cell (MFC), a recently developed type of bioreactor that greatly reduces soluble COD by harnessing the electrochemical potential found in the chemical bonds of these organic materials through redox reactions under anaerobic conditions facilitated by exoelectrogenic microorganisms. MFC technology treating homogeneous substrates such as acetate at the laboratory scale has advanced to the point where COD removal efficiencies of over 90% are commonly achieved; however, efficiencies at treating less uniform, high COD level industrial scale food manufacturing wastewaters have only been investigated in a handful of studies. Since most real world wastewaters are non-uniform, MFC performance characterization of treating these actual discharges is crucial in determining their efficacy and cost effectiveness in large scale applications. To help fill this gap, this paper gives a relative efficacy comparison of five identical 3 L bench scale single chamber and three dual chamber MFC configurations (SCMFCs and DCMFCs, respectively) to a simulated POTW aeration process treating high COD whey effluent from a tofu manufacturing plant. Standard parametric EPA water quality tests of COD reduction were performed to assess the extent of the MFCs and POTW simulant effectiveness. COD levels in the MFC’s were reduced between 72% and 92%, while the POTW aeration process reduced levels 98%. This corroborates previously published studies showing that POTW systems are effective in reducing COD, but also that MFCs could be a more sustainable option due to their unique ability to directly produce, rather than consume, electric current. While these findings are promising, more studies are required to accurately determine the relative proportion of bioelectrochemical and methanogenic processes in the actual lowering of the COD levels.

En Ren Zhang, Jun Le Niu, Lei Liu

Applied Mechanics and Materials • 2012

PAN-based carbon fiber was used to prepare brush anode, and its electrochemical performance was investigated in a tubular microbial fuel cells. Experimental results showed that electricity production can be enhanced by using brush anode, with maximum current (up to 25 mA) much higher than that of reported microbial fuel cells using other types of carbon materials. Heat treatment is demonstrated to be an effective method to further increase the performance of the brush anode, not only reducing the start-up time of the microbial fuel cells, but also increasing the duration of electricity production and polarization properties.

Yue-Tzu Yang, Kuo-Teng Tsai, Cha’o-Kuang Chen

Journal of Applied Mathematics • 2012

The objective of this study is to use a new style of waved flow channel instead of the plane surface channel in the proton exchange membrane fuel cell (PEMFC). The velocity, concentration, and electrical performance with the waved flow channel in PEMFC are investigated by numerical simulations. The results show that the waved channel arises when the transport benefits through the porous layer and improves the performance of the PEMFC. This is because the waved flow channel enhances the forced convection and causes the more reactant gas flow into the gas diffusion layer (GDL). The performance which was compared to a conventional straight gas flow channel increases significantly with the small gap size when it is smaller than 0.5 in the waved flow channel. The performance is decreased at the high and low velocities as the force convection mechanism is weakened and the reactant gas supply is insufficient. The pressure drop is increased as the gap size becomes smaller, and the wave number decreases. (gap size) δ > 0.3 has a reasonable pressure drop. Consequently, compared to a conventional PEMFC, the waved flow channel improves approximately 30% of power density.

Peng Wang, Hironori Nakajima, Tatsumi Kitahara

Journal of The Electrochemical Society • 2023

Water flooding under high current and humidity conditions is a main barrier to enhancing the performance of polymer electrolyte fuel cells (PEFCs). This study evaluated a double microporous layer (MPL) coated gas diffusion layer (GDL) consisting of a thin hydrophilic layer coated on a hydrophobic MPL coated GDL. An accurate measurement of the contact angle was introduced to assess the wettability of the MPL. Besides, the water breakthrough pressure and water vapor permeance values were measured to evaluate the water transport ability of the MPL. The oxygen transport resistance was measured using the limiting current density in polarization curves. Appropriate hydrophilic MPL containing 5% Nafion, 25% TiO 2, and carbon black in the double MPL enhanced the ability of the GDL to discharge water at the catalyst layer, effectively reducing water flooding. The total oxygen transport resistance obtained with the double MPL was reduced by about 20% compared to that obtained with a hydrophobic MPL. Moreover, the pressure-independent and pressure-dependent resistances were separated from the total oxygen transport resistance measured under various back pressure conditions. The double MPL exhibited a substantially reduced pressure-independent resistance at the interface between the MPL and the catalyst layer.

International Journal of Maritime Engineering • 2019

Energy efficiency subject has been gaining importance in maritime sector. The compressed air is a valuable energy source in operational manner, by the reason of intrinsic lack of efficiency in pressurization process. Operational pressure and leakage rate are the major variables which affect operational efficiency of the system. This study aims to reveal potential energy saving for the compressed air system. To this end, several pressure ranges, 29-30 bars to 14-18 bars, and different leakage rates 2.4% to 45% are evaluated. After the data was obtained from ships, thermodynamic calculations had been carried out. Optimization of pressure saves 47.3% in daily power requirement, 58,2% in compressed air unit cost, 18.4 and 57.4 tons of reduction in fuel consumption and CO2 emissions in a year respectively. High leakage rates can cause 2.7 times more power and fuel consumption. Finally, operating load, as an important indicator of compressor, makes imperfections identifiable.

Matteo Martinelli, Stefano Campanari, Dario Montinaro et al.

ASME 2024 Power Conference • 2024

Abstract This work presents the simulation and techno-economic evaluation of the SOS-CO2 cycle, a novel hybrid cycle combining a pressurized solid oxide fuel cells with an oxy-turbine cycle. The cycle and its components are modelled and sized with the aim of assessing its performance and cost of electricity. A fuel cell design with high single-pass fuel utilization factor is considered. Sensitivity analyses on the fuel cell operating voltage and costs are performed to quantify their effects on the overall cycle performance. The results show that the cycle is expected to achieve outstanding net electric efficiency values, in the range 65.7%–69.3%, while capturing 95% of the generated CO2. The resulting specific CO2 emissions are as low as 15.9 gCO2/kWh. The cost of electricity is expected to be in the range 133 vs. 128.4 €/MWh (depending on the fuel cell voltage), a value competitive with the best available technologies for CO2 capture and storage.

Gurwinder Singh, Amandeep Singh Oberoi, Harmesh K. Kansal et al.

Environmental Progress & Sustainable Energy • 2022

Abstract We present an experimental investigation on a proton battery, that could run both as electrolyser and fuel cell, using six different flow channel orientations viz. pin‐type, parallel, interdigitated, spiral, serpentine, and parallel serpentine. The battery stores energy in the form of hydrogen ions and its performance is determined in terms of hydrogen wt. % stored in an integrated carbon‐based electrode. In this paper, the fabrication of electrode, development of an experimental proton battery and its testing are disclosed. The characterization of the employed activated carbon electrode is done using scanning electron microscopy, X‐ray diffraction analysis, energy dispersive spectroscopy, and fourier transform infrared spectroscopy. The fabricated proton battery is tested by charging (E‐mode operation) and discharging (FC‐mode operation) subsequently at normal temperature and pressure conditions. In the E‐mode operation, electrochemical hydrogen storage of the battery with six different flow channels is found to be in the range of 1.36–1.97 wt. %. The corresponding desorption of hydrogen in the FC‐mode operation is found to be in the range of 1.047–1.479 wt. %, respectively, for six different flow channels. The comparative result analysis revealed that parallel serpentine flow channel outperformed, with energy storage capacity of 1.97 wt. %; and pin type channel design showed comparatively low performance with energy storage capacity of 1.36 wt. %. The presented research work is an effort towards meeting the set targets of hydrogen storage set by the U.S. Department of Energy to make the hydrogen technology commercially viable. Statement of Industrial Relevance The presented research work has relevance with the power industry as it reveals the optimum design of flow channels for enhanced hydrogen adsorption. It is a way forward towards developing a fuel‐cell based proton battery that does not emit harmful fumes like lithium batteries and therefore, is environmentally friendly. Novelty or Significance The presented research work is a maiden attempt of testing different designs of micro‐flow channels in an experimental proton battery that is a single unit capable of performing dual tasks i.e., electrolyser and fuel cell to store energy and give out power when required.

El Mahdi Halim, Lisa Pierinet, Rémi Blanchard et al.

ECS Meeting Abstracts • 2023

The polymer electrolyte membrane fuel cell (PEMFC) is one of the most promising energy sources for replacing fossil fuels in vehicles, as it does not produce greenhouse gas emissions during operation. As a key player in hydrogen mobility, SYMBIO is developing and producing PEMFC systems for a large field of applications. SYMBIO masters the electrochemical core (the Membrane Electrode Assembly - MEA), the complete stack (bipolar plate, stacking and housing) and the fuel cell system (Balance of Plant, operating conditions, control-command, packaging) [1]. The widespread use of fuel cell vehicles is strongly linked to the price of the PEMFC system, in which the MEA as a high share. Decreasing the total PGM content, as well as moving to high-speed roll-to-roll production methods are important levers in the cost roadmap of MEAs. And from a performance point of view, systems for the heavy-duty market will need to show high efficiencies at low current densities (<1 A/cm 2 ). Exploring the potential of highly active cathode catalyst is therefore mandatory for these applications. State of the art cathode catalyst layers consists in either Pt or PtCo-alloy supported on carbon material, the latter being more active for the ORR but also less resistant towards potential cycling. Regarding the ink formulation, the use of PtCo poses the challenge that Co atoms could dissolve, even if the catalyst has been previously acid leached, leading to the release of free Co 2 + . These free ions will latter lower the catalytic activity and the transport of reactants (H + and O 2 ) to the active sites in the catalytic layer [2-3]. The manufacturing of a catalyst coated membrane (CCM) can be done with different printing processes involving a catalytic ink and a substrate. Each coating process has different constraints (ink rheological behaviour, particle size) leading to optimisation of ink recipe (solvent matrix, solid content ...). The ink must also be compatible with the substrate that can be directly an MEA component such as the membrane (direct coating) or the GDL, or a decal-carrier substrate. All these parameters lead to catalyst layer structure differences that impact the MEA performance. In this study, the impact of three coating processes, hence three solvent systems for a same catalyst, ionomer, and I/C ratio, on the MEA performance is explored for commercial Pt and PtCo catalysts. The coating processes compared are direct coating on membrane via bar coater and spray coater and non-direct coating using decal method. The inks properties including the granulometry and the viscosity of different prepared inks were characterized before coating. Ex-situ techniques (SEM-EDX, TEM, N 2 adsorption/desorption) were used to figure-out the impact of the coating process on the morphology and porosity of the cathodic catalyst layer. The influence of these parameters on the electrochemical performance was studied using H 2 -Air polarization curves, electrochemical impedance spectroscopy and the electrochemical surface area (ECSA). It will be highlighted how important the final PEMFC performance must be understood by taking into account the used ink system and coating process, as well as the intrinsic stability of catalyst, ionomer and membrane during these stages. References [1] www.symbio.one [2] Nagappan Ramaswamy et al 2021 J. Electrochem. Soc. 168 024519 [3] Deborah J. Myers et al 2021 J. Electrochem. Soc. 168 044510

Rao Muhammad Asif, Mustafa Shakir, Ateeq Ur Rehman et al.

Journal of Sensors • 2022

Massive multiple-input and multiple-output (MIMO) systems have become the most persuasive technology for 5G as it increased the energy efficiency gigantically as compared to other wireless communication systems. Being the most vibrant research technology in the communication sector, this research work is based on the optimal model development of energy-efficient massive MIMO systems. The proposed model is a realistic model that augmented the spectral efficiency (SE) of massive MIMO systems where a multi-cell model scenario is considered. Channel estimation is carried out at the base stations (BSs) based on uplink (UL) transmission while the minimum mean-squared error (MMSE), Element-wise MMSE, and Least-square (LS) estimators are used for the estimation. We analyze the achievable SE of the UL based on the MMSE channel estimator with different receive combining schemes. Moreover, the downlink (DL) transmission model is also modelled with different precoding schemes by taking the same vectors used in combining schemes. The simulation results show a significant improvement in spectral efficiency by developing UL and DL transmission models and also realized that the average sum of SE per cell can be improved by optimized MMSE channel estimation, installing multiple BS antennas, and serving multiple UEs per cell. The findings of this work specify that the massive MIMO system can be developed by optimizing the channel estimation for the augmentation of SE in UL and DL transmissions. Conclusively, it can be summarized that some complex computations of MMSE channel estimators can enhance the average sum of SE per cell as per the results verified in this model.

Shirlee Emmons, Alma Thomas

Power Performance for Singers, Transcending the Barriers • 1998

Abstract Singers, professional or amateur, regard the spectacle of the Olympic Games as virtually identical to their own work. Even an inexperienced singer knows-as Gertrude Stein would say-that performance is performance is performance, whatever the field. It matters not that an athlete broke an Olympic record back home in Indiana on a Thursday afternoon at 2:00 P.M. It only counts when he or she does it at the appointed time and in the appointed place, under pressure, in Montreal or Atlanta, say, at 10:17 A.M. Similarly, it matters not how well the singer performed the aria at the Monday rehearsal; it only counts when he or she sings it well on Wednesday evening at 8:26 P.M. before an audience.

Minghua Zhou, Hongyu Wang, Daniel J. Hassett et al.

Journal of Chemical Technology & Biotechnology • 2013

Abstract Bioenergy is a renewable energy that plays an indispensable role in meeting today's ever increasing energy needs. Unlike biofuels, microbial fuel cells ( MFCs ) convert energy harvested from redox reactions directly into bioelectricity. MFCs can utilize low‐grade organic carbons (fuels) in waste streams. The oxidation of the fuel molecules requires biofilm catalysis. In recent years, MFCs have also been used in the electrolysis mode to produce bioproducts in laboratory tests. MFCs research has intensified in the past decade and the maximum MFCs power density output has been increased greatly and many types of waste streams have been tested. However, new breakthroughs are needed for MFCs to be practical in wastewater treatment and power generation beyond powering small sensor devices. To reduce capital and operational costs, simple and robust membrane‐less MFCs reactors are desired, but these reactors require highly efficient biofilms. Newly discovered conductive cell aggregates, improved electron transport through hyperpilation via mutation or genetic recombination and other advances in biofilm engineering present opportunities. This review is an update on the recent advances on MFCs designs and operations. © 2012 Society of Chemical Industry

Jim Cowart, Dianne Luning Prak, Len Hamilton

Journal of Engineering for Gas Turbines and Power • 2015

In an effort to understand the effects of injection system pressure on alternative fuel performance, a single-cylinder diesel engine was outfit with a modern common rail fuel injection system and piezoelectric injector. As future new fuels will likely be used in both older mechanical injected engines as well as newer high pressure common rail engines, the question as to the sensitivity of a new fuel type across a range of engines is of concern. In this study, conventional diesel fuel (Navy NATO F76) was compared with the new Navy hydroprocessed renewable diesel (HRD) fuel from algal sources, as well as the high cetane reference fuel nC16 (n-hexadecane CN = 100). It was seen that, in general, ignition delay (IGD) was shortened for all fuels with increasing fuel injection pressure and was shortened with higher CN fuels. The combustion duration for all fuels was also significantly reduced with increasing fuel injection pressure, however, longer durations were seen for higher CN fuels at the same fuel pressure due to less premixing before the start of combustion. Companion modeling using the Lawrence Livermore National Lab (LLNL) heavy hydrocarbon and diesel primary reference fuel (PRF) chemical kinetic mechanisms for HRD and nC16 was applied to understand the relative importance of the physical and chemical delay periods of the IGD. It was seen that at low fuel injection pressures, the physical and chemical delay times are of comparable duration. However, as injection pressure increases the importance of the chemical delay times increases significantly (longer), especially with the lower CN fuel.

Vitalii Peshko, Sergii Lishchuk

POWER ENGINEERING: economics, technique, ecology • 2023

In the context of insufficient maneuvering capacities in the United Energy System of Ukraine, 200 MW power units are used to cover peak loads in variable operating modes. At the same time, there is a deterioration in the economic performance of power equipment. The efficiency of power generation directly depends on the operating modes of the power unit. Therefore, the task was set to develop a system to rationalize operating modes in order to increase efficiency. The average annual specific fuel consumption was chosen as the objective function. To calculate the specific consumption during the year, the method of bringing all losses during start-up and stationary operation to similar consumption of conventional fuel was used. The following factors were selected as optimization factors: the power unit operation time during the year, the total number of starts from different thermal states for 1 year, and the proportion of starts from different thermal states. The limits of change in the factors were chosen as follows: the number of hours of power unit operation ti from 2000 to 6500 hours per year; annual number of starts ni from 25 to 75 times per year; the share of starts from the cold state of metal CSi from 0.1 to 0.9; the share of starts from the hot state GSj within the share of all starts (hot and un-cooled) from 0 to 1 The developed mathematical model allows to estimate fuel consumption for all possible combinations of operational factors. To demonstrate the operation of this system, calculations were performed for a specific 200 MW power unit with a TP-100 power boiler and a K-200-130 steam turbine. The main parameters of the power unit operation mode were determined using the start-up map and the operating instructions developed by the manufacturer. The calculations established a rational distribution of operating parameters, at which the consumption of conditional fuel is 334-340 g.c.f./kWh. It has been established that the rational number of hours of power unit operation is ti = 5500-6500 h/year, with the annual number of starts ni = 25-36 year-1, while the share of starts should be: from the cold state of the metal CSi = 0.72-0.9; from the hot state HSj = 0.1-0.28; from the un-cooled state USi,j = 0-0.18, and then the difference between the most rational and irrational operating modes is 16.5 % (fuel consumption of 55 g.c.f /kWh).

Shang Xinyuan, Zhang Shaoyang, Zhang Aimin

Volume 3: Nuclear Fuel and Material, Reactor Physics and Transport Theory; Innovative Nuclear Power Plant Design and New Technology Application • 2017

SiC fiber composite material as fuel cladding is proposed to increase the power density and maximum allowable fuel burnup in light water reactors. Empirical models about thermal properties of the SiC material are developed as a function of operating temperature and neutron fluence. A fuel rod modeling code frapcon2-SiC based on frapcon2 is compiled to predict the performance of SiC cladding when operating. Comparison of the behavior between the SiCf/SiC cladding and Zr-4 cladding in different thickness reveals that higher temperature will get due to the poor thermal conductivity of the SiC. As far as the Conclusion shows that Poor thermal performance of SiC cladding makes the design margin becomes smaller.

Brian H. Bowen, James A. Myers, Agon Nixha

International Journal of Energy Sector Management • 2011

Purpose The Kosova Government is promoting energy efficiency and the purpose of this paper is to make a contribution to the efforts being made, in the form of a household survey which visited 2,370 homes in the capital city Prishtina. Design/methodology/approach Student teams from the American University in Kosovo (AUK) conducted the survey under faculty guidance and their collected data provide valuable information. Findings The survey indicates that Kosova's progress on energy efficiency is not far behind the EU requirements. Research limitations/implications The AUK survey results are from the most densely populated area of Prishtina and so these results will be of special interest to the city planners. Practical implications The survey indicates that an average of 7.58 m 3 of wood is consumed per home annually. From the data for all homes, 78 per cent heat one to three rooms and for the medium‐size category it was 83 per cent. For all homes in the phase 1 survey, 62 per cent spend between 10‐30 per cent of family income on electricity. The weighted average of the electricity costs in a medium‐size home is €63 each Winter month. The government therefore needs to effectively implement appropriate incentives or subsidies to promote a wide household energy efficiency program. Using an average wood cost of €35 to €40/m 3 and the 1.525 million m 3 /year total consumption, the total wood revenue is €60.6 million. Social implications There also needs to be thousands of smaller personal investments for household high efficiency wood stoves. Both types of investments will reduce Kosova's environmental problem of particulates from ash. Originality/value The combined Phase 1 and Phase 2 surveys are expected to provide the most comprehensive household energy survey ever conducted in the Balkans.

Ashley Fly, Rob H. Thring

ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology • 2015

Evaporative cooling through liquid water injection directly into the fuel cell flow channels removes the requirement for external humidification and liquid cooling channels within the stack. However, the amount of liquid water injected must be accurately controlled, to prevent on one hand membrane drying due to lack of water vapor and on the other hand flooding due to excessive liquid water. In this paper a one-dimensional, non-isothermal model of an evaporatively cooled proton exchange membrane fuel cell (PEMFC) is produced. The model accounts for changes in relative humidity and temperature along the anode and cathode flow channels, water transfer through the membrane and liquid accumulation within the gas diffusion layers. The model was used to study liquid water injection strategies at both cell and localized level. The influence of current density, operating pressure and inlet humidity were investigated. Results show that provided high humidity is maintained throughout the cell, exhaust gas temperature increase from low to high current densities (0.4–1.4A/cm2) is less than 4.0°C, without the need for active temperature control. Furthermore both temperature regulation and good membrane hydration can be managed by uniform injection of liquid water throughout the cell to maintain a target cathode exhaust humidity.

Qian Lin, Cong Lu, Pengfei Zhao et al.

Research Square • 2023

Abstract In order to meet the requirements of the high efficiency for the wireless communication system, this paper introduces a high efficiency power amplifier (PA) based on the harmonic control technique. Compared with other works, this method can realize the second and third-harmonic impedance matching accurately. Besides, to avoid the problem of transmission line with high characteristic impedance in bias network, the π-typed and L-typed structure is utilized. For demonstration, a high efficient PA using CGH40010 GaN HEMT is designed and fabricated. The measured results show that it obtained an output power (P out ) of 39.5 ± 1 dBm, a Gain of 14.5 ± 1 dB, a maximum drain efficiency (DE) of 74.6% within the frequency range of 0.3–1.75 GHz. After comparison, this PA is superior in terms of efficiency and gain and has predominant engineer application.

A-Andrew D. Jones, Cullen R. Buie

Volume 9: Micro- and Nano-Systems Engineering and Packaging, Parts A and B • 2012

Microbial fuel cell technology is a new technology for producing green energy from wastewater. While lab scale and commercial microbial fuel cells typically utilize graphite as the film substrate, it is difficult to rapidly prototype micro-patterned graphite and it has not been used to date. Our design sandwiches graphite sheets under a channel layer creating a microfluidic microbial fuel cell with graphite electrodes. The microfluidic microbial fuel cell uses Geobacter sulfurreducens fed with acetate in a phosphate buffer media. Ferricyanide is used as the catholyte so that the system is anodically limited. Current versus time and open circuit voltage are reported showing biofilm growth microbial fuel cell operation.

Gvidonas Labeckas, Arvydas Pauliukas, Stasys Slavinskas

TRANSPORT • 2006

The purpose of this research is to perform comparative analysis of the effect of fuel additive SO‐2E on the economical and ecological parameters of a direct‐injection Diesel engine, operating on Diesel fuel and shale oil alternately. It was proved that multifunctional fuel additive SO‐2E applied in proportion 0,2 vol % is more effective for improving combustion of shale oil than Diesel fuel. At light operation range the treated shale oil savings based upon fuel energy content throughout wide speed range 1400–2000 min−1 reduce from 14,6–12,3MJ/kWh to 11,6–11,8 MJ/kWh or by 20,5–4,1 %. Maximum NO emission for treated Diesel fuel was reduced by 7,8–11,8 %, whereas NO2 simultaneously increased by 3,8–7,4 %. In the case of treated shale oil both harmful pollutants were reduced by 22,9–28,6 % and by 41,6–13,4 %, respectively. The exhaust gas opacity and CO emissions at the rated performance regime for both fuels were obtained a bit higher, whereas HC emission for treated shale oil increases 1,9 times and for Diesel fuel remains on the same level.

M. S. Çögenli, S. Mukerjee, A. Bayrakçeken Yurtcan

Fuel Cells • 2015

Abstract Cathode electrodes of proton exchange membrane fuel cells were fabricated by using Pt sputter deposition to increase the gravimetric power density (W mg Pt −1 ) with reduced Pt loading. Ultra low Pt‐based electrodes having Pt loading in between 0.0011 and 0.06 mg Pt cm −2 were prepared by a radio frequency (RF) sputter deposition method on the surface of a non‐catalyzed gas diffusion layer (GDL) substrate by changing the sputtering time (20, 90, 180, 1050 s). The effect of cathode Pt loading on the performance of membrane electrode assembly were investigated using polarization curve, impedance, H 2 crossover and cyclic voltammetry techniques. The effect of backpressure on PEMFC performance was also investigated. Sputter1050 (0.06 mg Pt cm −2 ) exhibited the best power density at 80 °C cell temperature and without backpressure for H 2 /O 2 , 100 %RH (297 mW cm −2 and 5 W mg Pt −1 at 0.6 V). On the other hand sputter90 (0.005 mg Pt cm −2 ) showed the peak gravimetric power density (15 W mg Pt −1 and 75 mW cm −2 at 0.6 V). The Pt utilization efficiency increased as the Pt loading decreased. Sputter20 and sputter90 electrodes yielded insufficient electrochemical surface area (ECSA), higher charge transfer and ohmic resistance, but sputter180 and sputter1050 yielded sufficient ECSA and lower charge transfer and ohmic resistance.

Cassidy Houchins, Greg Kleen, Jacob Spendelow et al.

Membranes • 2012

Low cost, durable, and selective membranes with high ionic conductivity are a priority need for wide-spread adoption of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Electrolyte membranes are a major cost component of PEMFC stacks at low production volumes. PEMFC membranes also impose limitations on fuel cell system operating conditions that add system complexity and cost. Reactant gas and fuel permeation through the membrane leads to decreased fuel cell performance, loss of efficiency, and reduced durability in both PEMFCs and DMFCs. To address these challenges, the U.S. Department of Energy (DOE) Fuel Cell Technologies Program, in the Office of Energy Efficiency and Renewable Energy, supports research and development aimed at improving ion exchange membranes for fuel cells. For PEMFCs, efforts are primarily focused on developing materials for higher temperature operation (up to 120 °C) in automotive applications. For DMFCs, efforts are focused on developing membranes with reduced methanol permeability. In this paper, the recently revised DOE membrane targets, strategies, and highlights of DOE-funded projects to develop new, inexpensive membranes that have good performance in hot and dry conditions (PEMFC) and that reduce methanol crossover (DMFC) will be discussed.

Julian K. A. Schöning-Langowski, Anna Wendker, Ursula Pieper et al.

Tenside Surfactants Detergents • 2025

Abstract Developing programs for automatic domestic dishwashers requires balancing energy consumption and program duration with cleaning and drying performance. For the EU-regulated ECO program, an inherent trade-off in program duration and energy consumption may contribute to a usage frequency of around 20–30 %, thus offering potential for further improvement of dishwasher real-life-efficiency (RLE). Academic research suggests that dishwasher RLE may be enhanced by modifying consumer behaviour to increase ECO program use and by employing ‘high-performance’ (HP) detergents in short programs. Here, we show that a recently proposed chemistry-aided ‘short ECO’ program cleans and dries worse while consuming more energy than a modern ECO program, if measured according to the compulsory methodology of EN/IEC 60436. Hence, HP-detergents alone do not suffice to develop a ‘short ECO’ program equipotent to the conventional ECO program. Overall, enhancing dishwasher RLE is a complex topic involving both technological and social aspects. We propose crucial questions that should be addressed in future discussions, and argue that (a) a common definition of (types of) short programs, (b) an in-depth analysis of the relevance of short programs for dishwasher consumers, and (c) the consideration of practical issues are pivotal aspects for further enhancements of the real-life-efficiency and sustainability of dishwashers.

Y. Yang, X. Ning, H. Tang et al.

Fuel Cells • 2014

Abstract The effect of potential on the corrosion behavior of uncoated stainless steel SS316L as bipolar plate material in proton exchange membrane (PEM) fuel cell cathode environment is studied. Electrochemical methods, X‐ray photoelectron spectroscopy, scanning electron microscope are employed to characterize the corrosion behavior of SS316L at different polarization potentials in PEM fuel cell cathode environment. The results show that the corrosion current density of SS316L increases with the increase of polarization potential significantly. When the potential is higher than 0.7 V versus SCE, severe corrosion occurs on SS316L. The work also shed light on the corrosion mechanisms of SS316L at different potential in the PEM fuel cell cathode environment.

Peter Dahl, Jens Neu, Yangqi Gu et al.

Research Square • 2024

Abstract Mixed electronic-ionic conductors are crucial for various technologies, including harvesting power from humidity in a durable, self-sustainable, manner unrestricted by location or environment 1,2 . Biological proteins have been proposed as mixed conductors for 50 years 3,4 . Recently, Geobacter sulfurreducens pili filaments have been claimed to act as nanowires to generate power 5,6 . Here, we show that the power is generated by G. sulfurreducens -produced cytochrome OmcZ nanowires that show 20,000-fold higher electron conductivity than pili 7 . Remarkably, nanowires show ultrahigh electron and proton mobility (>0.25 cm2/Vs), owing to directional charge migration through seamlessly-stacked hemes and a charged, hydrogen-bonding surface, respectively. AC impedance spectroscopy and DC conductivity measurements using four-probe van der Pauw and back-gated field-effect-transistor devices reveal that humidity increases carrier mobility by 30,000-fold. Cooling halves the activation energy, thereby accelerating charge transport. Electrochemical measurements identify the voltage and mobilities required to switch pure electronic conduction to mixed conduction for power generation. The high aspect ratio (1:1000) and hydrophilic nanowire surface captures moisture efficiently to reduce oxygen reversibly, generating large potentials (>0.5 V) necessary to sustain high power. Our studies establish a new class of biologically-synthesized, low-cost and high-performance mixed-conductors and identify key design principles for improving power output using highly-tunable electronic and protein structures.

Eli Danladi, Muhammad Kashif, Thomas Daniel et al.

East European Journal of Physics • 2022

Sourcing for an alternative to the liquid electrolyte in dye-sensitized solar cells (DSSCs) have been the subject of interest in the photovoltaic horizon. Herein, we reported by means of simulation, the performance of dye-sensitized solar cell by replacing the liquid electrolyte with a copper (I) thiocyanate (CuSCN) hole conductor. The study was carried out using Solar Capacitance Simulation Software (SCAPS) which is based on poisson and continuity equations. The simulation was done based on an n-i-p proposed architecture of FTO/TiO2/N719/CuSCN/Pt. The result of the initial device gave a Power Conversion Efficiency (PCE), Fill Factor (FF), Short Circuit Current Density (Jsc) and Open Circuit Voltage (Voc) of 5.71 %, 78.32 %, 6.23 mAcm-2, and 1.17 V. After optimizing input parameters to obtain 1×109 cm-2 for CuSCN/N719 interface defect density, 280 K for temperature, 1.0 μm for N719 dye thickness, 0.4 μm for TiO2 thickness, Pt for metal back contact, and 0.2 μm for CuSCN thickness, the overall device performance of 7.379 % for PCE, 77.983 % for FF, 7.185 mAcm-2 for Jsc and 1.317 V for Voc were obtained. When compared with the initial device, the optimized results showed an enhanced performance of ~ 1.29 times, 1.15 times, and 1.13 times in PCE, Jsc, and Voc over the initial device. The results obtained are encouraging and the findings will serve as a baseline to researchers involved in the fabrication of novel high-performance solid-state DSSCs to realize its appealing nature for industry scalability.

Shie Wu, Zhimin Zeng, Hailun Xia

IET Communications • 2017

In this study, the authors focus on energy efficiency (EE) optimisation via the cooperation of small cell base stations (SBSs) in dense small cell networks (DSCNs) where the control plane (C‐plane) and data plane (D‐plane) are decoupled. They propose a coalition‐based sleep mode and power allocation (CSMPA) scheme to improve the DSCN EE while guaranteeing the target rates of users and maintaining the system capacity. In the CSMPA scheme, the cooperation of SBSs is formulated as a coalitional game in partition form and a centralised heuristic coalition formation algorithm without power cost is developed to achieve the final stable coalition structure. Each SBS can serve users in the active subframes and sleep in those subframes without data transmission. Afterwards, since the interference between coalitions affects EE, a distributed price‐based power allocation algorithm is presented to optimise the transmit power of active SBSs per subframe. System‐level simulation results show that the proposed CSMPA scheme can yield less number of outage users and significant EE performance gain without jeopardising system capacity.

, Mitra Gilasgar

• 2017

The increasing demand for wireless products to be part of our daily lives brings the need for longer battery lifetime, smaller size and lower cost. To increase battery lifetime, high efficiency power amplifiers (PAs) are needed; To make them smaller, integration or reconfiguration is aimed and to reach lower costs, technologies such as CMOS are final goals. However integration of high efficiency PA in CMOS is challenging due to the technology limitations which restricts the achievable output power and efficiency of the PA. In order to bring solutions for the above-mentioned requirements, in this thesis novel reconfigurable class-F PAs, frequency-reconfiguration, CMOS integration, impedance-reconfiguration and CMOS-MEMS implementation are addressed. Starting with a single frequency operation, a novel class-F PA for mobile applications is proposed in which with a proper harmonic tuning structure the need for extra filtering sections is eliminated, achieving an excellent harmonic-suppression level. This topology uses transmission lines and is developed to cover multiple frequency bands for purpose of global coverage with aim of size reduction. Three novel frequency reconfigurable PAs are proposed using MEMS and semiconductor switches to accomplish class-F operation at two frequencies. The main novelty of this structure is that the reconfiguration is done not only at fundamental frequency but also at harmonics with reduced number of tuning elements. Moreover, by proper placement of the switches in the stubs, the maximum voltages over the switches are minimized. The proposed structure overcomes the narrow band performance of class-F, giving an efficiency more than 60% over a 225 MHz and 175 MHz bandwidth at 900 MHz and 1800 MHz respectively. Measurement results showed high performance at both frequency bands giving 69.5% and 57.9% PAE at 900 MHz and 1800 MHz respectively. A novel CMOS class-F PA is proposed that controls up to the 3rd harmonic and can adapt to load variations due to the effect of the human body on mobile phones. It enables the integration of the PA with other devices in a single chip leading to better matching, higher performance, lower cost and smaller size. In addition, it achieves load impedance reconfigurability by using impedance tuner in its output network and by proper tuning of the network, effects of load variation on the performance are compensated. Two designs at 2.4 GHz have been done using either MOS varactors or MEMS variable capacitors as tuning devices. The design using MOS varactors show a maximum measured values of 26% PAE and 19.2 dBm output power for 50 load. For loads other than 50 ohm an improvement of 15% for PAE and 4.4 dB for output power is obtained in comparison to non-tuned one. The second design is done using MEMS variable capacitors integrated in CMOS technology through a mask-less post-processing technique. Simulations results for 50 ohm load show a peak PAE of 32.8% while delivering 18.2 dBm output power. La creixent demanda de productes sense fils en la nostra vida diària requereix dispositius de menor grandària, menor cost i amb una gran autonomia. Per reduir la mida i augmentar l'autonomia és necessari utilitzar sistemes integrats multiestàndard o reconfigurables, amb amplificadors de RF d'alta eficiència, mentre que per reduir el cost, és preferible utilitzar tecnologies econòmiques com CMOS. No obstant això, la integració en CMOS d'amplificadors de radiofreqüència, i en especial, d'alta eficiència, és un repte a causa de les limitacions de la tecnologia que restringeixen la potència de sortida realitzable i l'eficiència de l'amplificador. En aquesta tesi es tracten els diferents reptes anteriorment esmentats, proposant una nova topologia d'amplificador classe-F amb reconfiguració de freqüència, i proposant la integració d'un amplificador classe-F que s¿adapta a impedància de càrrega variable, implementat en CMOS i CMOS-MEMS. Inicialment en la tesi es proposa una topologia d'amplificador classe-F en què, gràcies a una estructura adequada a la xarxa d'adaptació, s¿elimina la necessitat de filtrat extra, aconseguint un nivell de rebuig d'harmònics excel·lent. La topologia proposada utilitza línies de transmissió i s'ha desenvolupat per dues bandes diferents, amb el disseny orientat a implementar un sistema reconfigurable. S'han aconseguit PAE de l'ordre del 80 % amb potències properes a 10 W. Un cop descrita i analitzada la topologia, s'han proposat tres amplificadors reconfigurables per doble banda freqüencial. Per a la reconfiguració s'han utilitzat MEMS i commutadors basats en semiconductors. L'estructura proposada permet la reconfiguració no només en la freqüència fonamental sinó també en els harmònics, però mantenint un nombre reduït d'elements d'ajust. A més, gràcies a l'adequada col·locació dels commutadors en les línies de transmissió, s'ha minimitzat la tensió màxima en els mateixos. Així mateix, l'estructura proposada evita la característica de banda estreta a classe-F, proporcionant una eficiència superior al 60% en unes amplades de banda de 225 MHz i de 175 MHz, per a les banda de 900 MHz i 1800 MHz respectivament. En aquestes bandes, la PAE màxima mesurada és del 69,5% i del 57,9% respectivament. Finalment, s'ha proposat un amplificador integrat en CMOS, classe-F amb control fins al tercer harmònic. L'amplificador proposat incorpora un sintonitzador a la sortida, podent així adaptar-se a variacions d'impedància de càrrega, típiques en dispositius sense fil (WLAN), degudes a l'efecte del cos humà sobre l'antena. La implementació en CMOS permet la integració de l'amplificador de potència amb altres dispositius en un únic xip, donant lloc a una millor adaptació, millor rendiment, menor cost i menor grandària del sistema. A més, gràcies a l'adaptació a les variacions de la impedància de càrrega, permet mantenir el rendiment en diferents rangs d'operació. S'han realitzat dos dissenys de l'amplificador a 2,4 GHz, un basat en varactors MOS i un altre en condensadors variables MEMS. El disseny que utilitza varactors MOS mostra una PAE màxima del 26% i una potència de 19,2 dBm per a càrrega adaptada 50 ohm. Per altres càrregues, gràcies a l'adaptació d'impedància, s'obté una millora de PAE del 15% i de 4,4 dB en potència de sortida. El disseny utilitzant condensadors MEMS s'integra en CMOS gràcies a post-processat sense màscares addicionals. Els resultats de simulació per a 50 ohm mostren una PAE del 32,8% per 18,2 dBm de potència de sortida

Bingjie Cheng, Keyang Yu, Xing Weng et al.

Microbial Cell Factories • 2024

Abstract Background Pichia pastoris is a widely utilized host for heterologous protein expression and biotransformation. Despite the numerous strategies developed to optimize the chassis host GS115, the potential impact of changes in cell wall polysaccharides on the fitness and performance of P. pastoris remains largely unexplored. This study aims to investigate how alterations in cell wall polysaccharides affect the fitness and function of P. pastoris , contributing to a better understanding of its overall capabilities. Results Two novel mutants of GS115 chassis, H001 and H002, were established by inactivating the PAS_chr1-3_0225 and PAS_chr1-3_0661 genes involved in β -glucan biosynthesis. In comparison to GS115, both modified hosts exhibited a looser cell surface and larger cell size, accompanied by faster growth rates and higher carbon-to-biomass conversion ratios. When utilizing glucose, glycerol, and methanol as exclusive carbon sources, the carbon-to-biomass conversion rates of H001 surpassed GS115 by 10.00%, 9.23%, and 33.33%, respectively. Similarly, H002 exhibited even higher increases of 32.50%, 12.31%, and 53.33% in carbon-to-biomass conversion compared to GS115 under the same carbon sources. Both chassis displayed elevated expression levels of green fluorescent protein (GFP) and human epidermal growth factor ( hegf ). Compared to GS115/pGAPZ A- gfp , H002/pGAPZ A- gfp showed a 57.64% higher GFP expression, while H002/pPICZα A- hegf produced 66.76% more hegf . Additionally, both mutant hosts exhibited enhanced biosynthesis efficiencies of S -adenosyl-L-methionine and ergothioneine. H001/pGAPZ A- sam2 synthesized 21.28% more SAM at 1.14 g/L compared to GS115/pGAPZ A- sam2 , and H001/pGAPZ A- egt1E obtained 45.41% more ERG at 75.85 mg/L. The improved performance of H001 and H002 was likely attributed to increased supplies of NADPH and ATP. Specifically, H001 and H002 exhibited 5.00-fold and 1.55-fold higher ATP levels under glycerol, and 6.64- and 1.47-times higher ATP levels under methanol, respectively, compared to GS115. Comparative lipidomic analysis also indicated that the mutations generated richer unsaturated lipids on cell wall, leading to resilience to oxidative damage. Conclusions Two novel P. pastoris chassis hosts with impaired β -1,3-D-glucan biosynthesis were developed, showcasing enhanced performances in terms of growth rate, protein expression, and catalytic capabilities. These hosts exhibit the potential to serve as attractive alternatives to P. pastoris GS115 for various bioproduction applications.

Wenyong Guo, Liye Xiao, Shaotao Dai

IET Power Electronics • 2013

This study proposes control and design methods for a current source united power‐quality conditioner (CS‐UPQC). Unipolar modulation and parameter design methods are proposed for the series CS converter. The proposed modulation method doubles the equivalent switching frequency, which makes it possible to reduce the filter size and improve the control dynamics. Modified repetitive control schemes are presented for the voltage and current compensation strategies, which provide large open‐loop control gains at the integral multiple of the fundamental frequency and guarantee good harmonics compensation performance. A fault current limiting scheme is also presented, which limits the fault current effectively by utilising the large DC link inductor of the CS‐UPQC. Simulation results in Matlab/Simulink are presented to clarify the theory and feasibility of the proposed approaches.

Nancy Kariuki, Dionissios D. Papadias, Deborah J Myers et al.

ECS Meeting Abstracts • 2017

The catalysts of choice in polymer electrolyte fuel cells (PEFCs) remain Pt-based nanoparticles on high-surface-area carbon support. One critical challenge facing commercialization of this fuel cell is the gradual decline in performance during operation, mainly caused by the loss of electrochemical surface area (ECA) of the Pt or Pt alloy nanoparticles at the cathode. In this respect, the understanding of the dominant mechanisms of the loss of ECA and loss of oxygen reduction activity, such as the electrochemical dissolution of Pt or the transition metal alloy component, is of vital importance. Several mechanisms for dissolution of platinum have been proposed including direct Pt dissolution and electrochemical oxidation of the Pt surface atoms followed by chemical dissolution of the resulting Pt surface oxide. This presentation will outline the dissolution of PtCo under various operating conditions. Studies are performed to quantify the amount of dissolved Co and Pt during potentiodynamic conditions in an electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (<ppb) of dissolved elements in solution. The electrochemical data combined with the ICP-MS data are used to evaluate the influence of various factors such as potential, potentiodynamic profile parameters (e.g., scan rate, upper and lower potential limits), particle size, and support type on the dissolution processes in acidic electrolytes at room temperature. Preliminary measurements showed that Pt dissolution occurs during both the positive-going and negative-going potential sweeps. When the potential was cycled from 0 to 1.0 V RHE , two distinct dissolution peaks were detected by the ICP-MS online analysis. The ratio of the amount of Pt dissolved during the two sweeps was found to be dependent on the sweep rate, potential hold times, and potential profile. Fundamental models will be developed to explain the mechanisms of degradation process under various potential conditions. This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office under the auspices of the Fuel Cell Performance and Durability Consortium (FC-PAD). Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357.

Ç. İyigün Karadağ, G. Behmenyar, F. G. Boyacı San et al.

Fuel Cells • 2015

Abstract Carbon supported bimetallic PtAu electrocatalysts for sodium borohydride electrooxidation are prepared by a modified citrate stabilized NaBH 4 reduction process at different pH and temperature values. The physical properties of the materials are characterized by X‐ray diffraction spectroscopy, energy dispersive spectrometry, X‐ray photoelectron spectroscopy and transmission electron microscopy. Nano sized electrocatalysts have narrow size distributions and are uniformly dispersed on the surface of carbon support. Electrochemical performances of catalysts for sodium borohydride electrooxidation are tested with 25 cm 2 single fuel cell. The highest performance is obtained at a peak power density of 161 mW cm −2 with 20 wt. % PtAu/C catalyst of 7.03 nm. Impact of the fuel cell operation parameters including concentration of NaBH 4 , flow rates of oxidant and fuel, and fuel cell operation temperature are investigated. The best operation parameters are obtained at 1 M NaBH 4 concentration, 3 cm 3 min −1 NaBH 4 flow rate, 0.2 dm 3 min −1 oxygen flow rate and 65 °C fuel cell temperature.

Ulf Schirmeister, Frederick Mohr

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems • 2016

Power output and compressor efficiency of the gas turbine decrease over time due to compressor fouling. A major part of this power and compressor efficiency loss can be recovered by compressor online and offline washing. Nevertheless, with an enhanced filtration in the EPA class, it is possible to reduce the deployment of degradation and the necessity of washings to a minimum. After providing an overview of published research work from the past, this paper presents a thorough investigation and quantification of the effect of different air filter classes on degradation based on fleet wide analysis. The operating data of a total of 12 gas turbines (Alstom’s GT13E2, GT24 and GT26) from 6 power stations in 5 different countries are analyzed, giving a sum of 34 filter cycles for evaluation (1 cycle represents the time period between two filter exchanges or compressor offline washings). The filter houses of the assessed plants are equipped with 2- or 3-stage filtration systems with filter classes ranging from G4 to E11 and various combinations thereof. The relevant data for power output and compressor efficiency together with the exchange history of the air filters is used to determine the degradation as a function of the last filter stage class, which allows for a quantification of the degradation and reveals a clear correlation. As it is shown that not only the last stage filter with the highest filter class determines the degradation, but the filter system with all stages as a combination, this paper additionally evaluates the effect of the second-last filter class on the degradation. Due to more and more challenging market environments for the plant owners, the decision to opt for highly efficient EPA filters must be well-considered: more efficient filters generally have a higher pressure loss with a negative influence on power output and are generally more expensive. Nevertheless, EPA filtration can be a strong business case when all factors such as prices for electricity and gas, operating regime of the plant, pressure loss and exchange scenarios of the filters, necessity for compressor washing etc. are considered. An exemplary profitability analysis considering all the above mentioned factors is presented in this paper. The insights of this paper shall be used as a basis for decision making when it comes to the question of how to lay out the project specific GT air inlet filtration system, as well as of how to modify the existing GT air inlet filtration for improved performance and economics.

Leya Roshani Kober, Pranay Shrestha, Spencer Lytle et al.

ECS Meeting Abstracts • 2023

The catastrophic effects of atmospheric greenhouse gases and the depletion of non-renewable resources has led to the urgency to develop clean, sustainable energy technologies to meet increasing energy demands. However, the intermittent nature of current renewable energy technologies warrants the acquisition of on-demand renewable energy through either energy production or storage methods. Polymer electrolyte membrane fuel cells (PEMFCs) are promising candidates for this task, as they utilize the most abundant element on Earth, hydrogen, to produce high amounts of power under rapid changes in load with little to no greenhouse gas emissions (1). Therefore, PEMFCs have great potential to help offset the negative impact of atmospheric pollution due to excessive carbon emissions. However, liquid water management issues associated with high power output of the fuel cell typically leads to reduced performance and durability of the fuel cell, and thereby hinders global implementation of these devices (2). To minimize these losses and improve GDL material designs, an understanding of the relationship between product liquid water distributions in the cathode GDL and transport properties of PEMFCs under varying operating conditions is highly valuable. Previous works have characterized the effect of operating temperature on liquid water pathways and distributions in GDLs by visualizing operando PEMFCs with 3D imaging techniques such as X-ray computed tomography (CT) (3). The high-speed, high-resolution capabilities of these imaging techniques enable the visualization of dynamic pore-scale activity to elucidate transport mechanisms in the GDL. In this work, the effect of inlet relative humidity on the formation and distribution of liquid water pathways in cathode GDLs is investigated by imaging a PEMFC operando with synchrotron X-ray CT at high spatial resolution, enabling the resolution of water in the individual pores of the GDL. The contribution of a microporous layer (MPL) is also explored by imaging a cell with an MPL and without. Imaging is conducted on a specialized cell designed to facilitate continuous rotation about the CT stage, enabling fast acquisition of consecutive scans to achieve high temporal resolution useful for visualizing the dynamic development of preferential water pathways. Additionally, electrochemical impedance spectroscopy was performed to quantify mass transport losses. The sequence of CT images was utilized to capture the dynamics of liquid water development as well as stabilized water distributions. Visualizing the reconstructed images shows that as current increases, water production increases, and the development of water pathways to breakthrough at the flow field interface is observed. Additionally, results show that an increase in relative humidity led to a significant increase in cathode GDL water saturation. The contribution of this study to understanding transport mechanisms in GDL materials is significant to the characterization and optimal design of materials for improved PEMFC performance. Ultimately, the goal of this work is to accelerate the worldwide adoption of PEMFCs as a sustainable, reliable solution to replace conventional carbon-emitting energy sources. 1. Alaswad et al. , J. Hydrog. Energy , 41 , (2016) 2. Nagai et al. , J. Power Sources , 435 , (2019) 3. D. Shum et al. , Electrochem. Acta , 256 , (2017)

Natalia Macauley, Derek James Strasser, Kathryn Coletti et al.

ECS Meeting Abstracts • 2024

Heavy-duty PEM fuel cells are expected to last 25,000-30,000 hours in the field. Therefore, materials, components, and interfaces used in these systems must be highly resistant to severe mechanical and chemical stress. Novel, highly active stable Pt and ordered PtCo intermetallic nanoparticles with well-controlled particle size and composition have been synthesized on a highly efficient PGM-free single metal active site rich carbon, to maximize their synergistic effects for enhanced performance and durability. Integrating these catalysts integrated with high O 2 permeability ionomer (HOPI) in membrane electrode assemblies (MEAs) improved their fuel cell performance and durability, allowing the MEAs to achieve >1.2 A/cm 2 at 0.7 V after 150k square wave accelerated stress test (AST) cycles, with a performance loss < 40 mV after 150K AST cycles. In a PEM fuel cell, the catalyst ink formulation and mixing processes control catalyst layer coating quality, electrode morphology, and the resulting fuel cell performance and durability. Catalyst ink properties are a result of complex solvent-catalyst-ionomer interactions that depend on the mixing method employed. Here, we compare the performance and durability of electrodes made from ball milled inks for Mayer rod coating before and after the catalyst scale up. Ink rheology and catalyst particle size are used to correlate ink properties to electrode morphology and structure and ensure consistency from batch to batch, and from small lab scale to subsequent scale-up. We evaluate and discuss the challenges that arise when coating the more viscous inks on decals, where the HOPI creates many bubbles in the ink. We also present the challenges of hot-pressing inks that contain HOPI, and how employing a Nafion overspray made with different solvents (isopropanol vs. ethanol) can improve hot-pressing. We investigate the how ionomer to carbon ratio affects hot pressing with HOPI and crack formation in the electrode via scanning electron microscopy (SEM). This work provides a comprehensive understanding of interactions between Pt, PtCo, carbon, ionomer, membrane, and GDLs and their impact on electrode structure, fuel cell performance and durability, as well as considerations for scale up to a R2R fabrication process. The attained information will be used to improve fuel cell electrode design, fabrication and scale-up. Acknowledgement: The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-FOA-0002360 (Phase I) and DE-SC0021671 (Phase II). Figure 1

Chong Yang Gao, Ai Jie Wang, Yang Guo Zhao

Advanced Materials Research • 2014

Double-chambered microbial fuel cells (MFCs) were used to investigate the effect of sulfate and sulfate-reducing bacteria (SRB) on electricity generation by molybdate inhibition coupled with PCR-DGGE technique. Results showed that low influent sulfate (< 1470 mg/L) improved power density and voltage, while higher sulfate blocked the MFC efficiency. Molybdate inhibited the activity of SRB and consequently decreased MFC voltage and power density which confirmed some SRB were involved in the electricity generation. Microbial community analysis indicated that Desulfovibrio desulfuricans contributed to the electricity production and stability of MFC.

Charles B Staub, Jason M Christ, Guido Bender et al.

ECS Meeting Abstracts • 2015

Extensive research on fuel cell stack materials has led to advances in lower cost, high performing materials. With the decrease in the cost of stack materials, lowering the cost of the balance of plant (BOP) components has increased in importance. In order to decrease the overall cost of the automotive and stationary fuel cell systems and make them as competitive as possible, low-cost system component materials that provide similar function, performance and durability are needed. However, intelligently selecting low cost materials for application in polymer electrolyte membrane fuel cell (PEMFC) systems requires understanding the potential adverse effects that system contaminants may have on the fuel cell performance and durability. Limited work in this area has been conducted to-date. There are many prospective BOP materials that can be used in fuel cell systems. Our material selection was based on the material’s physical properties (i.e., whether it will be stable in fuel cell operating conditions), commercial availability, cost and input from OEMs and fuel cell system manufacturer. Families of material chosen for the study include structural materials, elastomers for seals and (sub)gaskets, and assembly aids (adhesives, lubricants). Two types of low cost structural plastic materials – a polythlalamide and a polyamide – were studied. Leachates obtained from these plastics were a mixture of organics, inorganics, and ions and were introduced to a working fuel cell to determine their effect on the fuel cells performance. Organics that were identified in the leachate solutions via gas chromatography mass spectrometry (GCMS) include 1,8 Diazacyclotetradecane-2,7-dione (DCTDD), aniline, and caprolactam. These plastic materials also released anions: chloride, phosphate, nitrates, and sulfates . In-situ measurements such as infusion, cyclic voltammetry, impedance spectroscopy, and I-V curves were carried out to better characterize the contaminants effects of the mixtures of compounds in the extracts. The effect of the individual organic model compound (caprolactam), anion (sulfate) and mixtures of the two species were also studied to better understand the contamination mechanisms of specific species and their interaction with one another. This presentation will also briefly describe the ex-situ electrochemical quartz crystal microbalance (EQCMB) technique used to study the adsorption effect of organic compounds, derived from system contaminants, on Pt surface. EQCMB was used to measure the change in mass of the electrode as a function of potential. The authors would like to acknowledge funding from the U.S. Department of Energy EERE Fuel Cell Technologies Office, under Contract No. AC36-08GO28308 with the National Renewable Energy Laboratory and collaborations with colleagues at GM and 3M. Structural plastic materials were provided by GM and membrane degradation products for this study were provided by 3M.

Jin Xin, Xiaohan Liu, Xiaoyan Wei

Volume 3: Nuclear Fuel and Material, Reactor Physics and Transport Theory; Innovative Nuclear Power Plant Design and New Technology Application • 2017

For most fuel rod codes, the time independent heat conduction equation, which is a steady heat conduction equation, is applied in fuel temperature calculation. However, it can affect the fuel temperature prediction in II condition, which the linear power has much change in some seconds. For improving the fuel temperature prediction in II condition, this paper gives a new numerical method, which combines classical thermal conduction integration method and the difference applied in time partial derivative. For guaranteeing the numerical method’s stability and convergence rate, the multi-dimension Newton-Raphson procedure are applied in fuel temperature calculation. This paper describes the theoretical deduction of the numerical method, and Halden fuel thermal conductivity model applied in fuel temperature calculation. In order to verify new numerical method’s correctness, stability and convergence rate, the comparison between numerical solution and analytic solution is performed in 4 hypothetical conditions that the power transient duration is respectively 3s, 15s, 30s and 120s, the linear power changes from 15kW/m to 45 kW/m, and the fuel pellet surface temperature changes from 400 degree to 750 degree. And fuel density, specific heat and thermal conductivity are assumed as constants so that there exists analytic solution in this condition. The 4 hypothetical conditions have covered the worst II condition. According to the results in 4 hypothetical conditions, the fuel centerline temperature relative difference between numerical solution and theoretical solution is less than 0.6%, and the iterations are less than 5. So the numerical method possesses excellent correctness, stability and convergence, and this method has much potential in application in fuel rod code.