Validation of an externally oil-cooled 1 kWel HT-PEMFC stack operating at various experimental conditions (original) (raw)
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International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/effect-of-voltage-operation-temperature-on-performance-of-self-humidified-pem-fuel-cell-stack https://www.ijert.org/research/effect-of-voltage-operation-temperature-on-performance-of-self-humidified-pem-fuel-cell-stack-IJERTV3IS10867.pdf The Proton Exchange Membrane Fuel Cell (PEMFC) is a promising candidate as zero-emission alternative power source for transport & stationary application due to its high efficiency ,low temperature operation ,high power density ,quick start-up and system robustness. In this paper, under the condition of steady state and flow in cell is considered to be laminar, the performance of 300w &100w PEMFC stack has been studied.300w fuel cell is compact &100w fuel cell is openable. This cell is self-humidified. Series of polarisation curves with different loading of voltage have been studied. various values of voltage, current density, power density &related temperature have been recorded using lab VIEW software. For this class of fuel cell, optimal operating temperature is found to be 75 0 c at 0.3v loading.the results obtained would lead to improvements in the design of fuel cell.
Thermal and electrical experimental characterisation of a 1 kW PEM fuel cell stack
International Journal of Hydrogen Energy, 2013
The present work describes the experimental characterisation of a self-humidified 1 kW PEM fuel stack with 24 cells. A test bench was prepared and used to operate a PEMFC stack, and several parameters, such as the temperature, pressure, stoichiometry, current and voltage of each cell, were monitored with a LabView platform to obtain a complete thermal and electrical characterisation. The stack was operated in the constant resistance load regime, in dead-end mode (with periodic releases of hydrogen), with 30% relative humidity air and with temperature control from a cooling water circuit. The need to operate the stack for significant periods of time to achieve repeatable performance behaviour was observed, as was the advantage of using some recuperation techniques to improve electrical energy production. At low temperatures, the individual cell voltage measurements show lower values for the cells nearer to the cooling channels. The performance of the fuel cell stack decreases at operating temperatures above 40 C. The stack showed the best performance and stability at 30 C, with 300 mbar of hydrogen and 500 mbar of air pressure. The optimised hydrogen purge interval was 15 s, and the most favourable air stoichiometry was 2. Between 15 A and 32 A, the maximum electrical efficiency was 40%, and the thermal energy recovery in the cooling system was 40.8%; these values are based on the HHV. Electrical efficiencies above 40% were obtained between 10 and 55 A. The variation in the electrical efficiency is explained by the variation in the following independently measured factors: the fuel utilisation coefficient and the faradic and voltage efficiencies. The deviation between the product of the factors and the measured electrical efficiency is below 0.5%. Measurements were taken to identify all the losses from the fuel cell stack; namely, the energy balance to the cooling water, which is the main portion. The other quantified losses by order of importance are the purged hydrogen and the latent and sensible heat losses from the cathode exhaust. The heat losses to the environment were also estimated based on the measured stack surface temperature. The sum of all the losses and the electrical output has a closure error below 2% except at the highest and lowest loads.
Effect of operative conditions on a PEFC stack performance
International Journal of Hydrogen Energy, 2008
The operative conditions influence the performance of a polymer electrolyte fuel cell (PEFC). In particular, when a multi-cell (stack) instead of a single cell is investigated, a proper water management and flow stoichiometric ratio are essential for obtaining high electrical conversion efficiency. In this paper, a five cell air cooled PEM fuel cell stack was designed and realized, and systematic studies on the influence of the reactants humidification have been carried out to optimize the operative conditions. Polarization curves and time test at a fixed current have been conducted for various cathode (RHC) and anode (RHA) inlet humidity conditions. In particular, a small decay and low performance were obtained for RHA and RHC<70%RHC<70% and a considerable decay and low performance for RHA and RHC>70%RHC>70%. A good compromise for water management, in terms of decay and performance, is obtained when a symmetrical RH of 70% was used, because in this case an optimal water balance was probably reached considering that high flow of gases was used. In fact, insufficient water content implies a lower ion conductivity of the membrane whereas excess of water yields to flooding of the electrodes and parasitic losses due to the presence of water in the gas channels. Consequently, these effects lead to a lowering of voltages during lifetime tests. In any case, the cathode RH has a stronger influence on the stack decay compared to the anode one. In the optimal selected conditions of RH a constant and stable power of about 55 W (at 20 A) was obtained during the 15 h of operation.
1.5 kWe HT-PEFC stack with composite MEA for CHP application
International Journal of Hydrogen Energy, 2013
In this work, the performance of a High Temperature (HT) Polymer Electrolyte Fuel Cell (PEFC) stack for co-generation application was investigated. A 3 kW power unit composed of two 1.5 kW modules was designed, manufactured and tested. The module was composed of 40 composite graphite cell with an active area of 150 cm 2. Composite Membrane Electrode Assemblies (MEAs) based on Nafion/Zirconia membranes were used to explore the behavior of the stack at high temperature (120 C). Tests were performed in both pure Hydrogen and H 2 /CO 2 /CO mixture at different humidification grade, simulating the exit gas from a methane fuel processor. The fuel cells stack has generated a maximum power of 2400 W at 105 A with pure hydrogen and fully hydrated gases and 1700 W at 90 A by operating at low humidity grade (95/49 RH% for H 2 /Air). In case the stack was fed with reformate simulated stream fully saturated, a maximum power of 2290 W at 105 A was reached: only a power loss of 5% was recorded by using reformate stream instead of pure hydrogen. The humidification grade of Nafion membrane was indicated as the main factor affecting the proton conductivity of Nafion while the addition of the inert compound like YSZ, did not affectthe electrochemical properties of the membrane but, rather has enhanced mechanical resistance at high temperature.
High performance PEMFC stack with open-cathode at ambient pressure and temperature conditions
International Journal of Hydrogen Energy, 2007
An open-air cathode proton exchange membrane fuel cell (PEMFC) was developed. This paper presents a study of the effect of several critical operating conditions on the performance of an 8-cell stack. The studied operating conditions such as cell temperature, air flow rate and hydrogen pressure and flow rate were varied in order to identify situations that could arise when the PEMFC stack is used in low-power portable PEMFC applications. The stack uses an air fan in the edge of the cathode manifolds, combining high stoichiometric oxidant supply and stack cooling purposes. In comparison with natural convection air-breathing stacks, the air dual-function approach brings higher stack performances, at the expense of having a lower use of the total stack power output. Although improving the electrochemical reactions kinetics and decreasing the polarization effects, the increase of the stack temperature lead to membrane excessive dehydration (loss of sorbed water), increasing the ohmic resistance of the stack (lower performance).
Theoretical and experimental investigations on thermal management of a PEMFC stack
Fuel and Energy Abstracts, 2011
In recent years micro-cogeneration systems (μ-CHPs), based on fuel cells technology, have received increasing attention because, by providing both useful electricity and heat with high efficiency, even at partial loads, they can have a strategic role in reduction of greenhouse gas emissions. For residential applications, the proton exchange membrane fuel cell (PEMFC), is considered the most promising, since it offers many advantages such as high power density, low operating temperature, and fast start-up and shutdown.In this paper the electrical and thermal behaviors of a PEMFC stack, suitable for μ-CHP applications, have been investigated through experimental and numerical activity.The experimental activity has been carried out in a test station in which several measurement instruments and controlling devices are installed to define the behavior of a water-cooled PEMFC stack. The test station is equipped by a National Instruments Compact DAQ real-time data acquisition and control s...
Thermal and electrical energy management in a PEMFC stack – An analytical approach
International Journal of Heat and Mass Transfer, 2008
An analytical method has been developed to differentiate the electrical and thermal resistance of the PEM fuel cell assembly in the fuel cell operating conditions. The usefulness of this method lies in the determination of the electrical resistance based on the polarization curve and the thermal resistance from the mass balance. This method also paves way for the evaluation of cogeneration from a PEMFC power plant. Based on this approach, the increase in current and resistance due to unit change in temperature at a particular current density has been evaluated. It was observed that the internal resistance of the cell is dependent on the electrode fabrication process, which also play a major role in the thermal management of the fuel cell stack.
PEMFC stacks for power generation
Proceedings of the …, 1999
Industries promoting polymer electrolyte membrane (PEM) fuel cells for stationary and auxiliary power applications are receiving considerable attention because of the attractiveness of the primary markets, such as small, home-based power generation on the roughly 3 -5 kW level. More recently, interest in auxiliary power applications down to about the 1 kW level has also been steadily increasing. Plug Power, LLC, a fuel cell manufacturer, is primarily pursuing the development of the home-based power systems. Technological advances in PEM fuel cells at Los Alamos National Laboratory (LANL) are of potential utility for the development of readily manufacturable, low-cost and high performance fuel cell systems operating at near-ambient reactant pressures. As such, the two parties are collaborating on addressing some of the more pressing needs as well as some longer term issues. The primary tasks involve the investigation of both stainless steel and composite bipolar plates, CO tolerant anodes, and novel fuel cell system operation schemes.