Experimental study of the pressure drop in the cathode side of air-forced Open-cathode proton exchange membrane fuel cells

Barreras, Félix; López, Ana M.; Lozano, Antonio; Barranco, J.

doi:10.1016/j.ijhydene.2011.03.149

Cited by 41 publications

(25 citation statements)

References 24 publications

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“…The tasks described in this "in the classroom" paper are in the first place for students of hydraulics, petroleum engineering and water resources [71] but also for students of all engineering branches where fluid flow can occur [72][73][74], including fuel cells [75,76].…”

Section: Resultsmentioning

confidence: 99%

Solution of the Implicit Colebrook Equation for Flow Friction Using Excel

Brkić

2017

Preprint

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Empirical Colebrook equation implicit in unknown flow friction factor (λ) is an accepted standard for calculation of hydraulic resistance in hydraulically smooth and rough pipes. The Colebrook equation gives friction factor (λ) implicitly as a function of the Reynolds number (Re) and relative roughness (ε/D) of inner pipe surface; i.e. λ 0 =f(λ 0 , Re, ε/D). The paper presents a problem that requires iterative methods for the solution. In particular, the implicit method used for calculating the friction factor λ 0 is an application of fixedpoint iterations. The type of problem discussed in this "in the classroom paper" is commonly encountered in fluid dynamics, and this paper provides readers with the tools necessary to solve similar problems. Students' task is to solve the equation using Excel where the procedure for that is explained in this "in the classroom" paper. Also, up to date numerous explicit approximations of the Colebrook equation are available where as an additional task for students can be evaluation of the error introduced by these explicit approximations λ≈f(Re, ε/D) compared with the iterative solution of implicit equation which can be treated as accurate.

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Section: Resultsmentioning

confidence: 99%

Solution of the Implicit Colebrook Equation for Flow Friction Using Excel

Brkić

2017

Preprint

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“…As the Colebrook equation is empirical [1,16], its accuracy can be disputed [17,18] (e.g., the new Oregon and Princeton experiment related to pipe friction [18]); nevertheless, the equation is widely accepted as a standard and is in common use in the design of water and gas pipe networks [19]. It can be also adapted for special cases such as air flow through fuel cells [20], water flow in rivers [21,22] and blood flow in blood vessels [23].…”

Section: 51mentioning

confidence: 99%

Colebrook’s Flow Friction Explicit Approximations Based on Fixed-Point Iterative Cycles and Symbolic Regression

Brkić

Praks

2019

Computation

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The logarithmic Colebrook flow friction equation is implicitly given in respect to an unknown flow friction factor. Traditionally, an explicit approximation of the Colebrook equation requires evaluation of computationally demanding transcendental functions, such as logarithmic, exponential, non-integer power, Lambert W and Wright Ω functions. Conversely, we herein present several computationally cheap explicit approximations of the Colebrook equation that require only one logarithmic function in the initial stage, whilst for the remaining iterations the cheap Padé approximant of the first order is used instead. Moreover, symbolic regression was used for the development of a novel starting point, which significantly reduces the error of internal iterations compared with the fixed value staring point. Despite the starting point using a simple rational function, it reduces the relative error of the approximation with one internal cycle from 1.81% to 0.156% (i.e., by a factor of 11.6), whereas the relative error of the approximation with two internal cycles is reduced from 0.317% to 0.0259% (i.e., by a factor of 12.24). This error analysis uses a sample with 2 million quasi-Monte Carlo points and the Sobol sequence.

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“…The geometry of these channels is one of the most important factors to obtain a good performance of the fuel cell system. For simplicity and to ensure a low pressure drop [19,20], parallel straight channels are normally preferred in air-cooling systems.…”

Section: The Excess Of Heat Management Systemmentioning

confidence: 99%

Optimal design and operational tests of a high-temperature PEM fuel cell for a combined heat and power unit

Barreras

Lozano

Roda

et al. 2014

International Journal of Hydrogen Energy

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Development of new materials for polymer electrolyte membranes has allowed increasing the operational temperature of PEM fuel cell stacks above 120C. The present paper summarizes the main results obtained in a research devoted to the design, fabrication and operational tests performed on a high-temperature PEMFC prototype. A 5-cell stack has been assembled with commercial Celtec P-1000 hightemperature MEAs from BASF Fuel Cells, but the rest of elements and processes have been developed at LIFTEC research facilities. The main innovations of the present study are related to the design of the stack, and to the manufacturing and operation procedures. The novelties in the design include the flowfield geometry for both anode and cathode plates, the way in which reactant gases are supplied to the flowfield, the concept of block that eases the assembly and maintenance processes, and the heating strategy for a very fast start-up. The changes introduced to the assembly, closing and conditioning procedures are extensively described and discussed in the manuscript and contribute to the improvement in the stack performance. Results obtained in the preliminary operational tests performed are very promising, and it is expected that the 30-cells HT-PEMFC stack will deliver an electric power 2.3 times larger than the one initially predicted. A well known highly efficient technology to generate electricity and thermal energy from a single fuel source is co-generation, also known as CHP (combined heat and power). This approach can also be used in a decentralized way, improving energy efficiency, security in energy supply, and reduction of CO 2 emissions. The EU and National Governments encourage the use of micro-combined heat and power systems (µ-CHP), in order to meet international and domestic targets on carbon emissions. For example, it is expected that by 2050 µ-CHP systems could provide 30-40% of the UK electricity needs [6]. To achieve this goal, the UK Government has lowered VAT from 17.5% to 5% for households that install µ-CHP systems, and has increased the planned reduction of carbon emissions for households up to 60% by 2050. In the same way, the Dutch Government is promoting similar initiatives and made public funding available to companies developing mass-market CHP systems [7]. µ-CHPs are especially interesting for small family houses (SFH) and medium family houses (MFH), small buildings and small and medium scale enterprises (SME) due to the very low noise and vibration levels. As both electricity and thermal energy demands fluctuate seasonally and hourly in residential buildings, it is necessary to take into account operational strategies for the variations in load demands. Then, it is necessary to develop a rational method of determining the size of the systems, as well as the operational strategies throughout the year [8].As the minimum required temperature in buildings may vary between 40C and 80C, an output temperature close to 100C is a convenient value for a µ-CHP system.In this context, fuel cell...

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Experimental study of the pressure drop in the cathode side of air-forced Open-cathode proton exchange membrane fuel cells

Cited by 41 publications

References 24 publications

Solution of the Implicit Colebrook Equation for Flow Friction Using Excel

Solution of the Implicit Colebrook Equation for Flow Friction Using Excel

Colebrook’s Flow Friction Explicit Approximations Based on Fixed-Point Iterative Cycles and Symbolic Regression

Optimal design and operational tests of a high-temperature PEM fuel cell for a combined heat and power unit

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