A Volt-Ampere Method to Estimate the Energy Efficiency Evolutions of Proton Exchange Membrane Fuel Cells along with Load and Time

Abstract

<p class="MsoNormal" style="text-align:justify;"> <span lang="EN-US">The energy efficiency of proton exchange membrane (PEM) fuel cells always keeps changing with load and time. Con</span><span lang="EN-US">sidering cell diversity and operation variety, it’s of necessity to find a simple method to estimate the changes. The work is done with the recently developed ideal cell model on behalf of various real cells, and results in a complete set of effi</span><span lang="EN-US">ciency formulae including one for the instantaneous and three for the average. The formulae stand for a volt-ampere method which permits the average efficiency to be estimated in the form of state function of cell output like the instan</span><span lang="EN-US">taneous efficiency. With cell constants for cell specialty representation in this method, the formulae can extend to cover various real cells and make it realized to broadly overview the instantaneous and average efficiency movements with both load and time throughout cell operating ranges. The energy efficiency formulization and overviews may help make clear the correlative parameters with the efficiency, help deepen acquaintance with efficiency change and assist in cell operation optimization.</span><span lang="EN-US"><o:p></o:p></span> </p

The Two-Constant Cost Model and the Estimation of the Cost Performance Evolutions of the Proton Exchange Membrane Fuel Cell Power Generation

“…A comparison between the first ECR basic expression and the basic expression for the average energy efficiency given in our last work [9] may well reveal the close connection between the average energy efficiency and the ECR. It may be indicated that an internal fusion of average energy efficiency and cost items is required for the ECR calculation, while the external fusion in which the average energy efficiency was included as an independent parameter [1,3] may not be the most appropriate treatment.…”

“…The ECR first basic expression can be unfolded as the average energy efficiency basic expression has been done [9]. To get the ECR basic expression manifested, the relationship between l and j should be firstly obtained, as given in Formula (5) or (6).…”

“…It is derived by jointly solving the cell and load characteristic equations according to the ideal cell model. See our recent works [5,9] for details of the two characteristic equations.…”

“…According to our recent works [5,9], the working zone may well define the whole operating range of a cell, so it may just be the application range of the ECR equation. In j/U plane, the working zone is an enclosed area by the initial SSP curve, the final SSP curve or the absolute lifetime end-curve, the relative lifetime end-curve and the j = 0 line.…”

Discrimination and Estimation of the Maximum Cost Performance of Proton Exchange Membrane Fuel Cell Power Generation with Seven Constants

“…3) Restrictions on the extraction As stated in our recent works [1,3], in order to meet load requirement, PEM fuel cells should operate in a certain range of current and voltage. Termed the working zone of the cells, the range is determined jointly by cell characteristic, load characteristic and cell absolute lifetime (the fifth cell constant, denoted by L a ).…”