Some comments to the paper 'Energy, exergy and sustainability analyses of hybrid renewable energy based hydrogen and electricity production and storage systems: Modeling and case study'

摘要

With the methodological approach described by the authors for the determination of the turbine's exergy efficiency, the main problem in the calculation lies in the measurement of the outlet air speed. The determination of the other parameters present no great difficulty [6]. The analysis of the data used by the authors to solve their case study shows that they appear to have calculated the outlet speed assuming that the process that takes place in the turbine is reversible. Consequently, their value is given by the expression: v_2 = 3 {the squar root of}(2(E_(potencial) - E_(generated))/ρAt (13) which was used by Dincer et al. in a previous work [3]. If, as appears to be the case, this is so then it is unnecessary to perform any exergy analysis of the wind turbine since the results would simply be those corresponding to the reversible process. Consequently, the exergy efficiency would be 100%, as for any reversible process.