Efficiency Analysis Of The Hydrogen Energy System

In the past decades,hydrogen had attracted wide attention as a kind of electrochemical energy converter.Compared to traditional gasoline motor car,the reason why hydrogen fuel cell be favoured of the public is it’s high energy conversion rate and the production contains no air pollutant,so that the hydrogen fuel cell is expected to be a competitive choice.Therefore,we need to define the efficiency of the fuel cell and the system of fuel cell and analyze them elaboratively.Based on this,we need to summarize the efficiency of other parts of the hydrogen production chain,so that we can have a comprehensive understanding of the whole industry,the system of fuel cell and the single fuel cell.With the help of this,we can create a firm foundation.This article uses a system of PEM fuel cell as a model,and base on energy and exergy analysis,combining the unit consumption analysis theory,so that we can calculate the energy consumption distribution detailedly.Firstly,this article divide the system of fuel cell into oxygen system and hydrogen system,and point out the corresponding solutions of the main material state parameters and the performance parameters of equipment.Especially,this article has set up the mathematical model for several complicated equipment.Next,this article has set up the model based on exergy analysis for the subsequent analysis,and established correspondingly irreversible loss calculation model for each thermal process for the sake of calculating irreversible loss of every stage.In the phase of energy consumption analysis,firstly,this article ensure parameters of equipment under the given operating conditions,then calculate the irreversible loss of each subsystem,so that we can the energy consumption distribution of the whole system.At last,this article calculates the exergy efficiency of system by using the positive and negative balance,and contrasting them.Especially,this article has calculated the practical transfer efficiency of the fuel cell stack.After calculating and analyzing the system of the 260KW fuel cell,we can come to these conclusions:(1)The largest irreversible loss happens in the fuel cell stack,and in the best case,the irreversible loss is 339.39kW and the irreversible loss rate of fuel cell stack is 0.502;(2)By using the positive and negative equilibrium,we can figure out the exergy efficiency of the system of fuel cell is 30.24%and 30.76%respectively.But if we calculate the irreversible loss by backstepping other thermal processes,the exergy efficiency of the system comes to 38.01%.(3)Combining the efficiencies of other parts of Hydrogen production chain,the efficiency of the whole hydrogen system would come to 18.3%.