Compressors for PEMFC Thomas Nietsch»This document is s property and should not be copied or transmitted without prior authorization
Overview Compressor power consumption Compressor power consumption vs PEMFC power Compressor types Compressor examples Comparison Conclusions»This document is s property and should not be copied or transmitted without prior authorization
Calculation of air compression power p c η T 1 p = cp ηcom p : heat capacity : efficiency * 1 m γ : gas compression factor cp/cv * p p comp p com m : gas flow 2 1 : outlet pressure :inlet pressure 2 1 T1: inlet temperature U: voltage γ 1 γ T air,out 0,28 T air,in p out = T air,in+ 1 ηc pin»warning: T out let > 100 C @ p > 3 bar possible»this document is s property and should not be copied or transmitted without prior authorization
Compressors and pumps / Wanted characteristics Supply reaction air Supply fuel (hydrogen) Circulate / supply coolants Wanted characteristics Low cost High efficient / low electrical power consumption Flow rate Noise / vibration Reliable (for long time) Start up time Dynamics Number of starts / stops Out let gas quality Inlet gas quality others»this document is s property and should not be copied or transmitted without prior authorization
Compressor types»this document is s property and should not be copied or transmitted without prior authorization
Exemples 1 Spiral pump Water driven pump Might be used for humidification Needs water Low efficiency Spiral pump Air is compressed between a fixed and a mobile spiral»this document is s property and should not be copied or transmitted without prior authorization
Examples 2 Screw compressor High pressure and good efficiency possible 2 counter rotating screws Type 1: only one screw is driven by a motor, second by the first one. Oil is need for lubryfication. Type 2: both screws are driven via a gear box. High precision is need for the screw for not being in contact but limiting the leakage in-between. Oil free.»this document is s property and should not be copied or transmitted without prior authorization
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Examples 3 Roots compressor Roots compressor»cheap»wide flow rate range»acceptable efficiency for small pressure ratios»this document is s property and should not be copied or transmitted without prior authorization
Examples 4 Piston compressors»this document is s property and should not be copied or transmitted without prior authorization
Examples 5 Diaphragm compressors Cheap Good separation of gases Limited flow rate»this document is s property and should not be copied or transmitted without prior authorization
Examples 6 Centrifugal or radial compressors Centrifugal or radial compressors Cheap Wide flow rate Efficiency as others Efficient only for design point (flow, pressure,..) Efficiency drops out of design point => poor dynamic»this document is s property and should not be copied or transmitted without prior authorization
Injectors»Total passive system»no energy consumption»gas A mixes with gas C»Pressure in A > pressure B, C & D»Geometry has to be adapted to flow rate, pressure, etc.»this document is s property and should not be copied or transmitted without prior authorization