70 Mpa Hydrogen Refuelling Stations

Transcription

1 70 Mpa Hydrogen Refuelling Stations Ph.d. Student: Erasmus Rothuizen DTU/MEK Section of Thermal Energy Systems In cooperation with H2Logic Supervisor: Masoud Rokni

2 Agenda Hydrogen Vehicles Meeting costumers demand Simple hydrogen refuelling Optimization of simple hydrogen refuelling Pressure losses Example from Holstebro refuelling station Objectives for PhD 2 DTU Mekanik, Danmarks Tekniske Universitet

3 Hydrogen Vehicles Why Fuel cell vehicles? Peak oil Global warming Limitations of raw materials for batteries and biofuel Advantages of hydrogen vehicles Unlimited source Ideally 100 % carbon free No health threatening emissions Costumers demand Driving distance Refuelling time Comfort/equipment Mercedes F-Cell How can we fulfil the demands? 3 DTU Mekanik, Danmarks Tekniske Universitet

4 Hydrogen as Fuel for Vehicles Fulfilments of costumers demands Driving Distance Low density but high energy density Low energy per volume ratio at 1 atm 5-7 kg hydrogen for km Need for compression or liquefaction Liquefaction vs. 700 bar compression Compression to 700 bar Infinite storage time App L high pressure vessels Liquefaction App. 5 times more energy needed Limited storage time as expansion is needed to keep liquid 4 DTU Mekanik, Danmarks Tekniske Universitet

5 High Pressure Hydrogen Fuelling Fast filling costumer demand 3-5 min fuelling from 20 to 700 bar Safety Safety of pressure vessel requires -40 < T < 85 C SAE TIR J2601 is a costumer acceptable fuelling protocol Describes the important aspects of a fast safe fuelling Average filling rate (Average pressure ramp rate APRR) Mpa/min (decides the filling time) Hydrogen temperature at nozzle (T=-40 C) State of charge (SOC) 5 DTU Mekanik, Danmarks Tekniske Universitet

6 Simple systems for refuelling hydrogen 2 methods for refilling a moveable hydrogen vessel Direct compression The simplest system using a compressor directly connected to the vessel. Hard to control APRR Large/expensive compressor Vessel to vessel filling Compresses hydrogen to e.g. 900 bars in a stationary vessel which then fills the moveable vessel Requires more energy Easy to control Vessel to vessel filling is the most common today and used for fast filling hydrogen refuelling stations 6 DTU Mekanik, Danmarks Tekniske Universitet

7 Vessel to Vessel refuelling Has to be throttled to slow down the filling process Lost energy Negative Joule-Thomson coefficient for hydrogen above 200 K or 16 MPa. Needs cooling in order not to exceed the temperature limit of the hydrogen vessel Compression in cylinder forces hydrogen to heat up 7 DTU Mekanik, Danmarks Tekniske Universitet

8 Example with and without cooling 8 DTU Mekanik, Danmarks Tekniske Universitet

9 Mass of the system The total mass of the system at finished fuelling's to 720 bar High vessel temperature (lower hydrogen density) Lower mass (smaller driving distance) Lower final pressure at ambient temperature > State of charge (SOC) -> cooling 9 DTU Mekanik, Danmarks Tekniske Universitet

10 The Cooling Demand 10 DTU Mekanik, Danmarks Tekniske Universitet

11 Simple Optimization 11 DTU Mekanik, Danmarks Tekniske Universitet

12 Multiple Step fuelling Advantages More energy efficient Lower cooling demand for 2 step fuelling Lower compressor work Drawbacks More complicated setup More components 12 DTU Mekanik, Danmarks Tekniske Universitet

13 Systems with Pressure Drop Changes in the system Mass flow start in 0 and peaks Lower peak cooling demand 13 DTU Mekanik, Danmarks Tekniske Universitet

14 Holstebro Hydrogen Refilling Station DTU Mekanik, Danmarks Tekniske Universitet

15 Objectives for PhD study Dynamic simulation Analyse pressure drops, temperatures and mass flows Compare systems Energy optimization of the system Energy optimization using exergy analysis Economic energy optimization Vessel optimization Numbers Size Pressure Compressor Work producing expansion How much energy could be recovered 15 DTU Mekanik, Danmarks Tekniske Universitet

16 Questions? 16 DTU Mekanik, Danmarks Tekniske Universitet