Engineering Safe and Efficient Hydride- Based Technologies(ESEHBT)

Transcription

1 Engineering Safe and Efficient Hydride- Based Technologies(ESEHBT) Engineering Safe and Compact Hydrogen Energy Reserves (ESCHER) David Grant, Gavin Walker, Evangelos Gkanas, Alastair Stuart Materials, Mechanics and Structures Research Division, Faculty of Engineering, University of Nottingham David Book, Rex Harris, Shahrouz Nayebossadri, Lydia Pickering, Yanmeng Chao, School of Metallurgy & Materials University of Birmingham W. Malalasekera (Malal), Salah Ibrahim, Maxim Bragin, Tom Beard Wolfson School of Mechanical and Manufacturing Engineering, Department of Aeronautical and Automotive Engineering, Loughborough University

2 AIMS To optimise metal hydride based technologies that are extremely compact but also have a high level of safety. Develop a module sized for the smallest application, i.e. daily top-up for a commuter vehicle, with the system able to be expanded by increasing the number of modules to fully charge multiple vehicles for either a community charging point, or for servicing a small fleet of commercial hydrogen vehicles. Address design issues related to deployment of the module in the selected applications and integration issues with hydrogen generators, such as effective heat management of the whole system and safety.

3 OBJECTIVES To deliver: A Metal Hydride (MH) store with a system capacity of 40 g(h 2 ) L -1. To achieve this, every aspect of the store will be investigated, from the container to the bed formulation, heat transfer and recovery mechanisms, economically viable store materials, container and fabrication methods to demonstrate mass deployment feasibility. A Metal Hydride cascade for compressing hydrogen from 10 to 350 bar. This will require a compact system which can deliver 10 g (H 2 ) min -1 for rapid refuelling (scenario A) or can deliver 1 g (H 2 ) min -1 for overnight charge refuelling (scenario B) Components for scenarios A or B identified above (electrolyser, MH store, MH compressor, heat recovery system, controls) all within the size of a large chest freezer for installation in a garage or outhouse. An investigation of all aspects of safety and hazards within the system, focussing on hydrogen safety, hydride bed exposure and reactions to trauma such as fire and collision.

4 Contents Introduction to the system Material Challenges and Targets Numerical Study on a Two Stage Metal Hydride Hydrogen Compressor (MHHC) Early Results on Models and Materials Development of modelling capabilities and assessment of safety in hydrogen technologies involving metal hydrides

5 Introduction to System First Stage MH Second Stage MH High Pressure Tank Scenario B trickle charge Target H 2 production over 10 hours g H 2 storage capacity of each stage (based on minute cycle) - 60 g Mass of MH stage kg Mass of MH stage 2 4 kg Refuelling time minute cycles Required electrolyser production rate mol/min.

6 Introduction about the performance of a two-stage MHHC Advantages of MHHC over Mechanical Compressors Simplicity in Design and Operation Absence of Moving Parts Safety and Reliability No Problems Related to Lubrication and Maintenance Possibility to Consume Waste Industrial Heat Instead of Electricity Typical Commercial Mechanical Compressor High Delivery Pressure Valve 1 Valve 2 Stage 1 Stage 2 Coupling Process Low Pressure Hydrogen Supply 3/14 Heat Transfer Fluid High- Pressure Tank Valve 3 P d : Delivery Pressure P s : Supply Pressure T h : Dehydrogenation Temperature T s : Hydrogenation Temperature P in

7 Material Challenges and Targets Tuneable P-c-T properties (High compression ratio in available temperature range) High Reversible Hydrogen storage capacity Reduction of the Amount of the MH Fast Kinetics Low plateau slope Low hysteresis Stability during cycling Scalability of MH alloys synthesis and affordable costs

8 lnp Material Selection Material Combination Second Stage Dehydrogenation First Stage Second Stage Pd Δp First Stage Dehydrogenation Second Stage Hydrogenation AB 5 - Type LaNi 5 Mm-Ni- Al AB 5 Type LaNi5 AB 2 Type Ti-Zr-Mn AB 5 Type Ca-Mm-Ni Ps Xmin First Stage Hydrogenation H/M Xmax AB 2 Type Ti-Cr-Mn AB 2 Type Ti-Zr-Cr-Fe-V 5/14

9 Numerical Study of the MHHC Basic Assumptions and Equations H 2 and metal are in local thermal equilibrium T ( Cp) e ( gcpg ) vg T (k e T) Q t Solid Phase is Isotropic and has uniform porosity Hydrogen is treated as an ideal gas from a thermodynamic point of view. Heat transfer by Radiation is negligible ( Cp) ( C ) ((1 ) C The equilibrium pressure is described by Van t Hoff Law S x 1 S 5 ln Peq [ ( s 0) tan[ ( ) ] 10 RT R x 2 2 f e g pg s ps k k (1 ) k e g s φ s and φ 0 plateau flatness factors S Hysteresis Factor The thermal conductivity and the specific heat of hydride bed are constant 6/14 Hydrogenation Process Kinetic Term Dehydrogenation Process Kinetic Term m C Eabs p exp[ ]ln[ ]( ) RT P C E P des eq p exp[ ] ( ) RT P abs abs s eq m des des s eq

10 Potential alloys Low pressure stage Comments 1) LaNi 5 Purchased from Sigma-Aldrich 2) Hydralloy C, TiZr(MnVFe) 2 (Ti 0.65 Zr 0.35 ) 1+x MnCr 0.8 Fe 0.2 Purchased from Sigma-Aldrich Induction melted UoN High pressure stage Comments 3) Ti 0.29 V 0.14 Mn 0.51 (FeCrZr) Purchased from Sigma-Aldrich 4) Ti 0.5 V 0.45 Nb 0.05 Mn Synthesised by Arc melting, UoB 5) Ti 1.1 Cr 1.5 Mn 0.4 V 0.1 Synthesised by Arc melting, UoB 6) TiMn 1.5 V 0.45 Fe 0.1 Synthesised by Arc melting, UoB 7) (Ti 0.97 Zr 0.03 ) 1.2 Cr 1.6 Mn 0.4 Synthesised by Arc melting, UoB Alloys are selected based on the reported enthalpy and entropies values in the literature to compress hydrogen above 350 bar using a two-stage MH compressor 10

11 Materials Used for the Simulation Study First Stage Alloy Case 1 LaNi C: Peq=20.19bar C: Peq= bar Dehydrogenation Second Stage Alloy Hydrogenation 20 0 C Zr-V-Mn-Nb (AB 2 type) Peq=32.95 bar Case 2 MmNi 4.6 Al C: Peq=56.96 bar Zr-V-Mn-Nb (AB 2 type) Peq=32.95 bar Case 3 LaNi C: Peq=20.19bar C: Peq= bar Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 Peq=31.63 bar Case 4 MmNi 4.6 Al C: Peq=56.96 bar Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 Peq=31.63 bar

12 Hydrogenation Capacity (wt% H 2 ) Dehydrogenation Capacity (wt% H 2 ) Pressure (bar) lnp (atm) o C absorption 30 o C desorption 50 o C absorption 50 o C desoprtion 75 o C absorption 75 o C desorption Validation of the simulation results with the experimental Material Used for the Validation: LaNi 5 2,6 2,4 2,2 2,0 1,8 1,6 1,4 1,2 1,0 H=-29.8 kj/mol S=104.9 J/Kmol H=-28.3 kj/mol S=102.1 J/Kmol 1,4 1,2 1,0 0,8 0 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1, C Hydrogen uptake (wt%) 50 0 C 0,8 0,6 0,0-0,2-0,4 0,0029 0,0030 0,0031 0,0032 0,0033 1/T (K) Experimental Data Simulation Results 0,6-0,6 0,4 0,2 Simulation Results Experimental Data 0, /14 Time (s) -0,8-1, C 50 0 C Time (s)

13 Pressure (bar) lnp (atm) 4) Ti 0.5 V 0.45 Nb 0.05 Mn: PCI characteristics High pressure alloys o C Absorb. 27 o C Desorb. Ti-V-Nb-Mn o C Absorb o C Desorb. 60 o C Absorb. 60 o C Desorb. 4.5 H abs = kj/mol S= J/Kmol H= kj/mol S= J/Kmol Hydrogen uptake (wt%) /T *10 3 Sloping plateaux, hysteresis factor (ln P a /P d at 27 o C=0.46) Hydrogen capacity at 27 o C: 1.51 wt% Plateau width ( C) significantly decreases with temperature increase 13

14 Geometry of the reactors Both Reactors are 60 % Full with Material to Avoid Lattice Expansion Issues For 60g H 2 stored per cycle in the High Pressure Tank LaNi 5 : 4.45 kg Ti-Zr-V-Fe-Cr-Mn: 3.42 kg MmNi 4.6 Al 0.4 : 4.12 kg Zr-V-Mn-Nb: 4 kg External Jacket Stage 1 H 2 Supply Filter Tank Walls 3 mm Stage 2 Hydride 9/14

15 Mass and Energy Balance During the Coupling Between the Reactors n des n abs H Hydride Stage 1 2 Flow Hydride Stage 2 Total Number of Hydrogen moles in the interconnector anytime n n n n t t t des abs Pressure of Hydrogen in the combined space anytime Dehydrogenation Kinetics m P E Peq P des t t C exp[ ] RT P des des s eq t t n R T V V t t t t A B Hydrogenation Kinetics m Eabs Pt t C exp[ ] ln( ) RT P abs abs s eq 10/14

16 Simulation Results Case 1: First Stage (AB 5 ) LaNi 5 Second Stage (AB 2 ) Zr-V-Mn-Nb Tank Avg Temperature ( 0 C) Hydrogen Concentration Tank Avg Pressure (bar) Pin = 15 bar T cold = 20 0 C T hot = C S. H Process LaNi 5 Hydrogenation LaNi 5 Dehydrogenation S. H Process Zr-V-Mn-Nb Hydrogenation Zr-V-Mn-Nb Dehydrogenation Time (s) Pin = 15 bar T cold = 20 0 C T hot = C S.H Process LaNi 5 Hydrogenation S.H Process Ti-V-Mn-Nb Dehydrogenation LaNi 5 Dehydrogenation Ti-V-Mn-Nb Hydrogenation Time (s) Time (s) Coupling Between 20 0 C (Hydrogenation) and C (Dehydrogenation) Time for a full cycle: min Energy Required: kj Maximum Compression Ratio: 22-23:1 11/14

17 Comparison of the Performance of all cases Cycle Time (min) Compression Ratio Energy Penalty (kj) Case : Case : Case : Case :1 8-9 First Stage Second Stage Case 1 LaNi 5 ( C) Zr-V-Mn-Nb ( C) Case 2 MmNi 4.6 Al 0.4 ( C) Zr-V-Mn-Nb ( C) Case 3 LaNi 5 ( C) Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 ( C) Case 4 MmNi 4.6 Al 0.4 ( C) Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 ( C) 12/14

18 Outcomes so far Presentation of a mathematical model and simulation results for a two stage MHHC Four Different Systems were considered and studied System 1: LaNi 5 (130 0 C) - ZrVMnNb (20 0 C) Deliver Pressure after coupling: 36 bar/ Final Pressure: 318 bar System 2: MmNi 4.6 Al 0.4 (100 0 C) - ZrVMnNb (20 0 C) Deliver Pressure after coupling: 43 bar/ Final Pressure: 182 bar System 3: LaNi 5 (130 0 C) - Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 (20 0 C) Deliver Pressure after coupling: 37 bar/ Final Pressure: 280 bar System 4: MmNi 4.6 Al 0.4 (100 0 C) - Ti 0.99 Zr 0.01 V 0.43 Fe 0.99 Cr 0.05 Mn 1.5 (20 0 C) Deliver Pressure after coupling: 49 bar/ Final Pressure: 157 bar Future Targets Decrease compression cycle time to min Materials with higher compression efficiency Heat Management of the Tanks Geometries

19 Maximising the kinetics External Jacket Thin Hydride Shell Wall Thickness 3mm Hydrogen Supply Filter Thickness of Shell 5.48mm Cooling/Heating Medium Hydride Text in External here Jacket Tank s Text Wall in here External Text Tank s in Wall here Co-central Tubes Wall Thickness 3mm Tube Radius: 5mm Cooling Tube Thickness 1,5 mm Hydrogen Supply Filter Tube 2 Tube 3 Tube 4 Tube 1 Co-central Tubes with Al foam 40 ppi Average Cell Diameter 2.3 mm Al Foam Packed with the powder

20 Development of modelling capabilities and assessment of safety in hydrogen technologies involving metal hydrides Hydrogen fire simulations Fundamental modelling and assessment of explosion hazards of hydrogen Experiments (University of Sydney) Modelling and assessment of explosion hazards of hydrogen Experimental testing of dust explosions (FSA GmbH)

21 Dispersion model validation RCS framework for hydrogen Hydrogen fuelling standards and current potential restrictions on ESCHER project Processing of the experimental data for combustion model development

22 Geometry of the validation case Matsuura et al., Numerical simulation of leaking hydrogen dispersion behaviour in a partially open space, International Journal of Hydrogen Energy, 2008, Volume 33, Issue 1, Pages

23 Sensor readings validation T. Beard, M. Bragin, W. Malalasekera, S. Ibrahim, Numerical simulation of hydrogen discharge in a partially enclosed space submitted to the 12th International Conference on Combustion & Energy Utilisation, Lancaster, 29 Sept 3 Oct 2014

24 Contents Dispersion model validation RCS framework for hydrogen Hydrogen fuelling standards and current potential restrictions on ESCHER project Processing of the experimental data for combustion model development ESCHER Meeting 04 July 7th,

25 Risk Control Strategy Framework for hydrogen HSE only regulates safety at the work place When it comes to regulating residential garages, all of the regulations become suggestions HSE recommends to follow the same approach as for work spaces Dangerous Substances and Explosives Atmospheres Regulations (DSEAR) 2002, which implements in the UK ATEX 137 The User Directive (Workers at risk) Control of Major Accident Hazard Regulations 1999 (COMAH), which implements in the UK Seveso II Directive Equipment and Protective Systems for Use in Potentially Explosive Atmospheres (EPS) 1996 Others: Pressure Equipment, Gas Appliances, Low Voltage, Electromagnetic Compatibility Directives, etc

26 Dangerous Substances and Explosives Atmospheres The key requirement of the DSEAR is that risks from dangerous substances are assessed and controlled DSEAR requires: Identification of fire and explosion hazards Classification of areas where explosive atmospheres may exist Evaluations of risks Specifications of measures to prevent or mitigate the effects of an ignition

27 Risk Control Strategy stipulated by DSEAR Risk Control Strategy stipulated by DSEAR: Substitution (for less dangerous substance) Preventing the formation of explosive atmospheres (containment, dilution through effective ventilation) Preventing the ignition of explosive atmospheres Zone classification Mitigating the effects of an explosion (explosion resistant equipment, pressure relief, prevention of flame acceleration and DDT, explosion progression and Domino effect)

28 Control of Major Accident Hazard COMAH applies mainly to the chemical industry, but also to storage facilities where threshold quantities of the dangerous substances identified by the Regulations are kept or used. There are two threshold levels given in the regulations. Sites with quantities exceeding the lower level are known as lower-tier sites and those exceeding the upper value as top-tier sites. Threshold values for hydrogen are 5 tonnes and 50 tonnes, which means that this regulation may not even apply to many of the larger hydrogen refuelling stations, let alone a home hydrogen refueller.

29 Notification of Installations Handling Hazardous Substances The NIHHS Regulation (1982, 2002) prohibit the handling of certain hazardous substances in quantities equal or exceeding the threshold quantity specified in the regulations unless HSE has been notified. The threshold quantity for hydrogen is two tonnes

30 Equipment and Protective Systems for Use in Potentially Explosive Atmospheres (EPS) The legal requirements for equipment and protective systems intended for use in potentially explosive atmospheres are given in the ATEX 100A Equipment Directive (sometimes also called the ATEX 95 Directive) The Directive covers both electrical and non-electrical (mechanical) equipment The requirements also extend to controlling and regulating devices intended for use outside the explosive atmosphere, but required for, or contributing to, the safe functioning of equipment or protective systems in the explosive atmosphere

31 Classification of hazardous areas IEC/EN Electrical apparatus for explosive gas atmospheres. Part 10. Classification of hazardous areas Hazardous areas are classified into zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows: Zone 0: An area in which an explosive gas atmosphere is present continuously or for long periods (>1000 hours/year) Zone 1: An area in which an explosive gas atmosphere is likely to occur in normal operation ( hours/year) Zone 2: An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it does occur, is likely to do so only infrequently and will exist for a short period only (1-10 hours/year)

32 Classification of hazardous areas Another important consideration is the temperature classification of the electrical equipment. The surface temperature or any parts of the electrical equipment that may be exposed to the hazardous atmosphere should be tested that it does not exceed 80% of the auto-ignition temperature of the specific gas in the area where the equipment is intended to be used T1 450 C, T2 300 C, T3 200 C, T4 135 C, T5 100 C, T6 85 C The above table tells us that the surface temperature of a piece of electrical equipment with a temperature classification of T1 will not rise above 450 C The auto-ignition for hydrogen is 560 C so we will require the highest temperature grading T1

33 Pressure Equipment Regulation/Directive Pressure Equipment Regulation (PER) 1999 stems from EU Pressure Equipment Directive (PED) For pressure equipment > 0.5bar above atmospheric pressure It defines, based on contents, maximum allowable pressure and volume, the conformity procedure, which is then linked to the risk presented in the event of an uncontrollable release of stored energy PER will apply to MH storage vessels and all associated pipework Pressure systems should have means for venting and also have to be subjected to a regular inspections

34 Contents Dispersion model validation RCS framework for hydrogen Hydrogen fuelling standards and current potential restrictions on ESCHER project Processing of the experimental data for combustion model development

35 Hydrogen Refuelling Standard SAE J2601 Establishes guidelines for communicating and noncommunicating refuelling Applies to light duty vehicle fuelling for vehicles with storage capacity from 1 to 10 kg for 70 MPa and 1 to 7.5 kg for 35 MPa Operating conditions limitations: Gas temperature in vehicle fuel system < 85 C No more than 10 complete stops during refuelling (defined if flow reduces below 1% of the max flow rate) Leak test should be carried out before any fuelling But The SAE J2601 is due for renewable in Autumn 2014

36 Hydrogen Refuelling Standards ISO ISO 20100, which is currently under development will include indoor refuelling operation (mainly for warehouses). Current Technical Specifications (ISO/TS 20100:2008) explicitly exclude residential and home applications Specific requirements will be provided for H 2 systems in enclosures: ventilation requirements to avoid the development of a flammable atmosphere in case of expectable leaks, even if all electrical equipment is designed for operation in a flammable atmosphere maximum H 2 concentration thresholds will be defined for initiation of safety measures for system shutdown requirements for hydrogen refueling in a warehouse

37 Some useful points to consider (ISO/TS 20100:2008) Installation and equipment design shall minimize the number of connections and other possible points of leakage or release to atmosphere It is recommended to use joints that are permanently secured and so constructed that they limit the maximum release rate to a predictable value

38 Hydrogen generators Hydrogen generators using water electrolysis process shall meet the requirements of ISO During normal fuelling system shutdown, the hydrogen generators using water electrolysis process and the hydrogen generators using fuel processing technologies shall not rely on safety devices to shut down Actuation of any emergency shutdown device of the fuelling station shall shut down the hydrogen generators using water electrolysis process and the hydrogen generators using fuel processing technologies

39 Hydrogen compressors Valves shall be installed such that each compressor can be isolated for maintenance. Where compressors are installed for operation in parallel, each discharge line shall be equipped with a check valve The inlet pressure shall be monitored by a pressure indicator/switch to avoid a vacuum in the inlet line and consequent ingress of air. This pressure indicator/switch shall cause the compressor to shut down before the inlet pressure reaches atmospheric pressure The temperature after the final stage of compression, or the temperature after the cooler, where fitted, shall be monitored by an indicator/alarm that shall be arranged to shut down the compressor at a predetermined maximum temperature

40 Filters and separators Filters and, if applicable, separators shall be included if hydrogen is expected to contain function-impairing impurities The filters and separators shall be sized for the maximum hydrogen gas flow and for the expected impurities in the hydrogen gas, and shall be provided with sufficiently large sumps or collecting tanks As far as possible, filters and separators should be combined in a single unit Clogging of the filter insert in the main hydrogen gas flow shall be monitored

41 Other Relevant Standards Electrical resistance trace heating (if available) should comply with IEC All electrical equipment installed should be suitable for the area classification according to IEC and other applicable parts of series

42 Contents Dispersion model validation RCS framework for hydrogen Hydrogen fuelling standards and current potential restrictions on ESCHER project Processing of the experimental data for combustion model development

43 Sydney Combustion Chamber 50 Frame Mar 2008 No Data Set Vent 4 5 Turbulence generating grid Solid Obstacle 50 S3 Turbulent generating baffle plates X Z Y S2 S1 Fuel/air inlet Ignition Point ESCHER Meeting 03 April 24th,

44 Test Case Large eddy Simulations (LES) were carried out using an in-house code PUFFIN Hydrogen/air mixture with equivalence ratio 0.7 is modelled for the current case The Dynamic Flame Surface Density (DFSD) model is tested on the case of for Sydney combustion chamber for hydrogen explosion and identified to be successful.

45 Results. Validation Comparison between sequence of images showing flame structure after ignition. (a) LIF-OH images from experiments. (b) Numerical snapshots for reaction rate contours generated at 2.2, 2.4, 3.6, 4.2 and 4.4 ms. Equivalence ratio 0.7. ESCHER Meeting 03 April 24th,

46 Overpressure (mbar) Results: Overpressure - validation Exp LES Time (ms) Overpressure time traces of LES simulation compared with experimental data Equivalence ratio 0.7

47 Results: Range of equivalence ratios Movies of LES simulation for equivalence ratios 0.4 (left), 0.7 (centre), and 1 (right) ESCHER Meeting 03 April 24th,

48 Sydney Combustion Chamber 50 Vent 4 5 Turbulence generating grid 50 Solid Obstacle S3 Turbulent generating baffle plates X Z Y S2 S1 Fuel/air inlet Ignition Point (a) (b) The two baffle configurations studied here (a) OOOS. (b) BBBS

49 Processing of the experimental data I The flame front speed of the three fuels through the chamber for both the OOOS and BBBS configurations ESCHER Meeting 04 July 7th,

50 Processing of the experimental data II The flame front length expansion through the chamber for the three fuels at both configurations, plotted to the peak flame front lengths witnessed

51 Processing of the experimental data III The flame stretch rate along the explosion chamber for the OOOS configuration

52 Processing of the experimental data IV The flame stretch rate along the explosion chamber for the BBBS configuration ESCHER Meeting 04 July 7th,

53 ESCHER progress Store requirements, capacity and scenarios evaluated. COMSOL models of stores and compressors completed. Compressors. Initial metal hydride couples analysed Exploration of stage 2 metal hydrides for compressor, improving kinetics, compression ratio and reducing hysterisis Hydrogen Dispersion model validation against experimental data completed Review of standards related to hydrogen use indoors started, ongoing Fundamental model development (with PUFFIN code): processing of experimental data started, ongoing Progress on schedule 53-33

54 Collaborations HSL: Steffan Laden. ITM Power: Nick Van Dyke University of Sydney: Asaad Masri FSA GmbH GL Industries Ltd Eminate Ltd Dissemination E.I Gkanas, D.M Grant, A.D Stuart, G.S Walker D.Book, S. Nayebossadri, L. Pickering, Metal Hydrogen Systems MH th International Symposium on Metal-Hydrogen Systems 20-25th July 2014 T. Beard, M. Bragin, W. Malalasekera, S. Ibrahim, Numerical simulation of hydrogen discharge in a partially enclosed space submitted to the 12th International Conference on Combustion & Energy Utilisation, Lancaster, 29 Sept 3 Oct 2014