1. Experimental and Computational Study on Burning Velocity of Ammonia Hydrogen Blends
Xinlu Han, Yong He, Zhihua Wang State Key Laboratory of Clean Energy Utilization, Zhejiang University, China . Zhiwei Sun, Bassam Dally, Graham Nathan Centre for Energy Technology (CET) and School of Mechanical Engineering, The University of Adelaide, Australia

2. Introduction
Both hydrogen (H2) and ammonia (NH3) are renewable energy carriers.
Co-burning H2 and NH3 as fuels has been proposed:
H2 is very active chemically and physically in combustion
NH3 has very low burning velocities
They are two complementary fuels.
University of Adelaide

3. Overview of Carbon Neutral Fuels Usage
University of Adelaide

4. Maritime Energy Use by 2050
2.25 EJ annual demand = ~120 million tons of ammonia per year.
DNV GL Energy Transition Outlook 2019: Maritime Forecast to 2050, September 2019
University of Adelaide

5. Maritime Energy Use by 2050
DNV GL Energy Transition Outlook 2019: Maritime Forecast to 2050, September 2019
University of Adelaide

6. Hydrogen vs Ammonia Hydrogen Ammonia Flammability limits
(by mole, bar)
Burning velocity
(cm/s, Φ=1 in 1 bar)
~ 220
~ 6
Diffusion coefficient
1 bar, 25oC)
0.756
0.228
Auto-ignition temperature (oC)
500
651
Boiling point (oC)
- 33.3
Ammonia is more safe in terms of flammable.
Ammonia can be easily separated from hydrogen by cooling and pressurizing the mixture.
University of Adelaide

7. Aims
To study experimentally the burning velocities of the mixtures at different blending levels (i.e., in VolNH3%)
To assess the accuracy of the chemistry tools for predicting the burning velocity of NH3-blended H2 gases.
University of Adelaide

8. Heat flux method for SL measurement
Heat flux burner:
See a detailed introduction on Youtube
fuel/air
Nonaka et al, Fuel, 182 (2016) p:382
University of Adelaide

9. Heat flux method for SL measurement
Burner plate:
thermocouple
Nonaka et al, Fuel, 182, p:382
Bosschaart et al, CNF, 132, p:170
When vfuel/air= SL, the burner plate has a flat radial profile of temperature.
University of Adelaide

10. Experiment setup
The flow rates of gases were accurately controlled and supplied into the burner, adjusting vfuel/air to achieve a flat temperature profile on the burner surface.
University of Adelaide

11. Results (1): validation
Measurement accuracy validation:
Using methane/air flames
Good agreement
University of Adelaide

12. Results (2): SL at different blending levels
Mole fraction (NH3)
SL (cm/s)
NH3 H2
SL significantly decrease in with blending ammonia.
20% NH3 can halve SL !!!
Non-linear dependence of SL on the mole fraction of ammonia (XNH3).
But discrepancies exist between the measured and modelled results.
University of Adelaide

13. Results (2): SL at different blending levels
SL (cm/s)
Mole fraction (NH3)
Large discrepancies exist between the measured and modelled results.
A similar value of SL with methane (CH4) when XNH3 = 0.5.
Suggest that the prediction capabilities of the chemistry tools need to be improved.
University of Adelaide

14. Results (3): SL at different equivalence ratios
SL (cm/s)
Equivalence ratio, Φ
XNH3 = 0.6
Again, large discrepancies exist (max ~ 30%).
Further suggest that the prediction capabilities of the chemistry tools need to be improved.
University of Adelaide

15. Conclusions
Blending ammonia into hydrogen can significantly reduce the burning velocity of the mixture, thus enhancing the safety of the gases in storage and transport;
The available chemistry tools poorly predicted the burning velocities of H2/NH3 mixtures; thus further improvement is needed;
H2/NH3 mixture has a similar burning velocity as methane when XNH3 = 0.5;
In addition, NH3 has relatively high vapour pressure kPa at oC and kPa at 20 oC, and is easily separated from hydrogen by cooling and pressurizing the mixture.
University of Adelaide

16. Many thanks!
5-6 bar
University of Adelaide