Investigation on toxicity of ammonia releasing from storage tank onboard through CFD simulations

Figures & data

Figure 1. Methodology adopted in this study.

Table 1. The principal characteristics of the ship model used in this study.

Main particulars	Symbols	Full scale
Length overall	$L_{\mathit{OA}}\left(\mathit{m}\right)$	18.5
Length between the perpendiculars	$L_{\mathit{BP}}\left(\mathit{m}\right)$	18.0
Breadth (MDL)	$\mathit{B}\left(\mathit{m}\right)$	7.00
Depth (MDL)	D$\left(\mathit{m}\right)$	1.80
Draft	$\mathit{T}\left(\mathit{m}\right)$	1.00

Figure 2. Ship geometry used in this study.

Figure 3. Annual climate characteristics of Busan port (Windfinder, 2018).

Table 2. Wind conditions applied in this study.

Wind Direction	Wind Speed (mph)	Wind Speed (m/s)
0 degrees (from Port)	3	1.35
	12	5.36
	24	10.73
	38	16.99
90 degrees (from Bow)	3	1.35
	12	5.36
	24	10.73
	38	16.99
180 degrees (from Starboard)	3	1.35
	12	5.36
	24	10.73
	38	16.99
270 degrees (from Stern)	3	1.35
	12	5.36
	24	10.73
	38	16.99

Figure 4. The operating pressure of the ammonia storage tank and the vent mast diameter.

Table 3. Sixteen simulation cases carried out in this study.

Scenarios					Simulation results
No.	Leak rate (m^3/s); 50 A case	Wind Direction	Wind Speed (mph)	Wind Speed (m/s)	Gas concentration levels (at critical places)
1	0.028	0 degrees (from Starboard)	3	1.35	To confirm whether all critical places can keep the ammonia gas concentration no higher than 30 ppm (0.003%vol/vol).
2			12	5.36
3			24	10.73
4			38	16.99
5		90 degrees (from Stern)	3	1.35
6			12	5.36
7			24	10.73
8			38	16.99
9		180 degrees (from Port)	3	1.35
10			12	5.36
11			24	10.73
12			38	16.99
13		270 degrees (from Bow)	3	1.35
14			12	5.36
15			24	10.73
16			38	16.99

Figure 5. The computation mesh generated in this work.

Figure 6. The number of grids generated in each compartment and the zoomed view of the vent mast.

Figure 7. The boundary conditions applied to the background domain.

Figure 8. The boundary condition applied to the ship.

Figure 9. The boundary condition applied to the upper part of the vent mast.

Figure 10. The locations of the gas detectors installed.

Figure 11. Ship coordinate system.

Table 4. The coordinates of the detectors.

Detector [x, y, z (m)]
No.1 [1.5, 6.9, 0]	No.2 [1.9, 7.3, 0]	No.3 [2.6, 7.3, 0]
No.4 [0.5, 2.0, 0]	No.5 [2.2, 3.0, 0]	No.6 [5.0, 5.5, 0]
No.7 [8.0, 2.0, 0]	No.8 [10.0, 2.0, 0]	No.9 [12.0, 2.0, 0]
No.10 [12.0, 4.0, 0]	No.11 [12.0, 6.0, 0]	No.12 [12.0, 2.0, −2.0]
No.13 [12.0, 4.0, −2.0]	No.14 [12.0, 6.0, −2.0]	No.15 [12.0, 2.0, 2.0]
No.16 [12.0, 4.0, 2.0]	No.17 [12.0, 6.0, 2.0]	No.18 [13.5, 7.0, 0]
No.19 [15.0, 7.0, 0]	No.20 [16.5, 2.0, 0]	No.21 [17.5, 2.0, 0]

Figure 12. Computational grids generated in Star-ccm+.

Figure 13. The boundary conditions applied to the gas dispersion CFD model.

Figure 14. The physics adopted in Star-ccm+.

Figure 15. The results of the grid sensitivity study.

Table 5. Results for the gas dispersion simulation, obtained from PyroSim.

Scenarios				Simulation results (PyroSim)
				Gas concentration levels (PPM)
No.	Leak rate (m^3/s); 50 A case	Wind Direction	Wind Speed (m/s)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21
1	0.028	0 Degree (from port)	1.35	99.4	1.3x10^−5	8.0x10^−5	Gas concentration level < 1x10^−16
2			5.36	2.5x10^−3	1.5x10^−6	1.8x10^−5
3			10.73	5.5x10^−4	1.4x10^−6	6.3x10^−6
4			16.99	9.0x10^−4	1.4x10^−5	4.6x10^−5
5		90 Degree (from bow)	1.35	8,149.0	4.1x10^−6	3.7x10^−11
6			5.36	221.9	1.3x10^−9	1.2x10^−9
7			10.73	3.4x10^−1	4.0x10^−13	3.9x10^−15
8			16.99	2.6x10^−2	1.1x10^−10	1.3x10^−10
9		180 Degree (from starboard)	1.35	1.6x10^−6	6.7x10^−5	7.6x10^−7
10			5.36	2.3x10^−1	2.8x10^−6	3.4x10^−5
11			10.73	4.5x10^−3	1.5x10^−6	1.4x10^−5
12			16.99	1.5x10^−3	3.3x10^−6	2.7x10^−5
13		270 Degree (from stern)	1.35	9110.02	2,410.62	860.142
14			5.36	1990.52	5.3642	1.8x10^−2
15			10.73	0.10685	8.1x10^−7	2.1x10^−3
16			16.99	1.4821	5.8x10^−7	9.5x10^−1

Table 6. Results for the gas dispersion simulation, obtained from Star-ccm+.

Scenarios				Simulation results (STAR-CCM+)
No.	Leak rate (m^3/s); 50 A case	Wind Direction	Wind Speed (m/s)	Gas concentration levels (PPM)
				1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21
1	0.028	0 Degree (from port)	1.35	5.1x10^−3	1.4x10^−7	2.0x10^−9	Gas concentration level < 1x10^−16
2			5.36	1.2x10^−4	3.2x10^−8	1.2x10^−9
3			10.73	4.3x10^−5	9.0x10^−9	5.7x10^−10
4			16.99	3.2x10^−6	6.1x10^−10	2.9x10^−13
5		90 Degree (from bow)	1.35	2938.3	3.2x10^−5	2.7x10^−9
6			5.36	367.3	3.7x10^−7	1.1x10^−10
7			10.73	6.4x10^−2	1.9x10^−10	9.2x10^−11
8			16.99	7.5x10^−4	5.1x10^−11	5.3x10^−10
9		180 Degree (from starboard)	1.35	2.5x10^−2	2.9x10^−3	3.6x10^−5
10			5.36	1.9x10^−3	5.5x10^−5	8.2x10^−6
11			10.73	4.1x10^−4	5.6x10^−6	9.4x10^−8
12			16.99	2.3x10^−7	5.8x10^−9	1.5x10^−12
13		270 Degree (from stern)	1.35	3,529.12	2,579.3	1,250.23
14			5.36	2,158.35	50.3918	3.5x10^−3
15			10.73	0.73	1.5x10^−2	8.3x10^−7
16			16.99	3.19	1.2x10^−5	3.4x10^−9

Figure 16. Gas dispersion simulation during ship operation (condition: winter, south wind 20 kts).

Figure 17. Gas dispersion simulation during ship operation (condition: summer, south wind 20 kts).

Windfinder. (2018). Wind, Waves & Weather Forecast [ cited 2019]. https://www.windfinder.com/forecast/donghae.

 Google Scholar