TFAWS Active Thermal Paper Session

Thermal Analysis of Cryogenic Hydrogen

Liquid SeparatorJ. F. CongiardoC. R. Fortier(NASA KSC)

Presented ByJared F. Congiardo

Thermal & Fluids Analysis WorkshopTFAWS 2014August 4 - 8, 2014NASA Glenn Research CenterCleveland, OH

Background

• Space Launch System Core Stage engine conditioning requires a high flowrate of liquid hydrogen to be accommodated by the launch pad systems.

• Launch pad flare stack designed to dispose of gaseous hydrogen.

• Analysis of ground system performance indicated that liquid hydrogen would not completely vaporize prior to arrival at the flare stack.

Background

• Therefore, a cryogenic liquid separator is being developed in order to detain liquid hydrogen and protect the flare stack.

TFAWS 2014 – August 4-8, 2014 3

Flare Stack

Design Considerations

• Separator must:– Detain liquid hydrogen at approximately 20% quality flow >10

lbm/s for 5 minutes.– Add minimal resistance to overall system flow. – Be capable of being emptied within 12 hours for scrub

turnaround, by some combination of drain and boiloff. – Have inlet and outlet piping above the anticipated maximum

liquid level.

Separator Performance Modeling

• The separator tank component was modeled in Thermal Desktop – Thermal node network generated with TD surfaces– Tank liquid volume represented with twinned lump– Lump connected to the tank surface with pool boiling ties– Inlet/outlet pipe represented with macros– Flow simulated with Set Mass Flow component

Component Model Assumptions

• The tank performance during the high flow portion of the operation was contingent on the following assumptions:– Environmental temperature at 99°F. (Per NASA-HDBK-1001)– Natural convection horizontal heat transfer around cylinder– Preliminary system operations chills the tank to cryogenic temps

(-400°F)– ½ inch thick tank wall

Tank Performance (Uninsulated)

Possible high temperature differential during boiloff

Approx. 2.5 psi delta P initially (possible startup artifact) Max 0.2 psi delta P during high flow

Boiloff in approx. 3 hours

Tank Performance (Insulated)

Lower temperature differential during boiloff

Approx. 2.5 psi delta P initially (possible startup artifact) Max 0.5 psi delta P during high flow

Boiloff in 18+ hours

Integrated Model

• Component model integrated into overall model of engine conditioning subsystem to validate:– Minimal resistance to system flow– Tank chilldown assumption

• Assumes:– Environmental boundary conditions at NASA-HDBK-1001

Min/Max (19°F/99°F)– Varying polyurethane insulation thickness on tank– Natural convection horizontal heat transfer on tank

Integrated Model

TO PAD

SEPARATOREXPANSION LOOP

FLARE STACK

System Performance, 99°F, Frost-Insulated Inlet Pipe

Tank Bottom/Bulk Temp, T=99F, Frost on Pipe

tem

pera

ture

, deg

F

0.0 0.5 1.0 1.5 2.0

100

0

-100

-200

-300

-400

-500

Time hr time from start of replenish

WinPlot v4.55 rc1

10:14:49PM 07/20/2014

f_10i_t99.csv T_37 deg F wall temf_10i_t99.csv T_1000 deg F liq tef_25i_t99.csv T_37 deg F wall temf_25i_t99.csv T_1000 deg F liq te

f_50i_t99.csv T_37 deg F wall temf_50i_t99.csv T_1000 deg F liq tef_75i_t99.csv T_37 deg F wall temf_75i_t99.csv T_1000 deg F liq te

f_100i_t99.csv T_37 deg F wall tef_100i_t99.csv T_1000 deg F liq t

Tank Liquid Volume, T=99F, Frost on Pipe

Volu

me,

ft^3

0.0 0.5 1.0 1.5 2.0

800

600

400

200

0

-200

Time hr time from start of replenish

WinPlot v4.55 rc1

10:04:04PM 07/20/2014

f_0i_t99.csv V_1000 ft^3 tk liquidf_10i_t99.csv V_1000 ft^3 tk liqui

f_25i_t99.csv V_1000 ft^3 tk liquif_50i_t99.csv V_1000 ft^3 tk liqui

f_75i_t99.csv V_1000 ft^3 tk liquif_100i_t99.csv V_1000 ft^3 tk liqu

Hydrogen in tank becomes saturated vapor

Liquid begins to form in tank during low flow portion

Tank begins to fill with liquid during low flow portion

Wall temp at bottom of tank

System Performance, 19°F, Frost-Insulated Inlet Pipe

Tank Bottom/Bulk Temp, T=19F, Frost on Pipe

tem

pera

ture

, deg

F

0.0 0.5 1.0 1.5 2.0

100

0

-100

-200

-300

-400

-500

Time hr time from start of replenish

WinPlot v4.55 rc1

9:53:46AM 07/21/2014

f_0i_t19.csv T_37 deg F wall temf_0i_t19.csv T_1000 deg F liq temf_25i_t19.csv T_37 deg F wall temf_25i_t19.csv T_1000 deg F liq te

f_50i_t19.csv T_37 deg F wall temf_50i_t19.csv T_1000 deg F liq tef_75i_t19.csv T_37 deg F wall temf_75i_t19.csv T_1000 deg F liq te

f_100i_t19.csv T_37 deg F wall tef_100i_t19.csv T_1000 deg F liq t

Tank Liquid Volume, T=19F, Frost on Pipe

volu

me,

ft^3

0.0 0.5 1.0 1.5 2.0

1000

800

600

400

200

0

Time hr time from start of replenish

WinPlot v4.55 rc1

9:56:28AM 07/21/2014

f_0i_t19.csv V_1000 ft^3 tk liquidf_25i_t19.csv V_1000 ft^3 tk liqu

f_50i_t19.csv V_1000 ft^3 tk liquf_75i_t19.csv V_1000 ft^3 tk liqu

f_100i_t19.csv V_1000 ft^3 tk liq

Performance similar to 99°F. Time to first liquid formation shortened by 15 minutes.

System Performance, 99°F, Bare Inlet Pipe

Tank Bottom/Bulk Temp, T=99F, No Frost

tem

pera

ture

, deg

F

0.0 0.5 1.0 1.5 2.0

100

0

-100

-200

-300

-400

-500

Time hr time from start of replenish

WinPlot v4.55 rc1

12:11:36AM 07/21/2014

nf_0i_t99.csv T_37 deg F wall temnf_0i_t99.csv T_1000 deg F liq tenf_25i_t99.csv T_37 deg F wall tenf_25i_t99.csv T_1000 deg F liq t

nf_50i_t99.csv T_37 deg F wall tenf_50i_t99.csv T_1000 deg F liq tnf_75i_t99.csv T_37 deg F wall tenf_75i_t99.csv T_1000 deg F liq t

nf_100i_t99.csv T_37 deg F wall tnf_100i_t99.csv T_1000 deg F liq

Tank Liquid Volume, T=99F, No Frost

Volu

me,

ft^3

0.0 0.5 1.0 1.5 2.0

400

300

200

100

0

Time hr time from start of replenish

WinPlot v4.55 rc1

9:50:51AM 07/21/2014

nf_0i_t99.csv V_1000 ft^3 tk liquinf_25i_t99.csv V_1000 ft^3 tk liqu

nf_50i_t99.csv V_1000 ft^3 tk liqunf_75i_t99.csv V_1000 ft^3 tk liqu

nf_100i_t99.csv V_1000 ft^3 tk liq

Hydrogen in tank cold, but still superheated during

Liquid begins to form in tank during high flow portion

Tank begins to fill with during high flow portion

Wall temp at bottom of tank

System Performance, 99°F, Frost-Insulated Inlet Pipe, Thin Walled Tank

Tank Wall/Bulk Temperature, 1/2" vs 3/16"

tem

pera

ture

, deg

F

0.0 0.5 1.0 1.5 2.0

100

0

-100

-200

-300

-400

-500

Time hr time from start of replenish

WinPlot v4.55 rc1

10:10:43AM 07/21/2014

f_25i_t99.csv T_37 deg F wall tempf_25i_t99.csv T_1000 deg F liq temp

f_25i_t99_thin.csv T_37 deg F wall tempf_25i_t99_thin.csv T_1000 deg F liq temp

Tank Liquid Volume, 3/16" wall, Frost on Pipe

volu

me,

ft^3

0.0 0.5 1.0 1.5 2.0

1200

1000

800

600

400

200

0

Time hr time from start of replenish

WinPlot v4.55 rc1

10:16:14AM 07/21/2014

f_10i_t99_thin.csv V_1000 ft^3 tkf_25i_t99_thin.csv V_1000 ft^3 tk

f_50i_t99_thin.csv V_1000 ft^3 tkf_75i_t99_thin.csv V_1000 ft^3 tk

f_100i_t99_thin.csv V_1000 ft^3f_0i_t99_thin.csv V_1000 ft^3 tk

Liquid formation begins approx. 30 min sooner

Tank Differential Pressure

Tank Differential PressureD

iffer

entia

l Pre

ssur

e, p

sid

0.0 0.5 1.0 1.5 2.0

0.02

0.00

-0.02

-0.04

-0.06

-0.08

Time hr time from start of replenish

WinPlot v4.55 rc1

10:06:17AM 07/21/2014

f_25i_t99.csv [P_11970]-[P_11971]f_25i_t99_thin.csv [P_11970]-[P_1

f_25i_t19.csv [P_11970]-[P_11971]nf_25i_t99.csv [P_11970]-[P_1197

nf_25i_t99_thin.csv [P_11970]-[P_

Conclusions

• Separator is capable of detaining flow as required• Insulation has direct effect on boiloff time and liquid

formation– Drain line necessary

• Tank will chill, though not necessarily as assumed in component model– Little effect on prepress behavior for warmer tank – Potential for initial liquid formation affects volume assumptions– Tank wall thickness affects system performance significantly

• Separator tank shows no evidence of adding major resistance to overall system.

Questions?