raman shift (cm t (k)

HEAT STORAGE OF CRYOGENIC FLUIDS OF OCEAN WORLDSVictoria Muñoz-Iglesias and Olga Prieto-Ballesteros

Centro de Astrobiología (CSIC-INTA). Ctra. Ajalvir km. 4, 28850 Madrid, Spain. E-mail: [email protected], [email protected]

Run 1: Run 2:

a)

900 1000 1100 1200 1300 1400 1500

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

275 K

270 K

264 K

258 K

256 K

253 K

(C-O)

(CH3)

a)

900 1000 1100 1200 1300 1400 1500

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

275 K

266 K

261 K

259 K

258 K

257 K

256 K

255 K

b)

2600 2800 3000 3200 3400 3600

FR2

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

FR1

b)

2600 2800 3000 3200 3400 3600

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

a) ν (C-O)

250 255 260 265 270 275

1018

1019

1020

1021 freq1_C-O

Linear Fit

Ra

ma

n S

hift

(cm

-1)

T (K)

a)

250 255 260 265 270 275

1018

1019

1020

1021

1022

Ra

ma

n S

hift

(cm

-1)

T (K)

freq1_C-O

Polynomial Fit

b) δ (CH3)

250 255 260 265 270 2751444

1448

1452

1456

1460

1464

1468

1472

Ram

an S

hift (c

m-1)

T (K)

b)

255 260 265 270 2751444

1448

1452

1456

1460

1464

1468

1472

Ram

an S

hift (c

m-1)

T (K)

c) Fermi resonance (FR)

250 255 260 265 270 2752840

2842

2844

2946

2948

2950

2952

2954

2956

Ram

an s

hift (c

m-1)

T (K)

c)

255 260 265 270 275

2844

2846

2950

2952

Ram

an S

hift (c

m-1)

T (K)

2800 3000 3200 3400 3600 3800

Inte

nsity (

a.u

.)

Raman shift (cm-1)

outside chamber

286 K

278 K

269 K

265 K

258.5 K

256 K 12 h

259 K 15 h

256 K 18 h

O-H H2O-NH

3

240 260 280 300 320 340 3601.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Cp (

J/g

*K)

T (K)

Na2CO

3_5 wt% (eutectic)

NaHCO3_5 wt% (eutectic)

MgCO3_0.01 wt% (eutectic)

MgSO4_5 wt%

MgSO4_17 wt% (eutectic)

NaCl_23 wt% (eutectic)

H2O

235 240 245 250 255 260 265 270 275

4

6

8

10

12

14

16

18

20 NH

3 10wt%

NH3 10wt%

NH3 30wt%

Cp (

J/g

*K)

T (K)

melting

220 240 260 280 300 320 340 360

0

3

6

9

12

15

18

21

24

27

boiling 100%wt

Cp

(J/g

*K)

T (K)

MeOH 10wt%

MeOH 10wt%

MeOH 20wt%

MeOH 20wt%

MeOH 40wt%

MeOH 50wt%

MeOH 100wt%melting 20%wt

melting 10%wt

INTRODUCTION

It is well-known the variation in the chemical composition of the planetary

bodies of the solar system according to their position to the Sun, since the

decrease in temperature allows the condensation of volatiles that are

incorporated to the internal geochemistry of the bodies. Thus, while in Galilean

icy moons (Io, Europa, Calisto and Ganymede) salts seem to have an important

role, when we go farther carbon dioxide, ammonia and methanol can start to

have a major presence at the interior, as it can be the case of Titan, Enceladus

and Triton. All these compounds are mixed with water, altering dramatically its

properties, as for example its melting point.

RESULTS

Specific Heat (Cp) and Raman spectroscopy of:

- Salt aqueous solutions of Na2CO3, NaHCO3, MgCO3, MgSO4 and NaCl

- Aqueous solutions of 10-30wt% ammonia (NH3)

- Aqueous solutions of 10-100wt% methanol (MeOH)

- Mixtures NH3 + MeOH

AMMONIA + WATER METHANOL + WATER SALTS + WATER

Cp:

- Salts: Cp (solid) < Cp (liquid state)

- NH3 and MeOH,

Below “liquidus”, when co-existing with water ice (at concentrations below

the eutectic) anomalous Cp: increases gradually up to “liquidus” curve

Raman spectroscopy:

15 wt% NH3: New bond NH3-H2O (Raman signature at 3316 cm-1)) when

there is water ice co-existing with NH3 aqueous solution

20 wt% MeOH: Characteristic MeOH Raman signatures shift in presence of

water ice

Above “liquidus”: The higher is the NH3/MeOH concentration, the higher is

the decrease in the Cp values.

CONCLUSIONS

The obtained data help to understand the thermal behavior of those icy

bodies that could have accumulated heat during their evolution, and

potentially form aqueous oceans. Our data show that the retention of

heat is more favorable at certain conditions in cryogenic environments.

References: [1] Kargel J. S. (1991) Icarus, 94, 368–390. [2] Kargel J. S. (1992) Icarus, 100, 556–574. [3] Des-champs F.

et al. (2010) Astrophys. J., 724, 887–894. [4] Fortes D. and Choukroun M. (2010) Space Sci. Rev., 153, 185–218. [5]

Dougherty A. J. et al. (2018) J Geophys. Res. Planets, 123 [6] Achchaq and Palomo del Barrio (2017 Energy Procedia,

139, 346-351.

Acknowledgement: This work is funded by the Spanish MINECO projects ESP2014-55811-C2-1-P and ESP2017-89053-

C2-1-P.

MOTIVATION

In this research we want to evaluate the effect of different salts (carbonates, sulfates and chlorides), ammonia and methanol on the

thermal behavior of water with the temperature. The goal is to determine experimentally how these compounds can influence in the

heat storage properties of the solutions in both states liquid and solid, considering that they have a temperature-dependent

speciation when dissolved in water.

Source: http://www.planetary.org/blogs/emily-lakdawalla/2015/03121716-ganymede-ocean.html

0 20 40 60 80 100140

160

180

200

220

240

260

280

liquidus curve

MMH + methanol

L + MMH

T (

K)

wt% MeOH

Ice Ih + L

Ice Ih + MMH

L

methanol + L

0 10 20 30 40 50140

160

180

200

220

240

260

280

300

T (

K)

wt% NH3

Ice Ih + L

L + V

AMH + L

Ice Ih + ADH AMH + ADH

liquidus curve

L

NH3-H2O

AMH: ammonia

monohydrate

ADH: ammonia

dihydrate

MeOH-H2O

MMH: methanol

monohydrate

AMMONIA + METHANOL + WATER

240 260 280 300 320 340 360

4

5

6

7

8

9

15wt% NH3 + 6wt% MeOH




Cp

(J/g

*K)

T (K)

melting

NH3-MeOH-H2O

MMA: methanol

monoammoniate

Phase diagrams

DISCUSSION

Cp anomalous behavior

Raman spectroscopy reveals new chemical interactions in the zone “Water Ice +

Liquid solution” (below “liquidus” curve).

Thermal Energy Storage (TES) systems based on:

- The heat accumulated in a material without experimenting structural changes

(sensible heat storage)

- Phase changes that store/release energy (latent heat)

- Thermochemical energy, related to sorption mechanisms (physical and

chemical processes by which one substance becomes attached to another)

The combination of several chemical processes that occur before reaching the

“liquidus” curve (incongruent melting/solidification processes followed by liquid-

solid reversible chemical reactions) may contribute to Cp behavior.

a)

3275 3300 3325 3350 3375

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

258.5K

3300 3320 3340

-0.010

-0.005

0.000

0.005

Raman Shift (cm-1)

2nd derivative

3320 cm-1

b)

3275 3300 3325 3350 3375

Inte

nsity (

counts

)

Raman Shift (cm-1)

256K 12h

3300 3320 3340

-0.005

0.000

0.005

Raman Shift (cm-1)

2nd derivative

3316 cm-1

3320 cm-1

c)

3275 3300 3325 3350 3375

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

259K 15h

3300 3320 3340

-0.010

-0.005

0.000

0.005

Raman Shift (cm-1)

2nd derivative

3320 cm-1

d)

3275 3300 3325 3350 3375

Inte

nsity (

a.u

.)

Raman Shift (cm-1)

256K 18h

3300 3320 3340-0.010

-0.005

0.000

0.005

3320 cm-1

Raman Shift (cm-1)

2nd derivative

3316 cm-1

raman shift (cm t (k)

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