Simulating phase change cooling
Dec 25, 2017 9:53:37 GMT
apophys, The Astronomer, and 3 more like this

### Post by zuthal on Dec 25, 2017 9:53:37 GMT

I had the idea that it might be possible to simulate the coolant changing phase (and thus taking a lot more heat away than it normally would) by altering the melting point and the heat capacity of the coolant to simulate the full heat absorbed during the phase change.

For example, aluminium boils at an acceptable pressure for use in our reactors, and has a heat of vaporisation of about 10800 kJ/kg. By increasing the melting point to 2300 K and the specific heat by 108 kJ/kg*K, we can simulate this for the outer coolant loop of a reactor with a 2400 K exit temperature.

Material Data:

Reactor comparison:

The reactor with boiling metal coolant is, for the same power output, about 33% lighter and shorter than the conventionally cooled one.

This should allow much lower pump speeds, and thus lighter reactors. The downside is that you must create a new material for each temperature differential (for the inner coolant loop) or for each coolant exit temperature (for the outer coolant loop, as there the coolant returns at the melting point) in order for it to work.

Changelong:

2017-12-25 11:18 Added 400, 500 and 600 Kelving delta-T Aluminium coolants.

For example, aluminium boils at an acceptable pressure for use in our reactors, and has a heat of vaporisation of about 10800 kJ/kg. By increasing the melting point to 2300 K and the specific heat by 108 kJ/kg*K, we can simulate this for the outer coolant loop of a reactor with a 2400 K exit temperature.

Material Data:

`Material Boiling Aluminum 2400 K Outer`

Elements Al

ElementCount 1

Density_kg__m3 2700

YieldStrength_MPa 20

UltimateTensileStrength_MPa 300

YoungsModulus_GPa 69

ShearModulus_GPa 25.5

SpecificHeat_J__kg_K 108900

MeltingPoint_K 2300

BoilingPoint_K 2743

ThermalConductivity_W__m_K 237

ThermalExpansion__K 23.1e-6

Resistivity_Ohm_m 2.81e-8

RelativePermeability 1.000022

ThermoelectricSensitivity_V__K -1.5e-6

LasingDamageThreshold_TW__m2 .00127

RefractiveIndex Aluminum

RoughnessCoefficient 0.3

Viscosity_Pa_s 0.0000029

`Material Boiling Aluminum 400 K Delta`

Elements Al

ElementCount 1

Density_kg__m3 2700

YieldStrength_MPa 20

UltimateTensileStrength_MPa 300

YoungsModulus_GPa 69

ShearModulus_GPa 25.5

SpecificHeat_J__kg_K 27900

MeltingPoint_K 933.47

BoilingPoint_K 2743

ThermalConductivity_W__m_K 237

ThermalExpansion__K 23.1e-6

Resistivity_Ohm_m 2.81e-8

RelativePermeability 1.000022

ThermoelectricSensitivity_V__K -1.5e-6

LasingDamageThreshold_TW__m2 .00127

RefractiveIndex Aluminum

RoughnessCoefficient 0.3

Viscosity_Pa_s 0.0000029

`Material Boiling Aluminum 500 K Delta`

Elements Al

ElementCount 1

Density_kg__m3 2700

YieldStrength_MPa 20

UltimateTensileStrength_MPa 300

YoungsModulus_GPa 69

ShearModulus_GPa 25.5

SpecificHeat_J__kg_K 22500

MeltingPoint_K 933.47

BoilingPoint_K 2743

ThermalConductivity_W__m_K 237

ThermalExpansion__K 23.1e-6

Resistivity_Ohm_m 2.81e-8

RelativePermeability 1.000022

ThermoelectricSensitivity_V__K -1.5e-6

LasingDamageThreshold_TW__m2 .00127

RefractiveIndex Aluminum

RoughnessCoefficient 0.3

Viscosity_Pa_s 0.0000029

`Material Boiling Aluminum 600 K Delta`

Elements Al

ElementCount 1

Density_kg__m3 2700

YieldStrength_MPa 20

UltimateTensileStrength_MPa 300

YoungsModulus_GPa 69

ShearModulus_GPa 25.5

SpecificHeat_J__kg_K 18900

MeltingPoint_K 933.47

BoilingPoint_K 2743

ThermalConductivity_W__m_K 237

ThermalExpansion__K 23.1e-6

Resistivity_Ohm_m 2.81e-8

RelativePermeability 1.000022

ThermoelectricSensitivity_V__K -1.5e-6

LasingDamageThreshold_TW__m2 .00127

RefractiveIndex Aluminum

RoughnessCoefficient 0.3

Viscosity_Pa_s 0.0000029

Reactor comparison:

The reactor with boiling metal coolant is, for the same power output, about 33% lighter and shorter than the conventionally cooled one.

This should allow much lower pump speeds, and thus lighter reactors. The downside is that you must create a new material for each temperature differential (for the inner coolant loop) or for each coolant exit temperature (for the outer coolant loop, as there the coolant returns at the melting point) in order for it to work.

Changelong:

2017-12-25 11:18 Added 400, 500 and 600 Kelving delta-T Aluminium coolants.