Insulation - Revision history

RichardWSmith: /* Insulation table */ Added link.

2024-09-17T06:10:14Z

Insulation table: Added link.

RichardWSmith: /* Insulation on Mars */

2024-09-17T05:26:45Z

Insulation on Mars

RichardWSmith: /* Insulation on Mars */ Added link to Smart Windows.

2024-09-17T05:26:12Z

Insulation on Mars: Added link to Smart Windows.

Michel Lamontagne: /* Multi layer insulation */

2023-04-27T17:20:08Z

Multi layer insulation

Michel Lamontagne: /* Insulation table */

2023-04-27T17:19:36Z

Insulation table

Michel Lamontagne: /* Tank insulation */

2021-09-02T16:22:30Z

Tank insulation

Michel Lamontagne at 16:00, 2 September 2021

2021-09-02T16:00:06Z

Michel Lamontagne: /* Tank insulation */

2020-12-15T14:15:07Z

Tank insulation

Michel Lamontagne at 02:51, 15 April 2020

2020-04-15T02:51:14Z

Michel Lamontagne at 02:37, 15 April 2020

2020-04-15T02:37:06Z

@@ Line 73: / Line 73: @@
 |No mechanical strength
 |-
-|Aerogel
+|[[Aerogel]]
 |0,005 to 0,01
 |16

@@ Line 14: / Line 14: @@
 [[Image:metal_foil_box.jpg|right|frame|A block of ice wrapped in aluminium foil to prevent melting.]]
-[[Smart windows]] would be useful.
+[[Smart Windows]] would be useful.
 ==Insulation table==

← Older revision		Revision as of 05:26, 17 September 2024
Line 13:		Line 13:

	[[Image:metal_foil_box.jpg\|right\|frame\|A block of ice wrapped in aluminium foil to prevent melting.]]		[[Image:metal_foil_box.jpg\|right\|frame\|A block of ice wrapped in aluminium foil to prevent melting.]]
		+
		+	[[Smart windows]] would be useful.

	==Insulation table==		==Insulation table==

@@ Line 138: / Line 138: @@
 '''U=4*B*T<sup>3</sup>/N*(2e-1)+1'''
-B is the Stephen Boltzman constant = 5,67e-8 W/m<sup>2</sup>K<sup>4</sup>
+*B is the Stephen Boltzman constant = 5,67e-8 W/m<sup>2</sup>K<sup>4</sup>
+*T is the average temperature between the two surfaces, Exterior and interior = Te+Ti/2
-T is the average temperature between the two surfaces, Exterior and interior = Te+Ti/2
+*e=Emissivity of the layers
+*N=number of layers
 The actual conductivity will be higher, due to the need for spacers in the MLI that add some conduction to the assembly.

@@ Line 125: / Line 125: @@
 Basic calculation:
-Q=k/t*A*(ti-to) or Q=UAdt where
+Q=k/t*A*(ti-to) or Q=UAdt      where:
+*k/t=U Heat transfer coefficient
-k/t=U Heat transfer coefficient
+*Q=Heat loss  (Watts) (J/s)
+*k= Thermal conductivity (W/m°C)
-Q=Heat loss  (Watts) (J/s)
+*A=Wall area  (m2)
+*t=material thickness (m)
-k= Thermal conductivity (W/m°C)
+*ti-to= dt= temperature difference between interior and exterior (°K)
 == Multi layer insulation ==

@@ Line 125: / Line 125: @@
 Basic calculation:
-Q=k*A/t*(ti-to) where
+Q=k/t*A*(ti-to) or Q=UAdt where
 Q=Heat loss  (Watts) (J/s)
 A=Wall area  (m2)
@@ Line 133: / Line 137: @@
 t=material thickness (m)
-ti-to= temperature difference between interior and exterior (°K)
+ti-to= dt= temperature difference between interior and exterior (°K)
 ==Tank insulation==
 Insulation of fuel tanks on Mars may be a requirement to prevent accumulation of frozen CO<sub>2</sub> on tanks.  CO<sub>2</sub> freezes a little bellow -67C and could accumulate significant mass on a fuel tank.  Tank insulation needs to have a vapor barrier, or be composed of closed cells to avoid the risk of condensation in the insulation and the accumulation of water or CO<sub>2</sub> ice in the material.
-== Coatings ==
+==Coatings==
 Coatings can modify the emissivity of surfaces or their solar absorbance significantly<ref>PETTIT, R. B. et SOWELL, R. R. Solar absorptance and emittance properties of several solar coatings. ''Journal of vacuum Science and technology'', 1976, vol. 13, no 2, p. 596-602.</ref><ref>HENNINGER, John H. ''Solar Absorptance and Thermal Emittance of Some Common Spacecraft Thermal-Control Coatings''. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC, 1984.</ref>.  Thermal radiation from a structure' surface and convection from the Martian atmosphere add loses to an insulated structure.  During the day, solar heat gain can be affected by coatings as well.

@@ Line 152: / Line 152: @@
 ==References==
 [[Category:Construction, Assembly, Maintenance]]
 <references />

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 The thin Martian [[atmosphere]] has a reduced capability for a convective flow of heat. More important is the heat radiation, which can be effectively reduced by choosing the material of the building's surface. A smooth bright metallic surface emits much less heat radiation than a rough black one. A simple [[aluminium]] coated foil wrapped around the settlement modules provides excellent insulation.  [[w:Multi-layer_insulation|Multi-layer insulation]] (MLI) of the same type of foil can reduce heat loss to very low numbers and is commonly used for satellites.  However, convection is still significant in insulation systems on Mars and this reduces the effectiveness of MLI<ref name=":0" /> to about the same as other systems. MeMLi, Multiple Environment MLI is under development to increase the effectiveness of this type of insulation on Mars<ref>https://data.nasa.gov/dataset/Multi-Environment-MLI-Novel-Multi-functional-Insul/5hw6-3x2x/data</ref>.
-[[w:Foam_glass|Foam glass]] is another form or insulation than can be produced locally and should have superior insulation properties,as well as good structural properties.  Foam insulation on Mars has very low convection and radiation rates.  The heat transfer comes essentially from conduction in the cell walls.
+[[w:Foam_glass|Foam glass]] is another form or insulation than can be produced locally and should have superior insulation properties, as well as good structural properties.  Foam insulation on Mars has very low convection and radiation rates.  The heat transfer comes essentially from conduction in the cell walls.
 Fiberglass and mineral wool would not function as insulators in the same way on Mars as they do on Earth.  Fiberglass is not itself an insulator.  The insulation comes from the thermal resistance of the air in the fiberglass mat.  The resistance of the air in increased because it cannot flow freely over the surfaces, reducing convective heat transfer significantly.  Fiberglass is also installed with a reflective vapor barrier, that adds to its insulation value.
@@ Line 15: / Line 15: @@
 ==Insulation table==
-The following table shows some insulation values for materials on Mars<ref name=":0">https://trs.jpl.nasa.gov/bitstream/handle/2014/22216/97-0683.pdf?sequence=1</ref>.  The exact value will need to be tested on Mars, and will vary significantly if the material is used inside a habitat at Earth atmospheric pressure or outside the habitat at martian atmospheric pressure.
+The following table shows some insulation values for materials on Mars<ref name=":0">https://trs.jpl.nasa.gov/bitstream/handle/2014/22216/97-0683.pdf?sequence=1</ref>.  The exact value will need to be tested on Mars, and will vary significantly if the material is used inside a habitat at Earth atmospheric pressure or outside the habitat at Martian atmospheric pressure.
 Most insulation is used in assemblies.  Structural elements may have high conductivity and decrease thermal resistance.  Combination of materials, films and radiation reflective surfaces can modify insulation values significantly.
@@ Line 137: / Line 137: @@
 ==Tank insulation==
 Insulation of fuel tanks on Mars may be a requirement to prevent accumulation of frozen CO<sub>2</sub> on tanks.  CO<sub>2</sub> freezes a little bellow -67C and could accumulate significant mass on a fuel tank.  Tank insulation needs to have a vapor barrier, or be composed of closed cells to avoid the risk of condensation in the insulation and the accumulation of water or CO<sub>2</sub> ice in the material.
 ==Production==

@@ Line 32: / Line 32: @@
+|
+|
-|0,5-1 space
+|0,2-1 space
 -50 Mars
 |This insulation's effectiveness varies with the number of layers. No mechanical strength.  Sensitive to convection. 20 to 40 layers. Usually a few mm thick. 1.5 kg/m2