5 votes

Effective R-value of radiant barriers

Insulating against thermal conduction can be represented as an R-value because it is a linear calculation. I can add two or more R-values together and I will see a linear benefit. Insulating against ...
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  • 7,489
4 votes
Accepted

Suggestions on how to keep electronics cool in high ambient temperature location?

I can think of three ways you could solve this problem: Insulate the device Add thermal mass to the device, e.g. make the case overly large and dense. Use some kind of cooling system, like a simple ...
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  • 2,989
4 votes
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What colour of tarp will let in the least amount of heat?

As a practical and cost effective solution, I'd advise using aluminium foil, or tin foil as it's also called. Please realise that it's rather fragile, so it's best to glue it to a plastic foil or ...
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  • 1,164
4 votes

What is the ideal gap between two panes of glass for insulation

Back in my graduate M.E. heat transfer days (the 1980's) we worked that out for typical window geometries. It turned out that the 1 1/2 to 2" separation for classic interior windows/storm windows ...
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4 votes

More efficient to use LED lighting than to open blinds for light and thereby lose heat when very cold outside?

The reason your utility company recommends to let the sunshine in is not to save on lighting energy. it is to take advantage of solar radition energy. a window can let the solar radiation in two ways, ...
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  • 21k
3 votes

Freezing water in bent copper pipe

If you really want to use the copper pipe, insert a thin strip of closed-cell foam into the length of the pipe. The ice expansion will crush it rather than the pipe, and unlike leaving an air gap, it ...
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3 votes

What colour of tarp will let in the least amount of heat?

I would suggest a reflective mylar film such as those used for survival blankets. That would be the most effective single layer solution. Adding additional layers of plastic would further insulate ...
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3 votes

DIY thermally insulating construction material

The aluminum can barely support itself at 400 C."Lightweight castable" refractory ( can be handled like concrete) should do the job; but you would need to find a supplier .It is what a petrochemical ...
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  • 5,894
3 votes

Heat Loss in Typical House

No, it's not meaningful to express it as a ratio. The best insulation is deep insulation everywhere. You also need to consider convection losses, and your ventilation strategy. The attic is usually ...
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  • 3,701
3 votes

Why Heat Exchangers are preferred to work in Constant Pressure Process than Constant Volume Process?

I'm assuming that you want to know why we use the heat capacity at constant pressure, $c_p$, instead of at constant volume, $c_v$, in analyzing heat exchangers. The main reason is that the pressure ...
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  • 2,989
3 votes

What material might by used to 'staple' coils down in this stovetop element?

I expect the same material as the coils would be the easiest answer ; nichrome ,Inconel ( 600, 601 or other number) , chromel. There are small differences but any one you can find would be good. That ...
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  • 5,894
2 votes

Determination of thermal expansion of a hollow cylinder

Plastics have a thermal expansion rate of approximately 5 to 10 times that of metals. The PTFE will expand the most and the brass expansion is about 50% more than a steel heater, so the assembly will ...
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2 votes

What is a transparent material that insulates well?

To borrow from a certain Brit physician, "I think it's a bit more complicated than that." For example, you could build/buy a double-walled box with a vacuum between the layers. That's esssentially ...
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2 votes
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Does attic insulation help cool a building?

Attics are much hotter than the outside air when the sun is shining on them (say 120F in an attic). When the air conditioning system is running the internal air temperature is less than the outside (...
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  • 7,489
2 votes

Does attic insulation help cool a building?

in the summer, the outside of the house- especially its roof- is hotter than the inside of the house. In this case, attic insulation does not physically "cool" the house- it just impedes heat transfer ...
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2 votes
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How thick do I need to make the insulation in my homemade furnace?

First off, the design problem is not trivial and it looks like you have done your homework. On high temperature, small vessels like this you need to consider the 3 dimensional transfer of heat (the ...
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  • 7,489
2 votes

How to connect butted or overlapping fiberglass insulation

First I recommend you use mineral wool or ceramic wool instead of fiberglass as they are rated for higher temperatures. Material Temperature Glass wool 230 - 260 °C Stone wool 700 - 850 °C ...
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2 votes
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DIY thermally insulating construction material

have you considered firebrick, a product designed to be used in high temperature kilns, for example? It's light weight and easily cut with ordinary hand tools. It may not tolerate severe compression, ...
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  • 6,282
2 votes

How does concrete perform in an Insulated Concrete Form (ICF) house?

I don't have experience with ICF houses specifically, but I do have experience with specifying concretes for outdoor use with significant frost exposure, so that is what I am basing my answer on. If ...
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  • 1,278
2 votes

How to calculate the volume of air required to keep electrical box cool?

This question can only be answered after many tests as to the convective properties of the box, it's geometry with respect to the geometry of the void, ignoring radiation. Because convection which is ...
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  • 21k
2 votes

How to calculate the volume of air required to keep electrical box cool?

If I get you right, there is a box having a small device that dissipates 30 Watts of heat continuously into the air. The air is blocked into a box, no way in or out. There are no fans/blowers trying ...
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2 votes
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More efficient to use LED lighting than to open blinds for light and thereby lose heat when very cold outside?

In order to assess the efficiency you need to compare the heat transfer rate $\dot{Q}$ with and without blinds. There are a few studies comparing the effect of blinds (internal/external/enclosed) on ...
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  • 22.7k
1 vote

Freezing water in bent copper pipe

The best ice cream is made with the outside bucket temperature below 0 oC. See this link https://www.icecreamnation.org/science-of-ice-cream/. The common approach is the tried and true method to use ...
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1 vote

Protecting heat-sensitive media from fire: fire-safe + Thermos?

Radiative heat transfer will be quite high in a house fire, so not every construction made for 100°C temperature differences will be applicable here- look for constructions that have glowing-metal ...
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  • 186
1 vote

DIY thermally insulating construction material

Don't consider this as an answer, but since i can't post a photo in comments, here i post it, i generated this diagram using CES, level two, i marked the most suitable and accessible materials. The ...
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1 vote
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How cold for lack of heat?

Imagine the system below at equilibrium. The energy balances are as follows: At the ball ... $$\epsilon_b T_b^4 =\epsilon_w T_w^4$$ At the wall ... $$\epsilon_w A_w \sigma T_w^4 = h_a A_w (T_a - ...
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1 vote

What colour of tarp will let in the least amount of heat?

White and silver are the most reflective (not absorb heat from the sun). There is some debate about which is more reflective. A white tarp is probably going to be cheaper.
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  • 479
1 vote

Insulator thermal resistance

You need to investigate the flammability properties of the insulating materials : wood can be a good insulator if it is dry, but it burns well etc.
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  • 14.1k
1 vote

Calculating R-value from temperature differential

There are a lot of things wrong with the demonstration, including: The temperature of the heat gun isn’t relevant - to measure the R value you need to look at the temperature difference across the ...
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  • 1,012
1 vote

When does window insulation have more impact than attic?

A project makes economic sense when the return from the project exceeds the rate you can borrow money at. Usually we want a fairly large return before we concern ourselves with the project however. ...
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