(lively music)
- [Vincent] Hi everyone, so I'm gonna show you today
how to use this little tool
that we've created for you for steady state heat transfer
in a composite wall.
I'll just run you through some of the variables
and then I'll show you a couple of test cases.
And then you can go along
and actually play around with it yourself
and actually use it to help you figure out some
of your tutorial questions as well.
We've got our composite wall up here on the left,
and it's currently showing us a three-layered structure
that has these three materials currently selected in them,
so they're all on sliders
and you can alter each of these materials,
so we have brick,
concrete, and plaster
that you can use as an external material
but just note that for brick,
they generally come in discrete sizes,
so you don't have a slider bar for your brick
but it will generally come
in about 100 mill discrete sizes for brick
and so, you can select across your insulation,
your internal, you can alter
to concrete or brick as well
and then plaster and concrete on the interior surface.
So, before you go through and you calculate anything,
we first wanna look at our resistor network
that we have, so this describes our steady state case
and that is our combined surface, the thermal resistance
and then the thermal resistances for each
of the materials that we have in our composite wall.
We also have our Q solid gain as well,
our radiative thermal resistance
to the sky and our radiative thermal resistance
to the exterior ambient temperature, so T out
which you can alter up here
in the top right, so almost all variables you can alter
except for the T sky temperature.
One important thing to note
in this thermal resistance network
is that we have one set which is just our wall construction
which is a series thermal resistance
and then we have our parallel thermal resistances
for everything that's exterior to our building,
so our radiation and our convention
that's in contact with that surface, that exterior surface.
So, we have conduction moving through
just our wall construction.
So, let's go through one test case for you.
I'm gonna leave the area of the wall to 10,
the only thing that's gonna change
for your particular simulations
are the magnitude of heat transfer
is the magnitude of heat transfer,
so you can see that changing here in these values
that are going in and out of your building,
so you can see the magnitudes changing.
So, I'm gonna fix that to 10 for now.
Leave that and we're gonna work on a test case
of let's 40 degrees exterior temperature,
so it's an extremely hot day in Sydney,
that's very uncommon.
Say one of the hottest days in summer.
40 degrees and let's say we want our interior temperature
of our building to be somewhere around 25
if we wanna maintain thermal conflict.
So, we have that interior temperature here,
it's 25 degrees.
So, let's set up, I want plaster on my interior surface,
let's go for a standard wall,
standard house, plaster on the interior surface,
we've got a little bit of insulation.
Sorry.
Yeah, we'll pick insulation,
we'll pick a little bit of insulation in between
and then we have brick on the exterior,
about 100 mills of brick on the exterior,
so it's a brick veneer.
So, after you've set your parameters,
you have to click the Calculate button
in order to calculate what the temperatures are
at each point along your wall.
And you can go and play through your various temperatures
if you want to alter the temperatures.
I'm just gonna click Calculate again
and just have a look at how that affects
the temperatures that are moving from your exterior
to the interior of your building
across these materials.
I hope this was helpful and I hope
that you can use this to assist you
in answering your tutorial questions.