When making my thermos, I need to understand how to minimize the 3 types of heat transfer
- radiation – transfer of heat through electromagnetic waves
- conduction – transfer of molecule movement through a solid
- convection – movement of heat through a liquid or a gas
Other criteria I had to meet for this grade 7 assignment is that it needs the practical (easy to hold) and it needs to be usable carrying at least 250mL or 1 cup of water.
Problem Definition and Considerations
To understand the bottom line stated above, someone told me to google how heat flows and to search things that are insulated.
The 3 forms of heat loss or transfer listed above came from this website (click) which explains it well with pictures and words.
We recently had our home upgraded and we insulated our attic. Here is a website that helped me understand that better (click). The measure of how good insulation is is called its R value. Here is a website (click) that define he R value and it has a table of materials with good to bad R values. Polyurethane foam, I was told was the first item on the list I could get a local hardware store that had the highest R value (1.2-1.4). This is the rigid foam panels (R=1.23) that new houses are lined with for insulation. It also comes in spray-foam varieties but R=0.93-1.1 . Due to cost, we went with polystyrene rigid foam (R=0.88-0.95) for the lid and spray foam (practicality and it fills all gaps).
Aluminum foil wraps nicely and stops electro-magnetic radiation before it can get to the foam. The foam and polystyrene boards do the rest limiting air movement (convection) and slowing conduction (it is hard for heat to travel through the foam due to the bubbles). The outer cover protects the foam and interesting duct tape was used to do this and integrate a handle into the design.
Using a glass jar would make sure it can be easily cleaned and it already comes with a lid. Most expensive thermoses are made of glass on the inside.
One thing that is important is that polystyrene and polyurethane will “melt” if the wrong kind of glue is used. We used glue that said it was compatible with polystyrene and polyurethane.
Construction & Design:
A good container to use was the glass Taster’s Choice instant coffee Continue reading
house with side with sun and shade
Can the kids try this and comment on this before Feb 23?
So look at this house – better yet look at YOUR house. There is always one side that gets all the light from the sun – but RIGHT NEXT TO THIS is the other side that has a shadow (normally this is the North side.) Put your hand on the corner that has had the sun on it for at least an hour. What does the sun side feel like? What does the shadow side RIGH NEXT TO IT feel like? What a difference right?
What colour feels hotter in the sun?
Now what about colour? Put your hand on a white or light grey car – the Continue reading
I have been thinking about doing a solar panels for my roof for years and have always said – one day I will have them up there. I love nature documentaries and know that I am affecting the earth I live on. So I thought I would instil a little tree-hugging into my kids, but in a practical way. Solar is a little complicated – but heat and the sun – that is do-able and concrete for kids to understand.
After watching way too much Blue Planet, Crocodile Hunter and lately River Monsters, I realize that EVERYTHING we have starts with the energy from the Sun. If it wasn’t there – nothing would work. I also know oil is simply the sun’s energy captured – plain and simple from vegetation long ago. What can we do to help I ask?
Living in Alberta (weather like Montana USA), I know that once that sun goes down – its game over as far as being warm. There are NO lakes, NO humidity, just rocks that give off latent heat from that day’s sun so it gets cold real fast. In the summer – we don’t REALLY need air-conditioning but taking edge off would be super nice for many days in July and August. After camping and buying a battery and solar panel, I don’t need to buy as many (if any) batteries for the tent trailer’s lights or lanterns and we have light after dark. That is what inspired me for this project – but electrical with young kids is a little much I thought. What else could we do?
So a VERY PRACTICAL and easy to understand concept was those Continue reading
This article, is merely to capture some of the research in selecting a PLC – a machine that will capture data and control things like valves, power and other things to control the whole system. What if the temperature gets to high in the pipes and starts to boil? Well, we would want to open a valve and drain EVERYTHING. It is only water so we would want some safety in the whole thing.
Some links I looked at so far…