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Heat Systems Technology, Heat Loss

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by

M Marinucci

on 27 January 2015

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Transcript of Heat Systems Technology, Heat Loss

If an object is warmer than absolute zero it gives off infrared radiation (IR). The infrared radiation can be photographed with special films or detected by special sensors that display colored images. The brightness or colour of the image indicates the temperature of the object.

*An example we will be using in class is an Infrared Thermal Heat Gun.

You Will Need:
-
Your Writing Journals

- A Science Text book to share

- A computer

- A Pencil and eraser


Heat Loss & Insulation
Components of Heating Technologies
The technologies used for thermal energy in heating and cooking have:


A sensor
- a material which is affected by changes in some feature of the environment, such as temperature.


A signal
- provides information about the temperature, such as an electric current


A responder
- which indicates the data with a pointer, light or other mechanism using the signal

Thermostats:
Some heating systems are controlled by thermostats. Thermostats are used to control the air temperature in indoor environments. They also are used to regulate temperatures in electrical devices, such as ovens or air conditioners.

How Thermostats Work
The switch in a thermostat is a bimetallic strip, made of two different metals attached together, and often formed into a coil. When heat is applied to the end, one of the metals expands faster than the other. This change allows the coil to operate a switch or valve just as the thermocouple does.
A Thermocouple
A thermocouple is made of two wires made of different metals that are twisted together. When heat is applied to one end, an electric current is produced. The amount of current depends on the temperature and the type of material the wires are made of. When a current is produced it can turn on and off a switch or valve.

The
Infrared Thermogram
Exploring
Heat Technologies
Today we will be exploring technologies, like micro sensor's, that have advanced the use of thermal energy in heating and cooking.
* Explore the diagram of a thermostat on page.231 in our textbook before examining the thermostat.
What type of professional jobs require the use of a thermal gun?

Discuss your ideas with your table group and together come up with 2 or 3 examples.


Remember think HEAT !
Where are
Infrared Thermograms used?
Heating Systems:
Please open the textbook to page.230
There are two types of heating systems:

Local Heating Systems & Central Heating Systems


1 • Local heating systems provide heat for only one room or a small portion of a building.


2 • Central heating systems provide heat from a single, central source, such as a furnace. Heat transfers throughout the building through pipes, ducts, vents and openings in many different areas of a building.


* Some examples of local heating are fireplaces, wood burning stoves and space heaters
* One examples of a central heating system is our schools heating system.
Their are two types of Central-Heating Systems:

1. Forced-Air Heating

2. Hot Water Heating


* Write down the 4 bullet points under each system's diagrams
in your journal
. It is on page. 231 in the textbook, you can draw a simplified diagram of each system.

Central Heating System Types:
Forced -Air Heating:
Hot-Water Heating:
Difference between the two systems
1. Air is heated by burning fuel in a furnace

2. The heated air travels through air ducts to registers usually found on the floor.

3. A blower helps pull in returning (cooled) air to the furnace for re-heating.

4. The air filter helps trap dust, hairs and other fine particles in the air before returning to the furnace
1. Water is heated by burning fuel in a furnace or boiler.

2. A pump forces heated water through a network of pipes that lead to metal radiators

3. Hot water heats the radiators, which then warm the air in the room.

4. As the water cools, it is returned to the boiler and heated up again.


Which type of heating System does your house have?

Which type of heating system does Arbour Lake have?
Convection at Work:
Heat Systems Technology
Lets think back to the tour of our school's heating system downstairs.

How is heat being created and controlled in our classroom as we currently read this sentance?

Do these appliances use thermal energy?

Do appliances that generate and maintain
colder
temperatures
also
use
thermal energy
in order to work?
Share your
hypothesis
and reasoning with
two students
beside you. Remember to share "Why" you think so.
Example:
I think thermal energy is used to make colder temperatures becuase ...
Convection at Work:
Convection at Work:
In
Forced-Air Heating Systems
and
Hot Water Heat Systems (our School)
convection is constantly working to transfer the heat evenly throughout the building.
Both central heating systems
are controlled by a thermostat which automaticcally adjust the air temperature by switching the heating system on and off.
Keeping Cool:
Thermal energy
is needed
to run refrigerators, freezers and air conditioners. Why?
The
5 basic parts
of a cooling system are:

1. A storage tank
2. A compressor
3. A freezer unit

4. Condenser coils
5. A refrigerant (liquid)

Parts of a
Cooling Sytems
:
What is a
refrigerant
?
A
refrigerant
(liquid) in cooling system devices such as, refrigerators, freezers and air conditioners,
evaporate at a very low temperature, which create freezing cold temperatures inside these devies.

Without this liquid substance, the temperature inside the devices would not stay cool
.

* With a group member, read the diagram of a refrigerator unit on page. 232 and locate where the
refigerant
is and compare how your refrigerator at home to the one shown.
What do
Refrigerants
do?
Is it similar?
Heat Loss
and
Insulation
One of the challenges for Arbour Lake School and Calgarians is to keep the temperature of their building consistent and comfortable.

Where is the heat in our rooms coming from? Walk around the room to see where it is warmer or cooler.


In
winter
, this means keeping the cold air out and hold in as much of the warm air as possible.



In
summer
, this means keeping the hot air out and hold in as much of the cool air as possible.




Insulation is used to reduce heat loss and limit cold air from entering buildings.

The building materials determine how effectively this is done. The
thermal conductivity of a material reflects its ability to transfer heat by conduction.

Materials with low thermal conductivity are useful – such as brick or stone. These are not always the most economical, so Styrofoam and fiberglass insulation is used in most buildings.

Doors and windows are also very important when determining what materials will work most effectively.
Insulation:

If you were to take an a few Infrared image of our school, where do you think it would show the most heat loss?


Typical Heat Loss In A House:

Heat in a typical home is lost from the roof, doors, walls and the windows.

Does this means that additional heat will be needed to replace the heat lost in order to maintain its desired temperature?


Heat Loss:
Research
into improving the materials to prevent heat loss is ongoing everyday.

New windows, doors, siding, weather stripping, and insulation that are more efficient at reducing heat loss are
constantly being developed.

A system of rating these insulators
has been developed to inform consumers how effective the material is.

Research on Insulators
Do you remember what rating system was talked about on our Eco home field trip?
Every insulator is given an

R-value
.

The higher the Rvalue, the most effective it is as an insulator.


Different areas of the home have different recommended
R-values
, depending on how what materials are used and how much space is available for insulation.
The recommended R-values for homes are:

Attic = R-38 to R-44
Sidewalls = R-11 to R-18
Basement = R-10 to R-19
Crawlspace = R-19

Insulator
R
ating System:
Turn to
page 237
and assess your learning
by
completeing all 5 questions in your journals


Once they are
all complete
... you may begin exploring the science stations
next class!
Class Work / Home Work:
Write these in you journal
Full transcript