Thermal Expansion and Thermal Insulation

Expansion

increase in size, temperature, length or density

coefficient

constant term related to the properties of a number

Thermal Expansion

defines the tendency of an object to change its dimension either in length, density, area, or volume; most solids and liquid expand when heated and contracted when cooled

Linear Expansion; Volumetric Expansion

types of expansion

Linear Expansion

defined as the increase in the length of the solid to heat

3.0054 cm

A brass strip is 3 cm long at 0C. How long will it be at 100C if the coefficient of linear expansion for brass is 1.8x10^-5/C?

100 cm

An iron rod heated from 30C to 80C. The final length of iron is 115cm and the coeffcent of linear expansion is 3x10^-3/C. What is the original length and the change in length of the iron?

Volumetric Expansion

The volume of a gas, solid, or liquid changes if the temperature, the pressure of the forces acting on that gas/solid/liquid change.

0.33 galloon

Suppose that a gas tank in your car is filled when the temperature is 17C. How many galloons will spill out of 20 galloons steel tank when the temperature rises to 35C?

heat flow

the flow of heat from warmer to cooler surface

heat transfer

the transfer of heat or exchange of thermal energy between physical systems.

conduction, convection, radiation

What are the three methods of heat transfer?

Thermal Insulation

Process of reducing heat transfer between objects or in radiative influence

Low Thermal Conductivity

Materials combined to achieve even lower system thermal conductivity

Asbestos

Historical insulation material with heat, water, and chemical resistance

Mineral Wool

Insulation made from melted rocks spun into fibers

Sheep's Wool

Insulation material made from natural wool fibers

Fiberglass

Material made from thin threads of molten glass

Cellulose

Insulation made from recycled paper products

Polyurethane

Plastic-based insulation material

PIR (Polyisocyanurate)

Insulation boards made from a plastic-based source

Polystyrene

Plastic material that can be expanded into closed-cell foam boards

Vermiculite

Naturally occurring mineral that expands when heated

Conduction

Heat transfer through direct contact of materials

Convection

Heat transfer through fluid motion

Radiation

Heat transfer through electromagnetic waves

Reflective Materials

Materials used to prevent heat transfer by radiation

Convection Currents

Fluid motion that transfers heat

Thermos Bottle

Container with shiny material to prevent radiation heat transfer

Dr. Montague Murray

Documented the first death from asbestos exposure in 1930

Environmental Protection Agency

Agency that began restricting asbestos use in the 1970s

Egyptian Buildings

Used thick stones for insulation to keep buildings cool

Vikings

Used mud plaster to insulate buildings and stop draughts

Big Energy Savings

One of the benefits of thermal insulation

Reduces Reliance on Aircon

Benefit of maintaining comfortable indoor temperatures

Long Lifetime Warranty

Benefit of using insulation materials