P.16-19

P.16-19

Rate of Heat Transfer
1. The rate of heat energy transfer depends on many things
  1. Surface area
    1. The larger the surface area the faster the rate of heat transfer
  2. Volume
    1. The larger the volume the slower the rate of heat transfer
  3. Type of material
    1. Objects made from good conductors transfer heat away quicker
2. Some devices are designed to limit heat transfer
3. Humans and animals have ways of controlling heat transfer too
  1. In the cold, the hairs on your skin stand up to trap a layer of air around your body
    1. This prevents convection
  2. When you're too warm, your body diverts blood to flow nearer to the surface of your skin
    1. This causes more radiation
Energy Transfer
1. There are nine types of energy:
2. Electrical Energy
3. Light Energy
4. Sound Energy
5. Kinetic Energy
6. Nuclear Energy
7. Thermal Energy
8. Gravitational Potential Energy
9. Elastic Potential Energy
10. Chemical Energy
  1. These are forms of stored energy
11. Energy can be transferred usefully from one form to another stored or dissipated- but it can never be created or destroyed
12. Energy is only useful when it can be converted from on form to another
Specific Heat Capacity
1. Specific Heat Capacity tells you how much energy materials can store
  1. It takes more heat energy to increase the temperature of some materials than others
2. E = m x c x ϑ
3. Energy transferred = Mass x specific heat capacity x temperature change
4. J = kg x J/kg°C x °C
5. Heaters are designed to have high heat capacities to store lots of energy
Energy efficiency in the home
1. Effectiveness and cost-effectiveness are not the same thing
  1. The most effective methods of insulation give you the biggest annual saving
    1. The money you've saved on heating bills will equal the initial cost
      1. This is the payback time
  2. The most cost-effectiveness methods tend to be the cheapest
    1. They have a short payback time
2. Cavity wall insulation, Loft insulation, Draught-Proofing, Hot water tank jacket, and Thick curtains
  1. U-Values show how fast heat can transfer through a material
By Stephen Thompson

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	Creado por stephen.tomo hace casi 11 años