E5: Efficiency — B level

Choose one or more of these options to learn about heat pumps.

There are many more information sources online if you want to search, but it’s challenging to find good ones.

Draw your own labelled diagram of the refrigeration cycle, showing the main parts with a short description of what happens there.

If you draw into your computer, it still needs to be hand-made. No copy/pasting.

Efficiency is often not very helpful when describing heat pumps. This is because heat pumps move more energy than they use.

The energy going into a heat pump is mostly used in the compressor. But the whole system doesn’t transform electrical energy into thermal energy. Instead, it moves thermal energy from one place to another.

The ratio of the amount of energy moved compared to the electricity used is called the coefficient of performance.

Do some web searching to find out common values of coefficient of performance. Record the range that you find, and give some actual numbers (that is, how many Watts or Joules of heating or cooling is produced by a certain number of Watts or Joules of electricity).

Compare reverse-cycle air conditioning (which is a heat pump that can both cool and heat air) with these other heating and cooling systems:

• Evaporative cooling
• Slow combustion wood stove
• Flueless gas heater
• Radiant electric heater

Compare these points:

• Energy efficiency
• Emission of greenhouse gases (the effect on climate change)
• Effects on health

Finally, recommend a way of keeping a house warm and cool to someone in Moree who doesn’t have any heating or cooling systems installed.