The first and most obvious is the transfer of heat from the heating coil, to the water in the tube sitting on top of the heating coil. The second is the transfer of heat from the heating coil to the hotplate that sits above the heating coil holding the coffee pot. The third area where heat transfer is applied is in the thermostat. When the thermostat reaches a certain temperature it breaks the circuit and automatically shuts off the coffee maker until it cools down again. The topic that applies to the coffee maker is filtration.
Filtration is when solid particles are separated from a liquid.
When the water stream is introduced to the coffee grounds the grounds that aren't diluted into the water are filtered out of the coffee by a piece of filter paper. The variables in the coffee maker that need to be adjusted are the amount of water heated and the amount of heat used. The thermostat is used to control the amount of heat used and the amount of water heated. It is also important to select materials that will properly shield heat sensitive materials from the high temperatures in the coffee maker. Economics - costs of various design and operating options When designing a coffee maker it would be wise to select a design that is energy efficient and cost efficient.