common applications of convection

1. Electric kettles
the heating coil of an electric kettle is always placed at the bottom of the kettle to aid transfer of thermal energy in water by convection. when the power is switched on ,the water near the heating coil is heated up, expands and becomes less dense. The heated water therefore rises while the cooler regions in the upper part of the body of water descend to replace the heated water.

2.household hot water systems

1Water is heated in the boiler by gas burners. The hot water expands and becomes less dense. Hence, it rises and flows into the upper half of the cylinder.

2To replace the hot water, cold water from the cistern falls into the lower half of the cylinder and then into the boiler due to the pressure difference.

3The overflow pipe is attached to the cylinder just in case the temperature of the water becomes too high and causes a large expansion of the hot water.

4 The hot water tap is led from the overflow pipe and must be lower than the cistern so that the pressure difference between the cistern and the tap causes the water to flow out of the tap.

3.Air conditions

The rotary fan inside an air conditioner forces cool dry air out into the room. The cool air, being denser, sinks while the warm air below, being less dense, rises and is drawn into the air conditioner where it is cooled.

4.Refrigerators

Refrigerators work in very much the same way as air conditioners. The freezing unit is placed at the top to cool the air so that the cold air, being denser, sinks while the warm air at the bottom rises. This sets up convection currents inside the cabinet which help to cool the contents inside.