Question

Two temperature sensors are fixed at different depths in a sealed circular tank. Both sensor are located at the same distance from the wall of the tank but are separated by a distance l=5m. The tank contains a transparent liquid that is maintained at approximately 40°C with the use of heating pipes that are located near the bottom floor of the tank. The heating pipes are only in contact with the liquid and not with the body of the tank. The tank is properly insulated but there is a discrepancy between the readings of TE-1 and TE-2. Both temperature sensors are working properly. The inner surface of the tank is made from an aluminum metal alloy. The liquid in the tank is in contact with the metal alloy. However, the outer surface of the tank is made from a polyurethane based material (foam). The air temperature outside of the tank is approximately 15°C.
a) Explain the reason(s) for the discrepancy between the readings of TE-1 and TE-2 from the point of view of heat transfer. TE-1 is displaying a larger temperature than TE-2 is. Your explanation should focus on the discrepancy between the readings of the two sensors and not the heat transfer that is taking place from the tank to the air outside of the tank.

Answer 1

Liquid is heated at bottom floor, and hot liquid generally is less denser so it moves up and cold liquid is more denser so it moves down.

Here TE-1 is kept upper part of liquid hence it displaying larger temperature.

Another reason might be, effect of pressure on temperature sensor.

That at low pressure temperature sensor displays more temperature. Here TE-1 is at less depth experiences less pressure and displays more temperature.