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Statement (I): Piston temperature profiles near full load are flattened in case of liquid cooled engines whereas for air cooled engines temperature profiles are steeper. Statement (II): The piston temperature profiles are different in nature for liquid cooled and air cooled engines because of the different values of heat capacities.

Statement (I): Piston temperature profiles near full load are flattened in case of liquid cooled engines whereas for air cooled engines temperature profiles are steeper. Statement (II): The piston temperature profiles are different in nature for liquid cooled and air cooled engines because of the different values of heat capacities. Correct Answer Statement I) is false but Statement II) is true

  • The air cooling system for piston is same as that of the fin cooling system in which cooling temperature profile is exponential curve. So, statement I) is false as it says that temperature profile is steeper. Also, liquid cooling system use convective cooling in which curve cannot be flattened.
  • Air-cooled engines utilize cooling fins that are either cast or machined into the exterior surfaces of the cylinder barrels and heads. Fins provide a very large surface area for transferring heat to the surrounding airflow. Liquid cooled engines are constructed with a metal water jacket that surrounds the cylinders. As coolant circulates in the water jacket, heat passes from the cylinder walls and heads to the coolant.
  • As different liquid cooling and air cooling follows different process of cooling because heat transportation medium in both cases are different i.e. (air and water) and hence, different heat capacities of cooling fluid. Water has a higher heat capacity than air, and can move heat more quickly away from the engine. Thus; temperature profiles are different in both cases. Statement II is correct.

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