Question Set 173

21) Explain mechanical refrigeration.

Mechanical refrigeration is a process by which heat is removed from a specific location using an artificial heat-exchange system. The refrigeration system can be cyclic, non-cyclic, magnetic, or thermoelectric depending on the application for which refrigeration is needed.

22) What are various types of brakes?

Various types of brakes are 1) hydraulic breaks, 2) electric breaks, and 3) mechanical breaks.

23) How will you classify sliding contact?

Sliding contact can be classified based on the various thickness of film bearings.

24) How will you create a piston head?

Piston head can be designed on the bases of the following points:

·          The crown must have enough strength to absorb the explosion pressure inside the cylinder.

·          You can consider Grashof’s formula to calculate the thickness of the head.

25) Explain knurling.

It is a manufacturing process conducted on the lathe tool to create a pattern on a bar that can be used a handle.

26) What is the importance of thermostat in the cooling system of an engine?

Thermostat makes sure to keep the engine cool at the optimum level. It prevents decreasing the overall efficiency of the engine.

27) What is the most basic characteristic of supercritical boilers?

Supercritical boilers do not have a heavy drum to separate steam from water and steam. They also require less steel metal.

28) What is the relation between the thickness of the thermal boundary layer and the depth of the hydrodynamic boundary layer?

The ratio of thickness = (Prandtl number)-1/3.

29) What do you understand by engineering drawing?

It is a technical document used to transfer technical details and define requirements.

30) Define the least count

It is the smallest value that can be measured by measuring instrument. Least count can be measured using the following formula: