Question No. 1

What happens if gasoline is used in a Diesel engine? Will diesel engine work?

Answer:

No, it will not work, as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to 22. Thus on such high compression, gasoline gets highly compressed & it may blast.

Question No. 2

Why boiler is purged every time before starting firing of fuel?

Answer:

Purging ensures that any unburnt fuel in furnace is removed; otherwise it may lead to explosion.

Question No. 3

What is the principle of mechanical refrigeration?

Answer:

A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding objects.

Question No. 4

Why high latent heat of vaporisation is desirable in a refrigerant?

Answer:

A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage.

Question No. 5

How a diesel engine works in generator?

Answer:

Diesel engine is a prime mover, for a generator, pump, and for vehicles etc. Generator is connected to engine by shaft. Mostly in thermal power plant, there is an engine is used to drive generator to generate power.

Question No. 6

What is flash-point?

Answer:

Flash point: the lowest temperature at which the vapour of a combustible liquid can be ignited in air.

Question No. 7

What is the critical temperature of a refrigerant?

Answer:

Critical temperature is the maximum temperature of a refrigerant at which it can be condensed into liquid and beyond this it remains gas irrespective of pressure applied.

Question No. 8

What is refrigerant?

Answer:

Any substance that transfers heat from one place to another, creating a cooling effect. Water is the refrigerant in absorption machines.

Question No. 9

What is the effect of reheat on Rankine cycle?

Answer:

This prevents the vapour from condensing during its expansion which can seriously damage the turbine blades, and improves the efficiency of the cycle, as more of the heat flow into the cycle occurs at higher temperature.

Question No. 10

As compression ratio increases, thermal n increases. How is thermal n affected by weak and rich mixture strength?

Answer:

Thermal n is high for weak mixture and it decreases as mixture strength becomes rich.