MCQ Questions and Answers on Thermodynamics

Q.

When the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust

A. increases

B. decreases

C. remains same

D. cannot say

Answer : Option:- A

Explanation :

In the Rankine cycle, which is used in steam power plants, increasing the pressure at which heat is added raises the temperature of the steam. This results in more moisture remaining in the steam as it expands and exits the turbine. The moisture content at the turbine exhaust increases because the steam doesn't fully evaporate, leading to a less efficient turbine performance. This effect is important when designing power systems for maximum efficiency and minimizing wear and tear on turbine components.

Q.

In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature

A. Which lies between the dry bulb and wet bulb temperatures of the incoming stream

B. Which lies between the wet bulb and dew point temperatures of the incoming stream

C. Which is lower than the dew point temperature of the incoming stream

D. Of adiabatic saturation of incoming stream

Discuss

Answer : Option:- C

Explanation :

To cool and dehumidify air, the air must be passed over a cooling coil that is set at a temperature lower than the air’s dew point. The dew point is the temperature at which air becomes saturated with moisture and condensation begins. When the air cools below this point, the moisture condenses, thus removing humidity. This principle is crucial in HVAC systems, where controlling humidity is key to ensuring comfort and preventing issues like mold growth.

Q.

Degree of saturation or percentage humidity is

A. The mass of water vapour present in 1 m³ of dry air

B. The mass of water vapour present in 1 kg of dry air

C. The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure

D. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure

Discuss

Answer : Option:- C

Explanation :

The degree of saturation, or percentage humidity, refers to the amount of water vapor present in the air relative to the maximum amount it can hold at a given temperature and pressure. It is calculated by comparing the actual mass of water vapor in a unit mass of dry air to the mass of water vapor that would saturate the air at the same temperature and pressure. This concept is important in understanding weather conditions, climate control, and processes like air conditioning or drying.

MCQ Questions and Answers on Thermodynamics

Q. When the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust

Q. In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature

Q. Degree of saturation or percentage humidity is

Q.

When the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust

Q.

In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature

Q.

Degree of saturation or percentage humidity is