Question

A thermal power station has a heat rate of 12 mJ/kWh. Its thermal efficiency is

Answer 1

The thermal efficiency of the plant is 30%

Explanation:

Heat rate is defined as the ratio of thermal energy in to electrical energy out

1 kilowatthour = 1000w x 3600sec = 3600000 J = 3.6 MJ

Hence 12MJ/KWh simply means that the power plant consumes 12 MJ of thermal energy(input) for producing 1 KWh or 3.6MJ of electrical energy(output)

Hence efficiency = output/input   x  100

= 3.6/12  x 100

= 30%

Hence the thermal efficiency of the plant is 30%

Answer 2

The efficiency of energy from a conventional Thermal depends on the fuel's heating value.

Heat rate is equal to the ratio of thermal energy in to electrical energy.

As we know, 1 kilowatt hour = 1000 w × 3600 sec = 3600000 J = 3.6 MJ

Given, the heat rate of the thermal power station is 12 mJ/kWh

This means that the power plant consumes 12 MJ of thermal energy which is the input for producing 1 KWh or 3.6 MJ of electrical energy as output

Hence efficiency is given by, E = output/input × 100

= 3.6/12 × 100

= 30%

Hence, the thermal efficiency of the plant with heat rate 12 mJ/kWh is 30%