Asteam power plant with a power output of 200 mw consumes coal at a rate of 700 tons/h. if the heating value of the coal is 40,000 kj/kg, determine the overall efficiency of this plant.

η = 2.57%

Explanation:

Given:

Output power of the steam power plant, P(out) = 200 MW

Consumption of coal, m = 700 tons/h = (700 × 10³)/3600 kg/s= 194.44 kg/s

Heating capacity of the coal, Cv = 40000 kJ/kg

now,

Input power,  P(in) = mCv

or

P(in) =  194.44 kg/s × 40000 = 7777.77 MW

thus,

efficiency, η = P(out)/P(in) = (200 MW) / (7777.77 MW) = 0.02571

or

η = 2.57%

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.