Question

A promising method of power generation involves collecting and storing solar energy in large artificial lakes a few meters deep, called solar ponds. Solar energy is absorbed by all parts of the pond, and the water temperature rises everywhere. The top part of the pond, however, loses to the atmosphere much of the heat it absorbs, and as a result, its temperature drops. This cool water serves as insulation for the bottom part of the pond and helps trap the energy there. Usually, salt is planted at the bottom of the pond to prevent the rise of this hot water to the top. A power plant that uses an organic fluid, such as alcohol, as the working fluid can be operated between the top and the bottom portions of the pond. If the water temperature is 35°C near the surface and 80°C near the bottom of the pond, determine the maximum thermal efficiency that this power plant can have. Is it realistic to use 35°C and 80°C for temperatures in the calculations? Explain

Answer 1

The maximum thermal efficiency is 12.7%

Step-by-step explanation:

The efficiency in the Carnot cycle can be calculated using the following equation

`n=1-(T_(L) )/(T_(H) )`

where n is the efficiency

TL = cold tank temperature = 35°C = 308 K

TH = hot tank temperature = 80°C = 353 K

Replacing

n = 1 - (308/353) = 0.127 = 12.7%

Answer 2

The calculation is on the attached diagram

Step-by-step explanation:

This value is an idealised value. In the true sense the temperature of the working fluid must be above 35 in the condenser and below 80 in the boiler. This will give room for the heat transfer to be effective.

So therefore the max efficiency will be lower than what I calculated vin my attached diagram