Question

An inventor proposes an engine that operates between the 27 deg C warm surface layer of the ocean and a 10 deg C layer a few meters down. The claim is that this engine can produce 100 kW at a flow of 20 kg/s. Is this possible?

Answer 1

Answer:

Engine not possible

Explanation:

source temperature T1 = 300 K

sink temperature T2= 283 K

therefore, carnot efficiency of the heat engine

η= 1- T_2/T_1

$\eta= 1-\frac{T_1}{T_2}$

$\eta= 1-\frac{283}{300}$

= 0.0566

= 5.66%

claims of work produce W = 100 kW,  mass flow rate = 20 kg/s

$Q=mc_p(T_1-T_2)$

$Q=20\times4.18(300-283)$

= 1421.2 kW

now $\eta= \frac{W}Q}$

now $\eta= \frac{100}{1421.2}$

=7%

clearly, efficiency is greater than carnot efficiency hence the engine is not possible.