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3 years ago

What is the maximum efficiency of a heat engine whose operating temperatures are 590 ?c and 325 ?c?

1 answer:

7 0

<span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir.
η_max = 1 - (T_c/T_h)

For this engine:
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66%

The actual efficiency of the engine is 30%, i.e.
η = 0.3 ∙ 0.664 = 0.20 = 20 %

On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir:
η = W/Q_h

So the heat required from hot reservoir is:
Q_h = W/η = 1000J / 0.20 = 5000J</span>

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How much heat is required to heat 2 kg of water from 25°C to 40°C?

Dominik [7]

Answer:

126000 J

Explanation:

Applying,

Q = cm(t₂-t₁).................. Equation 1

Where Q = Amount of heat, c = specifc heat capacity of water, m = mass of water, t₁ = Initial temperature, t₂ = Final temperature.

From the question,

Given: m = 2 kg, t₁ = 25°C, t₂ = 40°C

Constant: c = 4200 J/kg.°C

Substitute these value into equation 1

Q = 2×4200(40-25)

Q = 2×4200×15

Q = 126000 J

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3 years ago

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3 years ago

7. 13 a turbine receives steam at 6 mpa, 600°c with an exit pressure of 600 kpa. Assume the turbine is adiabatic and neglect kin

AnnyKZ [126]

The work done by the turbine will be 708.2 kJ/kg. The work done by the turbine is the difference of the enthalpy at inlet and exit.

<h3 /><h3>What is temperature?</h3>

Temperature directs the hotness or coldness of a body. In clear terms, it is the method of finding the kinetic energy of particles within an entity. Faster the motion of particles, more the temperature.

If the given turbine is assumed to be reversible;

$\rm P_I$ (Initial pressure)=60 mpa = 60 bar

$\rm T_i$ (Initial temperature)=600° C

$\rm P_e$ (Exit pressure)=600 kpa=6 bar

The heat balance equation is;

$\rm q-W_t=h_e-h_i\\\\ q=0\\\\\ W_t=h_i-h_e$

The change in the entropy is;

$\rm S_2-S_1=\frac{\delta q}{dt}$

The work done by the turbine is;

$\rm W_t = h_i-h_e\\\\ W_t =3658.4 -29.5019\\\\ W_t =708.2 \ kJ/kg$

Hence,the work done by the turbine will be 708.2 kJ/kg.

To learn more about the temperature, refer to the link;

brainly.com/question/7510619

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Answer:

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