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in a steady flow system, a substance flows at 4 kg/s. it enters at a pressure of 620 kN/m2, a velocity of 300m/s, an internal energy of 2100 kJ/kg and a specific volume of 0.37 m3/kg. it leaves the system at a pressure of 130 kN/m2, a velocity of 150 m/s, an internal energy of 1500 kJ/kg and a specific volume of 1.2 m3/kg. During its passage through the system, the substance has a loss by heat transfer of 30 kJ/kg to the surroundings. Calculate the power of the system in kilowatts, stating whether it is from or to the system. Neglect any change in potential energy.



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Answer:

To calculate the power of the system, we need to determine the rate of energy transfer. The power can be calculated using the equation:

Power = Mass flow rate * (Change in specific internal energy + Change in kinetic energy + Change in potential energy)

Since we are neglecting any change in potential energy, we can exclude it from the equation. The change in specific internal energy can be calculated by subtracting the specific internal energy at the exit from the specific internal energy at the entrance. Similarly, the change in kinetic energy can be calculated by subtracting the kinetic energy at the exit from the kinetic energy at the entrance.

Let's calculate the power:

Mass flow rate = 4 kg/s

Change in specific internal energy = 1500 kJ/kg - 2100 kJ/kg = -600 kJ/kg

Change in kinetic energy = (1/2) * (150 kg/s * (150 m/s)^2 - 4 kg/s * (300 m/s)^2)

Now, let's plug in the values and calculate the power:

Power = 4 kg/s * (-600 kJ/kg + Change in kinetic energy)

Power = 4 kg/s * (-600 kJ/kg + (1/2) * (150 kg/s * (150 m/s)^2 - 4 kg/s * (300 m/s)^2))

After calculating the expression, we can determine whether the power is from or to the system based on the sign of the result.

Explanation:

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