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4.94 Liquid water enters a valve at 300 kPa and exits at 275 kPa. As water flows through the valve, the change in its temperature, stray heat transfer with the surroundings, and potential energy effects are negligible. Operation is at steady state. Modeling the water as incompressible with constant r ⫽ 1000 kg/m3, determine the change in kinetic energy per unit mass of water flowing through the valve, in kJ/kg.

Respuesta :

Answer:

Change in kinetic energy=0.025\ KJ/Kg[/tex]

Explanation:

Given that

P₁=300 KPa

P₂=275 KPa

Density of water

ρ = 1000 kg/m³

Change in kinetic energy of per unit mass mass given as

Lets take initial velocity V₁ and final velocity V₂

From energy conservation

[tex]P_1+\dfrac{1}{2}\rho V^2_1=P_2+\dfrac{1}{2}\rho V^2_2[/tex]

 [tex]300+\dfrac{1}{2}mV^2_1=275+\dfrac{1}{2}mV^2_2[/tex]

[tex]\dfrac{1}{2}\rho V^2_2-\dfrac{1}{2}\rho V^2_1=300-275[/tex]

[tex]\dfrac{1}{2}V^2_2-\dfrac{1}{2} V^2_1=0.025\ KJ/Kg[/tex]