Ethanol is contained in a large tank under a pressure of 3.1 bar absolute. When a valve on the bottom of the tank is opened, the ethanol drains freely though a 1-cm ID tube whose outlet is 7.00 m below the surface of the ethanol. The pressure at the outlet of the discharge pipe is 1 atm. 

(a) Use the Bernoulli equation to estimate the ethanol discharge velocity and flow rate in L/min when the discharge valve is fully opened. Neglect the rate of fall of the ethanol level in the tank.

(b) When the discharge valve is partially closed, the flow rate decreases, which means that Δu 2=2 changes. However, the other two terms in the Bernoulli equation (ΔP/ρ and gΔz) remain the same. How do you account for this apparently contradictory result? (Examine the assumptions made in the derivation of the Bernoulli equation.) 

Transcribed Image Text:

3.1 bar CH;CH,OH 7 m