Question

please show work

1. Liquid water enters a horizontal iron pipe at 20°C and 101.3 kPa. The pipe is in surroundings of 20°C, and there is a suction pump at the other end. The pipe flow rate is 88 gpm, pipe diameter is 4". and velocity is 2.25 ft/s (these English unit data are not necessary to solve the problem; just to show the type of real-world problem). In this scenario the friction (viscosity) will typically cause the pressure to drop by about 3 kPa for each 100 of pipe that the water has flowed through. At what distance from the entrance will the water in the pipe begin to boil? Hint: consider what it means to "boil"

Answer 1

The level of boiling of water depends on the pressure of the vapour. The density of the water vapor is 2.334 kpa at 20 degrees. The liquid bubbles if the surrounding liquid exerts pressure on its vapor.

The pressure inside the tube should therefore be 2.334 kpa on the floor surface. Because the pressures are 3 kpa per 100' high, the tension is 2.334 kpa at 3298.86,' from 101.3 kpa.

100/3=33.33.

Pressure must be decreased by 101.3 to 2.334 = 98.966 kpa It occurs for 3298.86' in the duration.

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