A water stream at a mass flow rate of 0.3 kg/s and temperature of 70°C flows...

A water stream at a mass flow rate of 0.3 kg/s and temperature of 70°C flows through an aluminum horizontal pipe with an inner diameter of 0.025 m, wall thickness of 3 mm and length of 2 m. The ambient air is at 25 °C and the outlet temperature of water is 65 °C. Assume steady-state conditions are reached and temperature of air is constant.

Given data: Re= 4?̇/µ??,

Nu_D= 1.86 ( Re*Pr / (L/D) ) ^1/3 ; Re < 2300

Nu_D=0.023*Re^4/5Pr^0.3 ; Re >10 000

h_air = 12 W/m²K

k_Al = 237 W/mK

k_water = 0.66 W/mK

Cp,water= 4190 J/kg K

µ_water= 0.4125.10-3 kg/ms

a) Determine the rate limiting step for this system by comparing the thermal resistances.

b) Calculate the change in the total resistance when one of the resistances is halved while the others are held constant? Repeat your calculation for each resistance.

Expert Solution

Amanda K answered 1 hour ago

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