A double pipe heat exchanger consists of 1” Sch 40 steel pipe (Do = 1.315 in., Di = 1.049 in., ∆x=0.133 m) inside a 2” Sch 40 Steel pipe (Di = 2.067 in.) is used to heat water from 25 oC to 40 oC using hot air entering at 200 oC. Water flows in countercurrent through the inner tube at 1000 kg/hr while air flows through the annulus at 5000 kg/hr. For the steel: Thermal conductivity = 45 W/m-K Air properties at the bulk temperature: Cp = 1046 J/Kg-K, k = 0.035 W/m-K µ = 2.507 x 10-5 kg/m-s, and ρ = 0.727 kg/m3 Water properties at the bulk temperature: Cp = 4184 J/Kg-K -Determine the LMTD if the outlet temperature of the Air is 170 oC -Determine the Reynolds Number of Air -Determine the outlet temperature of the Air (oC) -If h of Water = 185 and h of Air = 2500, Determine the value of Uo or Ui -Determine the cross-section of the annulus (in mm2). -If Ui = 175, ΔTlm = 145 oC, determine the length of the heat exchanger (in in)
A double pipe heat exchanger consists of 1” Sch 40 steel pipe (Do = 1.315 in., Di = 1.049 in., ∆x=0.133 m) inside a 2” Sch 40 Steel pipe (Di = 2.067 in.) is used to heat water from 25 oC to 40 oC using hot air entering at 200 oC. Water flows in countercurrent through the inner tube at 1000 kg/hr while air flows through the annulus at 5000 kg/hr.
For the steel: Thermal conductivity = 45 W/m-K
Air properties at the bulk temperature: Cp = 1046 J/Kg-K, k = 0.035 W/m-K
µ = 2.507 x 10-5 kg/m-s, and ρ = 0.727 kg/m3
Water properties at the bulk temperature: Cp = 4184 J/Kg-K
-Determine the LMTD if the outlet temperature of the Air is 170 oC
-Determine the Reynolds Number of Air
-Determine the outlet temperature of the Air (oC)
-If h of Water = 185 and h of Air = 2500, Determine the value of Uo or Ui
-Determine the cross-section of the annulus (in mm2).
-If Ui = 175, ΔTlm = 145 oC, determine the length of the heat exchanger (in in)
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