Question

Can you please answer the following question

0. (CLO6 - 4 Marks) A counter-flow double-pipe heat exchanger is to heat water from 20°C to 80°C at mass flow rate of 1.5 kg's. The heating is to be accomplished by hot oil available at 150C at a mass flow rate of 2.5 kg/s. The inner tube is thin-walled and has a diameter of 1.5 cm with the length of 60 m. Fluid property: Fluid Type Mass flow rate, The Specific heat, [J/kg.K] Inlet Temp. T. ["C] Outlet Temp. To c] [kg/s] Oil 2300 150 unknown Water 80 4180 Assume that there is no heat loss to surrounding, therefore the heat is purely transferred from oil to water. Using conservation of energy, determine the outlet temperature of the oil? b. Determine overall heat transfer coefficient of the heat exchanger?

Answer 1

criven: mass flow rate of hot fluid, in h= 2.5 kgis " " " " cold "eine = 1.5kg/ Cp, h = 2300 , CP, C = 4180 . Tin, h = 150°c Tc, in = 20°c, Te, out = 80%. a) using conservation of energy, - heat loss by oil = heat gain by water - mich Cph (Tinch - Touth) = mc (p. c (Tc, out - Tc, in) » 2,5 x 2300 (150- Toul, h) = 1.57 4180x ( 80-20) - Toul, h = 84.57% by the temp profiles are plotted below here, ati= 64.57% 150 At₂ = 150-80=70°c. AT2 84.57 8457 - (LMID), Om= ATRATI ste 84.57-20 - 6457 en( Atalati) a Om = 70-64:57 67:25°C. en ( 7 n ) ( 64.57 now, 8 = Un Om = mc cpc (trout-te, in) A= adl= TX 0.015*60 = 0.9 T m² UX 10.9 21 )x 67.25 = 1.5x4180 x 60 Tu= 197815 W/m²-k T 7)