Calculate the Shellside Pressure Drop for the Following Heat Exchanger Specification
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Calculate the shellside pressure drop for the following heat exchanger specification, Process fluid = water Inlet pressure = 4 barg Inlet temperature = 50 0 C Outlet temperature = 30 0 C Tubeside flowrate = 50000 kg/hr Shell diameter =22 inches Number of baffles = 32 Baffle spacing = 6 inches Tube diameter = 1 inch Number of tubes = 10 Pitch = 1.25 inches, triangular pitch Shellside roughness = 0.06 mm Solution - Step 1. First step of problem solving requires determination the important physical properties of given fluid (water) at given temperature and pressure conditions. Since, water density will be lowest at inlet temperature (50 0 C), which corresponds to highest volumetric flow. Hence for conservative pressure drop estimate, physical properties of water are calculated at the inlet conditions. Using EnggCyclopedia's Liquid Density Calculator , water density at 50 0 C = 988.0 kg/m 3 Using EnggCyclopedia's Liquid Viscosity Calculator , water viscosity at 50 0 C =0.53 cP Step 2. Next the effective area for the crossflow across tubes between baffles is calculated using following equation, Effective Area = Ae = Ds × Bs × (P-Dt) ⁄ P where, Ds = shell diameter Bs = Baffle spacing P = pitch (distance between center axes of two adjacent tubes) Dt = Tube diameter
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Transcript of Calculate the Shellside Pressure Drop for the Following Heat Exchanger Specification
Calculate the shellside pressure drop for the following heat exchanger specification,Process fluid = waterInlet pressure = 4 bargInlet temperature = 500COutlet temperature = 300CTubeside flowrate = 50000 kg/hrShell diameter =22 inchesNumber of baffles = 32Baffle spacing = 6 inchesTube diameter = 1 inchNumber of tubes = 10Pitch = 1.25 inches, triangular pitchShellside roughness = 0.06 mmSolution -Step 1.First step of problem solving requires determination the important physical properties of given fluid (water) at given temperature and pressure conditions. Since, water density will be lowest at inlet temperature (500C), which corresponds to highest volumetric flow. Hence for conservative pressure drop estimate, physical properties of water are calculated at the inlet conditions. Using EnggCyclopedia's Liquid Density Calculator,water density at 500C = 988.0 kg/m3 Using EnggCyclopedia's Liquid Viscosity Calculator,water viscosity at 500C =0.53 cPStep 2.Next the effective area for the crossflow across tubes between baffles is calculated using following equation,Effective Area = Ae = Ds Bs (P-Dt) Pwhere, Ds = shell diameterBs = Baffle spacingP = pitch (distance between center axes of two adjacent tubes)Dt = Tube diameterFor our case, Ae = 0.0341 m2Velocity of the crossflow then becomes,V = Mass flow/(Ae3600)V = 50000/(9880.03413600) m/sV = 0.4127 m/sStep3Next, the effective diameter of fluid path is determined using following approximation,De = 4 (P2 - ( Dt2/4) ) / DtDe = 0.0484 mAnd the factor fk is then calculated as a function of Reynold's number,fk = 1.79(VD/)-1.9fk = 0.2424 3.710-9Step4The shellside pressure drop is finally calculated using the following equation,P = ( (N+1)fkDsV2 ) / ( 2De )where, N = number of bafflesP = 0.0777 barExample 1.1The block of 304 stainless steel shown below is well insulated on the front and back surfaces, andthe temperature in the block varies linearly in both the x- and y-directions, find:(a) The heat fluxes and heat flows in the x- and y-directions.(b) The magnitude and direction of the heat flux vector.
