ME 414 Thermal&Fluid Systems Design Heat Exchanger Design ME 414 Thermal / Fluid System Design William Donelson Josh Fosso Laurie Klank Jonathan Moore Fall 2005 December 13, 2005 Professor: John Toksoy

ME 414 Thermal&Fluid Systems Design Problem Cool a Fluid –From 35ºC to 25ºC –Mass Flow 80,000 kg/hr –Fluid is Corrosive –Fluid Properties are Approximated by Water Use City Water to Cool –Available at 20ºC

ME 414 Thermal&Fluid Systems Design Assumptions Shell and Tube HX Corrosive Fluid Requires Stainless Steel Tubes –Fouling is Negligible –Easier to Clean Shell is Thin, Light as Possible

ME 414 Thermal&Fluid Systems Design Begin Study Given Tube Arrangement Choose Tube Arrangement –Cleaning –Assembly

ME 414 Thermal&Fluid Systems Design Analysis

ME 414 Thermal&Fluid Systems Design Observations More on this Later Length can be Calculated Heat Transfer is Always as Desired Nusselt Number Correlation

ME 414 Thermal&Fluid Systems Design Minimize Cost Assume HX Lifespan is 7 Years Labor-Upkeep and Assembly –Arrangement and Materials Operating –Electricity for Pumps –Cooling Water Considered Separately Materials

ME 414 Thermal&Fluid Systems Design Cost Function Electricity –$ kW·hr(IPL) –Pump Efficiency = 0.7 Materials –Wholesale Metal Prices Compared with Finished Product Prices to Get Value Added Multiple Multiple = 5(McMaster) –Wholesale Stainless Steel = $2.86/kg –Wholesale Aluminum = $1.88/kg(metalprices.com)

ME 414 Thermal&Fluid Systems Design Approach Cost Function Automatically Weighs –Pressure Drops –Weight Q is Always Equal to Desired by Calculating Length With Trial the Only Other Constraints Were the Fluid Velocities

ME 414 Thermal&Fluid Systems Design Trial 1 Tubes Need to be Standard Size Velocities Must be Within Acceptable Range 0.6<Shell Velocity<1.5 m/s 0.9<Tube Velocity<2.5 m/s Minitab Does Not Recognize the Effect of M Dot on Cost

ME 414 Thermal&Fluid Systems Design Final Trial After Further Refinement Optimum M Dot = 55.25

ME 414 Thermal&Fluid Systems Design Final Design M Dot Cooling Fluid= 55 kg/s Tube OD = 0.38 inch BWG 24 Shell ID = 12 inches Length = m Tube Pressure Drop = 6047 Pa Shell Pressure Drop = 9308 Pa Total Weight = 443 kg

ME 414 Thermal&Fluid Systems Design Total Cost $5720 Plus Labor Plus Water

ME 414 Thermal&Fluid Systems Design Cost of Water  Since T C,o cannot Exceed T H,i the mass flow of the Cooling Water has Lower Bound of 15 kg/sec  This translates into 1,370,000 ft 3 /month $13,900/Month Indianapolis Water