Report

OWAIS NOORUDDIN Åbo Akademi Supervisor Prof. Henrik Saxen Optimization of refrigeration process Problem Description • To optimize the cooling system of 2 MW • Free cooling. Is it enough? • Free cooling alongwith vapor compression cycle. • Mix integer non linear optimization of cooling system for the whole year run. 1 Process Integration HE-1 Hot stream HE-2 HE-3 HE-4 Vapor Compression Cycle Storage Tank 2 Free Cooling Finned Tube heat Exchanger Figure1: Heat Exchanger (Finned Tube) 3 Ideal Vapor Compression Cycle Figure 2A: Vapor compression cycle Figure 2B: Ideal Vapor Compression Cycle COP = Coeffecient of performance COP(refrigeration)= Heat absorbed/Work supplied =m(ref)*(H1-H4)/Win COP(Heat pump) = Heat out/Work supplied = m(ref)*(H2-H3)/Win . 4 Real Vapor Compression Cycle Figure 2D: Vapor compression Cycle with subcooling and superheating • With sub cooling of the liquid, refrigerating effect and COP increases without increasing the work requirement but for superheating COP may increase, decrease or remain unchanged . It depend on the range of pressure of the cycle. • Decrease in inlet pressure decreases the refrigeration effect and increases the work of compression. The effects of these two lead to decrease the COP while increase in discharge pressure required more work from compressor and decline in COP. 5 Process Flow Diagram Figure 3: Flow sheet 6 Problem Solution • Sequential Method (by using Fmincon in Matlab environment) • Equation based -(By using Gams with Mixed Integer Non Linear Programming) -(By using Aspen Plus, only simulation of the selected cases without optimization) 7 Future Plan • To study the cooling storage tank with air heat exchanger. • To study the complex heat exchanger network system for the improvement in integration by varying size and optimizing cost of the process. • Multiobjective optimization. 8 Refrences Figure 1 http://www.pemco.fi/09/ilmalauhduttimet/v-malliset-tekninen-tieto Figure 2A and 2B Thermodynamic Engineerig approach, Younus A, Cengel, 5th edition chapter 11. Figure 2C http://engr.bd.psu.edu/davej/classes/thermo/chapter7.html Figure 2D http://www.alephzero.co.uk/ref/circeff.htm 9 Thank you for your attention