//Chapter-6, Illustration 7, Page 313 //Title: Refrigeration cycles //============================================================================= clc clear //INPUT DATA T1=-5;//Temperature at point 1 in oC T2=30;//Temperature at point 2 in oC m=13500;//mass of ice per day in kg Tw=20;//Temperature of water in oC COP=0.6;//Co-efficient of performance h2=1709.33;//Enthalpy at point 2 in kJ/kg s2=6.16259;//Entropy at point 2 in kJ/kg-K s1=6.16259;//Entropy at point 1 in kJ/kg-K sf=1.8182;//Entropy in kJ/kg-K sg=6.58542;//Entropy in kJ/kg-K hf=400.98;//Enthalpy in kJ/kg hfg=1278.35;//Enthalpy in kJ/kg h4=562.75;//Enthalpy at point 4 in kJ/kg S=4.187;//Specific heat of water in kJ/kg L=336;//Latent heat of ice in kJ/kg //CALCULATIONS x1=(s1-sf)/(sg-sf);//Quality factor h1=hf+(x1*hfg);//Enthalpy at point 1 from refrigerant-12 tables in kJ/kg COPi=(h1-h4)/(h2-h1);//Ideal COP COPact=COP*COPi;//Actual COP Qr=((m*S*(Tw-0))+(m*L))/(24*3600);//Total amount of heat removed in kJ/s mr=Qr/(h1-h4);//Circulation rate of ammonia in kg/s W=mr*(h2-h1);//Power required in kW //OUTPUT mprintf('Circulation rate of ammonia is %3.3f kg/s \n Power required is %3.3f kW \n COP is %3.3f',mr,W,COPact) //==============================END OF PROGRAM=================================