Problem 6: Blood is refrigerated for storage and needs to be warmed before use i
ID: 1278568 • Letter: P
Question
Problem 6: Blood is refrigerated for storage and needs to be warmed before use in patients. The blood enters a tank with an electric coil at a rate of 10 L/min and leaves from the tank at the same rate. A stirrer is designed for homogeneous mixing for the tank and it adds work to the system at a rate of 0.50 kw. Please make reasonable assumptions and calculate the rate of electric work that is needed to continuously warm 10 L of blood from 4 degree Celsius to 37 degree Celsius. (the heat capacity of blood is 1.0 calorie/(gram degree C); the density of blood is 1.0 g/mL)Explanation / Answer
c = 1 calorie/g.c
= 4.28 J/g.c
= 4280 J/kg.C
rho = 1 g/mL
= 1000 kg/m^3
V = 10 L = 0.01 m^3
mass, m = rho*V
= 1000*0.01
= 10 kg
Q = m*c*dT
= 10*4280*(37-4)
= 1412400
power = Q/t
= 1412400/(60)
= 23540 watts <<<<<<<---------Answer