1) How much heat must be removed from 400 pounds of blanched vegetables at 195 d
ID: 1419947 • Letter: 1
Question
1) How much heat must be removed from 400 pounds of blanched vegetables at 195 degrees F to freeze them to a temperature of 23 degrees F? (The vegetables have a 60% water content and the specific heat of solid vegetables is 0.24 BTU/lb F)
Heat = XXX BTU
2) A wooden icebox (k=0.6 W/m K) has walls that are 3.8 cm thick and the overall effective surface area is 1 m2. How many grams of ice will be melted in 2 min if the inside temperatures of the walls are 4 degrees C and the outside temperatures are 30 degrees C.
Mass of Ice Melted = XXX grams
Explanation / Answer
mass m=400 pounds
temperature T1=195 F
temperature T2=23 F
specific heat S=0.24 BTU/ib F
the concept belongs to thermal propertices of matter
the heat removed Q=ms[T2-T1]
=400*0.24[23-195]=-16512 BTU
2 ANS
coefficient of thermal conductivity K=0.006 W/cmC
thick d=3.8cm
area A=10000 cm^2
time t=120 sec
temperature [T2-T1]=30-4=26 c
this concept belongs to thermal propertices of matter
mL=KA[T2-T1]t/d
m*80=0.006*10000*26**120/3.8
mass m=615.8 grams
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.