Answer in Molecular Physics | Thermodynamics for Harshita #160119

A hot water tank has 10cm of foam (k= 0.02 Wm^-1 K^-1) insulation surrounding the 60°C tank which is placed in 20°C room. The tank has surface area of 3.5 m^2 . Find the thermal energy lost over a one day period. This will equal the standby loss of tank. Ignore air films.

Rate of heat flow is given by “frac{dQ}{dt} = KADelta T”

where K is thermal conductivity, A is the area, dt is the time, dQ is the heat and “Delta T” is the temperature difference.

Here we have, “K = 0.02, A = 3.5, Delta T = 60-20=40, t = 1day = 24*60*60=86400s”

Putting all values, Amount of heat flow is given by

“dQ = KADelta T (dt) = 0.02 times 3.5times40times86400 = 241920 J = 241.92 KJ”