Resistance wire heat Q=I Rt=Pt; I current, R resistance, T heating time.
Power P = U = a UI squared/R = I squared R; U voltage, I current, R resistance.
Heat balance Q = Pt = MC (T2 - T1); P power, T time, M mass, C specific heat capacity, T2 final temperature, T1 initial temperature.
Temperature rise t2-T1 =Pt/ MC.
Heating time t= MC (T2-T1)/P. (when phase transitions are not occurring, as in heated air)
When a phase change occurs (such as heating water from a liquid to a gaseous state), the latent heat of the phase change cannot be ignored and shall be calculated in stages.
Total heating time t= T liquid + T evaporation + T gas, namely: T liquid = MC liquid (100-T1)/P, T evaporation =m/V evaporation, t gas = MC gas (T2-100)/P. Where, time required for Liquid T to boil (water is 100), mass m, specific heat capacity of liquid C, 100 boiling temperature, initial temperature of T1, P power; V evaporation or evaporation rate per unit time, C gas specific heat capacity in the gaseous state, T2 termination temperature.
On 2018-08-08 11:45:46
