The invention discloses an on-line monitoring and controlling
system and method for
defrosting of an air conditioner. The on-line monitoring and controlling
system comprises an air conditioner
copper pipe, a dust guard, a filtering net, a plurality of
infrared sensors for measuring
radiation force of the air conditioner
copper pipes, at least one
thermocouple for measuring temperature of the air conditioner
copper pipes, and a central control
chip, wherein the central control
chip is used for obtaining data returned by the
infrared sensors and the thermocouples, and working out the actual
emissivity of the surfaces of the copper pipes according to the Stefan-Boltzmann law so as to judge whether
defrosting is needed or not and control a
defrosting component to operate. The frosting condition is monitored based on the Planck law according to the principle that the value of difference between the copper
pipe material
emissivity and the
frost emissivity is large, and the value of difference of the
radiation power is large at the same temperature; hardware is improved little, and cost is low. The direct judgment strategy is adopted, monitoring is conducted in real time, and whether frosting exists or not is judged directly and precisely, and a defrosting
signal can be emitted or interrupted in time; defrosting does not
lag, so that the air conditioner keeps operating with the optimal performance, and the defrosting situation is judged accurately.