| 摘要 |
The present invention relates to a defrosting initiation method of evaporators of heat pumps taking off low-potential heat from air, with a compressor, at least two heat exchangers and an expansion valve. When the heat pump is in operation, there is monitored a time characteristic of frost deposit growth on the evaporator at evaporation pressure, which is lower than the evaporation pressure at the beginning of frost deposit formation (poN), and namely such, that there is monitored an ambient air temperature (tex) and an ambient air relative humidity ({phi}ex), a medium evaporation temperature (to) in the heat pump circuit and the evaporator surface temperature, which all determine dehumidification ({DELTA}x) and changes in enthalpy ({DELTA}h) at monitored change in formation and growth of the frost deposit, wherein the ratio thereof is continuously evaluated as a frost deposit coefficient (Kn), and at the same time there is monitored a refrigerating output (Qo´) of the heat pump circuit that is given by the compressor cooling power, which is the driving element of the heat pump, and which depends on the evaporation temperature (to) of the medium in the heat pump circuit and the condensation temperature (tk) in the heat pump circuit, whereby the product of the frost deposit coefficient (Kn) and the refrigerating output (Qo´) of the heat pump circuit is continuously and in predetermined time intervals summarized and at the moment at which the sum of its values corresponding to the amount of frost deposit on the evaporator exceeds a predetermined limit value, the evaporator defrosting process is initiated. |
