Control method for defrosting the outdoor coil of a heat pump machine
AssigneeIngersoll Rand International
InventorGiuseppe Giovanni Renna
Life of this patent
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Abstract
Method for controlling defrosting of the outer exchanger of a heat pump machine, comprising the steps of: defining in the outer air temperature/evaporation temperature plane three zones; acquiring the outer air temperature and the evaporation temperature; individuating in which zone of the Taria_ext/T_evap plane the point falls, identified by the two acquired temperature measures; inverting the machine functioning cycle when the point falls in an unsafe zone; reducing the rotation speed of the compressor of said heat pump machine when the point falls in an intermediate zone.
Claims15
A control method for defrosting an outdoor coil of a heat pump machine configured to exchange heat in a first cycle between an external cold source comprising ambient outdoor air, and a hot source, and, on command, in a second reverse cycle between the hot source and the external cold source, the heat pump machine comprising a compressor, the method comprising:
- a) defining, in a plane of Outdoor Air Temperature (Taria_ext) against evaporation temperature (T_evap), a first and a second line of separation, said first and second lines of separation defining three zones (A,B,C) within said plane;
- b) measuring an outdoor air temperature (Taria_ext);
- c) measuring an evaporation temperature (T_evap);
- d) identifying in which of the three zones (A,B,C) of the plane of Taria_ext against T_evap a point identified by the Taria_ext and T_evap measurements falls;
- e) operating the heat pump machine in the second reverse cycle when the point falls in zone (C) and is below said second line of separation;
- f) decreasing a rotation speed of the compressor of the heat pump machine when the point falls in zone (B) and is between said first and second lines of separation;
- g) measuring Taria_ext and T_evap after a predetermined time interval;
- h) repeating steps d) to g) until the point identified by the Taria_ext and T_evap measurements falls in zone (A) and is above said first line of separation.
The control method for defrosting the outdoor coil of a heat pump machine according to claim further comprising the steps of:
- i) storing in a datalogger a duration of one or more occurrences of the second reverse cycle and the outdoor air temperature (Taria_ext) in which they have occurred;
- j) computing an average duration of second reverse cycles carried out;
- and
- k) increasing the value of DT when the average duration of second reverse cycles is less than a threshold value.
Dependencies are inferred from the claim text.