Method of optimising the performance of refrigerant vaporizers including improved frost control method and apparatus

A method of operating a refrigeration device, comprising the steps of:

• determining a first difference temperature between an air supply temperature and a vaporization temperature;
• multiplying said first difference temperature by a predetermined factor to provide a computed temperature;
• determining a second difference temperature between an air cooler outlet temperature at an outlet tube and said vaporization temperature;
• comparing said computed temperature with said second difference temperature;
• and
• controlling an expansion valve of the refrigeration device to provide said second difference temperature at least about equal to said computed temperature.

A refrigerator, comprising:

• means for measuring a first temperature difference between and air inlet temperature of a refrigerator and a vaporization temperature of a refrigerant of said refrigerator;
• means, coupled to said first temperature measuring means, for computing a temperature value from said first temperature difference by multiplying said first temperature difference by a predetermined factor;
• means for measuring a second temperature difference between a vaporizer outlet temperature and said vaporization temperature;
• and
• means, coupled to said second temperature difference measuring means and to said computing means, for controlling a temperature of said refrigerant such that said second temperature difference approximately equals said computed temperature difference.

Method of optimising the performance of refrigeration devices which are operated with a refrigerant and are fed via an expansion valve, in particular the performance of fan air refrigerators, in which, in addition to the air entry temperature or the supply air temperature (tL 1), both the vaporization temperature (t.sub.O) and also the temperature at the air refrigerator outlet (t.sub.Oh) are measured continuously or periodically and the difference value (.delta.t.sub.l) between the supply air temperature (tL 1) and the vaporization temperature (t.sub.O) is determined, in which this difference value (.delta.t.sub.1) is multiplied by a factor between 0.6 and 0.7, and the computed temperature value which is obtained is compared with the difference value (.delta.t.sub.oh) of the temperature at the air refrigerator outlet (t.sub.oh), and the vaporization temperature (t.sub.o), and in which the expansion valve (EV) at the inlet side of the air refrigerator is then controlled continuously or periodically in dependence on the result of the comparison in such a way that the temperature at the vaporizer outlet (t.sub.Oh ) is at least substantially the same as the computed temperature value, characterized in that the difference value (.delta.t.sub.1) between the supply air temperature (tL 1) and the vaporization temperature (t.sub.O) is monitored for the purpose of determining the ideal defrosting time point of the refrigeration device with respect to exceeding a predeterminable boundary value;

• in that, in the case of exceeding this boundary value, a compressor and fan are switched off and a defrosting heating device is switched in until the air refrigerator has reached a predeterminable temperature corresponding to the ice-free state;
• and in that the compressor is then switched on again and also the fan with a time delay relative to the compressor.