Variable-speed-compressor refrigeration systems were examined by many researchers for minimizing energy consumption. The results were interesting. However, this technique may be possible for new designed systems. My question is about systems which are in service right now.
It depends of the motor design AND if it was thought to work at different frequencies. Some can be tuned only for 50 or 60 Hz.
Hi
The compressor speed can be controlled by varying the electrical frequency, thus, a frequency invertor can be used to control the compressor frequency, please, see the reference below
Qureshi, T. Q., and S. A. Tassou. "Variable-speed capacity control in refrigeration systems." Applied Thermal Engineering 16.2 (1996): 103-113.
The speed can be adjusted by changing the frequency if the compressor is suitable for inverter use. It is necessary to know the sensitivity of the inverter with rpm change (Hz steps). There are various types and methods for this. It should not be forgotten that lubrication problems are encountered when operating at low frequencies.
When you consider variable frequency inverter for existing compressor, the important issue that you must take into consideration is the hydrodynamic oil layer accompilished in the bearings. You must notice oil quaility and minimum compressor speed that hydrodynamic oil layer doesn't disturbed
The question should be more specific which kind of refrigerator is considered? And then we fall again on my 1st comment not all motors accept a frequency variation. In any case the above remark is VERY pertinent ans should be taken into consideration with an add on the danger of low sliding speeds depends on the duration.
Thanks for all of you.
My question was about household refrigerators and air conditioners which were designed for constant speed compressors.
In this case for some refrigerators it can be difficult. If it is a motor with a starting capacitor it is not impossible but can be difficult because of many reasons which you can get explained in details in all books about electrical machinery. In general if the unit is bigger 3 phase motors are used and they can be within certain limits speed controlled by frequency changes.
Il you look at google you can get sources for all the informations you need. Some of them very well structured.
Take attention to the lubrication system. In many compressor this is depending on the compressor shaft speed.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Energy