## 6 Conclusions  
In this paper, the relationship between the compressor frequency, suction, discharge pressure ratio, superheated suction, evaporation temperature, and compressor electrical efficiency is studied through the R32 rolling piston compressor experimental setup. Meanwhile, a model of electrical efficiency for the rolling piston compressor under variable suction conditions is established. The conclusions are as follows:  
Figure 5: Verifying the change in compressor suction and discharge pressure ratio under different frequencies of working conditions.  
Figure 6: Experiment and calculation electrical efficiency at 40 Hz/50 Hz/60 Hz compressor frequency.  
Under the same pressure ratio and evaporation temperature, the compressor electrical efficiency with the larger opening of the electronic expansion valve has a linear downward trend, and the slope of the suction with the liquid section is greater than that of the superheated suction section; that is, in the compressor suction with liquid the compressor electrical efficiency declines to a greater extent.
2. Under the same pressure ratio, the larger the evaporation temperature, the smaller the electrical efficiency; under the same evaporation temperature, the larger the compressor pressure ratio, the smaller the electrical efficiency. At the same time, the higher the compressor pressure ratio, the greater the influence of evaporation temperature on the electrical efficiency of the compressor.
3. The accuracy of the rolling piston compressor electrical efficiency model is verified through operating condition tests. The results show that the maximum relative error between the calculated value and the actual value is 1.81%, and that the minimum relative error is 0.035%. This is better than the prediction error range of \(\pm\)4.95% in the compressor efficiency model proposed in reference [25], and the model established in this paper considers the influence of suction gas conditions on the compressor. Therefore, the proposed compressor electrical efficiency model is more reliable.
4. When the compressor operates at low frequencies, the actual performance of the compressor deviates further from the calculated values of the model. Additionally, when the suction dryness is low, it can lead to the occurrence of liquid slugging in the compressor, damaging its safe operation. Therefore, the rolling piston compressor electrical efficiency model applies to operating conditions where the compressor frequency is higher than the rated frequency and the suction gas dryness is greater than 0.9.  
Z.C., conceptualization, methodology, software, writing--original draft; L.T., conceptualization, resources, supervision, funding acquisition, writing--review and editing; L.H., visualization, writing--review and editing; Z.Y., data curation, writing--original draft. All authors have read and agreed to the published version of the manuscript.  
The support from \"Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power and Engineering\" (13 DZ2260900) is greatly acknowledged.  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.