Travail de fin d'études et stage[BR]- Travail de fin d'études : Oil Management in Heat Pump Systems Using Sumpless Compressors[BR]- Stage

Abstract

This master's thesis focuses on the oil management in heat pump systems using sumpless compressors, a new design developed by Copeland to reduce the amount of refrigerant trapped in the compressor's oil sump. The traditional design of compressors used in heat pumps could be enhanced by eliminating the oil sump, to satisfy European Union regulations, which limit the amount of propane to be used in heat pumps, avoiding to use smaller compressors. However, this new design presents challenges in controlling the optimal amount of oil for compressor lubrication, making effective oil management critical.

The primary objective of this thesis is to develop a model capable of calculating the oil circulation rate (\acrshort{ocr}) in a heat pump system equipped with a sumpless compressor. The model is based on the discharge line temperature (\acrshort{dlt}) and other measured parameters such as temperature, pressure, and mass flow rates. Two heat pumps equipped with sumpless compressors were tested to collect relevant data, and a numerical model was developed and discussed using these measurements. The study also explored the impact of different oil charges on the OCR.

The findings of this thesis suggest that while the discharge line temperature of the compressor provides some insight into the oil circulation rate (\acrshort{ocr}), it is not a definitive indicator and should be used in conjunction with other measurements for more accurate OCR predictions. However, the results of the proposed model also show that further testing and model refinement are necessary to improve the accuracy of OCR predictions. The thesis concludes with recommendations for future research, including the need for more advanced modelling techniques and the application of an uncertainty propagation analysis to better understand the influence of different measurements on the OCR computation.