Impact of refrigerant charge on the energy efficiency of reverse thermodynamic cycle systems: a review

Abstract

This paper presents a review of the latest scientific literature examining the effect of refrigerant charge amount and its influence on the energy efficiency and diagnostics of reverse thermodynamic cycle systems. Considering more strict environmental regulations, the paper compares the sensitivity of various system types to optimal refrigerant charge, analyzing both traditional and low global warming potential refrigerants (R32, R290, R513A). The performed analysis indicates that refrigerant undercharge has a critical negative impact on reverse thermodynamic cycle systems. It was determined that, depending on the system type, internal components, and control algorithms, various leaks can reduce heating capacity by more than 20% and the coefficient of performance by up to 30–40%. Meanwhile, overcharging is more likely to result in increased compressor power consumption and a higher risk of system failure. Based on the literature analysis, it was found that modern systems with variable speed compressors are able to compensate for refrigerant mass shortage and hide operational parameter deviations. In this way, the system can maintain the required capacity but with a lower efficiency, which can lead to up to 19% higher indirect CO₂ emissions. For this reason, the paper reviews advanced diagnostic methods, such as artificial intelligence algorithms. It allows to identify refrigerant charge level in the system with extremely high accuracy, up to 99.9%, thereby directly and indirectly reducing greenhouse gas emissions.

Article in Lithuanian