Exploring the influence of air fractions on the performance of a vapor compression refrigeration system: an energy, exergy, and environmental analysis

Abstract The ingress of air into the vapor compression refrigeration system is a frequent occurrence, typically occurring during installation, maintenance, or charging. Air, being a non-condensable gas relative to the refrigerant gas within the system, leads to system degradation mostly due to elevated condensing pressure. This experimental study investigates the impact of non-condensable gas (air) contamination on the performance of a vapor compression refrigeration system using R134a refrigerant. A chest freezer was tested under steady-state conditions with air fractions of 0%, 1.7%, 2.5%, and 3.3% at an ambient temperature of 32 °C. Energy, exergy, and environmental analyses were conducted to evaluate system efficiency, power consumption, and sustainability. Results revealed that increasing air fractions significantly degraded performance: at 3.3% air, power consumption rose by 37.1%, while the coefficient of performance dropped by 42.8% compared to the air-free system. Also, exergy destruction rate increased by 189%, and exergy efficiency decreased by 119.1%, indicating severe thermodynamic inefficiencies. Additionally, higher air fractions led to elevated compressor temperatures, increased noise, and greater environmental impact due to higher energy-related emissions. The study highlights the critical need for rigorous system evacuation and leak prevention in refrigeration systems to maintain optimal efficiency and reduce operational costs.