While high-pressure air as a refrigerant may have certain advantages, it also comes with several disadvantages when used in refrigeration cycles. Some of these disadvantages include:
Lower efficiency: Air has a relatively low specific heat capacity compared to traditional refrigerants like hydrofluorocarbons (HFCs) or hydrochlorofluorocarbons (HCFCs). This means that it requires a larger mass flow rate to transfer the same amount of heat, leading to lower energy efficiency in the refrigeration system.
Poor cooling capacity: Due to its low specific heat capacity, air may not be as effective at absorbing and transferring heat compared to other refrigerants. This results in reduced cooling capacity, which could limit the performance of the refrigeration system.
Large system size: To achieve the desired cooling effect, high-pressure air systems often require larger and bulkier components such as compressors and heat exchangers. This can lead to increased costs and space requirements for the refrigeration system.
Limited temperature range: Air as a refrigerant has a limited range of operating temperatures. It may not be suitable for extremely low-temperature applications, such as in deep-freezing or cryogenic processes, where specialized refrigerants are more commonly used.
Risk of leakage and safety concerns: High-pressure air systems can be prone to leaks, which can be challenging to detect and repair. Additionally, if a leak occurs, the presence of air in the environment does not pose the same safety risks as some other refrigerants, but it can still displace oxygen in confined spaces, leading to potential asphyxiation hazards.
Environmental impact: Although air itself is not considered a harmful refrigerant in terms of ozone depletion or direct global warming potential, using it as a refrigerant might lead to higher energy consumption due to its lower efficiency. This indirectly contributes to increased greenhouse gas emissions if the energy comes from fossil fuel sources.
No lubricating properties: Some refrigerants have lubricating properties that help extend the lifespan of compressors and other moving parts in the refrigeration system. Air does not possess such properties, which can result in increased wear and tear on the system components.
Overall, while high-pressure air can be utilized in certain refrigeration applications, it is not as efficient and effective as other specialized refrigerants designed for cooling purposes. For most refrigeration applications, using established refrigerants with proven performance and safety records is a more practical and reliable choice.