In a mixed refrigerant, if the methane content is on the high side, what are the effects?

A high proportion of methane may reduce the cooling efficiency of the mixed refrigerant, as methane has a low condensation pressure, which can affect the overall compression efficiency of the system. Furthermore, methane is flammable, and an excessive proportion may increase the safety risks associated with system operation. .

To what is the low condensation pressure of methane compared? It should be on the high side, right? Difficulty in condensation leads to reduced heat exchange efficiency, resulting in higher pressure at the compressor outlet

The energy consumption of the refrigerant is relatively high; the temperatures in the second and third stages are too low.

The refrigerant compressor has high pressure, great power, and increased power consumption

When the methane content in the mixed refrigerant is high: Phenomenon – In terms of temperature: In the refrigeration system, the evaporation temperature increases. Due to the relatively high boiling point of methane, a higher proportion of methane alters the overall evaporation characteristics of the mixed refrigerant. This causes the evaporation temperature of the refrigerant in equipment such as heat exchangers to deviate from the design value, thereby changing the temperature distribution throughout the entire system. - Regarding pressure: System pressure may increase. Due to the properties of methane, it causes the vapor pressure of the mixed refrigerant to rise at certain temperatures. This manifests as a pressure increase in pipes and equipment, particularly in the gas phase portion of closed refrigeration cycle systems. Impact – In terms of cooling performance: the cooling efficiency may decrease. Although methane is also a refrigerant, an excess amount of it can disrupt the optimal ratio of components in the mixed refrigerant. This prevents the thermodynamic properties of the refrigerant—such as its latent heat of vaporization during the refrigeration cycle—from reaching their optimum levels, thereby making it impossible to provide sufficient cooling capacity to cool media like natural gas that needs to be liquefied. - In terms of equipment operation: it may cause the equipment to become overloaded. Excessively high pressure and temperature increase the workload on equipment such as compressors and heat exchangers. For example, the compressor has to overcome higher pressures in order to transport the refrigerant, and remaining in such a condition for an extended period may shorten the equipment’s lifespan and increase the risk of malfunctions. - In terms of process safety: it introduces safety hazards. An increase in pressure may exceed the equipment’s designed pressure range, posing a risk of leakage or even explosion. At the same time, abnormal temperature changes can also affect the material properties of equipment and pipelines, leading to safety accidents.