On a vapour compression ammonia system, where should you charge the refrigerant?

Charging refrigerant in a vapor compression ammonia system should be done before the metering device for several reasons. The metering device regulates the flow of refrigerant into the evaporator, where it absorbs heat from the surrounding environment. By charging the refrigerant before the metering device, you ensure that the proper amount of refrigerant enters the evaporator and can effectively circulate through the system.

Charging at this location allows for more precise control over the refrigerant's state and flow rate, which is crucial for optimal system performance. Additionally, it helps to prevent potential issues, such as liquid refrigerant entering the compressor, which can cause damage.

This approach also helps maintain system efficiency by ensuring that the evaporator has the right charge to absorb heat effectively, leading to better overall cooling performance in the system. Thus, positioning the charge point before the metering device aligns with best practices for refrigerant charging in vapor compression systems.