Why does the refrigerant pressure decrease in a refrigerant cylinder while charging with vapor?
As the vapor refrigerant flows from high pressure side to low pressure side, the pressure inside the cylinder of the refrigerant decrease. This is because the vapor refrigerant cylinder at high pressure when opened to the system, vapor flows from high pressure side to low pressure side. This means that high pressure in the cylinder decreases. Due to this decrease in pressure, temperature also decreases due to ideal gas relationship.