What factors determine the amount of refrigerant that flows through a capillary tube metering device?

The quantity of refrigerant that flows through a capillary tube metering device is primarily influenced by the length and inside diameter of the tube.

The length of the capillary tube plays a crucial role because a longer tube increases the resistance to flow, leading to a higher pressure drop as the refrigerant travels through it. This pressure drop can significantly affect the flow rate. In contrast, a shorter tube would reduce this resistance, allowing for a higher flow rate.

The inside diameter is also critical because it directly impacts the cross-sectional area through which the refrigerant can flow. A larger diameter allows more refrigerant to pass through, while a smaller diameter restricts flow. This interplay between length and diameter is fundamental to the operation of capillary tubes, making it the primary factor governing refrigerant flow.

Other factors mentioned in the question, such as pressure, temperature, flow rate, and viscosity, can influence the overall behavior of the refrigeration cycle but do not specifically determine how much refrigerant flows through the capillary tube itself. These factors are more relevant to other components of the system or the thermodynamic properties of the refrigerant, rather than the specific metering action of a capillary tube.