An increase in head pressure causes ___ refrigerant to flow through a capillary tube.

An increase in head pressure causes ___ refrigerant to flow through a capillary tube.

• A. Less
• B. More
• C. No change
• D. Moderate amount

Answer: (B)

The capillary tube is a fixed restriction, so the rate at which refrigerant can pass through it depends on the pressure difference across it. When head pressure increases, the high-side pressure rises, widening the pressure drop across the capillary. That larger pressure drop pushes more refrigerant through the tube, so more refrigerant flows through the capillary. If head pressure dropped, the flow would decrease; if head pressure stayed the same, the flow would remain about the same.

The capillary tube is a fixed restriction, so the rate at which refrigerant can pass through it depends on the pressure difference across it. When head pressure increases, the high-side pressure rises, widening the pressure drop across the capillary. That larger pressure drop pushes more refrigerant through the tube, so more refrigerant flows through the capillary. If head pressure dropped, the flow would decrease; if head pressure stayed the same, the flow would remain about the same.