Capillary control in domestic refrigerators: The small-bore capillary tube meters refrigerant flow from the

Introduction / Context:
Domestic refrigerators commonly use a fixed-orifice capillary tube as the expansion device. It meters liquid refrigerant and creates the pressure drop required between condenser (high side) and evaporator (low side). Understanding its placement clarifies system flow paths and diagnostics.

Given Data / Assumptions:

• Standard single-evaporator domestic fridge with capillary tube.
• Condenser outlet provides subcooled liquid to minimize flash gas.
• Evaporator operates at low pressure to absorb heat.

Concept / Approach:
The capillary connects the high-pressure liquid line at the condenser outlet to the evaporator inlet. The long, narrow tube’s frictional resistance establishes the throttling pressure drop. Downstream, a two-phase mixture forms and evaporates, absorbing heat from the refrigerated space.

Step-by-Step Reasoning:

Verification / Alternative check:
Exploded schematics of household refrigerators consistently show capillary from condenser outlet (receiver optional) to evaporator inlet.

Why Other Options Are Wrong:

• (a) Mentions an “expansion valve”; capillary itself is the expansion device.
• (b) Thermostat is a control device, not a flow path.
• (c) Redundant with a separate expansion valve; not applicable here.

Common Pitfalls:
Ignoring the need for liquid at the capillary inlet; insufficient subcooling can cause flash gas and starve the evaporator.

Final Answer:
condenser to the evaporator