What are the advantages and disadvantages of common refrigerants?

Water:

Advantages: Good thermal conductivity.Low cost, non-toxic, and environmentally friendly.

Disadvantages: High freezing point ((0°C), suitable only for environments above 0°C; it evaporates easily and requires continuous replenishment; it has certain corrosiveness to metals, so corrosion inhibitors must be added.

Brine (sodium chloride / calcium chloride solution):

Advantages: Low freezing point (up to (-50°C), low cost, suitable for low-temperature refrigeration systems.

Disadvantages: Strong corrosiveness to metals, requiring large amounts of preservatives; it absorbs moisture easily, which may cause pipe icing; its high density increases pump energy consumption.

Ethylene glycol solution:

Advantages: Low freezing point (down to (-70°C), high boiling point, good thermal conductivity, and wide range of applications.

Disadvantages: Toxic (harmful to humans and animals), requiring proper protection; long-term use may cause swelling of rubber components; relatively high cost.

Propylene glycol solution:

Advantages: Non-toxic, highly safe, suitable for food, pharmaceutical and other industries with high safety requirements; low corrosiveness and good material compatibility.

Disadvantages: Slightly lower thermal conductivity than ethylene glycol, less effective in lowering the freezing point; higher concentration is required to meet the same low-temperature requirements, resulting in higher cost.