Cooling water selection in heat exchangers: which single property of liquid water most strongly explains why it is the most widely used industrial coolant?

Introduction / Context:
Choosing an efficient, readily available coolant is central to heat exchanger design in chemical and process industries. Water is almost universally preferred where freezing, scaling, or corrosion risks can be managed. This question asks which single thermophysical property most strongly explains that preference and ties directly to basic heat transfer principles and energy balances used by engineers during cooling-water system design.

Given Data / Assumptions:

• Aqueous cooling water at near-ambient conditions is compared with other potential coolants.
• Standard metallic heat-exchanger surfaces and typical industrial temperature ranges are assumed.
• We focus on the dominant property governing heat-storage capacity per unit mass.

Concept / Approach:
For sensible cooling or heating, the thermal energy change is Q = m * Cp * ΔT, where Cp is the specific heat at constant pressure. A higher Cp means a given mass flow rate can carry more heat per degree of temperature change. Among common, safe, inexpensive liquids, liquid water has an unusually high Cp, enabling smaller flow rates or smaller heat-transfer areas for the same duty, often outweighing other considerations when water quality is acceptable.

Step-by-Step Solution:

Verification / Alternative check:
In practical exchanger sizing, a higher Cp reduces required mass flow for a fixed duty and temperature rise, lowering pumping power and pipe sizes. Where corrosion or fouling is controlled (materials selection, treatment), water typically provides the best overall economics.

Why Other Options Are Wrong:

• Low corrosiveness: Untreated water can be corrosive; corrosion control is managed via materials and chemistry rather than being inherently “low.”
• Low dirt factor: Fouling risk with water exists; treatment and filtration mitigate it.
• Low viscosity: Water's viscosity is helpful for pumping, but Cp dominates heat-carrying capacity.

Common Pitfalls:
Confusing ease of pumping or availability with the fundamental thermophysical driver of heat capacity; overlooking water quality management requirements (scaling, microbiological control).

Final Answer:
High specific heat