What property should oils used as heat transfer fluids in hot oil systems possess?

Oils used as heat transfer fluids in hot oil systems should possess thermal breakdown resistance at normal operating temperatures because this property ensures the oil can maintain its integrity and functionality over extended periods of high heat exposure. When heat transfer fluids are subjected to high temperatures, they can undergo chemical changes that may lead to degradation, forming sludge or other deposits that can clog systems and diminish efficiency.

Having excellent thermal breakdown resistance allows the fluid to perform efficiently without losing its thermal properties, ensuring reliable heat transfer. This is crucial for maintaining system performance, optimizing energy usage, and preventing catastrophic failures.

In contrast, oils with high viscosity can impede the flow and reduce heat transfer efficiency. Low thermal conductivity is unfavorable as it would hinder the oil's ability to transfer heat effectively. While a high boiling point is beneficial for preventing evaporation and maintaining fluid levels, the most critical aspect for operational longevity and performance in this context is the ability to resist thermal breakdown.