Nonequilibrium Thermal Fluctuations of Flow in Thermal Systems

Abstract

Abstract Fouling is detrimental to the heat transfer performance of concentrated solar power plant components where heat exchange takes place with the cooling tower water. Wave elements cause an expression of deep insight of the fouling formation. A new physical concept of wave element is proposed; it is the wave interface between two molecule groups with an infinitesimal temperature difference in fluid. It is generated by density difference, which results from temperature difference. Tiny temperature differences always exist everywhere in a fluid. When a fluid is in motion, wave elements are generated among molecule groups. Wave motion and Brownian motion can serve as the two basic forms of motion of the molecules in flow. Temperature controls Brownian motion. Temperature differences and the fluid's motion cause the wave elements. Nonequilibrium thermal fluctuations present as wave elements in a flow. A wave element appears as wave behavior along the space and time dimensions that are based on the continuity relation. The direct experimental evidence for wave elements cannot be directly established at the present scientific testing cap ability because the temperature difference of two molecule groups adjoining each other in a flow is infinitesimal. A series of “enlarged size” experiments are conducted involving the cooling tower water fouling to show the wave elements’ behaviors by tracing the molecules’ movement. The experimental study presents that the wave interface along the space and time dimensions simultaneously exists between two densities due to fluid motion. The experimental evidence and theoretical analysis support each other.