Heat Flux Estimation and the Control of Nucleate Boiling in a Laboratory Test Rig 2005-01-2007

The pending introduction of controlled coolant flowrates in modern automotive cooling systems presents the opportunity to exploit a heat transfer phenomenon known as Nucleate Boiling. By allowing this initial phase of boiling, reduced coolant flowrates are possible yielding a reduction in cooling system losses and pumping effort. This paper will elaborate work on a proposed technique for controlling coolant flowrates such that an enhanced heat transfer coefficient due to nucleate boiling is maintained. Three heat flux estimation techniques are proposed and evaluated on a specially built test rig under laboratory conditions. The results will discuss the advantages and disadvantages of each technique and its applicability in an automotive cooling system. The paper extends the work in a publication presented previously at the JSAE, 2004 in Japan