Pool boiling characteristics of silica/water nanofluid and variation of heater surface roughness in domain of time

In present study, boiling of water-silica nanofluid on circular flat plate heater was carried out to investigate the variation of heater surface and characteristics of nanofluid boiling at periods of time. Boiling region of nanofluid was divided into four periods of time, and the results showed that as the boiling time increases, the nanofluid boiling behavior differs from boiling of DI water. Evaluation of heater surface roughness in different periods of time showed that the surface roughness increases with time duration of boiling. It was found that boiling heat transfer coefficient (BHTC) enhances with nanofluid concentration (<0.01 vol%) and indicated an optimum in 0.007 vol%, especially at higher period. Critical heat flux (CHF) increases compared to DI water for all concentrations. In addition, influence of duration time of nanofluid boiling at constant heat fluxes on surface roughness and on performance of the boiling of DI water on the obtained surface was investigated. The results showed that when boiling time is extended in a constant heat flux, surface roughness increases, and BHTC of DI water on the nanocoated surface obtained depending on value of constant heat flux may increase or decrease.