Combined effect of electric field and nanofluid on bubble behaviors and heat transfer in flow boiling of minichannels

Abstract

In this work, electric field and nanofluid are coupled to enhance flow boiling heat transfer in minichannel. Pin electrodes are adopted to create non-uniform electric field. The effects of nanoparticle mass concentration, surfactant type and mass concentration under electric field on nanofluid flow boiling heat transfer are studied. Image analysis technique is used to quantify boiling bubble behaviors. The results demonstrate that without electric field, bubbles for nanofluid flow boiling are smaller and more discrete than R141b. Under electric field, bubble size reduces and the number of bubbles increases, which reveals synergy effect of electric field and nanofluid on bubble behaviors is effective. Besides, electric forces mitigate bubble coalescence and delay transition from bubbly to slug flow. Maximum heat transfer coefficient of nanofluid is 80% higher than R141b. Under electric field, boiling heat transfer of nanofluid modified by anionic surfactant (SDBS) is better than cationic (CTAB) and nonionic (Span80) surfactant. • Electric field and nanofluid were devised to enhance flow boiling of minichannel. • Bubble behaviors and flow pattern transition in nanofluid flow boiling under electric field was discussed. • Synergy effects of electric field and nanofluids on enhancing flow boiling heat transfer was discussed. • Maximum heat transfer enhancement ratio of 1.8 for nanofluid and electric field is obtained.