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

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 tran-sition 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.