Study of coalescence-induced jumping droplets on biphilic nanostructured surfaces for thermal diodes in thermal energy storage systems

Y. Zhu, C. Y. Tso, T. C. Ho, Christopher Y.H. Chao

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

4 Citations (Scopus)


Thermal energy can be better harvested and stored by integrating thermal diodes with thermal energy storage systems. Among different types of thermal diodes, jumping-droplet thermal diodes exploiting superhydrophilic and superhydrophobic surfaces yield greater thermal rectification performance (i.e. diodicity) due to high latent heat. However, the condensation heat transfer and coalescing-jumping droplets are restricted by the ability of water to nucleate on the superhydrophobic surface, leading to a limited maximum jumping height, finally resulting in degradation of diodicity of the thermal diode. To solve this problem, we propose coating hydrophilic bumps on the superhydrophobic surface which can provide preferable nucleation sites, forming a new type of nanostructured surface, called biphilic surface. This work aims to investigate coalescence-induced jumping droplets on biphilic surfaces to enhance diodicity of phase change thermal diodes. Our experimental results show that the jumping height and jumping volumetric flux of the coalescence-induced jumping droplets on a biphilic surface are enhanced by 42% and 254% compared to those on a superhydrophobic surface, respectively. Based on the jumping droplet results, a mathematical model for diodicity is built. 244% improvement can be achieved in the thermal diode with an optimized biphilic surface as compared to that with a superhydrophobic surface, which provides an effective strategy to improve the diodicity of a phase change thermal diode and an alternative approach to enhance the energy harvesting and storage capability in thermal energy storage systems.

Original languageEnglish
Title of host publicationASME 2020 14th International Conference on Energy Sustainability, ES 2020
PublisherAmerican Society of Mechanical Engineers(ASME)
ISBN (Electronic)9780791883631
Publication statusPublished - 2020
EventASME 2020 14th International Conference on Energy Sustainability, ES 2020 - Virtual, Online
Duration: 17 Jun 202018 Jun 2020

Publication series

NameASME 2020 14th International Conference on Energy Sustainability, ES 2020


ConferenceASME 2020 14th International Conference on Energy Sustainability, ES 2020
CityVirtual, Online


  • Biphilic Nanostructured Surface
  • Coalescing Jumping Droplets
  • Condensation Heat Transfer
  • Thermal Management
  • Thermal Rectification

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology

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