A nanopump using carbon nanotube hetero-junction driven by symmetric temperature gradients

Abstract

In this work, we report a thermal pump using a carbon nanotube (CNT) hetero-junction, which is formed by connecting two CNTs of different diameters. Through molecular dynamics simulations, it is shown that water flows can be generated by symmetric temperature gradients. The flow velocity and flow rate reach 1.47 m/s and 47.2 μm3/min, respectively, under a symmetric temperature gradient of 7.5 K/nm. It is also demonstrated that the flow direction can be controlled by the direction of the temperature gradient. A theoretical model is developed on the basis of the excess enthalpy of water in the CNT hetero-junction to describe the flow. Furthermore, the effect of CNT chirality on the water flow is also studied. It is found that water transport in armchair CNT hetero-junctions is more favorable than that in zigzag CNT hetero-junctions. The numerical demonstrations in this work provide a new nanoscale design for generating fluid flows by symmetric temperature gradients, which can be used for chip-level cooling.