Thermal conductivity enhancement of the binary mixture (NH_3 + LiNO_3) by the addition of CNTs

摘要

The objective of this paper is to experimentally investigate the enhancement of thermal conductivity in the binary working pair (NH_3 + LiNO_3) by adding carbon nanotubes (CNTs). A stable distribution of CNTs in the base fluid is achieved by surface modification of CNTs through oxidation. The key parameters are the concentrations of NH_3 and CNTs in weight, ranging from 30% to 50% for NH_3, and 0.005%-0.2% for CNTs. The thermal conductivity of the binary nanofluid was measured at 1.5 MPa, from 303.15 K to 353.15 K, using a relative transient hot-wire apparatus. Uncertainty in the measurements was estimated to be less than 0.025 W m~(-1) K~(-1). The highest thermal conductivity enhancement was obtained with the combination of 0.01 wt.% of CNTs in the base fluid of 40 wt.% NH_3, where the maximum measured enhancements was 7.5% times than that of NH_3 + LiNO_3 solution.