Investigation of thermal conductivity enhancement of water-based graphene and graphene/MXene nanofluids

•MXene can effectively improve the dispersion stability of GR nanofluids.•The nanofluid with 2 wt% GR obtains maximum thermal conductivity enhancement of 65.34%.•The viscosity significantly decreases with an increase in MXene content.•The temperature at monitoring point decreases by 9.19 ℃ with 2.0 wt% GR relative to water.•The heat transfer efficiency of GR/MXene and GR nanofluids is almost the same. New nanofluids based on graphene (GR) and GR/MXene were prepared to enhance the thermal conductivity. The thermal conductivity and viscosity of nanofluids at various temperatures in the 5–60 °C range were tested, and their stability was investigated by zeta potential and visual observation. The thermal performance of the nanofluids was evaluated through numerical simulation analysis. The results demonstrate that MXene can effectively improve the dispersion stability of GR nanofluids. The nanofluid with 2.0 wt% GR at 60 °C exhibited the maximum thermal conductivity enhancement (65.34%) but also the maximum viscosity increment (70.69%). With the addition of MXene, the high thermal conductivity of nanofluids was maintained while the viscosity significantly decreased. GR can greatly improve the heat transfer efficiency of nanofluids, and the temperature at the monitoring point resulted from 2.0 wt% GR decreased by 9.19 ℃ compared to water. The heat transfer efficiency of GR/MXene nanofluids was almost identical to that of GR nanofluids.