Omitting Uncertainty of Thermal Conductivity Measurement in Liquids and Nanofluids by Steady-state Circular Parallel-plates

TL;DR

This study uses numerical simulations to determine the optimal conditions for measuring thermal conductivity of liquids and nanofluids with minimal natural convection effects in a steady-state circular parallel-plate setup.

Contribution

It introduces a numerical approach to accurately measure thermal conductivity by identifying the optimal plate distance to neglect natural convection effects.

Findings

Optimal plate distance is less than 2 mm for accurate measurements.

Natural convection effects can be omitted with proper apparatus design.

Simulation results guide experimental setup for nanofluids and liquids.

Abstract

In this paper, thermal conductivity measurement of liquids and nanofluids is numerically investigated by the steady state method. In which, it is required to omit the natural convection effects on the inaccuracy of measurement for heat lost quantification. One of the well-known steady-state apparatus is circular parallel-plate where the distance between circular plates is filled with liquids or nanofluids. So, it has to be designed accurately to neglect the effects of free convection. The numerical simulation is a convenient method which can omit the mentioned effects. Water, Ethylene and Ethylene Glycol are considered as base liquids and Al2O3 as a Nano-fluid in this work. Thermal boundary conditions, the distance between two parallel discs, physical and thermal quantities of fluids, size and volume fraction of nano-particles have extensive effects on the measurement process. The main result of the simulation indicates that for all of the cases, the distance between two parallel discs has to get less than 2 mm for accurate measurement of thermal conductivity in the parallel circular plate, wherein, uncertainty in the presence of the natural convection can be easily omitted.