Research on temperature dependent effective thermal conductivity of composite-phase change materials (PCMs) wall based on steady-state method in a thermal chamber

Effective thermal conductivity (lambda) is the key factor in characterizing thermal conductance and temperature field when studying the thermal performance of composite-phase change materials (PCMs). But relevant research focusing on the influence of temperature on lambda of composite-PCMs is scarcely reported. This paper aimed to examine the relationship between lambda of a kind of prevalent composite-PCMs wall (lambda(pcw)) and temperature as well as the percentage of the phase-changed amount of the wall. In this research, two walls with a dimension of 1.5 m (W) x 1.5 m (H) and composed of cement mortar/shape-stabilized PCMs bricks, Portland vitrified bricks, respectively were built and tested by a steady-state method in a thermal chamber. Results showed a good positive linear relationship of lambda with the increasing mean wall surface temperature for the regular vitrified brick wall as well as the composite-PCMs wall in solid and liquid states. In addition, as for the cases where the composite-PCMs wall partly experienced solid-liquid phase change, there was a negative proportional relationship between lambda and the increasing percentage of the phase-changed part, which exhibited the major difference with that of the common walls. (C) 2016 Elsevier B.V. All rights reserved.