Heat transfer analysis of diaphragm walls with high thermal insulation

Abstract

Diaphragm walls have come into wide use recently as elements with desirable structural properties. The presence of a large cavity also gives the opportunity for improving the thermal insulation performance beyond that which most cavity walls can achieve. The paper describes an investigation of the effects of the insulation thickness and thermal conductivity on the steady state heat flow rate and temperature distribution on the surface of diaphragm walls. The temperature distribution and the total rate of heat flow effects at the stiffening webs and corners of diaphragm walls are also described. The study was conducted on two-dimensional steady state heat flow with the aid of a computer program package which makes use of the Finite Element Method. The temperature and heat flow intensity patterns and total heat flow values were used to calculate the thermal behaviour of diaphragm walls with particular emphasis on the overall U-value and “cold-bridge” effects. Tables are presented which allow the accurate calculation of steady-state heat loss rates, with the effects of the webs and corners included. A numerical example is given.