Influence of Thermal Radiation on Heat Transfer through a Hollow Block

Hollow blocks are widely used in construction to reduce the thermal resistance of building walls. The air within the blocks has a low thermal conductivity, which makes it possible to consider such hollow blocks as a good insulating material. This work presents a numerical investigation of the impact of thermal radiation on energy transport and airflow inside a hollow block. The coupled heat transport by free convection, thermal radiation and conduction through the solid walls is taken into account. The finite-difference procedure is applied to work out numerically the control equations of conservation of momentum, energy and mass in both solid walls and air filled enclosure. The main parameters governing the problem are surface emissivity, Rayleigh number and thermal conductivity of solid walls. The influence of these factors on the overall heat transfer through hollow block is presented and investigated. The outcomes show that the low emissivity of the inner walls inside the hollow blocks will significantly help to reduce the energy consumption of buildings.