engleski

Estimation of the wall thermal properties through comparison of experimental and simulated heat flux

The aim of the paper is to estimate thermal properties (thermal conductivity and thermal diffusivity) of the concrete wall with unknown insulation. Short theoretical background of diffusive heat transfer and numerical solution of unsteady one-dimensional heat conduction equation is presented first. System of discretized equations is solved using MATLAB. Boundary conditions (i.e. temperatures on edges of the wall) required for solving parabolic partial differential equation are obtained from experimental measurements on the wall. One heat flux sensor and one temperature sensor is mounted on both sides of the wall. Temperature inside room is maintained on approximately constant value by air conditioner while outdoor temperature is varying through the day. Measured signals are collected using NI cDAQ and then analyzed, processed and displayed using LabVIEW. Measured heat flux and numerically calculated heat flux from room to wall are then compared and initially chosen thermal conductivity and thermal diffusivity of the wall are iteratively adjusted until difference between measured and simulated heat flux is minimized.

heat flux; in situ measurement; thermal diffusivity; thermal conductivity; direct problem

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