Investigation of temperature fields of an inhomogeneous external wall with a monolithic reinforced concrete frame

Introduction. One of the most unfavourable factors affecting building structures during their operation is moisture, which, if materials are incorrectly selected, can condense both in the thickness and on the inner surface of the fence. To prevent moisture condensation on the surface of the enclosing structure, the following condition must be fulfilled: the temperature of the inner surface of the enclosure must not be lower than the dew point temperature of the internal air. To avoid the above problems, it is necessary to carry out thermal engineering calculations of building structures with the greatest accuracy at the design stage.

Materials and methods. An analytical study of flat temperature fields in the thickness of a heterogeneous insulated external wall with a monolithic reinforced concrete frame was carried out using the method developed by K.F. Fokin. The calculation of plane temperature fields comes down to determining the temperature in each node of the enclosing structure. To do this, the wall structure was divided into nodes by a coordinate grid, then equations were compiled by which the above-mentioned values were determined and summarized in tabular form. Exact calculations were carried out by the method of integration (successive approximation) and stopped at the approximation in which the temperatures in each of the nodes did not differ from the temperatures of the previous approximation by more than 0.1 °C.

Results. To achieve the required result, eleven approximations were performed. Based on the calculated values, the heat transfer coefficient of the enclosure under study was determined. An analysis of the results obtained using the method of calculating flat temperature fields relative to the previously accepted values was carried out. The discrepancies between the values of previously accepted temperatures and the calculated values are determined.

Conclusions. After carrying out these calculations, it was revealed that the use of the temperature field method to calculate the heat transfer coefficient of a non-uniform structure is justified if the greatest calculation accuracy is required. To determine temperatures within the structure, especially in places of greatest heterogeneity, the temperature field method should be used, since it significantly increases the accuracy of the calculation.

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