FIELD: measuring.
SUBSTANCE: invention relates to determination of thermophysical characteristics of enclosing structures and can be used in construction for evaluation of thermophysical properties based on results of tests in natural conditions. Disclosed is a method for determining changes in the heat absorption index of the outer surface of a wall enclosure made of silicate brick when a physical effect of opposite heat flows occurs in the thickness of the wall which consists in using a laboratory complex for determining thermal characteristics of samples of wall enclosures during long-term test modes during full-scale thermophysical investigations, a year and more in full-scale conditions. As a result of investigations, we obtain graphs with temperature changes over the thickness of the enclosure during the day and the physical effect of opposite heat flows occurring in the thickness of the wall. Sharp fluctuations of ambient air temperature cause fluctuations of temperature on external surface and in thickness of wall enclosure caused by fluctuations of heat flow. In case of abrupt increase of ambient air temperature exceeding temperature on external surface, heat flow directed inside wall causes physical effect of opposite heat flows in the wall. At the moment when the temperature on the outer surface τ2 will show the same value with temperature τ3 layers adjacent to outer surface τ2=τ3, opposite heat flows balance each other. Moment of time during which τ2=τ3, we will take as initial T1. Section I-I on the graph (Fig. 2). Moment of time when temperature on outer surface τ3 reaches maximum values, section (II-II) is denoted by T2. Amplitude of heat flow Aq during time interval T1→T2 is determined by formula 
where Δt is temperature gradient at time T1, when τ2=τ3, and moment of time τ2, when τ3 reaches maximum values, °C; Ra is resistance to heat absorption of the surface (table value), 
heat assimilation index of outer surface is determined by formula 
, where Aq is amplitude of heat flux fluctuation, W; At is the amplitude of temperature fluctuations at time T1→T2, when physical effect reaches maximum values, °C; Y is the heat assimilation index of the outer surface, 
EFFECT: improving accuracy of determining changes in heat assimilation index of outer surface of wall enclosure during full-scale thermophysical investigations.
1 cl, 2 dwg
