Calculation of cooling of building premises in emergency modes at variable outdoor temperature

Introduction. Further development of methods of calculation the thermal regime of premises at emergency modes of operation of heat supply systems is actual. The aim of the research is to find an approximate analytical dependence of the air temperature in the building premises on time in conditions of a sharp cold snap with further linear decrease in outdoor temperature. As a scientific hypothesis, the position is put forward about the possibility of expressing this dependence through exponential functions using as an argument the square root of the time since the beginning of cooling.Materials and methods. The basic differential equation of the convective heat balance in the room, including the most significant components of the heat flow is used under the assumption of the linear character of the outdoor temperature decrease over time, taking into account the peculiarities of the temperature wave propagation in massive enclosures in the initial period of time. The Bernoulli method for the linear differential equation of the first order is applied by representing the solution as a product of two functions.Results. The analytical expression for the approximate dependence of the temperature change in the room at a sharp cold snap with the continuation of the further decrease of the outdoor temperature according to the linear law is found. The obtained refinement of this dependence is evaluated in comparison with the solution for the case of constant outdoor parameters on the example of one of the rooms in a residential building for the climatic conditions of Moscow.Conclusions. The structure of the obtained solution is analyzed and it is shown that the continuation of external cooling leads to acceleration of room cooling, and the solution for the cooling mode previously considered by the author at constant outdoor air temperature is its special case. It was found that the continuation of external cooling additionally leads to some straightening of the internal temperature graph, because the growth of heat loss through inertial-free structures begins to compensate to some extent for the cooling slowdown associated with the release of accumulated heat from massive encloses.

temperature, cold snap, cooling, heat supply, temperature wave, emergency mode