DETERMINING THE PARAMETERS OF HEAT LOSS OF PREMISES IN NON-STATIONARY THERMAL CONDITIONS
Problem. Most of the existing methods for determining the thermal resistance of enclosing structures use a room close to stationary thermal conditions. In fact, the thermal processes in the room are always non-stationary. The parameters of heat losses (thermal resistance of building envelopes and windows, air exchange rate of the building, as well as heat-inertia characteristics of building envelopes) must be known in order to analyze and improve the energy efficiency of premises, as well as save energy on their heating. There is no universal way to solve this problem in the literature.
Suggestion for solving the problem. Using 3D CFD-models to determine the parameters of heat loss in premises under non-stationary thermal conditions. Non-stationary measurements of temperatures and heat fluxes can be performed in a short period of time, regardless of the temperature difference between the room and the environment, and allow you to find the values of heat loss parameters corresponding to real thermal processes.
Fig. 1. 3D CFD model of the external fencing structure.
To improve the accuracy of determining the parameters of heat loss, it is proposed to use a three-dimensional thermal model of the external and adjacent internal enclosing structures of the room (Fig. 1). Short-term non-stationary temperature measurements are performed, according to which the method of identifying the parameters of heat loss in a room is used. Non-stationary changes in the power of the heater (in the heating-cooling mode) make it possible to reduce the time of the full-scale experiment. For the studied room, the duration of the experiment is about 16 hours.
A method is proposed for determining the parameters of heat loss in a room based on a thermal model of a part of the room and short-term non-stationary temperature measurements.
Pat 101564 Ukraine, IPC G01N 25/20, G01N 27/18: A method for determining the thermal and physical properties of heat losses [Text] / Krukovsky P.G., Metel M.O., Tadlia O.Yu., Sklyarenko D.I., Zakovorotny A.I., Deineko A.I. (Ukraine); Applicant and patent holder ITTF of the National Academy of Sciences of Ukraine. – № u201501431; stated. 19.02.15; published 25.09.15, Bull. No. 18/2015. – 4 s.