THE ROOMS HEAT LOSSES PARAMETERS DEFINING UNDER UNSTEADY THERMAL CONDITIONS

Problem. Most of the existing methods for determining the constructions thermal resistance  used closest to a stationary thermal regime of the room. In reality, the thermal processes in the room are always unsteady. Room heat losses parameters (thermal resistance room building walls and windows, room ventilation rate and the building walls thermal inertia characteristics) need to know to analyze and improve the energy efficiency of buildings, and energy savings in their heating. Universal method for solving this problem no published.

Proposal of solution. The use of 3D CFD-modeling parameters of buildings heat losses identified in unsteady thermal conditions. Unsteady measurement of temperatures and heat flows can be made in a short period of time in independence of the temperature difference between the room and the environment and allow us to find the values of the heat losses parameters, corresponding to real thermal processes.

For improved precision of determining the parameters of heat losses is proposed to use a thermal model the room, short-term unsteady measurement of temperature in it, and apply the method of identification of its heat losses parameters. Unsteady changes in the power of the heater (in “pump-cooling” mode) reduce the time natural experiment. Had created in Ansys Fluent three-dimensional model of external and adjacent internal building room walls (Fig. 1). For the experimental the room experiment duration was less than 16 hours.

Fig. 1. 3D CFD-model of the external building envelope.

 Patent
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.