Local analysis of airflow distribution in open concept passive houses

This paper presents the analysis of local air currents distribution near the inlet and outlet openings in a living room of study a pre-certified passive house located in Cluj-Napoca by CFD numerical simulation. The simulation domain is represented by an open space concept, comprising the living room and the kitchen, situated at the ground floor of the building. The used heat recovery ventilation system controls both the supply of fresh air through the inlet grilles, located on the floor of the living room and the extraction of exhaust air through outlet grilles with circular cross section positioned on the other side, in the kitchen’s ceiling. An area of interest has been selected to define the simulation domain. Numerical modeling has been carried out by means of a commercial software based on the finite element method to simulate a series of interconnected phenomena encountered in the analysed application. The dry air was chosen as working agent for the field of simulation/calculation. Its thermo-physical properties were selected from the program database. No slip limit conditions have been imposed for all the delimiting surfaces of the computational field. Inlet and outlet grilles were considered open borders for circulated air volume flow in three distinct analysed cases. For the simulation of the flow of the working fluid through the computational domain, the following simplifying assumptions were considered: stationary regime, incompressible fluid, constant temperature, isothermal jet, adiabatic system, without internal heat sources, without taking into account the mass forces. The discretization of the simulation domain was divided into an optimal number of finite variable elements, with a greater density near the border areas. The results of air currents distribution in the vicinity of grid areas, for inlet fresh air and outlet exhaust air, was done by analyzing the current lines, the velocity vectors and the velocity contours.