Numerical Study of the Effect of Bake-out on the Formaldehyde Migration in a Floor Heating System

摘要

To comply with concentration requirements in previously-constructed homes, many people are conducting bake-out in buildings prior to occupancy. The material temperature is considered a major factor that determines the effect of the bake-out To confirm the effect of the bake-out, an improved model of the coupled heat and formaldehyde migration process is developed and analyzed to investigate the transport features in under floor heating system. Based on the theory of non-equilibrium thermodynamics and molecular kinetics, the mechanisms of the heat and mass transfer in dry porous building materials are discussed. The coupled heat and formaldehyde migration process in a floorboard is simulated under non-isothermal conditions of the temperature. Numerical results show that the effect of under floor heating becomes more and more important with the increasing of the temperature of the bottom layer, and the emission of formaldehyde from the board increases with the increasing of bake-out frequency. The longer the time of ventilation is in bake-out, the smaller the concentration remained in the chamber is. The removal efficiency of formaldehyde from building materials with a under board heating process within the ventilation period is prominent, but the energy consumed under such a mode is unsatisfied.