The Research On The Effect Of Building Ventilation And Thermal Mass On Indoor Air Temperature In Sinusoidal Inflow

At present, the world is faced with great challenges posed by energy andenvironment. The development and application of building energy saving technologyis one of the heat issues that global academics discuss all the time. Natural ventilationis one of passive technology to maintain appropriate indoor environment, which is touse natural energy resource without using traditional mechanical systems. The role ofnatural ventilation is related close with thermal mass. This paper investigates theindoor temperature fluctuations affected by the building thermal mass on the conditionof sinusoidal inflow.On the basis of literature reviews, this paper elaborates the basic theory ofnatural ventilation and thermal mass, and then set up a simple single-zone buildingmodel with two-opening. The indoor thermal balance equation is established based onthe condition that the unsteady velocity of the air is sinusoidal. In additional, somecalculations and analyses are given based on the variations of the condition ofsinusoidal inflow, physical parameters, area, materials of building thermal mass andthe indoor heat sources. Then the change law for decrement factor and the time lag ofindoor air temperature is obtained. Finally, under the condition of sinusoidal inflow,this paper simulates the field of indoor air temperature by setting up a model thatcoupled natural ventilation with building thermal mass by Airpak. The main resultsand conclusions of this study are described as follows:（1）In constant and sinusoidal inflow conditions, indoor air temperaturecompared with the outside has an obvious attenuation and delay, and maintain thefluctuation variation law, whose periods is24hours. When the average wind velocityof two different airflows is equal, the fluctuation range of indoor temperature of asinusoidal inflow condition is smaller than constant air velocity condition.（2）When the parameters of building exterior and interior thermal mass remainconstant, under the condition of sinusoidal inflow, the different average wind velocity,fluctuation range and fluctuation cycle will have an impact on indoor temperaturefluctuations. Among them, the variation of average wind velocity has greatest impact.With the average wind velocity increasing, the decrement factor of indoortemperature increases sharply firstly and then remains stable, however, the time lagdecreases rapidly firstly and then also remain stable. （3）Under the condition of sinusoidal inflow, the impact of the physicalparameters, area, materials of building thermal mass on decrement factor and time lagof indoor temperature have different variant law, but the indoor average temperatureremains constant basically. And the change of the indoor heat sources has no effect onthe fluctuation of the indoor air temperature, indoor average temperature is linear tothe heat sources.（4）The distribution of indoor temperature is similar in constant and sinusoidalinflow conditions. Temperature declined from two opposite exterior walls to thecenter of the room respectively. The temperature distribution in middle area tends touniform. But under the sinusoidal inflow conditions, the temperature of each point inthe room is closer to the indoor temperature average value. Indoor air is mixed morefully by the fluctuation characteristics of natural wind.