Research On Wall Heat Storage Performance And Its Impact Onbuilding Energy Consumption

At present, the energy consumption in China is huge, among which buildingenergy consumption accounts for a large proportion. Therefore researching on thecharacteristics of building itself, and utilizing natural conditions to the maximumpossible extent to create a comfortable indoor thermal environment is the focus of thestudy of building energy efficiency. Building walls can store heat, and delay to release itafter decay. As a result, the heat storage and release properties of building envelope canbe applied to set up a reasonable running mode of heating and air conditioning, which isable to reduce building energy consumption effectively.This thesis unfolds the calculation method of wall’s unsteady heat transfer throughresearches on the impactmechanism of wall’s heat storage performance on heat transferprocess. On the other hand, from the perspective of basic thermophysical propertyparameters, thermal resistance, heat transfer coefficient, decrement factor,decrementdelay, heat storagecoefficient and thermalinertia index etc. are analyzed termby term in the present paper; moreover the relations betweenthesecharacterizationparameters and theireffects on the wallheat transfer process areintensively studied.On the comprehension of the nature of the heat storage property of wall, this paperaims to explore the temperature differences between outside, inside surface of differentwalls as well as the indoor air through experimental test by setting various walls ofdifferent heat storage properties. As a result, it analyzes the effects of walls on thedecrement and delay action of thermal wave and the effects of night ventilation on thewalls heat storage characteristics.The study found that the wall’s outside surfacetemperature is significantly affected by outdoor sol-air temperature, but lightly byoutdoor air dry-bulb temperature. However, compared to outdoor sol-air temperature,the outside surface temperature has some time delay.The time delay between the outsidesurface peak temperature of No.1and No.2chamber and the outdoor sol-airtemperature is about2~4hours. As to the inside and outside surface temperature ofwalls, the difference between the highest and lowest values of the western wall of No.1chamber is among12~13℃, and the time delay is among6~7hours.While themaximum difference between the outside and inside surface of walls in NO.2chamberis24~25℃, and the time delay is about6hours. The attenuationfactor of NO.2 chamber which is of better heat storage property is more than NO.1chamber, but itsdelay time is shorter. Furthermore, experimental study on night ventilation of thechambers found out that while night ventilation walls with different heat storageproperties lightly affect the temperature wave delay, however, it has obvious effect ontemperature wave attenuation. In summer, combined with night ventilation effects, thosewalls with excellent thermal storage properties can play a better role in heatstorage-release characteristics.Outdoor weather conditions have significant influence on large indoor thermalenvironment. So, on the basis of experimental studies, this thesis studies the wall heatabsorbing and releasing peculiarity in different climatic zones by the software EnergyPlus.Firstly, the the wall heat storage characteristics in different regions has beenresearched under no cold source. The heat by conduction, heat storage and heatconductivity cumulative hourly, heat storage reservoir analysis to explore the impact ofmeteorological conditions on the exothermic nature of the wall, and analysis thedifferences of the indoor thermal environmental impacted by the building wall locatedin different regions.Secondly, set in a simulated building air conditioning systems, heatstorage, building cooling load and energy consumption throughout the year has beencalculated. This can provide theoretical guidance for intermittent air-conditioningoperation mode. The analysis revealed that the air conditioning system in continuousoperation, better performance2#regenerative cell wall has been very objective onenergy efficiency.Calculation of air conditioning systems in different parts of thebuilding throughout the year draw power consumption, small room in Harbin2#airconditioning system energy saves the most. It is8.79percent. Guangzhou is theminimum of2.35%. Beijing, Urumqi, Chongqing Region2#small room airconditioning system energy savings were4.79%,7.27%,2.54%.Based on the resultsand conclusions ofthe above experimentaltesting andsimulationcalculation,thispaperdiscusseshow to achieveenergy-saving effect byapplying wall’s heat storage performance to practical engineering. Hence, this paperpresents a determination method for air conditioner intermittent operation mode. Inaddition, it puts out that the energy-saving effect and indoor thermal comfort effect ofintermittent operation can be evaluated comprehensively by the evaluation factor S.Moreover, the hourly heat transfer and accumulated heat transmission of the wall shallbe solved by response factor method with the aim to evaluate its heat storage capacity.The results show that wall’s heat storage property can be described to some extentby theendothermic reactionand heat transfercoefficient of inside and outside of the wall.People can make use of the hourly heat transfer and accumulated heat transmission toreflect the differences between buildings with various use functions, therefore, toevaluate wall’s heat storage property reasonably and comprehensively.