【作者】 张宇；

【导师】 张寅平；

【作者基本信息】 清华大学 ， 土木工程， 2013， 硕士

【摘要】 建筑墙体的热特性是影响建筑能耗的重要因素，因此遴选或研发合适的墙体对于建筑节能意义重大。传统研究一般针对常物性墙体，通过试算方法来确定墙体最优热物性，计算工作量大，且有限次试算很难获得最优的热物性；不仅如此，对变物性墙体，该方法更是捉襟见肘，无法获得最优热物性。针对以上问题本论文开展了研究，主要学术贡献为：（1）提出了一种确定被动式建筑墙体非常物性理想导热系数的反问题方法。该方法在已知建筑热性能要求的前提下可反求出建筑墙体理想导热系数。案例分析表明，北京地区一被动式建筑外墙理想导热系数接近方波函数，优化后室内全年综合不舒适度时数可降低64.3%。该方法为建筑材料设计者指出了方向，同时为建筑节能工程师遴选建筑材料提供了指导。（2）为解决传统热力学方法在建筑墙体热物性优化分析中的不足，提出了一种火积耗散阻抗方法。熵产是热功转化过程中不可逆损失的量度，不适合本问题中热量传递过程的优化分析（建筑外墙理想热物性与外墙传热过程中熵产极值不对应）。另外，前人基于火积耗散定义了热阻，但没有考虑热容的影响，故也不适合非稳态传热问题的优化。基于此，考虑热容影响，本文基于火积耗散定义了非稳态传热过程中的阻抗，基此可得到热流与火积耗散的关系，为优化墙体热物性提供了一个新的优化参数，分析表明主动及被动式建筑外墙理想热物性对应于外墙传热过程中火积耗散极值。（3）采用阻抗方法解析求解了建筑墙体理想热物性。由于非稳态传热中难以建立起通过墙体进入室内的热量与其它相关变量的关系，故利用反问题方法无法解析求得建筑墙体理想热物性。阻抗方法解决了这一问题。该方法以阻抗极值作为优化目标，结合相应约束条件，利用变分法获得用于确定主动及被动式建筑外墙理想热物性的优化准则。基此本文设计了优化算法以获得建筑外墙理想热物性。对前述北京地区被动式建筑外墙热物性优化发现阻抗方法得到结果与反问题方法基本一致，但其精度与速度要优于反问题方法。阻抗方法为建筑墙体热物性设计提供了指导准则。更多还原

【Abstract】 Building energy consumption is huge, and the thermophysical properties ofbuilding wall are important influencing factors. So selecting or developing anappropriate wall plays an important role in saving energy. Traditional researchesusually focus on the constant thermophysical properties wall and “trial anderror” method is used to determine the ideal thermophysical properties.However, this method will result in hgher calculation cost and cannot obtain theideal thermophysical properties easily by limited calculations. Besides, for thewall with the variable thermophysical properties, this method cannot obtain theideal thermophysical properties at all. In order to solve the addressed problems,some researches are carried out in this paper. The main academic contributionsare as follows:(1) An inverse problem approach of determining the ideal thermalconductivity (variable thermophysical properties) of passive building wall is putforward. The unknown ideal thermal conductivity of building wall is caclautedinversely according to the indoor thermal demond. For application, a passiveroom in Beijing is analyzed. The results show that the ideal thermal conductivityof the external wall approaches a square wave function and the indoor integrateduncomfortable degree in a year can reduce64.3%. This approach gives theguidelines for the designers of building materials and engineers of buildingenergy when they select the building materials.(2) In order to solve the limition of the traditional thermodynamics methodfor analyzing the ideal thermophysical properties of building wall, anentransy-dissipation-based impedance approach is put forward. Entropygeneration is recognized as a measure of the irreversibility in heat-workconversion process and it is unsuitable for the optimization analysis in heattransfer process (ideal thermophysical properties of building external wall is notcorresponding to the extremum of the entropy generation in the heat transferprocess of the building external wall). On the other hand, as the thermalresistance based on the entransy dissipation neglects the heat capacity, it cannot be used in the non-steady heat transfer problem. Based on this, considering theheat capacity, entransy-dissipation-based impedance in non-steady heat transferprocess is defined. It establishes the relation between the heat flow and theentransy dissipation and it provides a new optimization parameter foroptimizing the thermophysical properties. According to the analysis, it is foundthat for the active or passive building, the ideal thermophysical properties ofbuilding external wall are corresponding to the extremum of the entransydissipation in the heat transfer process of the building external wall.(3) Entransy-dissipation-based impedance approach is used to analyticallysolve the ideal thermophysical properties of building wall. As it is difficult toestablish the relationship between the input heat from wall and other relatedvariables in non-steady heat transfer process, the inverse problem approachcannot obtain the analytical ideal thermophysical properties of building wall.The entransy-dissipation-based impedance approach can solve this problem.This method takes the extremum of the entransy-dissipation-based impedance asthe optimization objectives, combining the corresponding restraints, and usesthe variational method to obtain the optimization criteria to determine the idealthermophysical properties of building external wall for active or passivebuilding. Based on the above optimization criteria, the optimization algorithmsfor determining the ideal thermophysical properties of the external wall aredesigned. According to the optimization for the ideal thermophysical propertiesof the previous passive building external wall in Beijing, it can be found that theoptimization results by the impedance method are almost the same with those bythe inverse problem method. In addition, the impedance method is superior tothe inverse problem method in the aspects of both optimization precision andspeed. The impedance method provides the guildline criteria for designing thethermophysical properties of building wall.更多还原