建筑墙体理想热物性的确定方法及其机理诠释

发布时间：2018-04-06 01:40

本文选题：建筑墙体　切入点：热物性　出处：《清华大学》2013年硕士论文

【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。
[Abstract]:The thermal characteristics of building wall is an important factor affecting the energy consumption of the building, so the selection or development suitable for the construction of energy-saving wall is of great significance. The traditional research for constant property wall, through the calculation method to determine the optimal wall thermal properties, thermal calculation workload, and limited time trial is difficult to obtain the optimal; not only so, the propertyvariable wall, the method is stretched, unable to obtain optimal heat. In view of the above problems, this paper carried out the research, the main academic contribution:
(1) proposed a method of inverse problem of determining the thermal conductivity of building wall is a very passive ideal. This method can reverse the thermal conductivity of building wall in the ideal building thermal performance requirement is known. The case analysis shows that the Beijing area of a passive building exterior wall thermal conductivity is close to the ideal square wave function, optimized indoor don't comfort when the number of 64.3%. can be reduced and the method of building materials designers pointed out the direction, and provides guidance for building energy engineers selection of building materials.
(2) in order to solve the traditional thermodynamic method in the construction of the wall thermal optimization problem analysis, put forward a kind of entransy dissipation impedance method. Entropy is a measure of the irreversible loss of power transformation in the process of analysis, this problem is not suitable for the optimization of heat transfer process (extreme thermal entropy not producing exterior ideal and the exterior building heat transfer process should be). In addition, based on the previous definition of entransy dissipation thermal resistance, but did not consider the influence of heat capacity, so the optimization is not suitable for transient heat transfer problems. Based on this, this paper consider the effect of heat capacity, entransy dissipation defined impedance based on the unsteady heat transfer process, this can be relationship between heat flux and entransy dissipation, provides a new parameter optimization to optimize the thermal wall, analysis shows that the active and passive building exterior wall thermal transfer process corresponding to the ideal wall. The entransy dissipation extremum
(3) the impedance method is solved analytically. The ideal building wall thermal properties due to unsteady heat transfer in difficult to build into the room through the wall heat and other relevant variables, so the inverse problem cannot be resolved by building wall thermal impedance. The ideal method to solve this problem. In this method, impedance minimum as the optimization goal, combined with the corresponding constraints, using the variational method for the optimization criterion of active and passive building exterior wall thermal ideal is determined. This paper based optimization algorithm is designed to obtain the exterior heat. The ideal Beijing building exterior wall thermal properties of passive optimization results and anti impedance method the problem of methods are basically the same, but its precision and speed is superior to the method of inverse problem. The impedance method for building wall thermal design provide guidelines.

【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU111.4

【共引文献】