有利于节能的采暖方式

供暖用热同用水、用电和炊事用燃气相比,有其特殊性,即户与户之间的热传递因素。传统的住宅设计,并不考虑户与户之间的热传递,当部分房间空置、或部分住房降低采暖标准、或有的住房间断采暖时,户与户之间就会有较大的热传递量,这个因素不容忽视,并应有具体的量概念。     

北京平原区浅层地下水热泵系统承载能力评价

鉴于目前地下水热泵系统应用的无序性,为了科学合理地评价含水层对热泵系统的能量承载力,本文采用地下热传递数值法、能量均衡法和热量储存法评价了北京平原区单位面积含水层利用地下水热泵系统可承载的能量负荷,评价结果表明：数值法评价以保证热泵系统的运行效率为前提,客观反映了地下水抽灌行为,能够充分发挥热泵系统节能环保的优点,优于均衡法和热储法;热泵系统承载能力与含水层的厚度呈显著的正相关,山前地区含水层易于回灌,但热泵系统的承载力较小,而东南平原区承载力较大,但难以回灌。     

Numerical Simulation of Heat Transfer and Deformation of Initial Shell in Soft Contact Continuous Casting Mold Under High Frequency Electromagnetic Field

  Heat transfer and deformation of initial solidification shell in soft contact continuous casting mold under high frequency electromagnetic field were analyzed using numerical simulation method; the relative electromagnetic parameters were obtained from the previous studies. Owing to the induction heating of a high frequency electromagnetic field (20 kHz), the thickness of initial solidification shell decreases, and the temperature of strand surface and slit copper mold increases when compared with the case without the electromagnetic filed. The viscosity of flux decreases because of the induction heating of the high frequency electromagnetic field, and the dimension of the flux channel increases with electromagnetic pressure; thus, the deformation behavior of initial solidification shell was different before and after the action of high frequency electromagnetic field. Furthermore, the abatement mechanism of oscillation marks under high frequency electromagnetic field was explained.     

温度测试中石英加速度计热传递方式研究

针对温度试验中仪表输出值测试准确性、重复性不高的现状,以石英加速度计为例,进行了阶梯保温试验。试验在不同位置设置测温电阻,在不同的温度条件下,对不同工位的仪表表芯、表芯上下位置及工装等不同位置的温度进行实际测量。试验获得了表芯、工装以及温箱的实际温度数据。通过热传递相关因素的分解,温度场边界条件分析并结合测试数据,找到仪表内部温度变化、仪表与环境温度变化、工装与环境温度变化的特点。建立并修正了温箱内仪表、工装的热传递模型,并找到了仪表测试数据误差的原因。最后,从仪表设计优化、测试设备优化、测试工艺优化等方面对后续改进提升石英加速度计温度模型测试精度提出了建议。     

织物结构对其干热传递性能的影响

本文在分析了织物传热机理的基础上,探讨了有关组织结构的参数对织物传热的影响以及能反映这些参数影响作用的综合评价指标.并以七种涤纶织物为试样,进行有关结构参数和传热性能的测试与分析,为建立织物结构与传热极能的关系进行了初步的工作.     

SIMULATION OF STEEL COIL HEAT TRANSFER IN HPH FURNACE

The mathematical model has been estublished for the simulation of steel coil＇s heat transfer during annealing thermal process in HPH （high performance hydrogen） furnace. The equivalent radial thermal conductivity is adopted by statistical analysis regression approach through the combination of a large quantity of production data collected in practice and theoretical analyses. The effect of the number of coils on circulating flow gas is considered for calculating the convection heat transfer coefficient, The temperature within the coil is predicted with the developed model during the annealing cycle including heating process and cooling process. The good consistently between the predicted results and the experimental data has demonstrated that the mathematical model established and the parameters identified by this paper are scientifically feasible and the effective method of calculation for coil equivalent radial heat transfer coefficient and circulating gas flow has been identified successfully, which largely enhances the operability and feasibility of the mathematic- model. This model provides a theoretical basis and an effective means to conduct studies on the impact that foresaid factors may imposed on the steel coil＇s temperature field, to analyze the stress within coils, to realize online control and optimal production and to increase facilily output by increasing heating and cooling rates of coils without producing higher thermal stress.     

哈克密炼机三维流场的非等温数值模拟研究

利用流体力学计算软件Fluent对69 cm~3哈克密炼机内的聚合物熔体进行了三维非等温非稳态数值模拟,得到三维流场的瞬时温度分布,并对熔体与密炼室之间的热量传递过程进行了分析。结果表明:当粘性耗散生热量等于向外传热量时,达到热平衡状态,熔体平均温度不再变化。由于聚合物熔体具有较高的粘性生热,仅靠自然对流不足以使密炼室壁保持初始的设定温度,壁温会有所增加。流场的混合指数分布说明混合流场中剪切流动占主导地位,还包括一小部分拉伸流动和收敛流动。     

Solidification and remelting of Al through Al2O3 fibrous preform under centrifugal force

The solidification and remelting of molten aluminum through a porous preform under centrifugal force field were modeled numerically. The results show that the transient solidification and remelting phenomena appear on the infiltration fi-ont and can be divided into two distinct regions： the remelting region and solid-liquid congruent melting region. The decrease of porosity always results in the increase of moving velocity difference between the infiltration front and the remelting fi＇ont, which leads to the increase of the solid-liquid congruent region extent. But for the decrease of the rotational fi＇equency, the difference of moving velocity between infiltration front and remelting fi＇ont decreases, which leads to the decrease of regional extent. The infiltration fi＇ont moving velocity is mainly influenced by the centrifugal infiltration pressure, whereas the remelting fi＇ont moving velocity is mainly influenced by the material thermodynamics. The transient solidification and remelting phenomena are the intercoupling results between the centrifugal infiltration dynamics and the material thermodynamics.     

非均匀热传递下传感网络节点选择改进算法

在非均匀热传递网络通信效率优化的研究中,由于非均匀热传递环境下的传感网络中的节点的能力消耗过程具有较强的随机性和动态性特征,使得节点能量消耗出现不规则发散问题.传统的传感网络节点选择以既定节点能量分布为前提,没有考虑温度造成的节点不规则能耗造成的能量下降问题,使得节点选择过程存在弊端.提出了一种自适应模糊差分和自适应粒子群的传感网络节点选择改进算法,分析非均匀热环境下传感网络通信原理,得到非均匀热传递下传感网络节点能量特征,依据节点的能量特征,自适应完成非均匀热传感网络簇首的选择,采用Logistics模糊映射对节点进行改进分区处理,获取最佳网络节点分区,将模糊扰动量融入最佳节点分区中,采用自适应粒子群算法对无线传感网络最佳分区节点的最优位置进行运算,获取无线传感网络最佳能量节点的最优位置,实现网络节点覆盖改进.仿真结果说明,所提算法可在非均匀热传递环境下实现传感网络节点节点的改进,具有较高的收敛效率.     

基于Fluent的蓄热体传热过程的数值模拟

在能源紧张的环境下,蓄热式电锅炉利用低谷电加热蓄热体耐火砖材料将不能存储的电能转化为热能暂时贮存起来,通过二次换热转化为用户可以利用的能源。蓄热体工作过程分为加热、保温、放热、保温、再加热的循环过程。放热过程是蓄热体工作的主要阶段,放热量的大小和时间长短直接影响设备的工作状态。通过对蓄热体模型的简化,建立三维模型,采用ANSYS Workbench中的Fluent模块对蓄热体的放热过程做了数值模拟,得到了蓄热体放热过程出口温度的分布情况。得到的结果和某工厂的电锅炉实际工作温度和时间相吻合,通过对蓄热体材料、加热时间等一些参数的设置得到的模拟结果对实际生产具有一定的指导意义。