Integrated Behavior of Carbon and Copper Alloy Heat Sink Under Different Heat Loads and Cooling Conditions

An actively water-cooled limiter has been designed for the long pulse operation of an HT-7 device, by adopting an integrated structure-doped graphite and a copper alloy heat sink with a super carbon sheet serving as a compliant layer between them. The behaviors of the integrated structure were evaluated in an electron beam facility under different heat loads and cooling conditions. The surface temperature and bulk temperature distribution were carefully measured by optical pyrometers and thermocouples under a steady state heat flux of 1 to 5 MW/m^2 and a water flow rate of 3 m^3/h, 4.5 m^3/h and 6 m^3/h, respectively. It was found that the surface temperature increased rapidly with the heat flux rising, but decreased only slightly with the water flow rate rising. The surface temperature reached approximately 1200℃ at 5 MW/m^2 of heat flux and 6 m^3/h of water flow. The primary experimental results indicate that the integrated design meets the requirements for the heat expelling capacity of the HT-7 device. A set of numerical simulations was also completed, whose outcome was in good accord with the experimental results.

Experimental Study on the Performance of ORC System Based on Ultra-Low Temperature Heat Sources

This paper discussed the experimental results of the performance of an organic Rankine cycle(ORC)system with an ultra-low temperature heat source.The low boiling point working medium R134a was adopted in the system.The simulated heat source temperature(SHST)in this work was set from 39.51°C to 48.60°C by the simulated heat source module.The influence of load percentage of simulated heat source(LPSHS)between 50%and 70%,the rotary valve opening(RVO)between 20%and 100%,the resistive load between 36Ωand 180Ωor the no-load of the generator,as well as the autumn and winter ambient temperature on the system performance were studied.The results showed that the stability of the system was promoted when the generator had a resistive load.The power generation(PG)and generator speed(GS)of the system in autumn were better than in winter,but the expander pressure ratio(EPR)was lower than in winter.Keep RVO unchanged,the SHST,the mass flow rate(MFR)of the working medium,GS,and the PG of the system increased with the increasing of LPSHS for different generator resistance load values.When the RVO was 60%,LPSHS was 70%,the SHST was 44.15°C and the resistive load was 72Ω,the highest PG reached 15.11 W.Finally,a simulation formula was obtained for LPSHS,resistance load,and PG,and its correlation coefficient was between 0.9818 and 0.9901.The formula can accurately predict the PG.The experimental results showed that the standard deviation between the experimental and simulated values was below 0.0792,and the relative error was within±5%.

Investigation on automated loading of dynamic 3D heat source model for welding simulation

Since programing complex and dynamic heat source model for welding simulation is a complex job,the parametric methods are studied in this paper.Firstly,an overall flow to achieve automatically modeling welding was introduced.Secondly,an expert module rule for selecting welding heat source model was founded,which is based on simulation knowledge and experiences.Thirdly,a modularity routine method was investigated using writing with C++programing,which automatically creates subroutines of 3D dynamic heat source model for user.To realize the dynamic weld path,the local weld path coordinate system was moved in the global coordinate system and it is used to model the direction of weld gun,welding path and welding pose.The weld path data file was prepared by the automatic tool for the welding heat source subroutines.All above functions were integrated in the user interface and the connection with architecture was introduced.At last,a laser beam welding heat source modeling was automatically modeled and the weld pool geometry was compared with the reported literature.It demonstrated that the automated tool is valid for welding simulation.Since modeling became convenient for welding simulation using the tool proposed,it could be easy and useful for welding engineers to acquire the needed information.

Heat and Humidity Transport Analysis Inside a Special Underground Building

The calculation of heat and humidity load serves as the cornerstone of Heating,Ventilation,and Air Conditioning(HVAC)design.Nevertheless,as the heat and humidity load characteristics of underground structures differ substantially from those of above-ground structures,it is a challenge to derive their accurate calculation procedure through engineering experience.Therefore,it is particularly important to carry out quantitative research on heat and humidity load.This study used Design Builder software to study the influence of the design state point of air conditioning in underground buildings on energy consumption.The study showed that compared with the single design temperature of 18℃,setting the temperature of 16℃ in winter and 22℃ in summer could reduce energy consumption by about 59%.And the hourly heat load,cooling load and humidity load in one year are simulated and calculated so as to quantitatively analyze the characteristics of the load.This provides a database for selecting suitable HVAC equipment.It is further emphasized that dehumidification is the key to HVAC design of underground structures,which provides a reference for similar engineering designs.

VARIABILITY OF BUILDING SIMULATION RESULTS DEP ENDING ON SELECTED WEATHER FILES AND CONDITIONING SET POINTS-A CASE STUDY FOR A RESIDENTIAL BUILDING IN VICTORIA,AUSTRALIA

Building simulation is a powerful way to evaluate the performance of a building.The quality of simulation results however strongly depends on the accuracy of simulation input data.Especially for weather data files and occupant behaviour it is difficult to obtain accurate data.This paper evaluates the variability of building simulation results with regards to different weather data sets as well as different heating and cooling set points for a residential building in Victoria,Australia.Thermal comfort accord-ing to ASHRAE Standard 55,final energy consumption and peak cooling and heating loads are assessed.Simulations have been performed with Energy-Plus,and weather data for a multi-year approach have been generated with the software Meteonorm.The results show that different weather files for the same location as well as different conditioning set points can influence the results by approximately a factor of 2.

中央空调负荷精细化调控双层优化技术研究

针对当前中央空调系统粗放式调节不能准确释放调控潜力的问题,深入分析中央空调各子系统工作原理与调控方式,提出基于双层优化的中央空调负荷精细化调控技术方案。首先,面向实际工程实践需求建立建筑湿热标度模型;然后,建立以舒适度和经济性优化目标函数为主的上层调控模型,采用Shapley值法对温湿设定值的进行分配;接着,建立以各子系统优化组合能耗最低为优化目标函数的下层调控模型,采用蚁群算法对优化目标函数进行求解;之后,通过求解双层模型,制定包括末端风机、冷冻水泵以及冷水机组等组件的精细化调控策略;最后,通过多个算例验证所提中央空调负荷精细化调控技术方案的正确性与有效性。

基于热负荷均匀分配原则的直接空冷系统轴流风机转速灵活调节策略

在直接空冷电站中,轴流风机功耗占厂用电比例较高。为获得更为高效的风机运行调整策略,以某典型2´600 MW直接空冷机组为例,基于热负荷均匀分配原则,采用数值模拟方法,研究轴流风机转速灵活调节策略。获得不同环境温度和风速条件下,各轴流风机转速分布规律以及通过空冷凝汽器单元的冷却空气质量流量分布规律。最终,计算得到不同环境气象条件下不同轴流风机转速调节策略风机总功耗变化规律。结果表明,基于热负荷均匀分配原则的轴流风机转速灵活调整策略明显优于轴流风机转速整体调节策略,结果可为直接空冷机组优化运行和深层次节能提供参考。

高效空气源热泵式烤房优化设计

针对普通燃煤烤房能源消耗大、污染环境和生物质燃料烤房存在较大的安全隐患等问题,对普通烤房进行改造,引入空气源热泵系统,利用流体力学软件FLUENT对烤房不同气流形式结构、装烟室地面分风坡结构、加热室底部导流板结构的烘烤过程进行数值模拟,以获得烘烤性能最优的烤房结构形式;同时对温湿度控制系统进行设计,以实现烤房温湿度的精准调控,最后开展节能应用效果和温湿度操控性能正交试验。试验结果表明:所设计的空气源热泵烤房与普通燃煤烤房和生物质燃料烤房相比,能源消耗减少,平均烘干1 kg烟叶可分别节约0.77元和0.35元,烟农节能增收成效显著;在温湿度调节上更加准确灵敏,烟叶烘烤质量明显提高。

针对夏热冬冷地区的新型承载蓄热超结构墙体力学性能与温控效能研究

相变蓄热墙体能够有效降低室外温度波动对内墙面温度的干扰,提升室内热环境的稳定性并降低建筑能耗.由于冬夏季气象条件的差异,相变材料(phase change material,PCM)熔点的选择成为影响墙体热工性能的重要因素.为了实现蓄热墙体冬夏两季的高效利用,该研究构建了新型承载蓄热超结构墙体数值模型,对墙体力学性能进行检验,并模拟了冬季典型日和夏季典型日空气对流换热下墙体传热特性.结果表明,新型承载蓄热超结构墙体的力学性能满足工程应用需求,同时相较普通墙体具有良好的传热特性.其中,熔点为20℃的墙体在冬季热工性能最好,峰值相变率达到0.30,且内壁面最大温度波动为5.8℃,在夏季工况中,熔点为30℃的墙体具有较高的相变利用率为0.48,熔点为24℃的墙体内壁面温度波动最小.最后,综合考虑相变利用率和衰减倍数,获得了夏热冬冷地区最佳相变墙体熔点为24℃.

采煤工作面空冷器位置及风流参数优化研究

针对济宁二号煤矿10303采煤工作面高温热害问题,采用数值分析方法,建立了工作面物理模型,分析了风筒长度、风筒的出风口距离及温度等多因素对降温系统的影响,确定了不同工况(生产和停产)的温度控制参数;通过自动启闭控温设施控制空冷器出风温度,实现了不同作业下采煤工作面所需的制冷量,解决了工作面高温热害问题。结果表明:100 m风筒长度、50m风筒出风距离的降温效果最好;当工作面正常开采作业时,出风温度设置应小于16.5℃,工作面的平均温度将降低3.7℃;当停采作业时,出风温度设置应小于20.5℃,此时工作面的平均温度将降低3.5℃;2种工况下的参数均能达到采煤工作面的温度控制目标。

Computation and field experiment validation of greenhouse energy load using building energy simulation model

Greenhouse Building Energy Simulation(BES)models were developed to estimate the energy load using TRNSYS(ver.16,University of Wisconsin,USA),a commercial BES program.Validation was conducted based on data recorded during field experiments.The BES greenhouse modeling is reliable,as validation showed 5.2%and 5.5%compared with two field experiments,respectively.As the next step,the heating characteristics of the greenhouses were analyzed to predict the maximum and annual total heating loads based on the greenhouse types and target locations in the Republic of Korea using the validated greenhouse model.The BES-computed results indicated that the annual heating load was greatly affected by the local climate conditions of the target region.The annual heating load of greenhouses located in Chuncheon,the northernmost region,was 44.6%higher than greenhouses in Jeju,the southernmost area among the studied regions.The regression models for prediction of maximum heating load of Venlo type greenhouse and widespan type greenhouse were developed based on the BES computed results to easily predict maximum heating load at field and they explained nearly 95%and 80%of the variance in the data set used,respectively,with the predictor variables.Then a BES model of geothermal energy system was additionally designed and incorporated into the BES greenhouse model.The feasibility of the geothermal energy system for greenhouse was estimated through economic analysis.

超深井矿山井下降温技术研究

针对某超深井矿山井下热害问题,利用Ventsim^(TM) DESIGN 5.4三维通风软件对矿山井下通风系统进行通风和热模拟计算,并通过热负荷计算对比需风量焓差,分析得到:矿山一期工程通过加大风量可以降低井下工作面气象环境至国家相关安全规程允许范围内(湿球温度不高于27℃)。二期工程通过加大风量不能解决井下高温问题,通过热模拟计算和分析后,根据矿山现状,在3个位置设置制冷站并进行核算,得到了每个制冷站所需负荷,最终对各个制冷机组进行了选型。

基于改进粒子群算法的分散式电采暖负荷模型参数辨识

分散式电采暖负荷是一种具有巨大调节潜力的需求响应资源,但是,用户行为差异、太阳辐照度等随机因素为建立精确的分散式电采暖负荷模型增加了一定难度。首先,结合具体应用场景,搭建基于气候模拟平台的分散式电采暖负荷实验平台,采集负荷建模实验数据。然后,针对分散式电采暖负荷二阶等效热参数模型方程较为复杂的问题,以仿真温度与实测温度之间的误差最小为目标,提出基于改进粒子群算法的模型参数辨识方法,建立分散式电采暖负荷模型。最后,通过改变数据采样周期,对负荷模型进行优化。结果表明,所提参数辨识及建模优化方法可以有效地提高分散式电采暖负荷二阶等效热参数模型精度。

新型轻钢龙骨复合墙体热、湿性能研究

为了精准预测轻钢龙骨复合墙体内部温湿度分布规律,解决当前建筑维护结构保温防湿性能研究不足的问题,提出了通过数值模拟的方法对复合墙体内部温湿性能进行分析研究。基于多孔介质传热传质理论,以轻钢龙骨复合墙体为研究对象,采用轻钢龙骨复合墙体三维瞬态的热湿耦合数学模型进行研究。对比分析不同腹板开孔长度和构造形式以及加入隔汽层对复合墙体内部热湿性能的影响,得出复合墙体内部的热湿耦合瞬态变化规律。实验结果表明:腹板开孔轻钢龙骨的存在对复合墙体内部的温湿度变化规律具有显著影响,开孔不同则材料内部的温湿度变化也不相同;在轻钢龙骨复合墙体中不同内夹层在性能上存在着明显的差异,聚苯乙烯泡沫(EPS)的保温吸湿效果优于泡沫混凝土;从防止发生冷凝的角度考虑,在加入隔汽层后,泡沫混凝土的保温和防湿性能皆有所提高,这说明在墙体内部加入防湿层可有利于防止发生冷凝现象。

极端热湿条件下含盐加气混凝土热湿传递特性

多孔建筑材料的湿物理性质是计算墙体传导负荷的重要输入项。盐分的存在会极大地影响多孔建筑材料的湿物理性质。然而,关于盐分对墙体传导负荷的影响却鲜有研究。因此以加气混凝土为例分析了盐分对导热系数的影响,通过COMSOL数值求解分析了稳态下的(含盐)加气混凝土墙体的热湿传递,并根据真实的室外气象数据分析了南海区域墙体的传导负荷。结果表明:在初始条件一样时,含盐墙体内的湿分更难散发出去。当含盐量为0.87%时,含盐墙体内部湿平衡所需时间延长了一倍;盐分的存在使得墙体的潜热和显热负荷明显增加。当含盐量为0.87%,潜热负荷的增加量为5.3%~21.0%,显热负荷的增量为4.2%~5.3%时,总传导负荷增量为4.1%~6.4%。

高寒地区临时建筑冬季供暖系统技术经济性分析—以青海格尔木为例

临时建筑因其可拆卸移动、便于运输组装的特点,在高寒地区具有广阔的应用前景。但临时建筑本身的保温能力差,导致建筑供暖能耗大大增加,加之临时建筑使用寿命周期短。因此,在选择供暖方案时应更注重经济性与技术性的结合。利用DeST软件对某一临时建筑在青海格尔木地区气候条件下的全年冷、热负荷进行了动态模拟。模拟结果表明,该建筑在格尔木地区的全年累计热负荷为60287.58kWh,全年累计冷负荷为134052.39kWh,格尔木地区冷负荷约为热负荷的2.2倍,绝大部分冷负荷是由厨房炊事和暖棚造成的。当地夏季凉爽,自然通风即可改善室内热舒适而无需空调,故仅需考虑冬季供暖。在分析该临时建筑的采暖方案时,选取了分体式采暖、柴油取暖机、锅炉房+散热器三种采暖方案。柴油取暖机采暖方案的初始投资费用和年运行费用均为最低,分别为2.5万元和14.08万元。结合技术性和经济性综合分析,柴油取暖机为该临时建筑的最优采暖方案。

热负荷快速变化下电站锅炉运行的数学模型分析

由于目前燃煤发电机组需要与可再生能源合作,因此其运行应具有高度灵活性。本文开发了一个自然循环动力锅炉的内部数学模型,以分析这种合作的可能性。本文实验验证了使用所开发数学模型获得结果的正确性。在化石燃料发电厂中进行了一项试验,该试验涉及锅炉出口处蒸汽质量流速的快速增加,模型验证包括比较在几个锅炉位置所测量和计算的流体温度和质量流量。为了估计使用所开发模型获得结果的准确性,计算了相对误差和均方根误差,这些误差值表明了采用内部开发的计算方法所获得结果的正确性。本文提出的数学模型可用于发电机组模拟器,可用于创建其他动力锅炉运行的内部模型,也可用于在快速变化的负载下与可再生能源的合作。

上海地区温室冷热负荷特征分析

目前针对温室空调系统的设计,常通过理论公式或数值模拟计算,缺少估算用冷热负荷指标值,对冷热负荷特征的分析也少有研究。文章以上海地区设施农业常规作物类型和常用温室类型的组合为研究对象,采用DeST软件模拟计算不同组合下温室的冷热负荷,分析其负荷特征,提出不同组合下温室冷热负荷指标参考值,为设计温室空调系统提供设计参数和计算方法。

夏热冬暖地区双热泵型泳池专用空调机组的适用性分析

为了验证双热泵型泳池专用空调机组在夏热冬暖地区的适用性,通过热湿负荷及空气处理过程计算,对福州市某游泳馆全年热湿负荷特征进行分析,结果表明:采用双热泵型泳池专用空调机组,可以较好地解决冬季供热不足的问题,冬季及室外含湿量较低的过渡季节,通过控制新风比使两套制冷循环均转化为制热循环时,机组提供的热量不仅可以满足空调系统所需的热量,还有富余的热量给池水加热,显著减少辅助热源的容量,减少电耗。

大功率柴油机缸内传热与热负荷分析研究

在对柴油机缸内燃烧和传热研究的基础上,结合所研究的柴油机缸内高温部件的实际结构,应用GT-POWER软件建立了某型柴油机整机数值仿真模型。通过对标定工况和最大扭矩工况下缸内热流分布以及各高温部件的温度场分析表明:高温燃气与活塞的对流传热量最大,缸套与冷却液的对流传热量远大于缸盖与冷却液的对流传热量;缸套、缸盖、活塞的最高温度在标定工况时均高于最大扭矩工况,进、排气门的最高温度在最大扭矩工况均高于标定工况;在所有缸内高温部件中,排气门头部温度最高,最大扭矩工况时达到813 K。