Energy Efficient Thermal Comfort Control for Residential Building Based on Nonlinear EMPC

For purpose of achieving the desired thermal comfort level and reducing the economic cost of maintaining the thermal comfort of green residential building,an energy efficient thermal comfort control strategy based on economic model predictive control(EMPC)for green residential buildings which adopts household heat metering is presented.Firstly,the nonlinear thermal comfort model of heating room is analyzed and obtained.A practical nonlinear thermal comfort prediction model is obtained by using an approximation method.Then,the economic cost function and optimization problem of energy-saving under the necessary thermal comfort requirements are constructed to realize the optimal economic performance of the dynamic process.The energy efficient thermal comfort MPC(EETCMPC)is designed.Finally,the comparison and analysis between EETCMPC and Double-layer Model Predictive Control(DMPC)is simulated.The simulation results reveal that when the clothing insulation is typical,the energy efficiency of EETCMPC is 8.9%and 11.6%,respectively,in the two simulation scenarios.When the clothing insulation varies with temperature,the energy efficiency of EETCMPC is 7.29%and 9.15%,respectively,and the total energy consumption is reduced by about 1.65%and 14.6%,respectively,compared with the typical clothing insulation.The economic performance is improved in the thermal comfort dynamic process of heating room.

Operating characteristic analysis on the ultra-thin low temperature floor-heating system

Prefabricated ultra-thin radiant heating panel,as a new heating terminal type,is becoming a highlight in Yangtze River Valley area,China recently.However,there is a lack of operating characteristic research in this region,especially the energy consumption and operating mode are even less.To obtain these data,a heating system was set up in a duplex house in Chongqing.The test results show that the floor heating system could almost satisfy thermal comfort requirement at supply water temperature 45°C.But the preheating time was up to 4.5 h which was 1 h longer than that at supply water temperature 50°C.Meanwhile,the energy consumption at supply water temperature 50°C increased 0.10 Nm3/h,and the operating efficiency decrease about 2.6%compared to those at water temperature 45°C.Considering both the thermal lag and operating efficiency,a reasonable suggestion was proposed in this paper.That was,the standard families which just stay home at night should adopt the interim mode of partial room with part time.And the supply water temperature should be properly raised during the preheating period and lowered down in the steady heating stage.

Energy Efficiency Assessment of Building Wall with PCM Layers in the Hot Summer Locations

This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experiments. One wall included (phase-change material) spheres, integrated into one styrofoam layer, installed at different positions, from 1 to 5, from the outside to the inside of the room. The other wall included one styrofoam insulation layer, perforated with holes, with changeable positions, from 1 to 5, from the outside to the inside of the room. The temperatures in the experiment corresponded to high summer temperatures in the tropical or subtropical zones. The obtained experimental results were further analyzed, while HVAC is off, for an indoor thermal comfort range, from 20˚C to 25˚C. This manuscript has analyzed the thermal comfort, effectiveness and optimal position of PCM spheres, incorporated in styrofoam thermal insulation, for a previously determined temperature range. The wall with integrated PCM should not be thick, (in total), but rather slender so that PCM can show its effectiveness. The farthermost position of the PCM layer should be the third because PCM combined with a lot of thermal insulation is not so effective and the thermal insulation has a buffer effect. The honeycomb or hollow-core thermal insulations should be avoided to put alone, because of natural air convection in them, which raises the heat flow. The monthly monetary saving, for a PCM-integrated wall, is calculated and amounts to 55.5 $, which shows that the integration of PCM in building walls, in hot summer locations, is very beneficial.

Experimental Study on the Thermal Performances of a Tube-Type Indirect Evaporative Cooler

The so-called indirect evaporative cooling technology is widely used in air conditioning applications.The thermal characterization of tube-type indirect evaporative coolers,however,still presents challenges which need to be addressed to make this technology more reliable and easy to implement.This experimental study deals with the performances of a tube-type indirect evaporative cooler based on an aluminum tube with a 10 mm diameter.In particular,the required tests were carried out considering a range of dry-bulb temperatures between 16℃ and 18℃ and a temperature difference between the wet-bulb and dry-bulb temperature of 2℃∼4℃.The integrated convective heat transfer coefficient inside the tube in the drenching condition has been found to lie in the range between 36.10 and 437.4(W/(m^(2)⋅K)).

An Updated Review on Low-Temperature Nanocomposites with a Special Focus on Thermal Management in Buildings

Buildings contribute to 33%of total global energy consumption,which corresponds to 38%of greenhouse gas emissions.Enhancing building’s energy efficiency remains predominant in mitigating global warming.Advance-ments in thermal energy storage(TES)techniques using phase change material(PCM)have gained much attention among researchers,primarily to minimize energy consumption and to promote the use of renewable energy sources.PCM technology stays as the most promising technology for developing high-performance and energy-efficient buildings.The major drawback of PCM is its poor thermal conductivity which limits its potential use which could be resolved by dispersing conductive nanofillers.The acquired database on synthesis routes,properties,and performance of nano-dispersed phase change materials(NDPCMs)with various techniques presented in the paper should deliver useful information in the production of NDPCMs with desirable characteristics mainly for building construction applications.An outline of contemporary developments and use of NDPCMs as TES medium is delivered.Finally,a brief discussion on challenges and the outlook was also made.In-depth research is needed to explore the fundamental mechanisms behind the enhanced thermal conductivity of NDPCM with nanofillers dispersion and also a thorough investigation on how these mechanisms drive improvement in building performance.

Optimal Thermal Insulation Thickness in Isolated Air-Conditioned Buildings and Economic Analysis

The removal building heat load and electrical power consumption by air conditioning system are proportional to the outside conditions and solar radiation intensity. Building construction materials has substantial effects on the transmission heat through outer walls, ceiling and glazing windows. Good thermal isolation for buildings is important to reduce the transmitted heat and consumed power. The buildings models are constructed from common materials with 0 - 16 cm of thermal insulation thickness in the outer walls and ceilings, and double-layers glazing windows. The building heat loads were calculated for two types of walls and ceiling with and without thermal insulation. The cooling load temperature difference method, CLTD, was used to estimate the building heat load during a 24-hour each day throughout spring, summer, autumn and winter seasons. The annual cooling degree-day, CDD was used to estimate the optimal thermal insulation thickness and payback period with including the solar radiation effect on the outer walls surfaces. The average saved energy percentage in summer, spring, autumn and winter are 35.5%, 32.8%, 33.2% and 30.7% respectively, and average yearly saved energy is about of 33.5%. The optimal thermal insulation thickness was obtained between 7 - 12 cm and payback period of 20 - 30 month for some Egyptian Cities according to the Latitude and annual degree-days.

Possibilities of Reducing Energy Consumption by Optimization of Ground Source Heat Pump Systems in Babylon, Iraq

Iraq is located in the Middle East with an area that reaches 437,072 km2 and a population of about 36 million. This country is suffering from severe electricity shortage problems which are expected to increase with time. In this research, an attempt is made to minimize this problem by combining the borehole thermal energy storage (BTES) with a heat pump, the indoor temperature of a residential building or other facility may be increased or reduced beyond the temperature interval of the heat carrier fluid. Due to the relatively high ground temperature in Middle Eastern countries, the seasonal thermal energy storages (STES) and ground source heat pump (GSHP) systems have a remarkable potential, partly because the reduced thermal losses from the underground storage and the expected high COP (ratio of thermal energy gain to required driving energy (electricity)) of a heat pump, partly because of the potential for using STES directly for heating and cooling. In this research, groundwater conditions of Babylon city in Iraq were investigated to evaluate the possibility of using GSHP to reduce energy consumption. It is believed that such system will reduce consumed energy by about 60%.

Sensitivity analysis of borehole thermal energy storage: examining key factors for system optimization

Borehole thermal energy storage(BTES)systems have garnered significant attention owing to their efficacy in storing thermal energy for heating and cooling applications.Accurate modeling is paramount for ensuring the precise design and operation of BTES systems.This study conducts a sensitivity analysis of BTES modeling by employing a comparative investigation of five distinct parameters on a wedge-shaped model,with implications extendable to a cylindrical configuration.The parameters examined included two design factors(well spacing and grout thermal conductivity),two operational variables(charging and discharging rates),and one geological attribute(soil thermal conductivity).Finite element simulations were carried out for the sensitivity analysis to evaluate the round-trip efficiency,both on a per-cycle basis and cumulatively over three years of operation,serving as performance metrics.The results showed varying degrees of sensitivity across different models to changes in these parameters.In particular,the round-trip efficiency exhibited a greater sensitivity to changes in spacing and volumetric flow rate.Furthermore,this study underscores the importance of considering the impact of the soil and grout-material thermal conductivities on the BTES-system performance over time.An optimized scenario is modelled and compared with the base case,over a comparative assessment based on a 10-year simulation.The analysis revealed that,at the end of the 10-year period,the optimized BTES model achieved a cycle efficiency of 83.4%.This sensitivity analysis provides valuable insights into the merits and constraints of diverse BTES modeling methodologies,aiding in the selection of appropriate modeling tools for BTES system design and operation.

基于变补油及冲洗回路联控的泵控马达系统热管理方法

针对静液压驱动的工程及农业装备中典型泵控马达系统低压回路存在连续功率损失,回路油液温度随负载及油箱温度变化大等问题,本文提出一种基于变补油及冲洗回路(ACFC)联控的节能热管理方法。在典型泵控马达系统低压回路中引入电比例恒压变量泵及电比例节流阀,实现冲洗流量可控调节及补油流量自动适应,以提供回路温度的控制自由度;基于实验测试数据,构建基于损失模型的泵控马达系统产热模型;依据系统产热模型设计了一种基于前馈+PD反馈控制算法的热管理方法对回路温度进行控制;采用基于功率跟随的泵控马达系统调速策略,在不同负载、不同初始温度等工况下,对典型泵控马达系统和基于ACFC的泵控马达系统开展对比实验。实验结果表明,所建立的损失模型可实现对泵控马达系统产热功率实时估计,估计精度达到±10%,验证了所建系统产热模型的正确性;在ACFC具有一定散热裕度的条件下,提出的热管理方法可使回路温度控制精度达到±0.5℃,并降低低压回路功率消耗24.7%~66.7%,使系统总传动效率提高0.9%~3.9%,有效验证了所提热管理方法的温控及节能性能。基于ACFC的热管理方法可为静液压驱动的工程及农业装备节能控制及热管理提供一种思路及方法。

太阳能与空气源热泵集成系统在医院生活热水供应中的应用与效益分析

文中以南昌大学第一附属医院象湖院区为例,对比分析了传统燃气热水系统与集成太阳能光热和空气源热泵系统,结果表明,后者在节能和经济效益上均优于前者。文中提出了改进系统设计和提升能效的策略,旨在为医疗行业太阳能光热技术的推广提供理论和实践指导,促进绿色能源在该领域的应用。

集中供热末端调控及分户热计量系统的实现

实现分户热计量收费是我国供热体制改革的主要目标之一,有效的末端调控和合理的计量收费策略,是关系着供热体制改革能否顺利推进的重要因素。给出了一种基于ZigBee技术实现的供热末端调控系统,可根据场所人员活动规律自动进行分区、分时段调控室内温度,节约热力资源,提高供热效率,降低取暖费用。同时,给出了一种按照供热效果进行统计分析的模型,提出了一种改善分户热计量的新方法;以每栋楼的用热总量计算该栋楼的总供热费用,按照用户的供热面积、实际供热效果和用热量相结合,计算每个用户的热效值和整栋楼总热效值,分摊计算出每个用户的取暖费用,使每个用户的取暖费用真实地反映其用热效果。

北京市昌平区马池口村地源热泵系统设计与热平衡分析

通过使用模拟软件对北京市昌平区马池口村项目的供热制冷设计负荷和全年逐时动态负荷进行计算,结合项目的能源条件与建筑的负荷特点,设计了以地埋管地源热泵系统为主,空气源热泵与复合式太阳能热水系统作为辅助热源的复合式能源系统。通过TRNSYS软件模拟,分析了地埋管地源热泵系统承担75%供暖负荷时存在的土壤热平衡问题,验证了使用复合式太阳能热水系统为地埋管系统补热后地下岩土温度可维持在一定范围内,基本保持冷热平衡,确保系统安全稳定、高效运行。通过对系统节能效益分析,检验该复合式能源系统的节能降碳效果,为寒冷地区同类型项目提供参考。

厚板线加热炉节能技术改造

针对莱钢厚板线加热炉能耗偏高的现状,依靠热平衡搭建能耗桥对加热炉诊断分析后并实施技术改造。现场对炉门进行了节能技术改造,优化了步进梁、装钢机、出钢机连锁程序,解决了厚规格钢坯因热送温度偏高无法连续热送装钢技术难题;通过试验试轧拓展了热送坯型,优化了热送钢坯加热控制工艺。厚板线加热炉技术改造后,节能效果显著,煤耗指标由1.491 GJ/t降到1.474 GJ/t。

快速充电条件下的新能源电池热管理

随着新能源汽车行业的迅猛发展,快速充电成为电动汽车普及的关键技术之一。然而,快速充电对电池热管理系统提出了更高的要求,电池在快速充电过程中的热积累、热失控风险、寿命缩短和性能不稳定等问题日益凸显。主要对新能源电池在快速充电条件下的热管理问题进行了深入分析,并详细探讨了高效散热材料应用、智能热管理系统应用、主动冷却技术以及热电效应技术等创新技术的应用,以期为新能源电池热管理提供有效的技术支持和解决方案。

不同型式加热炉在烧结SCR脱硝系统的应用效果分析

由于钢铁行业烧结烟气具有流量波动大、烟气温度低、烟气成分复杂、含氧量高等特点,半干法脱硫+SCR脱硝工艺成为目前国内钢铁行业烧结烟气脱硫脱硝实现超低排放的主流工艺。其中,SCR脱硝反应必须达到关键设备催化剂的活性温度窗口,导致该工艺需采用加热炉进行烟气升温。在此过程中燃气消耗量大、能耗高,成为烧结烟气脱硫脱硝工艺运行成本中的最大环节。某钢铁厂3套烧结烟气SCR脱硝系统共采用了3种不同型式的加热炉,通过对不同型式加热炉在SCR脱硝系统的应用效果进行分析,提出了热效率更高的加热炉型式,对于烧结SCR脱硝系统加热炉的选型和改造都具有理论指导意义。在当前节能降碳的大背景下,对原外置式加热炉进行改造,降低了烧结烟气SCR脱硝系统的煤气消耗,煤气耗量节省约12.44%,节能降耗效果显著。

焦炉自动加热系统在6.78 m捣固焦炉上的应用

介绍了焦炉自动加热系统的主要组成,对焦炉自动加热系统在6.78 m捣固焦炉加热过程中的实际应用效果进行了检验,达到了预期效果,提高了焦炉加热自动化控制水平,稳定了炉温,保证了焦炭成熟。

冷热双向全周期维度蓄能空调系统设计优化

蓄能空调系统涉及“源”侧电力供应和“荷”侧建筑冷热需求双重动态变化特性,系统的容量配置是一个技术经济寻优问题。受室内外多种因素共同影响,建筑冷热负荷每天的逐时分布规律差别较大,传统上仅基于设计日等典型周期逐时负荷分布规律的设计方法使得蓄能空调系统容量的配置不合理。突破传统设计方法的不足,提出以空调系统全年运行性能为导向的冷热双向全周期维度蓄能空调系统性能化设计方法,能够考虑到全供暖季、全制冷季每天的逐时动态负荷分布规律,耦合建筑冷热负荷双向需求,获得更加科学合理的蓄能空调系统容量配置方案。用具体案例进行了设计方法展示。

火电厂烟气余热再利用系统改造效果分析

随着国民经济水平的不断提高,我国的火力发电事业也发生了翻天覆地的变化。在这一变化的过程当中,针对当前火电厂锅炉余热利用率低、能源价格上涨导致发电亏损、环境压力逐渐增大的现状,提出通过对锅炉烟气余热利用系统改造,从而达到节能减排增加企业效益的目的。本文结合鄂温克发电厂1号机组烟气余热利用系统改造过程,介绍了改造思路及具体改造实验过程,并对改造后效益进行详细分析,结果显示系统改造净降低供电煤耗节能量为6.33g/(kW·h),为企业的创收和节能减排提供了一种新的途径。

地面加热系统温室热环境测定与经济分析

温室加热系统对温室冬季耗能有一定的影响。地面加热系统能够合理地利用加热系统的供暖热能 ,使之充分有效地供给座落在地面上的植物 ,并降低植物冠层上部温室空间的气温 ,减少了温室的能耗 ,这也是温室冬季节能的一种非常有效的方法。该文研究了应用地面加热系统的温室热环境 ,测试结果表明 ,温室有较好的空气温度分布。温度水平分布均匀 ,南北方向上温度差异在 1℃左右 ;温度垂直梯度分布为从地面附近到保温幕下气温逐渐降低 ,但温度降低幅度比较小 ,在 1℃以内 ,与传统加热方式的保温幕下高地面附近低的温度垂直梯度分布有明显不同。温室夜间植物根部温度在 19～ 2 5℃。与传统加热方式相比 ,采用地面加热的温室热环境比较有利于植物生长。该文还以传统加热系统为比较对象 ,简单分析了地面加热系统的节能效果、散热器投资和运行效益 ,结果表明地面加热系统比传统加热系统节约能源 2 8% ,散热器投资费用可以节省 3 4.1% ,每年降低运行费用 3万多元。

吸收式热泵在热电厂乏汽余热回收领域的应用

介绍了我国北方热电厂供热现状、吸收式热泵技术情况以及吸收式热泵在热电厂乏汽余热回收领域应用中应注意的问题,吸收式热泵能够在热电厂有效回收乏汽余热并可应用于城市集中供热,即会在节能减排方面发挥重要作用又会有效解决目前热电厂供热不足问题。