太阳能相变蓄热地面辐射供暖系统性能仿真

以北京某建筑为研究对象,建立太阳能相变蓄热地面辐射供暖系统,对系统热负荷、相变蓄热地板、集热器、电辅助加热器进行设计计算。以TRNSYS软件中的典型年1月为模拟时间,在相同运行策略下,对太阳能相变蓄热地面辐射供暖系统、太阳能地面辐射供暖系统(未设置相变材料层)的室内温度进行仿真模拟。最冷月1月两种系统均在大部分时间保证室内温度大于等于18℃。采用太阳能相变蓄热地面辐射供暖系统时,室内平均温度为19.13℃。采用太阳能地面辐射供暖系统时,室内平均温度为18.53℃。太阳能相变蓄热地面辐射供暖系统的热舒适性略高。     

太阳能热泵供暖系统在西藏地区的应用

分析了西藏地区应用太阳能供暖的有利条件。结合工程实例,对太阳能热泵供暖系统与太阳能直接供暖系统(设有辅助电加热器)的供暖情况及经济性进行了对比分析。当室外温度变化时,太阳能热泵供暖系统及太阳能直接供暖系统均可满足供暖要求。太阳能热泵供暖系统的经济性优于太阳能直接供暖系统。     

太阳能热泵低温辐射地板供暖系统研究

开发太阳能热泵低温辐射地板供暖系统,设计出可自由组合的低温辐射地板供暖模块。对太阳能热泵低温辐射地板供暖系统进行连续运行和间歇运行的性能试验,间歇运行方式的制热性能系数比连续运行方式高。将太阳能热泵低温辐射地板供暖系统与燃气、燃油小区供暖系统进行经济性比较,认为太阳能热泵低温辐射地板供暖系统具有较大的市场潜力。     

基于TRNSYS的太阳能-空气能高效供暖系统仿真模拟研究

针对内蒙地区农牧民居住建筑设计了一套户用太阳能-空气能高效供暖系统，使用TRNSYS软件搭建了供暖系统模型，模拟供暖季供热系统运行情况，从系统能耗、太阳能集热效率、供热性能系数等方面对比分析了该系统与太阳能复合空气源热泵供暖系统的性能。结果表明，与太阳能复合空气源热泵供暖系统相比，该系统的太阳能集热效率、太阳能转化总效率、供暖季制热性能系数分别提高了34.65%、51.15%、22.62%,该系统利用蓄热水箱低品位热源实现了太阳能高效供热，且节能效果显著。     

太阳能供暖系统的设计和实测

阐述了太阳能供暖系统的组成、运行原理、主要设计参数和经济效益等,并介绍了一个太阳能供暖系统的实测情况.     

太阳能蓄热水池传热特性模拟研究

以西藏某产业园太阳能供暖系统设计为例,介绍了太阳能供暖系统集热板面积及蓄热水池容积的计算。基于有限元分析法建立了蓄热水池三维非稳态传热物理、数学模型,并利用Matlab软件进行编程,对蓄热水池蓄热、取热和蓄热-取热3种运行工况下水池温度场及水池水温的变化规律进行了分析。通过数值模拟对蓄热水池设计进行了优化。研究结果可为太阳能供暖系统的实际应用及发展提供参考。     

中国西藏地区太阳能供暖系统优化研究

利用Trnsys软件对日喀则地区某公共建筑采用太阳能供暖系统建立了模型,利用实测运行数据进行了模型验证,根据模型对系统进行了优化,优化后的系统在减少了常规能源消耗的前提下,提升了系统的节能效果,优化后成本在可接受范围内,该研究成果将有助于蓄能型太阳能供暖系统在藏区的应用。     

主动式太阳能供暖系统故障诊断与量化调试

主动式太阳能供暖系统是一种充分利用可再生能源的供暖形式,具有节能高效、运行成本低等优点。但由于实际太阳能供暖工程缺乏必要的系统量化调试,导致实际太阳能供暖系统出现运行能耗高、热舒适度差等情况,甚至出现系统完全瘫痪故障,造成资金与资源的严重浪费。以西藏某实际主动式太阳能供暖工程为例,对某太阳能供暖系统进行了量化调试,以实测数据为依据,对系统存在问题进行量化调试,诊断出了该系统存在的故障,给出了进一步优化运行的措施。并通过对调试前后实际运行参数进行测试,验证了系统量化调试后的实际运行效果。     

严寒地区太阳能地板辐射供暖系统实验研究

乌鲁木齐地区位于中国严寒气候区,冬季采暖期长达6个月,但该地区太阳能资源较为丰富,高达5.4×109~6.2×109 J/m2·a,为太阳能热利用提供了有利条件。在太阳能日辐射强度利用价值高的时段,如何选择与当地气候条件相适应的集热元器件并构筑高集热效率的太阳能热水系统,将直接影响太阳能热利用技术的效果。本研究旨在结合乌鲁木齐冬季供暖的实际情况构筑太阳能地板辐射供暖系统,采用实验方法对太阳能地板辐射供暖系统的性能进行分析,重点分析乌鲁木齐地区冬季供暖期,室外气象条件(太阳辐射强度、室外干球温度、风速等参数)、集热器进出水温度、室内供回水温度等参数的变化规律,得出太阳能地板辐射供暖系统在冬季的运行控制方式,研究结果为乌鲁木齐地区太阳能地板辐射供暖系统的应用提供了基础参考数据。     

空气式太阳能供暖系统在西藏地区的应用

设计了一套空气式太阳能供暖及生活热水系统。阐述了其设计方案、运行特点、系统构成及控制原理。通过在西藏曲水县的实际应用,分析了其供暖系统的经济性和适用性。结果表明:空气式太阳能供暖系统在西藏地区运行稳定,室内温度可维持在18℃;与燃气锅炉和电加热锅炉相比,随着运行年限的增长,空气式太阳能供暖系统的节能效果越明显;该项目单个供暖季可节省257.36t标准煤。     

Numerical simulation of ground heat and water transfer for groundwater heat pump system based on real-scale experiment

The groundwater heat pump (GWHP) system is an open-loop system that draws water from a well or surface water, passes it through a heat exchanger and discharges the water into an injection well or nearby river. By utilizing the relatively stable temperature of groundwater, GWHP system can achieve a higher coefficient of performance and can save more energy than conventional air-source heat pump (ASHP) system. The performance of the system depends on the condition of groundwater, especially temperature and depth, which affect performance of the heat pump and system. For the optimization of design and operation of GWHP systems, it is necessary to develop a simulation tool which can predict groundwater and heat flow and evaluate system performance comprehensively. In this research, 3D numerical heat-water transfer simulation and experiments utilizing real-scale equipment has been conducted in order to develop the optimization method for GWHP systems. Simulation results were compared with the experimental results, and the validity of the simulation model was confirmed. Furthermore, several case studies for the optimal operation method have been conducted by calculating the coefficient of performance on various groundwater and well conditions.     

水库水作为水源热泵空调系统取水水源的研究

通过对安康水库的水温、水容量、水质的分析,以及系统运行后对水库水温影响的模拟,研究了安康水库作为水源热泵中央空调系统取水水源的可行性。结果表明,安康水库的水温、水容量以及经简单处理后的水质均能够满足水源热泵中央空调系统对取水水源的要求;夏季、冬季系统运行排水入库后,其水温仍能够满足系统对取水水源的水温要求。因此,安康水库作为水源热泵中央空调系统的取水水源是完全可行的。     

Interaction of an air system with concrete core conditioning

In Europe, hydronic concrete core systems are being increasingly used for room conditioning systems. The concrete slab acts as heat accumulator and permits dissipation of the load using, for instance, cooling towers. When using such systems the external climatic conditions limit the achievable water temperature. The convective loads, however, directly affect the room air temperature and reduce the storable part of the load. The ventilation system also has a large influence on the energy related operation of such a system. Moreover, the dimensions of the concrete slab and the layout geometry of the water pipes, especially the spacing, are important factors for the design of the system. A model is described which can be used to illustrate the transient two dimensional heat flow in such a construction. This method is suitable for simple hand calculations, but can also be integrated into existing building simulation programs without having to modify the program code. Thus, the complete system can be designed for practical applications to ensure optimum operation. In addition, this paper describes the interrelationship between heat storage capacity and pipe geometry. Finally, criteria are listed for suitable application of concrete slab cooling and further aspects are listed that need to be considered in connection with these systems.     

A novel on-off TRV adjustment model and simulation of its thermal dynamic performance

Field test results show that about 15% to 40% of building heat loss in China is attributable to poor heating systems regulation. The current method for addressing this problem is to install thermostatic radiator valves (TRVs) to the ends of radiators, a method adapted from northern Europe. However, this method has resulted in poor performance from delayed controlling action due to thermal inertia as well as insufficient system control accuracy. This is further compounded by incorrect operation by system users and a lack of financial incentives to regulate the system if users are not billed for their heat consumption. We present a new method for simultaneously heat controlling and metering. The core challenge is to design a control strategy that will maintain the room’s temperature. Thus, we established dynamic heat transfer models for water flow, the radiator and the building so as to obtain the optimal heating strategy. We also simulated the indoor thermal dynamic performance of the heating system with different heating loads, supply water temperatures, and supply water flow rates using three methods: a continuously changing flow rate (Method 1), a step-change flow rate based on temperature deviation (Method 2) and an intelligent step-change flow rate (Method 3) which predicts the duty cycle of the valve in the proceeding period and controls the valve’s on-time. The simulation results indicate the performance of these three methods. For Method 1, as the room temperature is above the set point, the flow rate can be automatically reduced to a level which is proportional to the room temperature deviation. Further, the scale factor of the flow rate is designed according to the +2°C deviation, so it is accepted that the room temperature is higher than the set point by +2°C using this method. However, this low control precision is unsatisfactory. The mean temperature is higher than the set point and greatly affected by the heating load and supply water’s temperature and flow rate. For Method 2, the controlling action is delayed by thermal inertia, the room temperature fluctuates between the highest and lowest levels, and the temperature deviation can be greater than the set value. For Method 3, both the simulation and field test results showed that room temperature deviation was maintained within a ±0.5°C range under the various conditions. This method appears relatively robust and adaptable, and was the best control strategy of the three methods.     

成都市某商业建筑地源热泵地下换热器动态模拟

对成都市某商业建筑地源热泵地下换热器进行动态模拟,解决地下冷热不平衡的问题。采用Design Builder(DB)软件对建筑冷、热逐时负荷进行计算。设计提出两种冷热源方案:空调热泵+热水锅炉、空调热泵+热回收热水机。采用动态数值模拟方法对U形地埋管换热器进行计算。结果表明:方案一地下换热器的累积吸放热量严重不平衡,方案二基本平衡。在冷热源方案二中,对750孔的地下换热器进行连续30年的动态模拟分析,地下温度可以保证系统正常运行。     

北京某小区多层建筑物热环境模拟分析及应用

为了实现北京某小区水源热泵空调系统的节能设计与运行管理,选择DeST热环境模拟软件对该小区建筑物室内热环境进行了模拟分析,得出了建筑物全年室内热环境特点,不同层位、不同方位房间室内热环境差异和特征,冬季高层和低层内部空间比中间层热环境差,北向房间比南向房间热环境差,角部房间比中部房间热环境差;建筑热环境的模拟对地热工程系统设备选型、管网和末端设备布置具有指导意义。通过对模拟结果的分析和总结,对该小区地源热泵采暖系统的节能设计和运行管理提供了理论依据。     

Numerical study on temperature stratification in a room with underfloor air distribution system

In this study, numerical prediction using computational fluid dynamics (CFD) was utilized to investigate air temperature stratification in a room with an underfloor air distribution (UFAD) system. The numerical modeling using CFD computation was validated with physical test in a full size experimental room with an UFAD system. The different supply air conditions and heat loads were discussed. The results show that the effect of three parameters, heat load, supply volume flux and supply air velocity, on room air temperature would be expressed by the length scale of the floor supply jet. When the length scale increased from 0.8 to 1.56 m, the ratio of vertical temperature difference between 2.5 and 0.1 m at the occupied zone to the difference between return and supply air temperature decreased from 0.62 to 0.25. When there was only one local heat source in the room, there was a thermal stratified interface at the occupied zone. The interface height was about 1.42 times the length scale. The results may suggest ways to optimize UFAD design and operation.     

单井循环热泵系统冬季运行特性的数值模拟

建立了单井循环系统中井水与土壤的传热数学模型,采用有限差分法对单井循环热泵系统冬季运行特性进行了数值模拟分析。在热泵运行初期,出水温度下降较快,井水从土壤中的吸热量少,热泵的吸热量基本来自井水自身的蓄热。井水初始温度对井壁处热流密度没有影响。相同运行工况下,在一定范围内,井的尺寸越大,井壁处热流密度越小。出水质量流量越大,对井水和周围土壤的传热越有利,但会缩短井的供热时间。     

Efficiently produced heat and cold is squandered by inappropriate control strategies: A case study

The large thermal time constant of thermally activated building systems (TABS) hampers communication between the system's production and emission. Therefore, conventional building control strategies, typically using room temperature feedback, are unadapted to control thermal comfort efficiently. In this paper, measurement data and simulation results reveal that unadapted TABS control has a dramatic impact on overall energy performance. Measurements in a TABS building with room temperature feedback show the HVAC system switching between heating and cooling in a very short time frame. A simplified, generic room model is used to simulate, understand and evaluate this behaviour. For room temperature feedback control, only 45% of the cold and 15% of the heat produced actually controls room temperature. The remainder is stored in the TABS and exchanged between the heating and cooling system. Enlarging the heating-to-cooling set point band improves this ratio, while maintaining thermal comfort. On the other hand, night time operation control of the circulation pump, adapted to the TABS thermal time constant, eliminates this ‘unused’ energy completely. In this case, however, even with perfect heat gain forecasts, it is difficult to avoid room temperatures dropping below thermal comfort limits during initial office hours. Hence, a supplementary air-conditioning system seems inevitable.     

浅埋竖管换热器地热源热泵夏季供冷试验研究

介绍了根据浅埋竖管换热器地热源热泵冬季测试结果,在夏季试验中对试验装置及实验方法的改进,测试了夏季定水量的运行效果籴水量运行时各性能指标的变化。采用系统能量平衡结合热传导方程建立的地下竖埋套管管群换热器传热模型和过渡季大地温度场模拟,与实测值吻合较好。