Field investigation on consumer behavior and hydraulic performance of a district heating system in Tianjin,China

With the implementation of heat reforms in China, the application of thermostatic radiator valves (TRVs) has been gaining popularity in the new-style district heating systems (DHSs). The objective of this study was to investigate consumer behavior (including regulation of TRVs and opening of windows) and its influences on the hydraulic performance and energy consumption of individuals and the whole system. The concurrence rate of individual behaviors and hydraulic interactions between individuals were analyzed. This study should be helpful to gain a comprehensive understanding of the new DHSs in China and consider a proper design/control strategy for these systems.     

散热器恒温阀控制有效性的模拟分析研究

本文以实际建筑及安装恒温阀的供热系统为研究对象,建立了热力水力综合仿真模型,进行了多工况模拟,分析了恒温阀对不同原因(流量分配不均、散热器面积过大和供水温度过高)引起的过热现象的改善程度,进而探讨了适合新型供热系统的运行调节方式。主要结论为:当恒温阀设置档位为2~3时,恒温阀改善过热的有效性与过热原因及过热程度有关;对流量偏大引起的过热损失的控制有效性小于0.6,对供水温度偏高及散热器面积偏大引起的过热损失的控制有效性约为0.8;过热损失越大,应用恒温阀后的节能潜力越大,但仍有约20%~40%的过热损失需要从改善不合理的运行调节和设计角度去解决。基于上述分析,本文提出水泵定压差变频运行、并以系统流量变化为反馈量分日调节供水温度的策略,从而适应系统负荷变化,并可将系统流量控制在较合理范围内。     

Gekoppelte Simulation zur Spezifikation von Heiz‐ und Kühlkörpern

Combined thermal building simulation for advanced heating and cooling specification. Modern concepts of buildings and rooms require a rethinking concerning conventional solutions for heating or cooling of buildings. But often it is not possible to quantify, whether a new idea is worthwhile because of missing sharpness of simple assessments. Therefore a programming system for combined thermal building simulation and indoor air flow calculation, mainly developed and successfully applied by the authors is extended by a highly resolved model for heating and cooling devices. In that way it is possible to model the specification of radiators in a test chamber or under operating conditions. In addition, the effect of cooling by radiators can be investigated. The approaches for modelling will be explained in short and some selected results are presented and discussed.     

Simulation and analysis on control effectiveness of TRVs in district heating systems

Based upon an existing building and heating system with thermostatic radiator valves (TRVs), an integrated model is developed for simulating the thermal and hydraulic behavior of the heating system under various operation cases. According to the simulation results, the effectiveness of TRVs in reducing overheating has been studied. The results indicate that when the set value of the TRV is kept at 2-3, its effectiveness in reducing the overheating phenomena caused by an excessive water flow rate is less than 60%. If the overheating phenomena is caused by an excessive supply water temperature and radiator area, the effectiveness of the TRV can reach about 80%; the TRV's effect becomes more obvious with increasing overheating degree; however, about 20%-40% of overheating loss still needs to be resolved by improving improper operation adjustment and design. Considering these results, a control strategy is proposed, in which the supply water temperature is adjusted daily according to the flow performance of the system, and the pump is operated with frequency conversion and constant pressure difference. Further simulation indicates that, under the new control strategy, the variation of the heat supply quantity of the system can match the heat load change, and the flow rate of the system can be controlled at an appropriate range.     

An algorithm for calculating convection coefficients for internal building surfaces for the case of mixed flow in rooms

The treatment of convective heat transfer at internal building surfaces has a significant impact on the simulation of heat and air flow. Accurate approaches for the range of flow regimes experienced within buildings (buoyant flow adjacent to walls, buoyant plumes rising from radiators, fan-driven flows, etc.) are required, as is the ability to select an appropriate method for the case at hand and to adapt modelling to changes in the flow.A new approach — drawing upon previously published methods — has been developed for modelling mixed convection within mechanically ventilated rooms. It is applicable for rooms ventilated with ceiling mounted diffusers and is appropriate for both heating and cooling. ESP-r simulations performed with the mixed flow model indicate that the prediction of heating and cooling loads is highly sensitive to the treatment of surface convection and that significant errors can result if an inappropriate model is employed. The results also reveal that the choice of convection algorithm can influence design decisions drawn from a simulation-based analysis.     

鄂尔多斯东胜体育场暖通空调设计

介绍了体育场空调风系统、水系统、供暖系统、通风及防排烟系统的设计及采用的节能措施.办公用房、会议室等小型房间采用风机盘管加新风系统,商场、超市大型空间采用双风机全空气空调系统.空调冷水系统为二次泵两管制变流量系统,冬季供暖采用空调和散热器相结合的方式.     

供暖散热器设计参数的实验研究

为了建立我国散热器的设计参数选用标准，以我国常用的散热器为对象，以闭式小室检测为主要实验手段，对设计常用的各种散热器选择参数，进行了全面的实验研究，给出了相应的计算选用方法，并对闭式小室检测值的实用性进行了研究。     

基于火炕的热水供暖火墙系统供暖效果研究

将火墙式火炕与热水供暖系统相结合,在火墙燃烧室的正上方加设集热器,在房间布置散热器,利用热水循环将火墙燃烧室的部分热量转移,供给其他无炕、无火墙房间.对加设热水系统后的火炕和热水系统的热工性能及室内热环境进行了实验研究.结果表明,该供暖系统在保证火炕房间供暖条件下,能够满足无炕、无火墙房间的短期供暖要求,并且提高了火炕的热舒适性;可以燃用各种生物质燃料,从而减少农村商品能的消耗.     

供暖设计中的一些常见问题

2001－2002年供暖季对几个运行不正常的供暖系统进行诊断和诊治，结合近年所遇到的供暖系统中存在的热媒设计温度、水力平衡、系统补水、散热器选择等8个常见问题逐一进行剖析，并给出建议。     

加阻水堵改善散热器传热性能的研究

研究了一种在散热器内部加阻水堵的方法以改变水流通道和水流组织方式的方法。试验结果表明，此举能显著改善散热器传热性能，而阻力系数有所提高，有助于提高供暖系统的水力稳定性和降低供暖系统的造价。     

黄河三角洲地区供暖设计应注意的问题

分析了该地区供暖设计中的供暖热负荷计算，散热器选型，回水干管及集气罐、放气阀设置位置，水力失调，防腐保温等方面存在的问题，指出设计时应充分考虑不同地区的地理气候条件，因地制宜地设计方案。     

低温热水地板辐射采暖系统设计

回顾了低温热水地板辐射采暖技术的发展历程；分析了作为加热管的四种主要管材的物化性能；阐述了地板辐射采暖房间热负荷的设计方法；探讨了地板辐射采暖系统的设计步骤；给出了采暖地面散热量数值、地表面温度计算公式、水力计算表；并就大家十分关心的水力工况稳定性、系统造价、加热管寿命、技术措施、应用场合等问题等进行了分析与讨论。这结于地板辐射采暖系统的设计具有一定的参考价值。     

双管热水供暖系统在高（多）层建筑中应用的设计计算方法探讨

在对双管热水供暖系统中存在的水力失调和热力失调的分析计算基础上，指出引入散热器散热面积修正后，双管热水供暖系统可以用于高层和多层建筑中，并得出了散热面积修正系数的计算公式及数据。     

简析低温热水地暖的优缺点及施工注意事项

通过与传统散热器对流供暖方式的对比,简要分析了低温热水地暖供暖方式舒适度高、节能、整洁、利于装饰等优点,以及适用环境要求高、设计精密,施工程序繁杂、不易维修等缺点,并根据这些缺点的产生原因,结合现实施工实践,对施工过程中的施工纪律,管件操作,水压试验的注水、施压、排水等施工注意事项给出了具体的建议。     

A combined low temperature water heating system consisting of radiators and floor heating

Space heating load is decreasing in modern Finnish apartments due to lower U-values of the construction, tight envelopes and heat recovery from exhaust ventilation air. This makes it possible to develop a new combined low temperature water heating system with nominal supply/return water temperatures of 45 °C/35 °C. Such a system includes radiators in rooms and floor heating in bathrooms.In this study, the performance of an apartment building is determined by using dynamic simulation. The simulation results for the combined low temperature water heating system are compared with those for three conventional radiator and floor heating systems. The results show that the combined low temperature water heating system performs well and is able to maintain the zones within the required temperature levels. The thermal comfort analysis indicates that the drifts and ramps in operative temperature using the four studied heating systems are within the limits of Ashrae Standard 55-2004.Temperature measurements in a test room are carried out to find the vertical difference of air temperature using two methods: radiator heating and floor heating. These measurements indicate that there is only a small vertical temperature difference that would not produce any significant thermal discomfort.     

不同分户采暖方式经济性分析

以抚顺市一住宅楼为基础,对该建筑的暖气片水平采暖系统和地板辐射采暖系统进行了经济性对比,从计算结果可以看出,不管是燃料使用量还是工程造价,地板辐射采暖系统均优于水平式暖气片水平采暖系统。     

会城门小区节能示范工程建设与节能分析

介绍了会城门小区节能示范工程的建设背景和示范内容。该工程应用先进的技术与设备，建设了三种不同模式的建筑供暖系统。通过对三类模式系统的测试对比以及大量数据分析，找到了消除水力热力失调、提高热能利用率、节约能源的有效方法，提出了带散热器温控阀的双管系统为未来建筑供暖系统的普选型式，并提出了改造现有单管顺流式系统的具体措施，得出了节能型系统比现有供暖系统节能３０％的结论。     

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.     

异程式热水供暖系统水平热力失调的修正方法

在推导了异程式热水供暖系统水力失调计算公式的基础上,指出引入散热器散热面积修正系数后,可以基本消除供暖房间的热力失调现象,异程式系统可以用于较大建筑物的供暖,并进一步分析了散热面积修正系数的计算公式。     

The impact of window opening and other occupant behavior on simulated energy performance in residence halls

A poor depiction of occupant behavior in building performance simulation frequently results in substantial divergences between real and simulated results. The problem may be of particular concern with simulation supporting the renovation of older multi-unit residential buildings, buildings whose occupants use windows for temperature control even during heating season. Here, we investigated the impact of window operation models (as well as other occupant behaviors) on simulated energy performance in university residence halls. Based on environmental monitoring, along with information collected from occupant surveys and wearable devices, we estimated air exchange rates and developed a probabilistic window-operation prediction model. The data were collected in 76 dormitory rooms sampled from a pre-renovated historic building and two similar buildings. We then evaluated the window-operation model’s predictive performance in 15 dormitory rooms in the post-renovated building with new occupants. The results of our predictive model were also compared with previously reported window-operation models. We implemented each window-operation model in a calibrated EnergyPlus building performance model, comparing the results of each simulation to metered hourly steam consumption. The impact of the different window operation models on simulated heating energy use was significant (annual error ranging from 0.2% to 10%). Our model demonstrated the highest capability of predicting window state (accuracy=85.8%) and steam use (NMBE=?0.2%); however, some previously published windowoperation models also produced satisfactory performance, implying that such models may be generalizable to some extent. The results suggest that data collected from somewhat ubiquitous indoor environmental quality sensors can glean insights into occupant behavior for building performance simulation. Furthermore, the energy impacts resulting from the variations in occupant behavior studied here were large enough to show that the choice of behavior model can have meaningful implications for real-world applications, such as estimating saving from heating and lighting system upgrades.