热水及电采暖系统动态响应的分析和比较

针对标准房间建立热水和电采暖系统动态模型,模拟和分析这两种系统动态响应。对热水采暖系统采用三通阀调节散热器循环水量,对电采暖系统采用启停控制模式来调节,并分别进行动态仿真和比较。总结出这两种采暖系统各自特性。     

Development of a testing method for control HVAC systems by emulation

CEN TC247 has prepared draft standards for main types of room controllers. These standards include a performance testing procedure that was designed to facilitate the introduction on the market of innovative controllers (adaptive controllers, fuzzy controllers …). The test procedure is based on the connection of the real controller to be tested to a virtual building and technical plants. The objective of the study which is part of the European SIMTEST project is the development of a testing method by emulation for control systems for heating ventilating and air conditioning applications. This study was focused on the development of numerical models of building and HVAC systems, which are the core of the test facility. The models developed are adapted to the needs of HVAC controller design and test. They take into account static and dynamic phenomena, which are necessary to assess, control functions in terms of comfort and energy consumption. These models are adapted to the test of all controllers, which are in the scope of the three draft standards CEN TC247, in particular to controllers for heating systems, fan coils, variable air volume systems and chilled ceilings. We present in this paper:

• (1)The testing method developed including the simulated environment with its models, the interfaces and the test procedure.
• (2)The validation of the testing method by inspection and comparison of the results obtained by emulation to the results obtained by real tests in a cell. Each application is tested with two different controllers: a high performance and low performance controllers. The same controllers are used in the two different testing methods.

     

Modelling floor heating systems using a validated two-dimensional ground-coupled numerical model

This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.     

Improvement of intermittent central heating system of university building

Most universities in Korea use intermittent central heating system which operates according to a preset intermittent schedule that is determined based on outdoor air temperature. This system is popular for university buildings due to its low initial cost and simple operation. But since it is not based on feedback control, the indoor thermal comfort is unsatisfactory. In this research, problem with the current control system is studied by experiment and dynamic simulation. The measurement shows that the indoor temperature rises to an uncomfortable range during heating and falls below comfortable range when heating is off. To solve this situation, an on-off control is implemented and simulated using a dynamic simulation program. Since there is a good agreement between experiment and dynamic simulation results, dynamic simulation is used to predict other results with different conditions of interest. The simulation shows that by implementing on-off control, the indoor space can be maintained within comfortable range, moreover using less energy. By reinforcing insulation to the walls that are exposed to the outdoor environment, heating energy can be saved further.     

地板辐射供暖系统埋管结构尺寸与地板表面温度均匀性的关系

对于地板辐射供暖系统,建立数值计算的数学模型,应用有限元法得出一定表面温度均匀条件下的适宜的地板结构尺寸,可作为地板辐射供暖系统的设计依据。     

基于分栋热计量的末端通断调节与热分摊技术的应用测试

为验证基于分栋热计量的末端通断调节与热分摊技术的调节策略的适用性及采用阀门累计开启时间比和供暖面积结合的分摊方法的合理性,将该技术应用于一栋实际建筑的供暖系统进行了测试,发现对于不同负荷、位置和朝向的用户室温控制偏差均较小,采用用户累计阀门开启时间比和供暖面积结合的分摊方式比较合理。     

散热器和低温水辐射采暖系统不同连接方式及控制策略动态仿真

散热器和低温水辐射采暖系统最佳连接方式一直是业界探讨的重要课题之一。本文以动态模型为手段,模拟和分析直接、混水泵及间接连接方式系统动态响应和能耗。仿真结果表明,地板热情性的提高延长了室内温度达到稳态时间;地暖系统直接连接方式是不适宜的;混水泵和间接连接系统可节省燃料消耗约17％。从控制角度看,间接连接系统具有更好的稳定性和控制精度。     

Unsteady thermal performance analysis of a room with serial and parallel duct radiant floor heating system using hot airflow

In this study, the unsteady thermal performance of a test room heated by circulating hot airflow under the floor was analyzed with a developed mathematical model based on heat transfer equilibrium among the air flow, the floor and the indoor air. The time variations in the indoor air temperature for the serial duct floor heating system were investigated theoretically and experimentally. The time variations in the floor surface and the indoor air temperatures were predicted theoretically for the parallel duct floor heating system. Experiments on the time variations of the dimensionless numbers such as Nu for the airflow in duct and the indoor air, Gr for the indoor air and the heat ratios of convection and radiation to total heat for the serial duct floor heating system were performed. The theoretical and experimental results showed a good agreement.     

太阳能地板辐射供暖制冷系统模型仿真

近年来,我国北方地区新建住宅的采暖系统多数采用地板辐射供暖技术,而制冷系统仍采用传统的空调制冷技术,有必要对地板辐射制冷技术的应用进行研究,为此,针对一套实验用太阳房,搭建了太阳能地板辐射供暖制冷系统.通过计算确定了集热器面积、蓄热水箱体积、吸收式制冷机组的制冷量.利用TRNSYS仿真平台建立了系统仿真模型,并对控制策略进行了验证.仿真结果表明,该系统能有效地利用太阳能保持冬季室温18℃左右、夏季26℃左右的舒适温度.     

供暖末端通断调节与楼栋混水技术示范工程测试

对应用供暖末端通断调节技术和楼栋混水技术的某高校学生公寓示范工程进行了测试。结果表明,将供暖末端通断调节技术应用于垂直单管串联系统,可以有效改善室温调节,消除楼内阴面、阳面,近端、远端的水平失调,特别是对热费公摊的办公建筑,不仅可以实现办公期间的室温正常调控,还可以在节假日等无人时段实现低温调控;采用楼栋混水技术,使楼内管网"大流量、小温差"运行,可有效降低垂直失调,因此对于垂直失调严重的楼栋,结合楼栋混水技术抑制楼内垂直失调,节能效果尤为明显。     

太阳辐射照度对供暖热过程影响研究

模拟了低温地板辐射供暖与对流散热器供暖系统在不同太阳辐射照度下的动态热过程.对比了室内温度及供暖耗热量等指标,结果表明在高太阳辐射照度地区地板辐射供暖系统室内过热现象更明显,地板辐射供暖能耗与散热器供暖能耗比值随太阳辐射照度的增大而增加,因此选择高太阳辐射照度地区的供暖形式时应优先采用热响应较快的散热器供暖形式.     

Analytical solution for heat transfer in a multilayer floor of a radiant floor system

In radiant floor systems, the distribution of the floor surface temperature, which can be used to determine the mean temperature and the lowest/highest temperature of the floor surface, is an important parameter. The mean temperature of the floor surface determines cooling/heating capacity and indoor thermal comfort. The lowest surface temperature, which considers the dew point in an indoor environment, is a crucial factor in the prevention of condensation on a floor surface. The highest surface temperature is typically considered for local thermal comfort. In this paper, an analytical solution for heat transfer in a multilayer floor structure of a radiant floor system is proposed based on the analysis of the heat transfer process of a multilayer floor, equivalent thermal resistance and separation of variables method. The corresponding formulas are derived to estimate the distribution of floor surface temperature. The calculation results are validated by experiments. The calculation and experimental results show good accordance. The absolute error between the calculation and experimental results for floor surface temperature is within 0.3°C. A method for the calculation of the dimensionless temperature of the floor surface, which can be used for radiant heating and cooling systems, is provided. Using this proposed method, the distribution of floor surface temperature and the influence of floor structure parameters on the thermal performance of floors can be estimated and analyzed.     

Experimental study on a duty ratio fuzzy control method for fan-coil units

This paper presents a novel energy-efficiency control method for a fan-coil unit, the duty ratio fuzzy control method (DRFCM), which employs the concept of duty ratio on the electric valve control to fully utilize the cooling and dehumidifying capacity of a fan-coil unit when the control valve is closed. By means of mamdani-type fuzzy rules and functioning-fuzzy-subset inference methods, the duty ratio of valve and fan speed signals are decided according to the deviation and deviation changes of the room temperature. This paper adopts a two-water-pipe FCU system with a three-fan speed control and an electric water valve on-off control as test objects to verify the application effect of DRFCM. Program controllers and software tools are employed to conduct DRFCM. The conventional control method is applied by individual FCU controllers. Experimental results show that DRFCM could obtain at least 30% energy savings (not including chilled pump power savings) over the conventional control method. A preferable room temperature control effect could be achieved as well.     

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.     

基于预制装配化的住宅热水地面辐射供暖系统若干技术问题分析

基于预制装配化的住宅热水地面辐射供暖系统是传统的地面辐射供暖系统和预制装配化技术在住宅项目上的集成。结合温州某项目工程实践,阐述了该套系统的地暖模块划分、各地暖模块中的水管布置等关键技术,并介绍了地暖模块在工厂预制中的要点。结果显示,该套系统能克服传统湿法作业的众多弊端,值得推广应用。     

通断调控模式的计量供热系统性能实验研究

建立了通断调控模式下计量供热系统的实验系统,对不同调节模式下的供热效果进行了模拟实验,得出了通断调控模式下房间的温度变化规律,分析结果表明房间的舒适度可以满足要求。     

兼具地面装饰与供热的一种轻型干式构造地板采暖的研究

地面供热装饰为一体的轻型干式构造地板采暖系统,是将热水盘管直接置于保温层、地面装饰层与龙骨托架构成的封闭夹层空间内。通过对该地板采暖构造传热性能的分析、模拟计算及实验测试,论证了这种干式地板构造的优势和技术经济可行性。     

Environmental impact and life cycle assessment of heating and air conditioning systems,a simplified case study

During the design process of heating and air conditioning systems, the designer must analyse various factors in order to determine the best design options. Therefore, the environmental aspects of a product should be included in the analysis and selection of design options if an environmentally aware design is to be produced or selected. The comparison between three different heating systems was made with the Eco-indicator 95 method. The study included the environmental impact at the production phase of the system, because alternative production methods have different kinds of environmental burdens. The results showed that the three different concepts of heating systems with different construction materials varied the Eco-indicator value. For radiator heating system the Eco-indicator value is far superlative than for floor or fan coil convector heating system. Copper pipes and other copper parts contribute to the greatest environmental impact. Radiator heating Eco-indicator showed three times higher value for copper pipes than for the steel pipes despite smaller dimensions. The lowest values are obtained for floor heating systems. Reasonable values are obtained for fan coil units; analysis shows up, that heat exchanger contributes the main part of the value.     

低温地板供暖房间负荷研究

低温地板供暖在利用低品位能源方面具有一定的优势,已经广泛应用于居住建筑。本文利用传热学的基本理论建立了低温地板供暖房间和散热器供暖房间的传热数学模型,在设定的室内空气温度条件下,分别模拟得出了2种供暖方式房间在稳态传热条件下的围护结构表面温度和内表面换热系数,并利用上述计算结果对2种供暖方式房间热负荷之间的差异进行了比较。分析结果表明,在节能65%阶段,相同室内空气温度条件下,低温地板供暖房间热负荷大于散热器供暖房间热负荷;对于北京地区和哈尔滨地区,不同空气温度下2种供暖方式房间热负荷面积指标差值分别约为0.5～0.7 W/m2和0.3～0.5 W/m2。     

An innovative lighting controller integrated in a self-adaptive building control system

An innovative and self-adaptive integrated system for building energy and comfort management has been developed. Both artificial and natural lighting controllers have been designed in order to fit the integrated approach. The shading device controller is split into two parts depending on the user presence. When the user is present, priority is given to visual comfort, and when he is absent, priority is given to thermal aspects (heating/cooling energy saving). The artificial lighting controller is used to complete the illuminance in the room up to the level desired by the user, which is learned by the system through the user wishes. Many simulations have allowed comparing different variants of the lighting controllers. The models used in the control system are regularly adapted to the measurements. Therefore, the system continuously adapts itself to the environment and the room characteristics. Four months of experiments in the occupied LESO-PB office building have demonstrated that this integrated system leads to interesting energy saving (25% less of total energy consumption) compared to a conventional one.