隔热涂层降低建筑空调负荷效果的参数分析

从降低建筑空调负荷的角度出发,对外壁面有隔热涂层的房间建立了稳态传热模型,用数值方法逐一分析了涂层的各种参数,包括导热系数、厚度、表面太阳吸收率、发射率以及地区因素等对空调负荷的影响。研究发现：隔热涂层能显著降低空调负荷及能耗；仅当涂层热阻与墙体热阻之比大于0．2时,涂层导热系数的降低才会对空调负荷产生显著影响；涂层表面太阳吸收率和发射率对空调负荷的影响非常大,是起主导作用的因素；隔热涂层用在太阳辐照密度越大、日最高气温越低、日较差越大的地区节能率越高,越有利于发挥其降低空调负荷及日累计能耗的功能；决定着空调运转时间长短的当地室外气温分布状况对于评价隔热涂层节能效果也有重要影响。     

不同典型气候区内建筑屋面及外墙使用隔热涂层后节能作用的分析与评价

利用典型气象年逐时数据,讨论寒冷、夏热冬冷和夏热冬暖地区典型城市的建筑在屋顶和外墙上使用低太阳辐射吸收率的隔热涂层后,全年空调和采暖能耗变化的情况。发现在属寒冷地区的北京使用隔热涂层,建筑冬季采暖能耗的增加量超过夏季空调能耗的减少量,这类地区更适合使用降低热损的保温层;在属夏热冬冷地区的上海,隔热涂层对全年能耗的影响与冬季采暖的方式有关:当采暖的能效比(EERh)与空调能效比(EERc)满足EERh/EERc<1.24时,使用隔热层全年没有节能收益;而采用集中暖气供暖方式(EERh=4.3),无保温层的建筑加装隔热涂层后,全年节能收益可达5.54kWh/m2,有保温层的建筑加装隔热涂层,全年节能收益也可达1.28kWh/m2。在属夏热冬暖地区的广州,与使用保温层相比,使用隔热涂层降低建筑空调能耗的效果更显著,全年单位面积节能收益是加装保温层时的2.65倍。     

基于能耗监管平台的现有医院空调系统运行节能优化

基于上海某医院能耗监管平台数据,利用EnergyPlus软件建立了该医院门诊楼建筑模型和空调系统模型,并验证了该模型的准确性。对该医院集中式空调系统运行策略进行优化分析,结果表明：当室内负荷低于冷水机组总额定制冷量80%时,负荷分配优化运行方案节能率最高,达到9.7%;当室内负荷高于冷水机组总额定制冷量80%时,机组联合运行并采用负荷平均分配时比一台机组满负荷运行另一台机组部分负荷运行时节能,节能率为1.5%～3.7%。分析了冷却水变流量对冷水机组和冷却水系统的影响及节能效果。结果表明,离心机组变流量运行时节能率达到17%,而螺杆机组在定流量45.13 kg·s⁻¹运行时比较合理和节能。     

新建建筑不同设置围护结构的热质耦合传递对建筑负荷的影响Ⅱ:冬季湿负荷

传统建筑室内湿负荷的计算大多不考虑围护结构内表面的散湿量,而围护结构内表面的散湿量尤其是新建节能建筑对室内湿负荷的影响是很大的。以哈尔滨地区为例,分析了严寒地区典型新建建筑不同设置的多层围护结构在最初四年内热质耦合传递对模拟房间湿负荷的影响,并与文献[5]的模拟结果进行对比。分析结果表明：新建建筑围护结构内表面粘贴墙纸或降低围护结构主体砌块的初始含湿量能够降低模拟房间冬季湿负荷;而保温层内侧隔汽层以及围护结构外表面釉面砖的使用都会增加新建建筑的模拟房间冬季湿负荷,但若延后釉面砖的粘贴时间会有所好转。     

地下水在小型建筑空调中的应用研究

针对夏季空调能耗高的问题,提出了一种利用地下水作为冷媒的建筑空调方案,直接利用地下水作为冷媒,冷媒水在室内风机盘管中与室内空气进行热量交换,降低室内温度,结合房顶喷淋降低房顶表面温度,以减小热负荷;通过工程实例的计算分析可以看出:与传统空调冷水机组相比,地下水空调系统节能效果达74%,系统简单,维护方便。     

不同气候区外窗对建筑能耗的影响分析

通过TRNSYS软件模拟不同传热系数的建筑外窗,在严寒地区和夏热冬暖地区,对建筑冷、热负荷的影响。分析得出,节能外窗在严寒地区夏季空调能耗的节能率为8.9%,冬季采暖能耗的节能率为39%,全年总建筑能耗的节能率为31%;在夏热冬暖地区夏季空调能耗的节能率为8.0%,冬季采暖能耗的节能率为22%,全年总建筑能耗的节能率为8.6%。由此可见,外窗在严寒地区的节能效果要明显优于夏热冬暖地区。因此,在新建建筑的节能设计和既有建筑的节能改造中,严寒地区应更加重视外窗部分。     

建筑外遮阳检测系统热负荷的计算与分析

建筑遮阳的目的主要在于节约能源,提高热舒适与视觉舒适性。建筑遮阳分外遮阳和内遮阳。根据实际应用效果来看,外遮阳的遮阳隔热性能明显比内遮阳要好。介绍了建筑外遮阳检测系统的构造原理,通过计算建筑外遮阳检测系统夏季工作时的冷负荷,来确定夏季建筑外遮阳检测系统工作时的制冷量,同时根据计算结果进行空调设备的选型,并在实践中检验了效果。     

局部采暖建筑非采暖房间平均温度模拟分析

局部采暖建筑热负荷与非采暖房间室内平均温度和外围护结构热工参数密切相关。通过对西安、大连、长春三地的典型建筑在不同外围护结构保温方式下全面采暖和局部采暖进行能耗模拟分析后发现：处于不同气候分区的局部采暖建筑,非采暖房间室内平均温度有差别;建筑中功能相同的各非采暖房间,处在中间层的室内平均温度最高,底层次之,顶层最低,热负荷反之;且各非采暖房间室内平均温度难以满足热舒适的要求。局部采暖建筑中,部分房间热负荷高于相同外围护结构保温条件下全面采暖建筑对应房间的热负荷,但建筑热负荷低于全面采暖建筑的建筑热负荷。     

余热复合式燃气机空调数值计算及性能研究

建立了燃气机热泵空调系统模型,包括燃气发动机、压缩机、换热器、空调系统和建筑负荷模型。通过对模型的求解及结果分析,得到了燃气机热泵空调的性能。结果显示夏季燃气机热泵系统的二次换热器能够替代常规电力空调的电再热器实现空调风再热。冬季二次换热器能够实现系统余热直接向室内供暖,室外温度不太低时可以充分利用发动机余热实现房间供暖。室外温度较低时,可以实现发动机余热和热泵系统联合供暖,节能效果明显。在夏季系统的最大一次能源利用率能达到1.6以上,冬季最高能达到1.8以上。系统具有良好的能源利用效率。     

低温地板辐射供暖节能作用分析

低温地板辐射供暖地板与外围护结构内表面存在辐射换热，散热器供暖房间的散热器附近以及散热器上部热气流与外围护结构存在热流短路。文章在低温地板辐射供暖室比散热器供暖房间室内设计温度降低2℃的情况下，分别对三个典型地区这两种供暖方式在上述情况下造成的房间热负荷和供暖季平均耗热量进行计算。结果表明此条件下，低温地板辐射供暖房间的热负荷可降低10％～15％，节能率约为15％～20％。     

A modified zone model for estimating equivalent room thermal capacity

The zone model has been widely applied in control analysis of heating, ventilation and air conditioning (HVAC) systems to achieve a high building efficiency. This paper proposed a modified zone model which is much simpler in the HVAC system simulation and has the similar accuracy to the complicated simulation model. The proposed model took into consideration the effect of envelop heat reservoir on the room indoor temperature by introducing the thermal admittance of the inner surfaces of the building enclosure. The thermal admittance for the building enclosure was developed based on the building thermal network analytical theory and transfer function method. The efficacy of the proposed model was demonstrated by comparing it with the complicated model — heat balance method (HTB2 program). The predicted results from the proposed model well agreed with those from the complicated simulation. The proposed model can then make the HVAC system dynamic simulation much faster and more acceptable for control design due to its simplicity and efficiency.     

相变墙房间传热特性研究

通过建立基于焓法相变墙板的传热模型,研究了其传热特性,分析了影响相变墙板传热性能的因素,选取出了适合于重庆地区的相变墙板,研究了重庆的相变墙房间和普通房间的传热特性,对比分析了夏季和冬季相变墙房间和普通房间的温度情况并经实测验证。结合削峰填谷政策做了经济性分析。结果表明相变墙房间不仅节省能源,能提供舒适的环境。而且投资回收期仅十四个月。     

Comparative study of room temperature control in buildings with and without the use of PCM in walls

The concept of thermal energy storage in building gains a specific importance in the present energy scenario related to energy consumption and indoor thermal comfort. The material used to store the thermal energy which undergoes a phase change referred as PCM and it is considered as a possible solution for reducing energy consumption in the building by storing and releasing heat within a certain temperature range; it raises the building inertia and also stabilizes indoor air temperature fluctuations. The room temperature is controlled by imposing PCM inside the walls. An attempt has been made to compare room air temperature with and without the use of PCM inside the walls of constructed modular building unit. The PCM imposed modular building shows the reduced temperature fluctuations in room, the PCM absorbs and liberates excess heat which is gained from the outer side of the room and maintains constant inner room temperature. The PCM imposed walls of modular building unit have an ability to reduce 10–30% of heat load in comparison with the plain wall. The results showed that reduction in room temperature is about 2–4°C and it has been concluded that the PCM imposed modular building unit has more energy saving opportunities than normal modular building unit.     

Assessment of Building External Wall Thermal Performance Based on Temperature Deviation Impact Factor under Discontinuous Radiant Heating

As the variation and timely meeting thermal environment requirement of indoor air temperature has a close relationship with the thermal performance of building external wall under discontinuous radiant heating condition, one appropriate assessment method or index for assessing the building external wall thermal performance is very necessary. In order to reasonably evaluate the thermal performance of external wall under discontinuous radiant heating condition and build the direct connections and interactions among the indoor air temperature, external wall inner surface temperature and outdoor air temperature, the first and second impact factors of temperature deviation were established, based on one mathematical model of room heat transfer. For one experimental room and four types of external walls under discontinuous radiant heating condition, both the influence of the external wall inner surface temperature deviation on the indoor air temperature and that of the outdoor air temperature deviation on the external wall inner surface temperature were determined effectively with the first and second impact factors of temperature deviation. In addition, favourable performance for the self-insulation and inner insulation walls were found, due to their superiority in effectively and timely improving the indoor thermal environment under discontinuous radiant heating condition.     

Modélisation d'un panache d'émetteur de chaleur pour le logiciel de simulation énergétique des bâtiments SPARK

Plume's convector modeling for object-oriented thermal building simulation software SPARK. In this paper, a zonal model used to predict air movement and temperature distribution in a room is presented. This model is based on a rough partitioning of the room: it is an intermediate approach between one-node models (that consider a homogeneous temperature in each room) and CFD models. Flow rates are calculated in respect to the pressure distribution in low velocity domains and specific laws describe plumes and jets. The airflow model is coupled with a building envelope model. They are implemented in an object-oriented environment called SPARK. The modularity of SPARK allows the creation of very flexible tools, and its strict syntax permits having the simulations automatically generated.     

Some aspects of modelling the energy balance of a room in regard to the impact of solar energy

The architecture of a building is crucial in determining its thermal energy balance and indoor comfort conditions. Knowledge of solar radiation availability and its transmission through a building envelope to the interior of the building helps an architect to design the building in an energy efficient way. Nowadays, in highly populated urban areas, attics are used as living spaces and the building envelope includes inclined external walls and windows in roofs. This paper presents some aspects of modelling the energy balance of rooms with different orientations and with vertical or inclined surfaces of building envelope, with stress on the impact of solar energy. The dynamics of energy flow through windows is analysed in more detail. One dimensional energy flow through the centre of glass area (based on a thermal resistance model), two-dimensional energy flow through the edge of glass area and two-dimensional heat flow through the opaque frame are analysed. The third dimension is also considered in a simplified way by taking into account the specific perimeter of the edge or frame. Stress is put on modelling the solar energy input. Solar radiation is modelled as short wave radiation that is transmitted directly to the room through glazing and as energy absorbed by the building envelope (glass panes, frame and opaque external walls) that becomes internal heat sources and is transferred indirectly to the room. The model developed has been used for numerical simulation using MATLAB as the programming language. This model predicts (amongst other things) the solar energy impact on the energy balance of a room in a building. It allows many cases of rooms and their envelopes to be run and evaluated and as a result both general and detailed conclusions can be drawn. Some results are presented in both graphical and tabular form.     

Conjugate Heat Transfer Analysis in a Glazed Room Modeled as a Square Cavity

A numerical study of conjugate heat transfer by turbulent natural convection in a room with three different glazed configurations is presented. The room is modeled as a square closed cavity, where the lower wall is adiabatic, the right wall is semitransparent, and the upper and left walls are opaque conductive surfaces. Governing equations of mass, momentum, and energy were solved by the finite volume method with a two equation turbulence model. The results are presented in terms of streamlines, isotherms, heatlines, turbulent viscosity isolines, and thermal parameters, such as indoor temperatures and heat transfer coefficients. From the three cases considered in this study, the reflective glass window was the optimal configuration from the thermal comfort point of view for both design days. On the contrary, the glass-film configuration showed the worst indoor thermal performance inside the cavity despite of being the configuration that allows lower energy transferred into the room through the glazed surface. A set of useful heat transfer correlations are obtained for building design applications and energy codes in temperate climates.     

多孔太阳墙结构热特性及应用分析

结合多孔太阳墙建筑,运用数值模拟方法分析了不同太阳墙结构对室内送风参数的影响,比较了太阳能房间与普通房间在工作区范围内的热舒适性,并对太阳能房间的窗墙面积比进行了优化改进。研究表明:对太阳墙的设计优化,增大了太阳墙面积,提高了室内热舒适性;改进后房间窗墙比为0.303,窗地比为0.2,符合节能建筑要求。