Effect of fixed horizontal louver shading devices on thermal perfomance of building by TRNSYS simulation

Buildings in most countries around the world require large amounts of energy both for cooling and heating. In fact cooling loads due to solar gains represent about half of global cooling loads for residential as well as non-residential buildings. While solar gains through windows contribute largely to these loads, any method of decreasing these gains through shading should be applied with caution, since a balance is required; decreasing cooling loads by shading may increase heating loads drastically and vice versa. So the overall energy requirements both for heating and cooling should be considered. With this in mind a study was done on the thermal performance of a building by TRNSYS simulation, and a shading model for windows was incorporated in it. The shading devices adopted were external fixed horizontal louvers with different slat lengths and tilts. The study was conducted for four different cities in Italy. The optimization of the shading devices was done with respect to primary energy loads for the whole year, and the optimum design was found to depend on location and weather conditions. It was also found that shading factor varies with time of day and is different for summer and winter. For example, for Milan it was found that 70% of gain is cut off in summer, while only 40% is cut off in winter by using optimum shading, which is desirable.     

Simultaneous application of different natural cooling technologies to an experimental building

In terms of performance, natural cooling technologies have always been studied by experimentation of single techniques. In order to obtain an improvement in global performance, particularly with regard to comfort, an investigation of the combined utilization of several techniques for the same location has been carried out. This paper gives the results of a series of experiments in which several techniques of natural cooling were applied simultaneously in an experimental building.     

Energy and exergy analysis of a micro-compressed air energy storage and air cycle heating and cooling system

Energy storage systems are becoming more important for load leveling, especially for widespread use of intermittent renewable energy. Compressed air energy storage (CAES) is a promising method for energy storage, but large scale CAES is dependent on suitable underground geology. Micro-CAES with man-made air vessels is a more adaptable solution for distributed future power networks. In this paper, energy and exergy analyses of a micro-CAES system are performed, and, to improve the efficiency of the system, some innovative ideas are introduced. The results show that a micro-CAES system could be a very effective system for distributed power networks as a combination that provides energy storage, generation with various heat sources, and an air-cycle heating and cooling system, with a energy density feasible for distributed energy storage and a good efficiency due to the multipurpose system. Especially, quasi-isothermal compression and expansion concepts result in the best exergy efficiencies.     

上海某图书馆建筑内外遮阳负荷研究

针对上海某图书馆建筑内外遮阳,采用计算法进行负荷计算,通过结果分析得到此图书馆在计算时刻下的日最大负荷值。从中可以看出除北向外,外遮阳都有不同程度的节能效果,而北向由于窗口不受太阳直射,没有遮阳效果;内遮阳的节能效果都随着材料的遮阳系数增加而增加。最后进行内外遮阳效果的对比,得到东、西向随遮阳板挑出长度增加,外遮阳节能效果更为显著;南向和北向以遮阳材料系数为0．5的内遮阳为佳。     

基于建筑环境的空调系统节能分析

针对暖通空调节能的趋势 ,分析了建筑环境对暖通空调系统的影响 ,提出从建筑环境方面考虑问题是暖通空调节能的必要途径 ,概括地介绍了空调能源的发展方向和空调节能的多种手法     

建筑形状比对办公建筑冷(热)负荷的影响分析

基于DeST软件,利用正交试验法对办公建筑室内的冷负荷影响因素进行了分析,得出室内冷(热)负荷随着形状比变化的曲线,并应用曲线分析负荷变化趋势,找出冷(热)负荷随着形状比变化的具体关系式,可依此确定最佳建筑节能形式的方案。     

Thermodynamic behaviour of an air-conditioning system employing combined evaporative-water and air coolers

The performance of an open absorption-system, energized by low-grade heat such as insolation and/or waste heat, has been investigated. This combined evaporative cooler (CEC) [i.e. an indirect evaporative cooler (IEC) together with a direct evaporative-cooler (DEC)] was used to cool the air. A computer simulation of the cooling cycle was devised, so that the performance characteristics of the system could be predicted for a range of operating conditions: the influences of various design-parameters on the coefficient of performance (COP) were also evaluated. The COP of the CEC system was at least 20% greater than those achieved when employing either the IEC or DEC systems alone.     

An optimal design analysis of a novel parabolic trough lighting and thermal system

In order to reduce the cost and improve the efficiency of daylighting, an innovative parabolic trough solar lighting and thermal (PTL/T) system is designed and analyzed in this paper. Parabolic trough solar lighting and thermal system uses parabolic trough collector (PTC) controlled by two‐axis solar tracking system as solar collector. The collected sunlight is split by a cold mirror into visible light and infrared. The visible light is reflected by cold mirror, re‐concentrated by a second‐stage Fresnel lens, and then delivered by plastic optical fiber to the buildings for daylighting. The infrared goes through cold mirror, reaches thermal system, and is used for heating generation. The basic structure of PTL/T was outlined and described. The dimension of fiber bundle and parabolic trough was chosen after an optimal analysis. The cost of illuminating unit area was expressed as a function of illumination space dimensions and critical components efficiency. A case study was conducted to get a specific optimized illumination area and PTC area for the first time. The optimized result is to use 8‐m² PTC as collector to illuminate 500‐m² office space. The total solar energy utilization efficiency is 39.4%, with the lighting efficiency of 16.3% and thermal efficiency of 23.1%. The maximum energy savings and simple payback period were calculated for 10 typical cities when applied in residential, commercial, and industrial sectors. The amounts of greenhouse gas‐emission reductions were also calculated. The payback period in Sunbelt region is as low as less than 10 years like in Los Angeles. The results show the proposed PTL/T system is competitive compared with traditional solar energy systems. Copyright © 2016 John Wiley & Sons, Ltd.     

涡轮叶片在空气和蒸汽两种冷却介质下冷却性能的对比分析

使用气热耦合的方法对某实际涡轮第一级空冷导叶叶片在使用空气和蒸汽两种冷却工质情况下分别进行了数值模拟,并对结果进行了对比分析。研究结果表明:在相同温比情况下,消耗相同的冷却工质质量流量时,使用蒸汽获得的冷却效率可以比使用空气时提高约0.1,但对主流的干扰相对较大;在获得相近的冷却效果时,蒸汽的消耗量仅需空气的60%左右,对于主流的干扰也相对较小。所建模型在空气冷却条件下进行了实验验证,结果吻合较好。     

某办公楼动态能耗模拟与节能分析

以eQUEST能耗模拟软件为工具,为重庆市某办公楼建立了能耗仿真模型,分析了空调设定温度、制冷机COP值、室内照明密度对能耗的影响,并对三者相应的节能潜力进行了比较分析。结果表明,建筑电耗随照明密度的减小线性降低,照明密度对建筑节能有着巨大的影响。     

Cost benefits analysis and emission reductions of optimum thickness and air gaps for selected insulation materials for building walls in Maldives

The demand for electricity in the Maldives continues to increase by more than 11% in recent years. This is mainly due to the growing number of high-rise air-conditioned buildings and the increasing use of electrical appliances in the residential and commercial sector. This paper investigates potential cost savings and emission reductions achieved by installing different insulation materials of optimum thickness in building's walls. The paper also investigates the effect when air gaps are introduced in the wall. The optimum insulation thickness is based on the cost benefits of each insulation material over its lifetime. This study found that by introducing optimal thickness of different insulation materials and by having air gaps of 2 cm, 4 cm and 6 cm, energy consumption and emissions can be reduced by 65–77%, in comparison to a wall without insulation or air gaps. And, hence have considerable cost savings.     

XPS板的性能分析及应用研究

对XPS板吸水率、尺寸稳定性、粘结强度等性能进行了较系统的阐述与分析,并根据工程中对XPS板在外墙外保温技术上的应用及其注意事项进行了探讨,为XPS板在外墙外保温系统的合理使用和发展提供了依据。     

Experimental and computational studies on Coanda nozzle flow for the air knife application

To control the film thickness of zinc in the process of continuous hot-dip galvanizing,it is known from the earlydays that the gas wiping through an air knife is the most effective one.The gas wiping using in galvanizing proc-ess brings about a problem of splashing from the strip edge for a certain high speed of coating.So,in the presentstudy,the effects of the deflection angle of Coanda nozzle on jet structure and the distribution of impinging pres-sure at the plate surface are investigated numerically and experimentally.In numerical analysis,the governingequations consisted of three-dimensional time dependent full Navier-Stokes equations,standard k-ε turbulencemodel to solve turbulent stress and so on are employed.In experiment,16 channel pressure scanning valve and3-axis auto traversing unit are used to measure the impinging pressure at the strip surface.As a result,it is foundthat the smaller the deflection angle for the same nozzle slit of air knife is,the larger the impinging pressure is.Toreduce the size of separation bubble and to enhance the cutting ability,it is recommendable to use an air knifewith the Coanda nozzle.     

联合国环境规划署亚太资源中心办公楼热回收空调系统应用研究

对联合国环境规划署亚太资源中心办公楼采用的新型热回收新风机加空调盘管的集中空调系统进行分析,详细阐述了热回收新风机的特点、优势及节能潜力。对办公建筑的空调系统改造具有一定的指导意义。     

Thermal analysis on the cooling performance of a porous evaporative plate for building

In this paper, a wet porous cooling plate has been used for a building wall. Cooling can be achieved due to the evaporation in the porous layer. A mathematical model on the heat and mass transfer in the unsaturated porous media is developed to analyze the influences of ambient conditions and the porous layer thickness on the cooling performance of the porous evaporative plate. With a decrease in ambient relative humidity and an increase in ambient temperature, more cooling of the porous evaporative plate can be supplied for the inside of the room. The heat exchange between the inside surface of the porous plate and the air in the room should be intensified to achieve a higher cooling efficiency of the porous plate. The ambient wind speed and the thickness of the porous plate also have significant influence on the average temperature of the porous plate. All these results should be taken into account for the utilization of the porous evaporative cooling plate. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20284     

The effect of ionisation of spray in cooling air on the wetting characteristics of finned tube heat exchanger

A major concern when introducing a water spray to pre-cool the air flowing into a finned tube heat exchanger is that wetting of the heat exchanger surface may cause corrosion. In an attempt to prevent droplets from impacting and wetting the heat exchanger, the use of an electrostatically charged spray was investigated. Experiments were performed whereby electrostatically charged spray was sprayed on a heat exchanger with an electric charge having the same polarity as the droplets. The results indicated that droplet deposition decreased significantly as the charge on the droplets was increased. However, total prevention of deposition could not be achieved, since the equipment used could not produce high enough voltages. This concept shows some promise, and it is recommended that further research be performed on it.     

自然通风条件下建筑围护结构及室内空气的温度计算

建立太阳照射和自然通风条件下建筑与室内、外环境的空气平衡方程与热平衡方程,以及沿围护结构厚度的非稳态一维导热方程,求解得到建筑围护结构和室内空气的温度。选取广州夏季某一天的气象参数,计算围护材料分别采用钢筋混凝土、灰砂砖砌体、浮石混凝土、橡木和平板玻璃情况下,从7时至19时一单室建筑围护结构及室内空气的温度。     

Performance and economic analysis of air flow windows in a tropical climate

An experimental study was conducted in Thailand to determine the thermal performance of twin glazed windows with dynamic insulation. The effects of blinds situated either between or outside the glazing were analysed. With an external blind, the heat transfer coefficient was 1–25 W/m²°C with natural convection and 0–6 W/m²°C for a flow of 20m³/h (glass area = 2–16m²). The solar flux transmitted was evaluated analytically and experimentally depending on the blind's position. An economic study was performed on a six-sotrey air-conditioned building in Thailand. It showed in tropical countries that it may be more economical to use air flow windows than to have tinted single or double glass windows.     

湿式冷却塔进风口加装导风板的优化设计

基于两相流传热传质理论,利用Fluent软件模拟300 MW机组冷却塔填料区使用多孔介质时的通风率,采用离散相模型（DPM）在配水区上表面加入热水,模拟研究新型旋流型叶片导风板的优化能力,给定不同弧度及安装角,分别在0、3和7 m·s^-1风速下计算冷却塔出塔水温,并分析侧风对冷却塔冷却性能的影响。研究结果表明：加装导风板可以降低侧风引起的不利影响,导风板数量为50块时效果最好,旋流型叶片导风板的最佳安装角为20°,此时旋流型叶片的最佳弧度为15°,最大温降可达0.787 4 K。研究结果为火电厂选择导风板提供了依据。