空调运行实验模拟负荷的研究

为了满足空调器控制方法的实验研究需要,作者提出用动态房间负荷模拟的方法模拟空调房间的负荷和房间的控制特性。本文采用计算机控制技术,研制了能独立模拟热、湿负荷的发生器,并利用风机盘管进行了全天动态模拟负荷实验,实验结果表明模拟负荷发生器能较好地模拟房间的逐时负荷。     

极端热湿气候区建筑湿负荷计算方法研究

针对极端热湿气候区建筑湿负荷计算值偏小的问题,本文对该气候条件下室内湿负荷的构成及计算方法进行了研究,在传统湿负荷计算方法的基础上,考虑了空气渗透及围护结构吸放湿引起的湿负荷。研究结果表明,极端热湿气候区建筑湿负荷占总负荷比例为58%左右。若采用附加百分数法计算建筑湿负荷,根据本文叠加法中湿负荷与显热负荷的比值得到附加百分数,其值宜取1.4。最后,根据本文湿负荷计算方法,本文列出了极端热湿气候区不同单位面积显热负荷对应的湿负荷,为空调装机容量的选择提供依据。     

双风道系统用于地下通讯机房

通过对已用工程的调查以及新建项目的设计,有下面几个问题应引起注意。一、地下建筑热湿负荷的理论计算值与实际情况有出入。围护结构散湿量和传热量目前计算方法还不成熟,还不能计算准确。二、地下建筑对冷热的需要是随使用时间的不同而变化的。地下建筑物刚刚建成时,往往又冷又潮,需要加热烘干。但随着使用时间的增长,可能会热起来,甚至需要送冷风。围护结构热负荷是随时间而改变的,计算公式中的z就反映了这个问题。另外,各房间内的热湿负荷也是变化的。内部安装的设备一般     

基于地下室恒温恒湿空调机组的控制策略研究

基于已有的直流变频变风量恒温恒湿空调机组,针对地下建筑常年湿度较大的情况,提出一种变频变风量结合主、副电子膨胀阀的多变量控制策略,并通过LabVIEW软件实现编程控制。为验证控制方法的可行性,采用模拟负荷发生器在实验室中模拟地下空间的实验热湿环境特征,根据机组处理的热湿能力选取不同热湿负荷工况下进行实验室温湿度控制实验。实验结果表明,在此控制方法下该恒温恒湿机组能满足实验工况下的地下空间热湿的控制要求,在两组总负荷不同的情况下,干球温度和相对湿度都能稳定在设定值附近,系统的控制精度和稳定性良好。     

东方医院洁净手术部净化空调设计关键问题分析

手术部空调设计中,空气处理过程及风系统设计是2个核心问题。介绍了东方医院的概况,计算了热湿负荷、送风量及新风量。通过对比分析3种空气处理过程,确定了采用新风深度除湿后新回风在空调机内混合的处理方式。保证了手术室空调系统等湿工况运行和温湿度独立控制,控制简单易行、能耗低。强调了为使风系统有效运行,应合理确定风量及系统阻力,核算风机单位风量耗功率。     

建筑围护结构内表面吸放湿对湿负荷的影响

通过分析多孔介质的热湿特性,在已有的理论和试验研究的基础上,建立了考虑建筑围护结构内表面吸放湿作用的室内湿负荷模型.利用MATLAB进行数值模拟计算,分析内表面吸放湿对湿负荷影响的主要因素,并将结果以表格形式列出,为工程设计提供参考.     

温湿独立控制的工位空调

本文介绍了工位空调产生的背景,指出了其优于混合式和置换式空调的特点.通过分析冷凝除湿的焓湿图,从负荷变化的动态角度和人体舒适感的角度论述了温湿独立控制的必要性.介绍了工位空调与热湿独立控制结合后的主要形式,以及与之相适应的热、湿独立处理的方法和优缺点.提出了温湿独立控制的工位空调存在的问题及需要继续研究的方向.     

关于室内冰上运动场馆热湿环境控制的模拟研究

人工冰场内存在大面积低温表面,其室内热湿环境控制远比普通公共建筑复杂.文章以冬奥会运动场地之一—国家体育总局冬季运动管理中心综合训练馆冰壶馆为例,讨论了冰场热湿环境特征和国内外对人工冰场的设计要求;列出了冰场室内热湿负荷的计算方法;并基于该场馆的暖通空调设计对室内环境进行了 CFD模拟,为该场馆的热湿环境控制提出了降低送风含湿量、减小壁面发射率等优化措施,对同类项目具有参考意义.     

影响负流量液压系统泵流量因素的试验分析

挖掘机的功率损失主要是因为发动机与泵的功率不匹配造成的,开展泵流量影响因素的研究可以为控制系统调节泵吸收功率提供依据.以负流量液压系统为研究对像,以泵出口压力、回油负流量控制压力和电液比例阀二次压力作为影响泵流量的主要因素,在挖掘机动作过程中,使用便携式采集系统对相关量进行采集.试验结果表明,泵工作过程中的流量主要受二次压力影响;负流量控制压力主要作用于无负荷阶段,泵出口压力主要作用于溢流阶段,二者主要功能是压力切断,减少能量损失.     

地铁环境控制系统的计算与设计

本文根据天津地铁1号线的实际情况,对天津地铁系统的逐时热湿负荷进行模拟计算分析,并论述了地铁内环境产生的热湿负荷、地铁围护结构的热量传递和地铁活塞风对地铁环境的影响,最后提出了适合天津地铁特点的变风量环境控制方案。     

A comparative study of different control strategies for indoor air humidity

There has been a rising concern in controlling the high indoor humidity of hot and humid countries. When an air-conditioned space experiences only part of its design heat load, its humidity tends to rise as a result of the air-conditioning system trying to control the indoor temperature by reducing its cooling capacity. In this study, the part-load dehumidification performances of three temperature control strategies are compared, namely, chilled water flow control, bypass air control and the variable air volume control. Coil simulations are employed to study the part-load performance of these control strategies. The coil model has been validated with experimental data to within ±6.5%. The relative humidity of a space depends of factors such as design sensible heat factor of the space, temperature control strategy employed and load condition experienced by the space. Simulation results have indicated that chilled water control strategy results in the highest indoor humidity throughout the range of conditions studied while variable air volume system provides highly effective dehumidification performance of the cooling coil. Bypass air control appears to be a good option for adoption as it is able to provide an acceptable humidity over a wide range of load conditions without having to affect the air movement within the space.     

Experimental investigation of dehumidification process in cooling coil by utilizing air-to-air heat exchanger in humid climate of Iran

Energy recovery systems can be used in HVAC to reduce energy consumption by recovering wasted energy from the exhausted air to pre-cool inlet fresh air. In this paper, experimental study of utilizing cooling coil (CC) and cooling coil combined with heat exchanger (CCHE) has been developed. Considering the different climate zones in Iran, the experimental study has been done for the areas with high humidity content. In each case, the effects of air-to-air heat exchanger (HE) on the sensible and latent cooling load are investigated. The analysis gives the applicability of HE in Iran for various operational conditions to obtain air with lower moisture content. In CCHE systems more latent load quota is allocated in cooling coils and lower air humidity ratio can be obtained. Also in the cities with higher dew point depression (difference between dry-bulb and dew point temperature) more humidity reduction is achieved and the difference between latent load quotas of CCHE system is higher than CC system.     

土壤源热泵SCADA系统的设计与应用

针对天津市一土壤源热泵工程,采用集散型计算机控制技术(DCS),设计研制了一套三级分布式计算机数据采集和控制(SCADA)系统。介绍了该系统的结构、功能和特点。运行结果表明,该系统能为土壤源热泵安全运行、监测管理和负荷能量调节提供可靠保证。     

Multivariable control of indoor air temperature and humidity in a direct expansion (DX) air conditioning (A/C) system

Controlling indoor humidity at an appropriate level is very important since this affects occupants' thermal comfort and indoor air quality (IAQ). The paper presents an investigation on developing a multi-input multi-output (MIMO) control strategy for simultaneously controlling the indoor air temperature and humidity by varying the speeds of both compressor and supply fan in an experimental DX A/C system. The MIMO-based controller was designed based on the linearized dynamic model of the experimental DX A/C system. The Linear Quadratic Gaussian (LQG) technique was used in designing the MIMO-based controller. The controllability tests with respect to both the disturbance rejection capability and the command following capability were carried out to assess the control performance of MIMO controller. The results of disturbance rejection capability test showed that the MIMO control strategy can effectively maintain the indoor air temperature and humidity to their respective settings after an unmeasured heat load disturbance was imposed by simultaneously varying speeds of both the compressor and the supply fan of the DX A/C system. Furthermore, in the command following capability test for indoor air temperature, the test results showed that the indoor air temperature can be controlled to its new setting while indoor humidity remained unchanged. Similar test results were also observed in the command following capability test for indoor humidity. Therefore, the MIMO controller developed can effectively control indoor air temperature and humidity simultaneously by varying compressor speed and supply fan speed of the DX A/C system. Compared to the previous related studies using conventional on–off control method or single-input single-output (SISO) control strategy, which can only effectively control either air temperature or relative humidity, the MIMO controller can simultaneously control the indoor air temperature and humidity with adequate control sensitivity and accuracy. The application of MIMO control strategy developed can be extended to other HVAC systems in the future to improve their operating performance and energy efficiency.     

南京某别墅温湿独立控制空调系统的设计

地源热泵联合毛细管网辐射末端应用于别墅中,能够结合二者的优点,充分利用低品位能源,节能效果显著。毛细管网辐射末端配合置换通风系统实现了温湿度的解耦,毛细管网承担几乎全部的显热负荷,新风系统承担潜热负荷,做到温湿度独立控制,能够创造超高的热舒适性和室内环境品质。防结露控制系统通过实时的温湿度监测和流量调节,避免房间结露,保障了系统正常运行。热回收系统为别墅提供基本生活热水,不仅平衡了负荷,而且进一步提高了能源的综合利用效率。     

A heat pump system with a latent heat storage utilizing seawater installed in an aquarium

This paper introduces a heat pump system with a latent heat storage utilizing seawater installed in an aquarium. Heat from the seawater is collected and used as the heat source for the heat pump system. This maintains the indoor conditions at constant temperature and relative humidity. With regard to the heat pump system using low-temperature unutilized heat source, development is introduced on a heat source load responsive heat pump system, with combines a load variation responsive heat pump utilizing seawater with a latent heat (ice plus water slurry) storage system using nighttime electric power serving for electric power load leveling. The desired outcome would be to show that the costs of generating heat energy with the seawater-source heat pump are significantly less than those with the air-source heat pump and the oil-fired system. Additionally, the CO₂ emissions for the seawater-source heat pump compare favourably as they maybe less than those for the other conventional assumed systems described.     

恒温恒湿空调系统的设计与研究

以冷藏陈列柜标准测试台为例,对恒温恒湿空调系统进行了设计和运行调试分析,提出恒温恒湿空调系统设计需注意的一些方面,如热湿负荷特点、气流组织、系统的风量等,指出空调设备中制冷系统变频调节技术的使用和温湿度分别控制等能够有效提高系统温湿度的精度。     

Saving energy in the heat-pump air conditioning system driven by gas engine

The main functions of the heat-pump air conditioning system driven by gas engine (GEHPAC) are to maintain the room temperature and control the humidity of the room. In summertime, the air can be reheated by the waste heat water from the gas engine, while the air can be reheated and humidified by the waste heat water in winter. Reducing or displacing electrical heating requirements can achieve the greatest opportunity for significant energy savings. This paper, therefore, aims to improve the energy performance of the AC system by using the waste heat from the gas engine. The mathematical model for the second heat exchanger, the sprayed room, the mixed air, was used to research the GEHPAC. Explicitly, we investigated the influence of various factors including the outdoor air temperature and humidity in summer and winter. Results from the analysis show that the GEHPAC can save more energy than the electricity engine heat pump. The GEHPAC runs beautifully in part load mode. PERx is higher in winter than in summer. The maximum PERx is over 1.6 in summer, while over 1.9 in winter. The GEHP which can control the room humidity can be used in more areas than the common GEHP.