辐射供冷加置换通风系统的数值模拟研究

以办公室为研究对象,采用数值仿真的方法,研究了地板辐射供冷加置换通风和顶板辐射供冷加置换通风在相同的室内负荷条件下,室内的温度及流场分布。结果表明,地板辐射供冷加置换通风系统的舒适性更好,而且其冷板表面结露的危险也比顶板辐射供冷加置换通风小。     

置换通风和地板送风在住宅辐射顶板空调系统中的应用比较

简述了置换通风与地板送风的原理、特性及常用设计方法,探讨了辐射顶板＋置换通风与辐射顶板＋地板送风系统在设计方法和使用效果上的差异。     

加膜冷却顶板/置换通风系统及其实验研究

对冷却顶板/置换通风系统中存在的两个突出问题:冷却顶板易“结露”以及形成“下降气流”破坏置换通风的流型进行理论分析,提出了用对长波具有高透过性的薄膜包裹冷却顶板,在冷却顶板下表面和薄膜之间保留真空或空气夹层的解决方法,并且设计了实验系统,选定了长波高透过性薄膜作为实验材料,通过实验对新系统的性能进行了验证.结果表明:在外界环境基本相同的条件下,加装长波高透过性薄膜后,冷却顶板/置换通风系统的室内温度略有升高,平均升高1.8％;污染度明显下降,在呼吸区以下,平均降低60％;在呼吸区以上,平均降低40％,空气品质明显得到了提高.     

热源局部控制与冷却地板在电子厂房中的应用分析

针对置换通风与地板送风工作区温度梯度问题,基于两种送风系统的原理对比分析,对工作区内温度场变化规律进行了理论分析.分析结果表明:由于热源点位置不同,置换通风温度曲线呈现出区域性变化特征,且随高度变化而具线性分布规律;地板送风温度曲线变化相对均匀且平缓.结合天津地区某电子厂房的热源特点,提出了热源局部控制与冷却地板(区域整体控制)两种热源控制方案.通过综合对比分析,认为在厂房空间允许的条件下,更宜采用地板送风结合冷却地板作为电子类厂房通风空调方案.     

置换通风与冷却顶板的热舒适性研究

置换通风与冷却顶板结合是一种新型的空调方式。本论述了在置换通风与冷却顶板结合的空调系统中,各种参数对人体热舒适性的影响,提出基于人体热舒适性要求最合适的设计值。另外,还分析了ＩＳＯ７７３０标准所依据的热舒适性模型在置换通风与冷却顶板系统中的适用性。     

辐射供冷方式室内舒适性数值模拟

辐射供冷系统中辐射板的布置位置对人体舒适性有较大的影响。本文以辐射板-置换通风空调房间为例,采用计算流体力学(CFD)软件,运用两方程湍流模型进行模拟,比较6种组合方式下的室内热湿环境。研究结果表明,辐射板布置在顶板或者墙面与置换通风组合的供冷方式均能满足人体舒适度要求,地板辐射供冷与置换通风结合供冷方式舒适性较差,单独顶面辐射+置换通风这一组合方式是6种组合方式中最舒适的方式。     

置换通风与冷却顶板房间露点温度的模拟研究

通过对置换通风与冷却项板房间的模拟研究,提出了顶板贴附层概念.分析在该空调系统下顶板贴附层和室内工作区窄气温湿度的变化规律,并对两个区域内的露点温度进行了计算比较,从而指出了用工作区空气露点温度替代贴附层露点温度的可行性.     

置换通风对地板供冷的影响

本文介绍了地板供冷置换通风复合式空调系统试验台,并以试验方式验证了置换通风可增强地板供冷对流换热效果.     

置换通风对地板供冷的影响

本文介绍了地板供冷置换通风复合式空调系统试验后,并以试验方式验证了置换通风可增强地板供冷对流换热效果.     

置换通风中风速对地板辐射供冷影响的仿真与试验研究

针对置换通风与地板辐射联合供冷方式存在供冷能力不足的问题,重点分析了风速对房间温度场和换热的影响,利用FLUENT软件对置换通风与地板辐射联合供冷方式中置换通风等进行了研究,得到不同风速下房间温度场的变化规律,并从换热角度分析风速对地板辐射供冷能力的影响;建立了置换通风与地板辐射联合供冷试验装置并进行相关试验,验证了置换通风中在不同出风速度下房间温度梯度的变化规律。结果表明：置换通风中风速的增加不仅可提高地板辐射供冷能力,同时还使房间温度场分布更加均匀且舒适性提高。研究可为置换通风与地板辐射供冷方式在大空调负荷建筑的应用提供指导。     

Modeling and multi-objective optimization of an M-cycle cross-flow indirect evaporative cooler using the GMDH type neural network

A model was presented to determine product air properties of dew-point indirect evaporative coolers with cross flow heat exchanger, M-cycle CrFIEC. In this regard, the most powerful statistical method known as the group method of data handling-type neural network (GMDH) was employed. Then the developed GMDH model was implemented for multi-objective optimization of a prototype CrFIEC and the average annual values of coefficient of performance (COP) and cooling capacity (CC) were maximized, simultaneously, while working to air ratio (WAR) and inlet air velocity were decision variables of optimization. Accordingly, features of the proposed system were optimized at twelve diverse climates of the world based on Koppen–Geiger's classification. Results implied that the optimized inlet air velocity for all climates varied between 1.796 and 1.957 m.s⁻¹, while the optimum WAR was 0.318 for “A” class cities. Moreover, the mean values of the COP and CC were improved 8.1% and 6.9%, respectively.     

恒温恒湿空调系统的优化控制与性能模拟

针对传统恒温恒湿空调系统表冷器采用固定露点方法导致热湿补偿损失较大的缺点,采用热湿独立控制装置和PID分程控制方法,研制了一套恒温恒湿空调系统。在实验的基础上,利用TRNSYS 16软件建模,对系统在不同热湿负荷下的运行状况及节能效果进行了模拟分析。结果表明,该系统能自动调节表冷器冷冻水流量与温度,以及加热器或加湿器的投入量,实现对空气温湿度的独立控制,并达到设定的温湿度;在设计此类表冷器时,换热面积应该以较高的冷冻水进口温度(如12℃而不是通常的7℃)来进行计算。该系统节能效果显著,比传统系统在低温高湿工况下节能30%以上;在高温低湿工况下节能50%左右。     

新型中部进风逆流闭式冷却塔的设计与分析

现有的逆流闭式冷却塔一般采用从塔体的下部进风方式,存在流通面积小、流动阻力大的缺点。本文提出一种从中部进风、上下分流的闭式冷却塔的塔型设计,流通面积是普通塔的2倍,可提高风量,增强冷却塔的冷却效果。与上下进风逆流闭式冷却塔相比,避免了由于上部进风容易造成湿热空气回流的缺点。这种新型冷却塔具有良好的应用前景。     

风机盘管干工况时进水温度的确定

就干工况风机盘管加独立新风空调系统的末端风机盘管的冷水进水温度的确定方法进行探讨，并得出干工况下风机盘管临界进水温度的计算公式，而临界进水温度随着室内空气露点温度的提高而提高。在实际应用中，干式盘管的实际进水温度应高于临界进水温度，但低于室内空气的露点温度。     

合肥正大购物广场中央空调方案设计

中央空调系统对大型商业综合体的使用,工程造价及日后的运行费用至关重要,中央空调方案包括空调冷、热源,空调形式等,以往空调方案的比较都集中在空调冷热源及其经济性,就空调的主要形式,比如是否采用温湿度独立控制等分析较少;对空调运行可靠性分析也较少。就合肥地区一大型商业综合体的中央空调方案,包括空调形式的设计做出分析,并得出最终空调形式与建议。     

Mathematical model and performance analysis of a novel outside evaporative cooling liquid desiccant dehumidifier

A numerical model of a novel outside evaporative cooling liquid desiccant dehumidifier (OECD) was developed and the effects of inlet parameters, including the inlet temperature and relative humidity of dehumidified air and evaporative cooling (EC) air, as well as the inlet mass flow rate of solution and so on, on the device performances were investigated in this paper. The results show that as the inlet temperature of solution increased from 31 to 42 °C, the moisture removal rates of OECD were increased by 14.0–18.0% and 31.1–101.5% compared to the non-evaporative cooling dehumidifier (NECD) and the adiabatic dehumidifier respectively, whereas the dehumidification rate was only decreased by about 1.6% with increase in the inlet temperature of LiCl solution from 24 to 44 °C. All these results can provide guidance for the structural design and performance analysis of the dehumidifier in the future.     

Comparison of performances of displacement and mixing ventilations. Part I: thermal comfort

A numerical simulation using a validated Computational Fluid Dynamics (CFD) model of several types of buildings was used to investigate the difference between mixing and displacement ventilation (DV). The comparison of performances of displacement and mixing ventilations (MV) will be reported in two parts, one on thermal comfort and the other one on indoor air quality. This paper, i.e., Part I, compares the performances of floor-supply DV systems with traditional MV systems for offices, classrooms, retail shops and industrial workshops under a wide range of Hong Kong thermal and flow boundary conditions, such as a very high cooling load. Through proper design, DV can maintain a thermally comfortable environment that has a low air velocity, a small temperature difference between the head and ankle level, and a low percentage of dissatisfied people.     

六流道喷嘴涡流管能量分离特性的研究

涡流管具有结构简单、无运动部件、价格低廉、可靠性高等优点,但管内发生的能量转换却极为复杂。以压缩空气为工作介质,对涡流管能量分离特性进行了实验研究,获得了涡流管制冷、制热效应随入口压力、冷端流率之间的关系,研究结果表明,进口压力越高,六流道喷嘴涡流管的制冷、制热效应越好,但获得最大制冷、制热效应时的冷端流率均有减小的趋势。     

Performance evaluation of a stack cooling system using CO2 air conditioner in fuel cell vehicles

A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO₂ air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 °C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO₂ air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling.