蒸发冷却空调技术在住宅建筑中的研究进展

介绍蒸发冷却空调技术在住宅领域的研究进展。主要包括:直接蒸发冷却空调技术在住宅建筑的应用、间接蒸发冷却在住宅建筑的应用以及蒸发冷却与其他技术相结合在住宅建筑领域的应用几个部分。参考国内外相关文献及其专利,得出蒸发冷却空调技术在部分地区住宅领域应用效果较好的结论,特别是将蒸发冷却空调技术与其他技术相结合的应用过程中,这项技术能够提高整个机组的运行能效比,使机组运行更加节能、环保。在广阔的农村住宅领域以及"干空气能"丰富的部分地区,蒸发冷却空调技术值得被大力推广。     

蒸发冷却技术在空调节能中的应用

介绍了近年来国内外对蒸发冷却技术的研究状况,分析了蒸发冷却技术应用在空调中的各种形式和节能效果。指出,蒸发冷却技术在我国东部地区和西部地区均有着广阔的应用前景。     

间接蒸发冷却技术的应用研究与现状

由于我国各地区气候条件不同,蒸发冷却的应用方式也有些不同.通过对直接蒸发冷却和间接蒸发冷却技术原理的分析,提供了分析研究的结果.着重介绍间接蒸发冷却技术在我国的应用研究与现状.     

蒸发冷却技术

蒸发冷却技术的应用,全世界有两千万台蒸发冷却空调机在运行,而我国只有2万台,以后肯定会更多。但要论绿色建筑、节能环保,蒸发冷却技术是不容忽视的。     

蒸发冷却技术

文章介绍了蒸发冷却技术的原理和分类，详细介绍了直接蒸发冷却和间接蒸发冷却的实际应用情况，指出该技术是节能环保的，是可持续发展的制冷技术，具有应用前景。     

再循环蒸发冷却技术及其在空调行业的应用探讨

文章提出了一种再循环蒸发冷却流程，根据此流程设计了一套再循环蒸发冷却装置，并计算分析了它的冷却效果。对再循环蒸发冷却技术在空调行业的应用进行了探讨，提出了相应的系统应用方法。这种技术为开发节能环保空调设备和空调系统提供了一个新的途径。     

适用于夏热冬冷地区的空调节能系统

介绍几种空调系统节能措施,并根据夏热冬冷地区气候条件,提出该地区空调系统节能的总体构想,即利用蒸发冷却、除湿机和机械冷却相结合,以达到空调系统节能的效果.     

节能型冷却除湿复合式空调系统

介绍了冷却除湿空调的基本原理,对已有系统提出了改进.利用热回收装置,对除湿过程中的吸附热进行回收,并采用室内回风作为间接蒸发冷却器的二次风,能够更有效的降低处理空气的温度.对两种方案的热利用效率进行了实例计算,改进系统更有效.     

大功率晶闸管的冷却技术

简要介绍了晶闸管各种冷却方式的特点、原理及其发展现状。认为浸泡式蒸发冷却具有不可比拟的优越性和很好的发展前途。由于浸泡式蒸发冷却要用完全密闭形式,导致系统内部压力在真空到0.3MPa之间波动。而大型冷却容器作为压力容器受到法律限制,因此严重影响了它的发展。鉴于此,提出了恒压浸泡式蒸发冷却系统,并对其特点及原理做了简单分析。     

家用蒸发冷却中央空调的应用研究

针对现有三种技术路线的家用中央空调缺点。结合国情,提出了利用蒸发冷却技术和变风量技术实施分室控制的家用蒸发冷却变风量中央空调的方案。     

Thermal performance of an evaporatively cooled building: Parametric studies

A single-storey office building in a hot and dry climate is modelled for evaporative cooling. The counterflow cooling tower is modified to precool the tower inlet air by the tower exit air in a heat exchanger. Centralized evaporative air cooling, using the modified cooling tower, and roof evaporative cooling are considered to provide comfortable living conditions in the space. The thermal performance of such a building is analysed for various operating parameters. The study indicates that centralized evaporative air cooling is feasible, to maintain near-perfect comfort conditions in hot and dry climates. Modified cooling tower and roof evaporative cooling further enhance the scope of evaporative cooling for comfort applications.     

Going below the wet-bulb temperature by indirect evaporative cooling: Analysis using a modified ε-NTU method

The objective of this paper is to study a method to achieve sub-wet bulb temperature by indirect evaporative cooling of air (without using a vapor compression machine). For this purpose, an analytical model is developed based on the effectiveness-NTU method (ε-NTU). The main idea for achieving a sub-wet bulb temperature by indirect evaporative cooling of air is by indirectly pre-cooling the working air before it enters the wet passage. It is shown that a modified analytical model for indirect evaporative coolers could be based on the ε-NTU method for sensible heat exchangers when proper adjustments are made by redefining the potential gradients, transfer coefficient, heat capacity rate parameters and assuming a linear saturation temperature-enthalpy relation of air. This modified model is used to find the performance of a regenerative indirect evaporative cooler. The model results show very good agreement with results from experimental measurements and a numerical model.     

Novel design and modelling of an evaporative cooling system for buildings

Passive evaporative cooling has great potential as an alternative to conventional air‐conditioning in arid hot climates because of its low cost and zero pollution. This paper describes a novel evaporative cooling system with an automatic wind‐tracking device to improve its operating efficiency. The design and operating principles are discussed. A mathematical model is simplified by the assumption of convective heat and mass transfer of staggered streamlets of water. A computer program has been developed to calculate the deflection and length of spray water streamlets, as well as evaporative water mass, minimum cooled water temperature and required cooling time. A typical example illustrates that approximately 20 kg water are evaporated and around 26 min are required for 980 kg of water to be cooled from 28°C to the wet bulb temperature of 19.2°C of ambient air in a typical arid hot climate (relative humidity = 0.30, dry bulb temperature = 32°C and wind velocity = 4 m s^?1). The application of adsorbents, would allow the evaporative cooling system to be applied in hot, humid climates, in addition to hot climates with low humidity. Copyright © 2006 John Wiley & Sons, Ltd.     

板式间接蒸发冷却换热器的层流特性研究

间接蒸发冷却换热器与传统空调相比具有环保与节能的优点。由于蒸发冷却过程的传热传质机理复杂,本文针对板式间接蒸发冷却换热器,建立了三维稳态传热传质数学模型,并确定了合适的边界条件。通过数值模拟得到了压力场、温度场和浓度场的分布,并讨论了通道间距、速度、温度以及相对湿度等因素对换热效果的影响,为间接蒸发冷却换热器的设计提供了理论指导。     

包覆吸水膜的管式蒸发散热器性能的实验研究

应用间接蒸发散热的原理,在空调冷凝器表面包覆吸水膜,利用水蒸发带走热量.这样蒸发面积达到了最大值,并且能够通过毛细力自动补充蒸发的水分.空调冷凝器中热工质的温度和热容比间接散热器中的一次空气大,能够提高蒸发表面温度,提高蒸发量,进而提高散热效率.通过对通有热水的表面覆盖吸水纸膜的单铜管的实验研究,得出了该方式的传热系数以及水膜的,导热系数,证明了该散热方式较空调冷凝器空气强制对流和其它蒸发散热方式的优势.     

Indirect evaporative cooling and economy cycle in summer air conditioning

The air‐side economy cycle has a large application in warm and dry climates, where the simple increase in the amount of outside air supplied to the conditioned space can substantially reduce the cooling load. Although the dry‐bulb economy cycle is the simplest implementation, requiring only a dry‐bulb temperature comparison to operate the air flow rate regulation, the greatest potential in cost reduction is achieved by the wet‐bulb economizer (WBE). Indirect evaporative cooling (IEC), based on energy recovery from the saturated exhaust airflow, is another technique to be applied in the reduction of a building cooling load. Preconditioning the outdoor airflow by IEC actually extends the applicability of the WBE. In such a way, specific synergies can be exploited when WBE and IEC are combined, even in humid climates. On the other hand, the largest benefits can be accomplished only by redefining the control strategy of the outside air flow rate. In the present paper, the outside air flow rate control strategies are described both for simple WBE and for preconditioned WBE cycles. Different regulation regions are defined on the psychrometric chart together with the relative control strategies. The incidence of these regions is evaluated for 14 different European and American climates. Finally, the seasonal cooling energy requirements are determined for the dehumidification by cooling process, which can be considered as mainly responsible for cooling energy costs in the considered localities. Traditional, preconditioned by heat recovery and IEC on the exhaust airflow, WBE and PWBE air conditioning cycles are compared. Copyright © 2003 John Wiley & Sons, Ltd.     

Performance of a solar liquid desiccant air conditioner – An experimental and theoretical approach

In this paper the results of testing a solar liquid desiccant air conditioner (LDAC) in the tropical climate of Queensland, Australia have been presented. The system uses polymer plate heat exchanger (PPHE) for dehumidification/indirect evaporative cooling, and a cooling pad as the direct evaporative cooler for the dry air leaving the PPHE. Lithium chloride, which is an effective desiccant in air dehumidification, was used in the experiments and a scavenger air regenerator concentrates the dilute solution from the dehumidifier using hot water from flat plate solar collectors. The data obtained from performance monitoring of the solar LDAC operating on a commercial site in Brisbane was compared with a previously developed model for the PPHE. The comparison reveals that good agreement exists between the experiments and model predictions. The inaccuracies are well within the measuring errors of the temperature, humidity and the air and solution flow rates. The above tests further indicate a satisfactory performance of the unit by independently controlling the air temperature and humidity inside the conditioned space.

In order to prevent carryover of the solution particles into the environment, eliminators are used at outlet of the absorber unit and the regenerator. An alternative method in preventing the carryover is the use of indirect cooling, in which the supply air does not contact the solution. The method can be used to produce potable water from the atmospheric air in remote areas.

The liquid desiccant system can be used in the HVAC industry, either as a packaged roof-top air conditioner, or as an air handler unit for commercial applications. The system could also be used for space heating in winter due to the property of desiccants to provide heat when wetted.     

Experimental investigation of new designs of wind towers

Two new designs of wind towers were tested side by side with a conventional wind tower in the city of Yazd, Iran. All the towers were of identical dimensions. The two new designs were one with wetted column, consisting of wetted curtains hung in the tower column, and the other one with wetted surfaces, consisting of wetted evaporative cooling pads mounted at its entrance. The air temperature leaving the wind towers with evaporative cooling provisions were much lower than the air temperature leaving the conventional design, and its relative humidity much higher. The air-flow rate was reduced slightly in these new towers. It was found that the wind tower with wetted column performs better with high wind speeds whereas the tower with wetted surfaces performs better with low wind speeds. It is recommended that these new designs of wind towers should be manufactured in different sizes and incorporated in the designs of new buildings. They can replace the evaporative coolers currently employed in Iran, and other hot arid regions, with considerable saving in electrical energy consumption.