闭式冷却塔冷却盘管的优化设计

以冷却盘管的优化设计为例,介绍一个完整的优化过程:建立数学模型,确定约束条件,选取优化变量,编制计算机程序分析其结构参数对投资费用和运行费用的影响。优化结果可以为闭式冷却塔中冷却盘管的设计提供参考。     

盘管与填料复合型横流式冷却塔热力性能分析

介绍了填料与盘管复合型冷却塔的布置形式及其换热流程,在t=20~40℃范围内,应用误差率不大于1%饱和空气焓值的回归公式,填料区应用平均焓差法联合盘管区的热力微分方程及边界条件对该复合塔进行求解。经分析可知盘管区喷淋水入口温度t_(w1)≠t_(w2)(盘管喷淋水出口温度),填料的应用增加了管内外的换热温差,减小金属盘管使用量,节约造价具有一定的经济效益。     

一种横流闭式冷却塔的实验与性能评价

创建填料与盘管间隔布置的新型横流闭式冷却塔,在冷却塔进风中引入部分排风,设计了可控制冷却塔空气进口湿球温度的简易实验室,并在设计工况下对该实验室内横流闭式冷却塔进行实验。通过分析换热温差和进口湿球温度与冷却塔换热能力的关系,提出在非标准工况下测试冷却塔的冷却能力评价折算方法,并根据实验结果对比验证了该评价方法的可行性。结果表明:采用该折算方法评价所测冷却塔的冷却能力为71冷吨,与冷却能力计算软件的结果接近。     

混流型闭式冷却塔在节能改造中的应用

在工业中,当采用水冷式冷水机组制冷时,若环境湿球温度比所需冷冻水温度低3~5℃,可关闭制冷机,利用闭塔直接冷却.阐述了混流型闭式冷却塔的工作原理,建立了相应的数学模型.针对具体工程实例,对天津某化工公司的制冷系统进行节能改造,同时比较风冷、水冷及闭塔直冷三种方式的能耗.实验表明:风冷与水冷的全年耗电量相差不大;冬季水冷与闭塔直冷耗电比接近于8.5∶1,闭塔直冷节能率高达87%以上.     

立式降膜闭式冷却塔设计程序研究

提出一种立式降膜闭式冷却塔的设计计算方法,按照此方法使用Visual Basic 6.0开发工具设计计算程序,并对程序流程进行详细说明。结果显示,该计算程序适用于立式扭曲管中不同工艺流体（冷却水、喷淋水和空气）进行换热的各种工况。通过对比程序计算和手工计算结果,发现二者吻合程度较好,因此通过计算程序能够提高开发人员的设计效率和准确性,减少迭代计算工作量,方便对不同设计方案结果进行比较。后续可以衍生出针对各种发生相变过程（制冷剂、水蒸气冷凝等）的热力计算。     

感应加热炉闭式冷却循环系统的应用

通过分析铝型材挤压成型的特点,介绍了铝棒感应加热炉闭式循环冷却系统的设计思路。针对实施过程中遇到的感应线圈堵塞以及绝缘等问题总结出合理的解决方案,从而提高该设备的稳定性和安全性。     

两相闭式热虹吸管传热特性研究

本文通过实验研究在不同热流密度下,两相闭式热虹吸管传热特性,并通过计算比较了三个较为常用的换热准则系统,同时提出了改进意见,为热管换热器的设计提供了较为可靠的依据。     

冷却塔冷却性能的评价模型

冷却塔是汽轮发电机组重要的冷端设备之一，其运行性能对电站的经济和安全运行有重要的影响。通过建立自然通风冷却塔出水温度和冷却性能的计算模型，为冷却塔的经济运行提供依据，并且还可以为冷却塔的检修和改造提供指导。     

闭式循环柴油机排出气体喷淋冷却传热模型及实验关联研究

闭式揭环柴油机(CCD)排出气体处理技术是各种不依赖空气动力装置(AIP)的共性技术，优选喷淋冷却方式并对其内部的气液传热模型化是该技术的核心。为此，分析对比了横流式、并流式、逆流式等喷淋冷却方式，对实际选用的CCDAIP横流式喷淋冷却器进行了气液传热分析。从单个液滴传热模型出发，采用分层计算方法建立了喷淋冷却传热计算模型，并应用Matlab语言编程计算各种工况下冷却效果。喷淋冷却实验结果与模型计算结果对比表明，该模型能够较精确地预测CCD排出气体喷淋冷却效果。     

Thermal optimization of a natural draft wet cooling tower

This study attempts to quantify the potential improvement in a natural draft wet cooling tower (NDWCT) performance that can be attained by optimizing the fill and water distribution profiles across the tower and to provide designers with the modelling tools for such an investigation. A simple two‐dimensional (2D) model is described, which allows rapid evaluation of NDWCT performance for use with an optimization procedure. This model has been coupled with an evolutionary optimization algorithm to determine the optimal fill shape and water distribution profile to maximize the cooling range of a typical NDWCT. The results are compared against a 2D axisymmetric numerical model. The extended 1D model is found to significantly reduce computational time compared with the numerical model, allowing a wide range of parameters to be tested rapidly with reasonable accuracy. The results show that the optimal layout differs significantly from a uniform profile, with both the water flow rate and the fill depth decreasing towards the centre of the tower where the air is warmer with reduced cooling potential. The overall improvement in the tower cooling range is very low under the design conditions tested, due largely to the highly coupled nature of the airflow and heat transfer in the tower. It is concluded that any design modifications of the type considered would need to be carefully optimized to have any possibility of improving performance. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal performance of a building coupled to an evaporative cooling tower

The thermal performance of a building fitted with an evaporative cooling tower has been evaluated in terms of discomfort index for two climates, namely, composite and hot-dry, typified by New Delhi and Jodhpur, respectively. The effects of various evaporative cooling parameters (height and cross-sectional area of the tower, packing factor, area of the pads, resistance offered to the air flow and local wind conditions) on the performance of the building have been analysed. It was found that, for given parameters of the tower and wind conditions, there is an optimum height of the tower for which the thermal discomfort condition in the building is minimum. The optimum values of the tower height for comfort conditions in the building for various other tower parameters have been obtained for each climate.     

Overall heat transfer coefficient in the presence of the axial dispersion coefficient for a forced draught cooling tower

An overall heat transfer coefficient was calculated for a forced draught counterflow cooling tower by using the pulse response technique. The presence of an axial dispersion coefficient for both gas and liquid was considered. Results indicate that, on neglecting the axial mixing and assuming a plug flow, the overall heat transfer coefficient is overestimated and can lead to errors in design applications.     

Thermal performance of a closed wet cooling tower for chilled ceilings: measurement and CFD simulation

A closed wet cooling tower, adapted for use with chilled ceilings in buildings, was tested experimentally. The thermal efficiency of the cooling tower was measured for different air flow rates, water flow rates, spray flow rates and wet bulb air temperatures. CFD was also used to predict the thermal performance of the cooling tower. Good agreement was obtained between CFD prediction and experimental measurement. Copyright © 2000 John Wiley & Sons, Ltd.     

水力冷却塔水轮机的节能分析

以水力冷却塔水轮机代替电动机驱动风机,节省了电机所消耗的电能,但是水轮机串联于冷却水循环系统中,增加了水循环系统的水力阻力,须消耗一部分水能克服水力阻力。利用试验和数值分析两种方法,研究了水循环系统中水轮机所引起的水力损失特点,提出水轮机节能的措施。     

侧风环境下湿式冷却塔性能参数变化规律的试验研究

外界侧风在很大程度上影响自然通风逆流湿式冷却塔的传热传质性能,根据相似理论,通过热态模型试验,以冷却数和刘易斯数为出发点,研究了外界侧风对冷却塔传热传质性能的影响.研究发现:冷却数和刘易斯数随着外界侧风的变化呈现先减小后增大的趋势,拐点风速值为0.4 m/s;当外界侧风风速小于0.7 ～0.8m/s时,侧风的存在严重恶...     

Thermal analysis of roof-spray cooling

Roof-spray cooling systems have been developed and implemented to reduce the heat gain through roofs so that conventional cooling systems can be reduced in size or eliminated. Currently, roof-spray systems are achieving greater effectiveness due to the availability of direct digital controls (DDC). The objective of this paper is to develop a mathematical model for the heat transfer though a roof-spray cooled roof that predicts heat transfer based on existing weather data and roof heat transfer characteristics as described by the transfer function method (TFM). The predicted results of this model are compared to the results of existing experimental data from previously conducted roof-spray cooling experiments. The mathematical model is based on energy balances at the exterior and interior surfaces of the roof construction that include evaporative, convective, radiative, and conductive heat transfer mechanisms. The transfer function method is used to relate the energy balances at the two surfaces that differ in amplitude and phase due to the thermal resistance and thermal capacitance characteristics of the roof. The model is shown to yield relatively good predictions of heat transfer rates through the roof. The calculation method shows promise as a relatively simple means of predicting heat gains based on calculation procedures that are similar to those frequently used by practicing engineers. © 1998 John Wiley & Sons, Ltd.     

盐水冷却塔经济性比较分析

针对北方电厂冷却水供水不足的问题,介绍了盐水冷却塔技术的应用,通过抑制盐水蒸发和减少排污损失可达到节水目的.经对比分析,以600 MW普通水冷机组的冷却量为基准,采用盐水冷却可以每年节约耗水量686.8万吨,节约耗水费用4265.0万元.     

Cooling potential of an evaporative cooling tower: Parametric studies

Dependence of the cooling potential of an evaporative cooling tower on the tower parameters (height h, cross-sectional area A_t, evaporative pad area A_p, packing factor of evaporating pads F_p and flow resistance f) has been investigated. The performance of the tower is studied for two different climates, namely hot-dry and composite, typified by Jodhpur and Delhi.