溴化锂水溶液绝热吸收过程实验研究

该文提出预冷却绝热吸收的空冷溴化锂吸收式制冷循环的吸收器设计方案，设计加工了一个溴化锂水溶液绝热降膜吸收的循环实验装置。实验研究李在湍流情况下，溴化锂水溶液在竖真光管外绝热降膜吸收的传质性能。研究了溶液浓度、温度、吸收压力对水蒸气吸收速率和吸收系数的影响以及添加表面活性剂后对吸收性能的影响。     

风冷垂直管降膜吸收器及其传热传质问题的研究

吸收器是吸收式制冷机的关键部分，传统的吸收器都是采用水冷却，该文提出了风冷吸收器的设计方案，建立了风冷吸收器降膜吸收过程中传热、传质耦合问题的物理数学模型。并在此基础上，对风冷垂直单管内溴化锂水溶液吸收过程的传热、传质问题进行了数值研究，得出了一些基本结论。这些结果对于垂直管降膜吸收过程的研究以及风冷吸收器的设计具有一定的指导意义。     

平板型吸收器的实验研究

由于其工作介质不含氟利昂，以及可利用较低品质废热和太阳能等从而节约能源减少二氧化碳的排放量等优点，近年来吸收式制冷机／热泵越来越受到关注。但是为了与压缩式制冷机在所有市场范围内进行竞争，还需要进一步提高性能，降低成本和减小尺寸。而其中吸收器是吸收式机组中的关键设备，无论对整机性能还是外形尺寸都有很大影响。与传统的溴化锂水平管式吸收器不同，本文从易于布置从而减小机组尺寸的角度出发，开展了平板型吸收器的研究并给出相关实验结果，以期为该类型吸收器的设计提供参考。     

溴化锂吸收式制冷机的应用分析

概述了溴化锂吸收式制冷的原理，分析了溴化锂吸收式制冷机的综合效益及其一次能源利用率，以热电厂热电冷三联供系统为例分析了溴化锂吸收式制冷机的节能效益，并指出了溴化锂吸收式制冷机在工程应用中应注意的问题。     

基于有限元方法的溴化锂降膜吸收传热传质的数值研究

吸收器是吸收式制冷系统的重要部件.溴化锂溶液的降膜吸收是吸收器中最常见的传质传热形式之一.通过对溴化锂溶液在降膜吸收过程中传质和传热特性的分析,使用基于有限元法的COMSOL Multiphysics软件,建立了溴化锂溶液和水蒸汽降膜吸收的物理数学模型,计算了液膜内部温度和质量分数的分布、界面处传质通量、界面处传热通量...     

溴化锂吸收式制冷机动态特性仿真系统

设计并完成了溴化锂吸收式制冷机动态特性的测量试验，通过试验，对溴化锂吸收式制冷机的动态特性进行了分析，求出了被控对象的传递函数，建立了动态数学模型。在此基础上，设计了溴化锂吸收式制冷机动态特性的仿真系统。并对控制器的控制参数进行整定，得到了最佳控制结果。     

传热传质分离式太阳能吸收式制冷机实验研究

设计研究了小型太阳能溴化锂吸收式制冷机组,对吸收器、蒸发器、发生器均采用传热传质分离设计,通过高效板式换热器的预先冷却或加热的方法,实现了对发生过程、吸收过程、蒸发过程的传热和传质分离,达到了制冷机小型化的目的.实验研究结果显示:制冷量和COP值随太阳能热水温度升高而升高;在某个全天的测试过程中,制冷量最大为3.7kw,COP最大为0.5,日平均制冷量为2.34kW,平均COP为0.34;实验机组的电制冷系数要高于普通的电制冷空调,其平均EER达到了3.25.     

塑料管单效溴化锂吸收式制冷机理论研究

分析了塑料管单效溴化锂吸收式制冷机的理论循环，对塑料管单效溴化锂吸收式制冷机进行了热力计算和传热计算，为塑料管单效溴化锂吸收式制冷机的结构设计及实验研究提供理论依据。     

溴化锂吸收式制冷机与蒸汽压缩式制冷机的能耗比较

本文对溴化锂吸收式制冷机与蒸汽压缩式制冷机的能耗进行了比较研究,认为溴化锂吸收式制冷机节电不节能,而溴化锂吸收式制冷机与离心式制冷机联合运行,既可缓解供电紧张,又可提高能量利用效率,应予以充分重视。     

直燃式溴化锂制冷机

浙江上虞联丰制冷机厂与华东工业大学、上海船舶研究设计院科研单位联合研制开发的第二代燃油直燃式溴化锂吸收式制冷机于八月底在绍兴鉴定成功,标志着浙江上虞联丰制冷机厂在直燃式溴化锂吸收式冷温水机组的研制上又上了—个新的台阶。     

Steam absorption into aqueous lithium bromide solution films falling inside vertical pipes

The realization of a compact and efficient air‐cooled absorber is the key technology for the small‐capacity absorption refrigerator for domestic use. A vertical pipe with absorbent flowing inside and air flowing outside is the best choice for the air‐cooled absorber due to the easy addition of fins to enhance heat transfer on the air side. In this paper, first, the modeling of the absorption process in the vertical pipe for a constant heat transfer coefficient on the outer surface is described. Then, experimental results are presented for pipes of inner diameters 8 to 26 mm, pressure 5 and 6 mm Hg, and outer surface heat transfer coefficient 2000 and 3300W/(m²·K). It was found that for pipes of diameter 13 mm or more, the absorption process is well estimated by the proposed model. The absorption with addition of surfactant is estimated by the pseudo‐turbulent method. The necessary heat transfer area for the air‐cooled condition is about three times that for the water‐cooled condition. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 740–752, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10128     

Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide–water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated.     

利用汽车发动机余热的溴化锂吸收式制冷研究

根据现有汽车空调的制冷系统和发动机冷却水及排气系统的结构特点,结合溴化锂吸收式制冷系统的工作原理,提出将汽车排气管和发动机冷却水箱进行结构改造作为溴化锂吸收式制冷系统的发生器,代替传统的汽车空调的制冷和采暖系统及发动机冷却系统。并对该溴化锂制冷系统进行了热力计算和传热面积的计算,计算结果表明,溴化锂制冷系统充分利用了废气余热和冷却水余热,减少了汽车油耗,并且改造后的排气热交换器和冷却水箱传热面积小,结构简单紧凑。     

Characteristic analysis of adiabatic spray absorption process in aqueous lithium bromide solution

The absorber is a key component in a thermally-driven absorption system which significantly influences the whole system performance. The adiabatic spray absorption is one type of absorption process, in which the absorption fluid is dispersed into fine droplets having immense surface exposed to the vapor. In the current investigation, an improved analytical Newman model is presented which can consider the absorption heat effect. Using the model, the absorption characteristics of the adiabatic spray in aqueous lithium bromide solution is studied. The results show that the absorption heat significantly affects the absorption process. When the droplet radius decreases, the absorption rate can be improved and the maximum absorption time can be reduced. The current investigation can result in a better understanding of absorption mechanisms of the adiabatic spray absorption.     

Experimental study of heat and mass transfer on an absorber with several enhancement tubes

An experimental study of the absorption process of water vapor into a lithium bromide solution was performed. For the purpose of the development of a high-performance absorption chiller/heater utilizing a lithium bromide solution as the working fluid, it is the most effective way to improve the performance of the absorber with the largest heat transfer area of the four heat exchangers. This paper considers a bare tube, bumping bare tube, floral tube, and twisted floral tube for the absorber of an absorption chiller/heater. The floral and twisted floral tubes have about 40% higher heat and mass transfer performance than the bare tube conventionally used in an absorber. Therefore, floral and twisted floral tubes are expected to realize high heat and mass transfer performance. © 1999 Scripta Technica, Heat Trans Asian Res, 28(8): 664–674, 1999     

Entropy generated and exergy destroyed in lithium bromide thermal compressors driven by the exhaust gases of an engine

This work is devoted to the study of the entropy generated and the exergy destroyed in the lithium bromide absorption thermal compressors of single and multiple effects, driven by the heat of the exhaust gases of an engine, when the absorption heat is directly transferred either to water or to air. Air‐cooled systems work with temperature and pressure gradients higher than those cooled by water. The absorption temperature in air‐cooled systems can reach and even exceed 50°C. Under these conditions, boiling temperature within the high desorber of the double and triple effect systems can exceed 200 and 300°C, respectively. Maximum pressures reach values of 1.7 and 15 bar, respectively. The thermal compressor cooled by air generates more entropy and destroys more exergy than the one cooled by water. The triple‐effect thermal compressor destroys less exergy than the one of double effect and the latter destroys less exergy than the one of single effect. The lithium bromide thermal compressor of single effect cooled by air is not feasible when working with absorption temperatures around 50°C. The one of double effect is feasible since the high‐pressure desorber can work at higher temperatures. Under these conditions, the solution cycle described within the high‐pressure desorber remains out of the zone of crystals formation, and offers the possibility of producing more refrigerant than the one of single effect. Also, in the double‐effect compressor less entropy is generated, and therefore less exergy is destroyed than in the single effect. The triple‐effect compressor cooled by air offers the possibility of producing more refrigerant than the one of double effect, but at higher expenses of temperatures and boiling pressures of the solution. This creates corrosion and control problems, which do not have an easy solution yet. Less exergy destruction does not compensate for the increase of these problems. In any case, the compression process of the cooling steam occurs with entropy reduction. Copyright © 2000 John Wiley & Sons, Ltd.     

Effect of component pressure drops in two-fluid pumpless continuous vapour absorption refrigerator

Miniaturisation of the vapour absorption refrigerator requires replacement of the solution pump by a heat operated bubble pump and air cooled condenser and absorber. The replacement necessitates the selection of working media restricted to vacuum operation, and the air cooling poses the problem of high pressure drops in the refrigerator. Thermodynamic analysis of the absorption refrigerator with such a suitable working medium is performed considering the pressure drops in the system as parameters. The analysis shows that the effect of the evaporator to absorber pressure drop on the system performance is more significant than that of the generator to condenser pressure drop, and it becomes more predominant at the low generator temperature normally encountered in solar operated systems.     

溴化锂吸收式制冷技术研究进展

回顾了近十年来有关溴化锂吸收式制冷技术的发展及主要研究成果。H₂O/LiBr作为一种广泛应用的吸收式制冷工质对,具有优良的热力学性能与环保特性,但存在结晶、腐蚀和循环性能低等问题。文章简述了醇类、盐混合物、离子液体及纳米颗粒等添加剂对H₂O/LiBr溶液传热传质、防结晶及防腐蚀等性能的提升;介绍了关键部件吸收器和发生器的理论及实验研究现状;回顾了吸收式制冷系统循环优化的研究成果。通过归纳分析,总结溴化锂吸收式制冷技术存在的一些问题及未来发展趋势,为后续的研究提供参考。     

Thermodynamic performance of a new type of double absorption heat transformer

The thermodynamic performance of a new type of double absorption heat transformer (DAHT) has been studied based on the thermodynamic properties of the aqueous solution of lithium bromide and the mass and energy balance for each component of the system in this paper. The solution cycle in this new type of DAHT is different from the ones reported in literatures, in which the temperature of the absorbing evaporator is not an independent variable and the degrees of freedom of the system is less than that of the DAHT with other solution cycles by one. The results show that compared with other types of DAHT this new type of DAHT has higher coefficient of performance especially when absorber temperature gets higher. The maximum coefficient of performance and the maximum gross temperature are about 0.32 and (60–100) °C respectively.