机械振动强化吸收式制冷机传热性能的实验研究

本文搭建了带有电动振动系统的吸收式制冷性能研究实验台,实验重点研究了振动对于吸收式制冷机传热性能的强化效果。结果表明,振动可有效地强化吸收式制冷机的传热性能,增加制冷量;在低频、低振幅的范围内,传热的强化效果随频率和振幅的增加而增加。本文的研究成果对于提高溴化锂吸收式制冷机的效率有一定的借鉴作用。     

塑料管单效溴化锂吸收式制冷机理论与实验研究

溴化锂吸收式制冷机在工业中有着广泛的应用,但传热管腐蚀及其引起的拎量衰减一直以来是人们难以解决的问题。采用塑料传热管代替铜传热管有望解决这个难题。分析了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,设计了塑料管单效溴化锂吸收式制冷机的结构,为塑料管单效溴化锂吸收式制冷机的实验性能测试提供参考依据。     

三效溴化锂吸收式制冷机的发展概况

本文综述了三效溴化锂吸收式制冷机的发展概况，介绍了三效式溴冷机新工质对、吸收循环方式、传热与传质和新型缓蚀剂的研究状况。同时，展望了三效溴化锂吸收式制冷机的发展趋势。     

适应于热水加热的溴化锂吸收式制冷机降膜式发生器的实验研究

一、前言 溴化锂吸收式制冷机在我国得到了迅速的发展及广泛的应用。除用蒸汽外,它还在回收85～95℃余热水方面也得到了应用,用热水作溴化锂吸收式制冷机的驱动热源,其品位较低,若用现常用的沉浸式发生器,与蒸汽驱动相比,它的过热度及热流密度均较小,因此,发生器的传热传质系数较低,发生效果较差。为了改善发生器的性能,提高它的传热传质系数,热水型溴化锂吸收式制冷机可     

利用低位余热的双级氨水吸收式制冷机的性能研究及其在冷库与冷饮生产中的应用

本文用实验方法研究了以低位余热蒸汽为热源的双级氨水吸收式制冷机的性能,初步得到了其变化规律,并介绍了该机在冷库与冷饮生产中推广应用情况。最后,将实验装置在设计工况下的各项性能指标与国外文献记录的数值进行了对比,同时将吸收式制冷机与压缩式制冷机作了初步的经济比较。     

吸收式制冷机用传热管

吸收式制冷机是热交换器的集合体,其中采用大量的传热管件。吸收器又是吸收式制冷机中最关键的部位,因此强化其传热和传质,是提高机器性能的重要手段。溴化锂溶液对管材又有一定的腐蚀性,解决其防腐问题,也为人们所关心。本文介绍几种强化的传热管的性能及其制造技术,一种风冷用降膜吸收管,并提供较好地解决防腐问题的特种钢管材。１ 同时顾及传热和传质的强化管 为了提高吸收器的性能和减小其尺寸,必须使传热管高性能化。此时可从吸收管的传热和传质两方面进行改进。通常的传热管在增强传热的同时,其传质却受到干扰,例如在改善传…     

不可逆四热源吸收式制冷机炯经济优化性能

应用有限时间热力学理论，基于利润率为目标函数，对牛顿传热规律下四热源吸收式制冷机进行优化分析，导出制冷机的[火用]经济优化性能，揭示了其与生态学优化性能的内在联系。所得结论可为四热源制冷机的优化设计和最佳工况选择等提供些新理论依据。     

喷雾吸收器在溴化锂吸收式制冷中的性能分析

喷雾吸收器是吸收式制冷机的一种新型吸收器,这种吸收器把传热和传质过程分开,具有低成本、高换热效率、能在摇摆工作条件下正常工作等一系列优点,具有很大应用前景.通过编制程序,对该吸收器进行了热力过程计算,确定了对这种吸收器性能影响较大的几个参数喷淋温度、喷淋浓度和吸收压力,这些参数应合理选择.这种吸收器对于船用吸收式制冷机的开发和吸收式制冷机的空冷化很有意义.     

有限热源四温位不可逆吸收式制冷循环模型及性能分析

建立了热源热容量有限、综合考虑热源与环境间的热漏、热源与循环工质问的热阻以及循环内部不可逆性时的不可逆四温位吸收式制冷循环模型，并导出了循环制冷率和制冷系数间的一般关系式；利用数值算例，分析了吸收式制冷机的一般性能和优化性能，得出了热漏、内不可逆性和工质放热量分配率对循环性能的影响规律。所得结论可为吸收式制冷机的设计和优化提供一些新的理论指导。     

蒸汽型溴化锂吸收式冷温水机组的设计与优化

根据溴化锂吸收式制冷机冷却负荷大的特点，本文提出了一种蒸汽型溴化锂吸收式冷温水机组的设计和优化方法，给出了所设计的６００ＫＷ制冷量冷温水机组的工作参数和技术指标，并通过与蒸汽单效溴化锂吸收式制冷机的性能比较和对本机组的节能效益和有效能利用率分析，认为蒸汽型溴化冷温水机组是一种值得大力推广的机型。     

GTCC排烟驱动的热管型溴冷机设计及传热分析

针对环境温度升高导致燃气轮机性能下降问题,提出利用GTCC烟气余热驱动热管型溴化锂吸收式制冷机制取冷量,以降低压气机进气温度,提高燃气轮机性能。介绍热管型溴冷机的工艺流程,分析分离式热管换热器的传热性能,应用VB软件编制计算程序,对热管型溴冷机进行具体设计及分析。结果表明,GTCC排烟驱动的热管型溴冷机运行费用低,换热效率高,能够综合利用能源。     

振动对于吸收式制冷影响的实验研究

利用已搭建的装有电动振动系统的溴化锂吸收式制冷实验台,对溴冷机各主要部件的性能进行实验分析。主要分析振动对于吸收式制冷过程中传热和制冷性能的影响。通过实验数据的处理和分析可以看出：在低频振动状态下,蒸发器、吸收器内的换热效果均优于静止的情形,表明低频振动有利于强化换热,同时增加了机组制冷量,提高了机组COP值。     

溴化锂溶液中添加活性炭颗粒对制冷机出力的影响

为改善吸收式制冷机的性能,基于活性炭的高吸附性,研究在溴化锂水溶液添加适量活性炭颗粒形成的悬浮液的传热传质性能,分析活性炭/溴化锂悬浮液替代溴化锂水溶液作为吸收剂的可行性。研究表明,悬浮液的粘度随活性炭浓度线性增长,以悬浮液作为吸收剂的制冷机的出力随透湿系数、悬浮液吸附平衡常数及换热表面积呈近似线性增长关系,并且,以活性炭/溴化锂悬浮液作吸收剂的制冷机出力较以纯溴化锂溶液作吸收剂的制冷机出力大。     

Theoretical evaluation of absorption and desorption processes under typical conditions for chillers and heat transformers

A comparison of absorption and desorption is conducted using a detailed model describing heat and mass transfer. First, the influences of various assumptions have been evaluated. Second, typical conditions for both absorption chillers and heat transformers have been defined. The performance of absorption and desorption processes have been analysed for a flow length of 0.1 m. In an absorption chiller, during desorption, the viscosity is lowered and the mass diffusivity is increased. These circumstances cause a 46% higher transfer rate as compared to absorption. Thus, the overall performance of the process is determined by the absorber component. In a heat transformer, during absorption at an elevated pressure and temperature level, the viscosity is lower and mass diffusivity is higher as compared to desorption. Therefore, the transfer rate of during absorption is 10% higher as compared to desorption. Hence, the desorber performance is somewhat more influential to the overall system performance.     

活性炭颗粒的添加对溴化锂溶液蒸汽吸收率/制冷量的影响

为强化吸收式制冷机的蒸汽吸收率及制冷效率,基于活性炭的高吸附性能,在溴化锂水溶液中添加适量活性炭颗粒形成活性炭/溴化锂悬浮液替代溴化锂水溶液作为吸收剂,通过实验研究了其蒸汽吸收率、制冷效率,分析了替代的可行性。研究表明,在活性炭添加量为0~300ng/L条件下或在0~1.5吸着平衡常数范围内,悬浮液的水蒸汽吸收量比和制冷机组的制冷量随活性炭添加量和悬浮液吸着平衡常数近似线性增长;悬浮液的粘度随活性炭添加量线性增长,随温度升高线性减小。     

Simulation study of a hybrid absorber–heat exchanger using hollow fiber membrane module for the ammonia–water absorption cycle

An innovative hybrid hollow fiber membrane absorber and heat exchanger (HFMAE) made of both porous and nonporous fibers is proposed and studied via mathematical simulation. The porous fibers allow both heat and mass transfers between absorption solution phase and vapor phase, while the nonporous fibers allow heat transfer between absorption solution phase and cooling fluid phase only. The application of HFMAE on an ammonia–water absorption heat pump system as a solution-cooled absorber is analyzed and compared to a plate heat exchanger falling film type absorber (PHEFFA). The substantially higher amount of absorption obtained by the HFMAE is made possible by the vast mass transfer interfacial area per unit device volume provided. The most dominant factor affecting the absorption performance of the HFMAE is the absorption solution phase mass transfer coefficient. The application of HFMAE as the solution-cooled absorber and the water-cooled absorber in a typical ammonia–water absorption chiller allows the increase of COP by 14.8% and the reduction of the overall system exergy loss by 26.7%.     

A method for design analysis of absorption machines

The lack of understanding of the processes taking place in some of the elements of absorption machines, as the absorber, typically results in using security values for the overall heat transfer coefficients at the design process and consequently producing oversized heat exchangers. In this study, a statistical method was employed in order to improve the design of a lithium bromide-water single effect absorption chiller. This method was based on reliable values of heat transfer coefficients and areas for the components integrating the machine. Experimental designs and variance analysis were used to measure the effects the variation of the heat exchangers areas had on the performance of an absorption machine. The conclusions extracted from this study will allow a redistribution of the total heat transfer area among the heat exchangers, which will in turn result in a significant improvement of the COP. Cooling capacity, external flow rates and design temperatures were kept constant and used as input data for the design process.     

单效溴化锂吸收式制冷循环吸收特性与工况关系的研究

以单效溴化锂吸收式制冷机为研究对象,对溴化锂水溶液的热力性质参数进行了计算机模拟。通过模拟计算,得到了求解溴化锂水溶液热力参数的较为精确的计算方法。溴化锂吸收式制冷机是以水为制冷剂,溴化锂为吸收剂,通过消耗热能来实现制冷目的的。通过对单效循环的仿真模拟计算,实现了对机组在不同工作工况下的性能预测。为进一步利用数字和模拟手段深入研究溴化锂吸收式制冷机组奠定了良好的基础。     

Experimental investigation on the drop-in performance of R407C as a substitute for R22 in a screw chiller with shell-and-tube heat exchangers

A drop-in test of a mixed refrigerant R407C is performed in a commercial screw chiller with shell-and-tube heat exchangers originally designed for R22. The test results show a severe performance reduction when substituting the refrigerant from R22 to R407C. The reason for the performance reduction is analyzed comprehensively, and the influence of thermodynamic properties, compressor efficiency, and heat transfer is evaluated quantitatively. The major factor causing the performance reduction is assessed as the degradation of the heat transfer in using the mixed refrigerant, R407C. The heat transfer degradation in the evaporator is found to be larger and influences more on the chiller performance reduction. The performance reduction caused by the evaporator is approximately two times compared with that of the condenser.