第二类吸收式热泵模拟研究

基于第二类吸收式热泵原理,建立了第二类吸收式热泵关键过程的数学模型,开发出第二类吸收式热泵循环模拟计算程序,研究了蒸发温度、发生温度、冷凝温度和吸收温度对吸收式热泵主要评价指标性能系数ηCOP、循环倍率R、温升能力ΔT和放气范围ΔX的影响.结果表明:当吸收温度一定时,循环倍率随着蒸发温度的升高逐渐减小,系统的ηCOP先急剧增大,然后缓慢减小;当吸收温度一定时,循环倍率随着冷凝温度的升高逐渐升高,系统的ηCOP先缓慢减小,然后急剧减小;当蒸发温度一定时,循环倍率随着吸收温度的升高逐渐升高,系统的ηCOP先缓慢增大,然后急剧减小.     

利用第二类吸收式热泵回收地热余热的模拟研究

根据溴化锂第二类吸收式热泵系统的传热、传质平衡以及各部件的传热关系,建立了系统的稳态数学模型,分析了系统主要参数对系统性能的影响。提出了利用第二类吸收式热泵回收地热余热的方案;利用模拟计算得出了相应的设计参数。对第二类吸收式热泵系统的模拟分析以及仿真编写了软件,并且对设计参数下的机组系统进行了仿真模拟,以观察主要参数的变化对机组运行的影响。     

低温热源驱动溴化锂第二类吸收式热泵的实验研究

根据溴化锂第二类吸收式热泵系统的传热、传质平衡以及各部件的传热关系,建立了系统的稳态数学模型.利用模拟计算得出了相应的设计参数,建它了热负荷为小型LiBr-H2O第二类吸收式热泵系统实验台,对废热驱动的实验系统在不同运行工况下进行了实验研究.分析了系统主要运行参数各换热设备的进口水温和质量流量对系统性能的影响趋势和规律.     

第二类吸收式热泵的研究及应用

介绍了第二类吸收式热泵的工作原理,阐述了第二类吸收式热泵在工质对、吸收器、表面添加剂和缓蚀剂四个方向的研究现状,例举了第二类吸收式热泵在冶金、酒精以及橡胶工业中的应用.指出以节能为目的的第二类吸收式热泵在工业中具有广阔的应用前景.     

一种新型第二类吸收式热泵的原理及性能分析

提出一种包含吸收溶液冷却结晶过程的新型第二类吸收式热泵循环,并对其工作过程及性能特性进行理论分析与实验研究。结果表明,该循环可在吸收器吸收溶液质量分数显著高于发生器吸收溶液质量分数的条件下工作,其热泵温升能力明显优于现有AHT循环。当冷却结晶终温和冷凝器温度为35℃、发生器温度和蒸发器温度为92℃时,其热泵温升理论上可达97℃。     

在第二类吸收式热泵中对螺旋槽管的换热性能研究

为了提高在以溴化锂为工质的第二类吸收式热泵吸收器的性能,在第二类吸收式热泵吸收器内对不锈钢螺旋槽管,即不锈钢光滑管的传热传质性能进行了实验研究.发现螺旋槽管的传热传质性能约为光滑管3倍,螺旋槽管内热媒工质-水的流体阻力系数是光滑管的17～20倍;应用于第二类吸收式热泵中间大大降低换热面积,促进热泵的高效紧凑化.     

应用一类热泵与二类热泵串联进行联合循环的模拟实验分析

提出将第一类吸收式热泵供热端作为第二类吸收式热泵蒸发器的联合循环。采用数值计算的方法对循环进行了分析，计算结果表明：当供热温度保持在150℃，冷凝温度在12—20℃变化时，联合循环可以将120℃左右的余热利用到40—50℃，性能指数为0．27左右。循环对余热的利用深度高，节能效果显著。     

太阳能-第二类吸收式热泵联合供热系统性能的数值研究

可再生能源和新型节能技术的综合应用,可以解决我国北方地区冬季采暖产生的能耗和污染问题。基于上述理论,文章构建了太阳能-第二类吸收式热泵联合供热系统,并提出了4种运行模式以达到冬季稳定供暖的目的。文章建立了第二类吸收式热泵机组的数学模型,并利用MATLAB软件编写了机组模块。同时,借助TRNSYS软件建立了太阳能-第二类吸收式热泵联合供热系统的仿真模型,并基于冬季典型日的模拟结果分析了该系统的性能。模拟结果表明:太阳能-第二类吸收式热泵联合供热系统是可行的,该系统在运行期间可为用户提供60℃以上的采暖热水,系统的太阳能保证率可达到0.615;与燃气锅炉供热相比,节省了45.7%的燃料费用。     

溴化锂第二类吸收式热泵系统仿真软件的开发

以溴化锂第二类吸收式热泵为研究对象,评价当低焓能源(50℃)作为驱动热源时的总体性能参数及工作效率.利用面向对象的分析方法,建立系统及组成部分的对象模型,并在此基础上利用Visual C 编写了模拟仿真软件,对溴化锂第二类吸收式热泵性能及多变参数进行了分析.     

汽轮机与吸收式热泵联合供热整体性能的优化分析

采用吸收式热泵回收循环水余热用于供热机组,节能效益显著。在供热量、供热温度一定的情况下,为便于直观反映汽轮机与吸收式热泵整体供热系统性能随工况变化情况,以某350MW调节抽汽式汽轮机供热系统为例,将热泵系统、汽轮机凝汽器、热网加热器整体考虑,建立了供热系统热泵性能系数(COP)和发电功率增加值随工况变化的数学模型,并对热泵系统、整体供热系统进行了经济性评价。结果表明:放气范围、循环水入口温度降低,热泵的性能系数COP减小,发电功率的增加值增加。循环水温降降低,COP与发电功率增加值均提高。本文的研究为吸收式热泵与汽轮机的联合整体性能优化提供理论依据。     

回收工业废热的吸收式热变换器技术

介绍了提升工业废热温位的吸收式热变换器的工作原理 ,工质的热力循环过程。应用热力学第二定律和工质的热力学性能数据 ,分别对工质的理论循环过程与实际循环过程的性能系数进行了理论分析和计算 ,研究了操作参数对性能系数和温升的影响规律     

Exergy analysis: an absorption refrigerator using lithium bromide and water as the working fluids

The thermodynamic processes in the absorption refrigeration system releases a large amount of heat to the environment. This heat is evolved at temperatures considerably above the ambient temperature, which results in a major irreversible loss in the system components. In this paper an exergy analysis is carried out on a single-effect absorption refrigeration cycle with lithium-bromide–water as the working fluid pair. Numerical results for the cycle are tabulated. A design procedure has been applied to a lithium-bromide absorption cycle and an optimisation procedure that consists of determining the enthalpy, entropy, temperature, mass flow rate, heat rate in each component, and coefficient of performance has been performed.     

Study on a new ejection–absorption heat transformer

Based on the performance analysis of the single stage, the two-stage and the double absorption heat transformer, a new ejection–absorption heat transformer is presented and analyzed in this paper. The results show that it has a simpler configuration than the double absorption heat transformer and two-stage heat transformer. The delivered useful temperature in the ejection–absorption heat transformer is higher than for a single stage heat transformer and simultaneously its system performance is raised.     

二类热泵在利用余热供热中的热力分析

对单级二类吸收式热泵进行热力分析,建立了热泵系统各部分质量守恒、能量平衡和火用分析数学模型。根据火用平衡方程计算了各个部分的火用损失和热泵系统的火用效率。分析了溶液换热器稀溶液温差、热源温差、余热源温度和冷却水温度对火用损失、循环倍率和COP等的影响。对热泵系统进行了火用能质量评定,确定了火用能的薄弱环节。     

Increase of COP for heat transformer in water purification systems. Part I – Increasing heat source temperature

The integration of a water purification system in a heat transformer allows a fraction of heat obtained by the heat transformer to be recycled, increasing the heat source temperature. Consequently, the evaporator and generator temperatures are also increased. For any operating conditions, keeping the condenser and absorber temperatures and also the heat load to the evaporator and generator, a higher value of COP is obtained when only the evaporator and generator temperatures are increased. Simulation with proven software compares the performance of the modeling of an absorption heat transformer for water purification (AHTWP) operating with water/lithium bromide, as the working fluid–absorbent pair. Plots of enthalpy-based coefficients of performance (COP_ET) and the increase in the coefficient of performance (COP) are shown against absorber temperature for several thermodynamic operating conditions. The results showed that proposed (AHTWP) system is capable of increasing the original value of COP_ET more than 120%, by recycling part of the energy from a water purification system. The proposed system allows to increase COP values from any experimental data for water purification or any other distillation system integrated to a heat transformer, regardless of the actual COP value and any working fluid–absorbent pair.     

Experimental performance of the water-lithium chloride system in a heat transformer

Heat tranformers are devices with the unique capability of raising the temperature of part of a low-grade heat source whilst simultaneously delivering the rest of the heat at a lower temperature. The gross temperature lift that could be attained in the process depends on the characteristics of the working pair. Many combinations of working fluid/absorbent have been proposed although until now the water/lithium bromide system is the most widely used. In order to study the performance of combinations of environmentally friendly working pairs, an absorption heat transformer was constructed and tested. The experimental equipment is described in this work. The performance of the water/lithium chloride system is discussed. The results showed that gross temperature lifts of more than 30°C can be obtained for absorber temperatures higher than 110°C. The enthalpic coefficient of performance indicated that more than 45% of the waste heat can be upgraded for flow ratios less than 10.     

Evaluation of a heat transformer powered by a solar pond

A single-stage heat transformer operating with the water/lithium bromide mixture was operated to demonstrate the feasibility of the use of these systems to increase the temperature of the heat obtained from solar ponds. Electrical heaters at temperatures not higher than 80°C were used to simulate the heat input to an absorption heat transformer from a solar pond. Gross temperature lifts, useful heat and coefficients of performance are plotted for the heat transformer against temperatures and solution concentrations. Gross temperature lifts as high as 44°C were obtained. The maximum temperature of the useful heat produced by the heat transformer operating with the water/lithium bromide mixture was 124°C. The maximum coefficient of performance for the unit was 0.16.     

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.     

Experimental evaluation of a single-stage heat transformer used to increase solar pond’s temperature

A heat source at temperatures not higher than 80°C was used to simulate the heat input to an absorption heat transformer from a solar pond. An experimental absorption heat transformer operated with the water/Carrol mixture was used to demonstrate the feasibility of these systems to increase the temperature of the heat obtained from the solar ponds. Carrol™ is a mixture of LiBr and ethylene glycol [(CH₂OH)₂] in the ratio 1:4.5 by weight. Flow ratios, gross temperature, useful heat, and coefficients of performance are plotted for the heat transformer versus temperature and solution concentration. Gross temperature as high as 50°C were obtained. The maximum temperature of the useful heat produced by the heat transformer was 132°C. The COP for the unit was in the range 0.14–0.36.