Thermodynamic and Experimental Analysis of an Ammonia-Water Absorption Chiller

A single stage ammonia-water absorption chiller with complete condensation is designed, built and tested. The apparatus is designed for a cooling capacity of 2814 W, which is obtained using electric heater as heating source. The thermodynamic models have been derived using the First and Second Laws. Calculated results are compared with experimental data. The results show that the cooling capacity of experimental apparatus is found between 1900 and 2200 W with the actual coefficient of performance (COP) between 0.32 and 0.36. The contribution of the components to internal entropy production is analyzed. It shows that the larger irreversibility is caused by spanning the largest temperature and dissipated thermal energy by heat transfer losses at the generator and evaporator. In the experimentation, the low pressure is lower than the designed value. This is a consequence of a large capacity in the falling film absorber which performs as expected. This decreases the evaporation pressure, and the evaporating temperature could be reduced to the designed value.

Dynamic Performance of On-off Operation for a Small Scale Direct Fired Absorption Chiller

A part load operation by turning the burner on and off intermittently is effective for a small scale direct fired absorption chiller. The dynamic performance of the system has been investigated. The relationship between pressure, temperature and concentration of the lithium bromide solution have been analyzed. The result obtained indicates that the pressure of the high pressure generator and the temperature of the exhausted smoke are the most sensitive parameters. It is also found that the transition time from a full load to a part load condition is quite long, and part load relative cooling capacity is almost near the intermittent running time ratio and oil consumption ratio.

Comparisons and optimization of two absorption chiller types by considering heat transfer area,exergy and economy as single-objective functions

Absorption cooling technology is an environmentally friendly method to generate continuous chilled water making use of multiple thermal sources,such as waste heat and renewable thermal energy.In this study,two absorption chillers(nominal capacity of 400 kW)with series and parallel connections are evaluated.To research the ideal configuration of chillers after thermodynamic analysis,the structures of the chillers are optimized using the particle swarm optimization algorithm by considering the heat transfer area(HTA),exergy efficiency and total annual cost as single-objective functions.The impact of temperature differences between external and internal flows,heat exchanger efficiencies and the solution allocation ratio is estimated.The optimized HTA,coefficient of perform-ance,exergy efficiency and total annual cost are 149.0 m^(2),1.56,29.44%and$229119 for the series-connected chiller,and 146.7 m^(2),1.59,31.45%and$234562 for the parallel-connected type,respectively.Under the lowest HTA condition,compared with the reference simulation results,the energy and exergy performances are improved,while the annual total cost is higher.The annual total cost is highest when maximizing the exergy efficiency,which is attributed to the increase in the HTA.The operating cost accounts for 27.42%(series type)and 26.54%(parallel type)when the annual cost is the lowest.

Characteristics of Absorption Equilibrium with HFC-134a and an Ionic Liquid Pair

Cold energy generation systems must be improved to prevent catastrophic climate change. In this study, we focused on an absorption chiller cycle with HFC-134a and an ionic liquid pair as the refrigerant and absorbent, respectively. It was expected that this absorption chiller cycle could generate cold heat below 0°C. Two liquids were selected and their absorption equilibrium with this pair was evaluated for the absorption chiller cycle. We measured the adsorbed amount at equilibrium with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [BMIM][Tf2N] and N-trimethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide [N1113][Tf2N]. The experimental results were reproduced using the non-random two liquid (NRTL) model. This analysis model corresponded well in terms of the amount of adsorption at equilibrium with the experimental results. A Duhring diagram was also generated the NRTL model, and the absorption cycle characteristics as a function of temperature were determined. The absorption chiller cycle obtained cold heat at 10°C with a regeneration temperature of 70°C in addition to generating cold heat below 0°C.

Thermodynamic Analysis of Double Effect Absorption System along with Boiler and Cooling Tower

Many researchers have studied single and double effect absorption cycles based on first and second lows of thermodynamics But so far the relation of different parameters inside these cycles to the second law of thermodynamics in boiler and cooling tower has not been investigated. In this paper, a system comprised of a series flow double effect water-Lithium bromide absorption chiller, a boiler and a cooling tower is studied based on the first and second laws of thermodynamics, and also exergy analysis is investigated. For this purpose, mass and energy conservation laws governing the system are written, and coefficient of performance of the system, exergy destruction （loss） of each component and exergy efficiency have been calculated.

青岛市某植物馆展览温室暖通空调设计

介绍了2014年青岛世界园艺博览会植物馆展览温室的空调、供暖及通风系统的设计特点。植物馆采用低温温室的设计理念,根据植物的不同生长习性确定合适的室内温度、湿度范围,夏季主要采用自然通风结合空调系统人行步道送风的方式满足室内植物降温需求,同时兼顾游客的热舒适需求;冬季采用散热器结合空调系统人行步道送风系统维持室内温度,同时室内竖直方向设置风扇以减小竖直温度梯度;海洋植物展示厅采用溶液除湿空调沿展缸壁面向上送风,防止展缸壁面结露。

太阳能吸收式制冷系统及其蓄能技术研究

在分析国内外现有太阳能吸收式制冷系统的基础上,从太阳能集热器、蓄能形式、辅助热源、吸收式冷水机组以及太阳能集热器与吸收式冷水机组的匹配等方面详细阐述太阳能吸收式制冷系统及其蓄能技术的发展现状,并对太阳能制冷空调系统的控制策略、优化分析及理论研究进行总结,最后指出太阳能吸收式制冷系统及其蓄能技术的发展方向。

离心式空压机余热制冷/热系统分析

离心式空压机余热以压缩空气的热能为主,通过采用换热器回收空压机余热用于冬季供暖和夏季制冷。离心式空压机余热的回收量主要受压缩空气排气温度、换热器排气端差及热水进出口温度共同影响。建立了进气温度、相对湿度及压缩后空气压力与压缩后空气露点温度的关系曲线,结果表明压缩空气的露点温度随着进气温度、相对湿度、压缩后压力的升高而升高。由于热回收后的排气温度仍然很高,余热主要以压缩空气显热为主。实际应用中,热电比为47.3%、冷电比为23.4%。在余热制冷方面,制冷量主要受热水型吸收式冷水机组驱动热水温度和性能系数影响,采用两级热水型吸收式冷水机组与系统匹配性更好,使用更为普遍。系统总投资回收期为0.38 a,收益主要来自于供暖;制冷设备投资回收期为1.82 a。

溴化锂吸收式冷水机组吸收器传热管腐蚀特性研究

本文采用挂样试验的方式,通过模拟溴化锂吸收式冷水机组吸收器与发生器中溴化锂溶液浓度45%与61%条件下,氧含量分别为0.5%、1%、5%、10%、20%、30%时对B30传热管的腐蚀情况,研究了B30传热管的有氧腐蚀特性,分析了溴化锂溶液浓度与氧含量的腐蚀影响因素与机理,结果表明当溴化锂溶液浓度为45%时,只要氧含量高于5%,B30传热管就会出现麻点状腐蚀,氧含量高于20%,B30传热管明显点蚀,深度达到0.5mm;当溴化锂溶液浓度为61%时,只有当氧含量达到30%,B30传热管才会出现明显的腐蚀麻坑。

Parametric Energy and Economic Analysis ofModified Combined Cycle Power Plant with Vapor Absorption and Organic Rankine Cycle

To meet the escalating electricity demand and rising fuel costs,along with notable losses in power transmission,exploring alternative solutions is imperative.Gas turbines demonstrate high efficiency under ideal International Organization for Standardization(ISO)conditions but face challenges during summer when ambient temperatures reach 40℃.To enhance performance,the proposal suggests cooling inlet air by 15℃using a vapor absorption chiller(VAC),utilizing residual exhaust gases from a combined cycle power plant(CCPP)to maximize power output.Additionally,diverting a portion of exhaust gases to drive an organic Rankine cycle(ORC)for supplementary power generation offers added efficiency.This integrated approach not only boosts power output but alsominimizes environmental impact by repurposing exhaust gases for additional operations.This study presents a detailed energy and economic analysis of a modified combine cycle power plant,in Kotri,Pakistan.R600A is used as organic fuel for the ORC while LiBr-H2O solution is used for the VAC.Two performance parameters,efficiency and energy utilization factor,Four energetic parameters,Work output of ORC,modified CCPP,original CCPP and cooling rate,and one economics parameter,payback period were examined under varying ambient conditions and mass fraction of exhaust gases from outlet of a gas turbine(ψ).A parametric investigation was conducted within the temperature range of 18℃to 50℃,relative humidity between 70%and 90%,and theψranging from 0 to 0.3.The findings reveal that under elevated ambient conditions(40℃,90%humidity)withψat 0,the Energy Utilization Factor(EUF)exceeds 60%.However,the ORC exhibits a low work output of 100KWalongside a high cooling load of 29,000 kW.Conversely,the modified system demonstrates an augmented work output of approximately 81,850 KWcompared to the original system’s 78,500KW.Furthermore,the integration of this systemproves advantageous across all metrics.Additionally,the payback period of the system is contingent on ambient conditions,with lower conditions correlating to shorter payback periods and vice versa.

利用热水型吸收式制冷机组回收纸机冷凝水余热的设计

介绍了国内某大型造纸厂利用热水型溴化锂吸收式制冷机组,回收纸机蒸汽系统末段冷凝水余热,并用于电气、仪表功能房制冷的系统设计方案(简称热水型吸收式制冷方案)。通过与传统电空调方案进行一次性投资和年电费对比分析可知,热水型吸收式制冷方案静态回收期为2.87年,对于返还公用电厂的冷凝水低品位热能利用,具有示范作用。

工业余热水制冷/热方法与应用

在“碳中和、碳达峰”战略背景下,余热利用是降低工业碳排放实现碳中和目标的重要方法之一。随着吸收式技术的不断发展,热水余热的利用形式趋于多元化:可以驱动5种吸收式制冷机制冷;可以驱动吸收式换热机组大温差换热或冷却;同样,热水还可以驱动二类热泵制取高品位的热水或蒸汽。

Experimental research of a novel vortex generator for solar absorption chiller

In this study, a novel generator for the single-effect LiBr-H2O absorption chiller using solar energy was investigated. A dual-chamber vortex generator (DCVG) consisted of a lower chamber and an upper chamber. The hot weak LiBr-H2O liquid entered the lower chamber tangentially through a small nozzle to create a strong vortex flow. Due to the rotating flow, the pressure was reduced toward the central portion of the lower chamber. Experiments were conducted under different solution flow rates and temperatures. The experimental results showed that the lower pressure developed in the lower chamber could reduce the saturated temperature and help the evaporation in the generator that is more heat could be utilized to generate more refrigerant vapor. When the inlet temperature was 90°C, the COP of a solar absorption chiller using the DCVG could reach 0.83, which was higher than of the conventional absorption chiller by 22%.

100kW太阳能制冷空调系统

我国第一座大型实用性太阳能空调热水系统在广东江门市建成投入运行。该系统采用５００ｍ ２ 高效平板太阳集热器和１００ｋ Ｗ 两级吸收式制冷机。介绍了系统的一些技术参数及运行情况，分析了太阳能空调系统的经济性和应用前景，以及对节能和环境保护的意义。

大型太阳能空调／热泵系统

详细介绍了位于北京天普集团工业园区的太阳能空调,热泵系统。该系统主要由太阳能集热器阵列、溴化锂制冷机、热泵、控制系统等几部分组成。系统以太阳能为主,热泵为辅,可以完全满足新能源示范大楼全年的空调、采暖及生活热水的需要。介绍了系统的技术参数及部分运行数据,分析了系统的特点及运行状况。

太阳能吸收式制冷机中弦月形通道热虹吸溶液提升管的研究

对弦月形通道热虹吸溶液提升管内传热及流动性能进行了分析与讨论,并对多种特殊设计的弦月形截面提升管在模拟实验台上进行了溶液提升效能实验。实验结果表明,弦月形通道提升管能较好地改善该类制冷机中热虹吸泵的热性能,具有起动温度低、运行温度范围大及对系统绝对压力要求不高等显著特点。介绍了不同通道面积条件下,运行温度与溶液提升量、冷剂水产量的关系,对影响提升管效能的其它因素也进行了分析及讨论。

氨鼓泡吸收的动力学模型及其吸收特性

本文利用气泡动力学原理,建立了氨水鼓泡吸收的数学模型;利用高速摄像机对氨水鼓泡吸收进行了可视化实验,得出了氨水鼓泡吸收过程中的最大气泡体积、气泡数、最大吸收高度、吸收过程中的舍伍德数等鼓泡参数随喷嘴口径、气体流量、氨水浓度之间的关系。结果表明,喷嘴口径越大,吸收效果越好;吸收溶液氨水浓度较高,吸收效果越差;氨气进口流量较大,吸收效果越好。理论模型和实验结果吻合良好。

太阳能溴化锂吸收式制冷循环的改进

由于单效溴化锂吸收制冷循环受太阳能热源温度较低的限制,需要采用适当的辅助手段。本文对增压辅助型太阳能溴冷机循环流程提出了在冷凝器前加装隔离阀的改进方案,该方案可降低发生压力,以充分利用低温热源,并可有效回收压缩功。通过计算分析了改进循环的热力系数COP与热源温度和循环溶液质量分数差的关系。给出了在不同的热源温度下对应的最佳发生压力的调整范围。