工质对吸收式制冷系统性能的影响研究毕业论文
2021-11-01 22:21:41
摘 要
当前,全球气候变暖,能源危机和严重的环境污染问题变得越来越突出,需要国家大力推广绿色节能和环保制冷技术。用热驱动制冷技术代替需要大量动力和制冷剂的传统电驱动压缩式技术,可以有效减少能源消耗,减轻对臭氧层的破坏,从而达到节能与环保的目的,符合绿色发展的要求。
LiBr-H2O或LiCl-H2O吸收式制冷可以很好的利用低品位能源,并且具有节省能源、对环境无污染和多功能性的优点。当前,大型船舶的主柴油机和发电柴油机的排烟温度因机型的不同能够达到150到200之间不等,其中蕴含大量废热,约占燃油发热量的10%~20%,吸收式制冷技术不同于以前的制冷理念,不使用压缩机,也不消耗电力,不会产生氟利昂,能够使用余热、废热,对能源反复利用,可以有效节省能源,提升能源利用率。制冷对于满足船舶上的日常生活需求至关重要,尤其是在远距离航行时,制冷不仅可以确保船上食物的新鲜度,还可以确保船员在高温环境中的舒适度。如今,船上很多制冷功能都是由辅机提供的,这不仅增加了成本,而且减少了航行里程。吸收式制冷循环可以将热量转化为冷量,从而很好地解决了这个问题。
首先选用MATLAB分别对冷机中的发生器、冷凝器等各个部件进行了建模计算并且进行热力学分析,它在LiCl-H2O和LiBr-H2O ARS模拟中被认为是可靠的,然后进行了详细的参数研究,设计了两个50kW水冷单效式制冷机模型来进行性能对比。结果表明,在相同工况条件下,LiCl-H2O ARS具有更高的制冷系数(COP)和更低的热负荷。
关键词:溴化锂;氯化锂;吸收式制冷;余热废热
Abstract
At present, the problem of global warming, energy crisis and environmental pollution is becoming more and more serious. It is urgent to implement energy saving and environmental protection. The use of heat-driven refrigeration technology to replace the traditional electric-driven compression technology that requires a lot of power and refrigerants can effectively reduce energy consumption and reduce the destruction of the ozone layer, and has the dual role of saving energy and protecting the environment.
Lithium bromide absorption refrigeration has great advantages in the use of low-grade energy, and also has the advantages of saving energy, non-polluting the environment and multi-use of one machine. At present, most commercial ships use internal combustion diesel engines as main propulsion devices and power generation , during the sailing of the ship or loading and unloading at the port, the exhaust temperature of the main engine of the large ship and the diesel engine for power generation is still up to 150 ~ 200 after passing through the turbocharger and exhaust gas boiler. It contains a lot of waste heat, which contains about 10% to 20% of the calorific value of fuel oil. The absorption refrigeration technology has abandoned the traditional cooling concept, without compressor, no electricity consumption, and no freon, the waste heat and waste heat of exhaust are used as a cascade recycling energy. It can save energy more effectively and improve the utilization rate of energy, especially when performing long-distance voyage tasks at sea. In order to meet the daily life needs of ships, refrigeration is essential. Refrigeration can not only ensure the freshness of food on board. It can also guarantee the comfort of the crew's life in a higher temperature environment. Today, much of the refrigeration on the ship is provided through auxiliary machines, which will not only increase the cost, but also reduce the mileage of the voyage. Absorption refrigeration cycle can be converted into cooling capacity by heat, which solves this problem well.
Firstly, MATLAB software is used to theoretically model the generator, condenser and other components in the chiller and perform thermodynamic analysis. It is considered to be reliable in the simulation of LiCl-H2O and LiBr-H2O ARS, and then a detailed parameter study was carried out. Two 50kW water-cooled single-effect refrigerator models were designed for performance comparison. The results show that under the same working conditions, LiCl-H2O ARS has a higher cooling coefficient (COP) and lower heat load.
Keywords: lithium bromide; lithium chloride; absorption refrigeration; waste heat
目 录
摘 要 3
Abstract 4
第一章 绪论 1
1.1课题研究背景 1
1.2目的及意义 1
1.3国内外研究现状 2
1.3.1国内吸收式制冷现阶段热门问题 2
1.3.2 国外研究现状 4
1.4本文研究内容 5
第二章 吸收式制冷系统介绍 6
2.1吸收式制冷系统的工质 6
2.1.1吸收式制冷系统的工质介绍 6
2.1.2溴化锂溶液和氯化锂溶液的性质 8
2.2 吸收式制冷系统工作原理 9
第三章 数学建模 12
3.1 软件介绍 12
3.2 模型假设 12
3.3 热力学配方 12
第四章 结果和分析 16
4.1 吸收器和冷凝器温度对两种不同工质系统的影响 16
4.1.1 吸收器和冷凝器温度同时对两种不同工质系统的影响 16
4.1.2 吸收器温度对LiCl-H2O和LiBr-H2O两种系统的影响 17
4.1.3 冷凝器温度对LiCl-H2O和LiBr-H2O两种系统的影响 17
4.1.4 关于吸收器和冷凝器温度两种不同工质系统影响的小结 18
4.2 发生器温度对LiCl-H2O和LiBr-H2O两种系统的影响 18
4.3蒸发器温度对LiCl-H2O和LiBr-H2O两种系统的影响 19
4.4溶液热交换器的有效性对系统的影响 20
第五章 船用主机吸收制冷系统应用分析 22
5.1 柴油机废热驱动吸收式制冷系统的数据依据 22
5.2废热量与吸收式制冷系统工况匹配 23
第六章 结论 26
参考文献 29
致 谢 31
第一章 绪论
1.1课题研究背景
随着化石能源的不断消耗,可开采储量日渐减少,当前我们面临的最主要的能源问题是能源短缺,就此发展下去我们可能将会面临的真正的能源问题是不断增加的能源消耗最终会作为热量消散,从而带来的全球增温效应。到2050年,中国的人均能耗根据预测为4.75~9.31 tce,最大值也仅为美国人均能耗的76%,而中国的整体能耗会持续增加,2050年能源消费总量预计可达到661.91×108~121.33×108tce[1]。
经济的发展使人们对资源的依赖度增长,而中国石油储量仅占世界总储量的2.3%[1],可采寿命也仅剩约20.6年,中国正面临着能源短缺与环境污染两大难题。面对这种情况,我们必须要节约能源,采取低能耗的工作方式,增加能源的二次利用,避免废热直接排放,减少废热损失。