两级压缩空气源热泵系统的性能分析

发布时间：2018-06-06 02:27

  本文选题：两级压缩循环 + 空气源热泵　； 参考：《东华大学》2014年硕士论文

【摘要】：现阶段我国经济飞速发展,城市化进程不断加快,能源过度消耗的问题愈发严重。空气源热泵系统作为一种高效、节能、环保的装置,非常符合我国的能源状况和环境要求,并且已在我国长江中下游、华南及西南等地区得到广泛应用。由于北方地区气温较低,空气源热泵在推广过程中出现了很多问题,采用普通的空气源热泵系统会发现压缩机的排气温度过高,输气系数剧减,压缩机压比过大,其制热能力和性能系数都大大降低,系统频繁启停,无法正常工作。本论文提出可以采用两级压缩两级节流中间不完全冷却空气源热泵系统,建立理论循环模型,并对模型进行优化分析。具体主要研究内容如下： 本课题通过介绍两级压缩热泵系统的研究背景及发展。引入对空气源热泵系统的原理和过程的研究,分别建立单级压缩空气源热泵系统模型和四种两级压缩空气源热泵系统模型,四种两级压缩模型为：两级节流中间不完全冷却、两级节流中间完全冷却、一级节流中间不完全冷却、一级节流中间完全冷却。通过单级压缩模型和两级压缩模型对比,得出两级压缩系统在降低系统压缩比、排气温度等方面优于单级压缩。通过两级压缩四种循环的对比,得出两级压缩中间不完全冷却循环形式因制热效率高、排气温度低等优点,可以作为一种比较理想的两级压缩循环方式应用于北方地区。 在此基础上,本课题基于已经建立的两级压缩两级节流中间不完全冷却制热循环模型,分两种情况来研究重要参数。两种情况分别是压缩机输气量可变和压缩机输气量不可变,重要参数为性能系数COP、单位制热量、工质质量流量、压缩机轴功率、高压级排气温度等参数随蒸发温度的变化情况。本课题将压缩机输气量不可变情况下的参数：系统压缩比、高压级压缩机排气温度、低压级压缩机吸气比容、制热量和性能系数COP的模拟值和其他文献实验值对比。 其次,对两次节流中间不完全冷却两级压缩空气源热泵系统,提出一种多目标优化方法,以单位制热量和性能系数COP为优化对象,以中间压力为优化变量。当COP和单位制热量同等重要时,COP少量降低,系统的单位制热量增加,减少能耗和环境污染的同时,满足冬季室内热舒适性和生活卫生用热水需求。当蒸发温度-30℃,冷凝温度30℃时,可使系统的单位制热量增加3.1%,而COP仅降低1.6%,COP达到2.6。当蒸发温度-30℃,冷凝温度60℃时,可使系统的单位制热量增加3.6%,而COP仅降低1.8%,COP达到1.9,最后,对未来的研究趋势提出设想与展望。
[Abstract]:At present, the economy of our country is developing rapidly, the process of urbanization is speeding up, and the problem of excessive consumption of energy is becoming more and more serious. Air source heat pump system, as a kind of high efficiency, energy saving and environmental protection device, has been widely used in the middle and lower reaches of the Yangtze River, South China and Southwest China. Because of the low temperature in the northern region, there are many problems in the popularization of air-source heat pump. Using the ordinary air-source heat pump system, it will be found that the exhaust temperature of the compressor is too high, the gas transmission coefficient is greatly reduced, and the pressure ratio of the compressor is too large. Its heating capacity and performance coefficient are greatly reduced, the system frequently start and stop, can not work normally. In this paper, a two-stage compression two-stage air source heat pump system with intermediate incomplete cooling is proposed, and the theoretical cycle model is established, and the model is optimized and analyzed. The main research contents are as follows: This paper introduces the research background and development of two-stage compression heat pump system. By introducing the principle and process of air-source heat pump system, the single-stage compressed air source heat pump system model and four two-stage compressed air source heat pump system models are established. The four two-stage compression models are: two-stage throttling incomplete cooling, The two-stage throttling is completely cooled, the first-stage throttling is not completely cooled, and the first-stage throttling is completely cooled. By comparing the single-stage compression model with the two-stage compression model, it is concluded that the two-stage compression system is superior to the single-stage compression system in reducing the compression ratio and exhaust temperature. Through the comparison of four cycles of two-stage compression, it is concluded that the incomplete cooling cycle in the middle of two-stage compression can be used as an ideal two-stage compression cycle in northern China because of its high heating efficiency and low exhaust temperature. Based on the established two-stage compression and two-stage throttling incomplete cooling and heating cycle model, the important parameters are studied in two cases. The main parameters are the performance coefficient COP, the unit heating capacity, the mass flow rate of the working fluid, the axial power of the compressor, the exhaust temperature of the high pressure stage and so on. In this paper, the parameters of the compressor under the condition of immutable air output: system compression ratio, exhaust temperature of the high pressure stage compressor, suction specific volume of the low pressure stage compressor, heating capacity and performance coefficient COP are compared with other experimental results. Secondly, a multi-objective optimization method is proposed for two-stage compressed-air source heat pump system with two throttling intermediate incomplete cooling. The optimization object is the unit heating capacity and the performance coefficient COP, and the intermediate pressure is the optimization variable. When the COP and the unit heating amount are equally important, the cop decreases slightly, the unit heating capacity of the system increases, the energy consumption and environmental pollution are reduced, and the indoor thermal comfort and sanitary hot water demand are met in winter. When the evaporation temperature is -30 鈩，

本文编号：1984617