采用双节流装置的CO2引射制冷系统的变工况性能实验研究

对采用双节流装置的跨临界CO_2引射制冷循环系统在不同工况下的性能进行了实验研究,比较了影响引射器性能和系统COP的因素。实验结果表明,在固定引射器几何尺寸的条件下,气体冷却器出口压力为8.5MPa、蒸发温度为-5和-1℃时,引射比随气冷器出口温度的增大而逐渐增大,系统COP则呈下降趋势;当气冷器出口温度为41℃、蒸发温度为-5℃时,工作流体、引射流体质量流量及引射比均随着气冷器出口压力的增大而出现不同程度的增加,系统COP则呈下降趋势。在相同工况条件下,采用两段式喷嘴引射器的双节流跨临界CO_2制冷系统的COP整体上大于传统带有膨胀阀的跨临界CO_2制冷系统的COP。     

氟利昂引射式制冷机的性能研究

本文研究了引射式制冷机的性能,当工质采用氟利昂时,可以利用低位热能来制冷,编制了计算机仿真程序,分析了状态参数对制冷机性能的影响。计算结果表明这一装置适合于空调系统。     

高压天然气引射升压装置

本文综述“高压天然气引射升压装置”的研制目的,运行机理,性能特点,计算软件,设计方法,台架试验,应用范围和前景。     

船舶柴油机混合式双级引射红外抑制喷管研究

为了提高船舶柴油机高温排气冷却效果,降低排气系统红外辐射信号,提出一种新型褶圆与圆排瓣形的混合式双级引射红外抑制喷管。同时引进传统单级褶圆喷管进行性能对比,采用数值模拟方法得到单级及双级不同瓣峰瓣谷相对位置下的气动差异及温度分布情况。结果表明:峰-峰双级喷管较单级褶圆喷管,在额定工况下压力损失减少3.72%,引射比提升11.11%, 0.45工况下压力损失减少3.76%,引射比提升13.04%;峰-谷双级喷管较单级褶圆喷管,额定工况下压力损失减少0.43%,引射比提升7.84%,在0.45工况下压力损失减少0.55%,引射比提升8.7%。在混合管壁面温度控制及主流中心高温降低效果上,峰-峰双级喷管最优,其次为峰-谷双级喷管,最后为单级褶圆喷管。     

引射泵及其在小型热水锅炉水循环布局中的作用

1．小型热水锅炉的自然循环问题我国生产热水锅炉的厂家，在设计时比较提倡自然循环．但小型快装锅炉的特点就是高度小．小于2．8MW热水锅炉自然循环的有效高度很难达到2m，因此，自然循环的动力压头很小。依据上式，当0．8MPa时．设计状态下为最大为15．83kg／m3．因此．310．63Pa。若真能让A下／A上达到0．4以上，则能使达到0．15～0．2m／s的量级．勉强可维持最低限度的在该压力下不发生表面沸腾的速度。但锅炉真正的运行压力常在0．4MPa左右（它取决于热网系统流阻状况和所取循环泵的特性线），且常为常小于。而真实有效高度h又常达…     

上海东海天然气引射调峰试验

本文介绍了天然气输配特性以及引射调峰装置在上海北蔡储配站的应用，进行了引射调峰试验并绘制了引射器的特性曲线。结果表明，通过引射调峰可提高球罐利用率，达到用气高峰时增加调峰量，低谷时增加储气量。在去冬今春的实际运行中的取得了较好的效果。     

蒸汽引射器引射汽轮机排汽供热的研究与应用

为了缓解电厂出现的供热不足问题和减少冷端损失,提出了通过蒸汽引射器引射汽轮机乏汽用于供热的方法,并对蒸汽引射器引射汽轮机排汽的工作原理进行了分析介绍。以某330 MW的机组为例,对其利用蒸汽引射器引射汽轮机排汽进行了热力和经济性分析。结果表明:增设蒸汽引射器后,在一个供暖周期内可以为电厂增加供热量367.62 GJ/h,有很大的节能潜力。     

引射器中工况参数对引射特性影响规律的数值分析

为完善引射式预混燃烧器中引射器的操作特性,对工况参数进行数值模拟分析,分别研究工作流体速度v、被引射压力P2和出口压力P3对引射器引射特性的影响.模拟结果显示,对预混燃烧器中引射器的运行优化,有助于提高燃烧效率.     

低压人工煤气储气罐的引射利用

提出一种改造费用低、效果好的低压人工煤气储气罐改造利用技术，并研究超音速天然气引射器的设计与分析方法。可充分利用现有设施，解决西气东输中沿途城市的天然气转换问题。     

Comparative analysis of thermodynamic performance of CO2 cascade refrigeration system assisted with expander and mechanical subcooling

In order to discuss the feasibility of using R744/R744 cascade refrigeration system (CRS) instead of R744/R717 CRS, six configurations of R744/R744 CRS assisted with expander and mechanical subcooling system (MS) are analyzed. Based on the thermodynamic analysis, the results show that the high pressure, the condensing temperature of the low‐temperature cycle (LTC), and the degree of subcooling of LTC and the high‐temperature cycle (HTC) are three important operating parameters with an optimum value corresponding to the maximum coefficient of performance (COP). Compared with other CRSs, CRS with HTC throttling valve and MS of HTC (CTS_H) and CRS with HTC expander and MS of HTC (CES_H) show an excellent performance. CES_H has the highest COP and is improved by an average of 13.8% compared with the COP of R744/R717 CRS. The COP of CTS_H is improved by an average of 4.2% compared with the COP of R744/R717 CRS. In conclusion, it is an efficient way to improve performance that CRS combines MS in HTC and HTC expander. And it is possible R744/R744 CRS instead of R744/R717 CRS.     

太阳能喷射/压缩复合制冷循环性能研究

研究了一种太阳能喷射/压缩复合制冷循环,由太阳能集热子系统、喷射制冷子系统及压缩制冷子系统组成,系统充分利用热电两种能源以及两种制冷方法各自的优点,优化喷射制冷子系统工作性能的同时,改善压缩式子系统的工作条件,从而提高复合制冷循环性能的同时节约高品位电能。采用性能较好的高蒸发温度式喷射制冷带走压缩机排气余热具有实际意义。通过数值模拟的手段分析系统性能及其主要影响因素,并优化工作条件。研究表明,与相同工作条件下的单压缩制冷循环相比,复合制冷循环工作日全天候运行时电力性能系数提升约为31.5%,节电优势显著。存在一个最佳的喷射子系统蒸发温度使得复合制冷循环性能系数达到运行工况的最大值。     

太阳能喷射式制冷系统性能的实验研究

对太阳能喷射式制冷系统进行了实验研究,采用电加热模拟太阳能辐射的方法,研究了冷凝器、发生器和蒸发器温度对制冷系统COP的影响,给出了太阳能喷射式制冷系统制冷能力与COP随时刻的变化关系。系统在80℃热源条件下,全天提供16℃的冷水,系统最大制冷量为0.43 kW。     

太阳能喷射式制冷系统的模拟

介绍了结构简单、工作可靠的太阳能喷射式制冷系统的原理和工作过程,给出了一个模拟计算。采用Ｒ１３４ａ为制冷剂,在发生器温度９０℃、冷凝器温度２０～３８℃和蒸发器温度 ６～１４℃时,对系统效率进行了模拟计算。结果表明,该系统具有一定的可行性。本文还对理想状况下水作为制冷剂的系统效率进行了讨论。     

发生温度对太阳能喷射式制冷系统性能的影响研究

为了确定发生温度对太阳能喷射式制冷系统性能的影响,基于太阳能喷射式制冷系统试验台,以蒸发温度、冷凝温度及室内环境温度为定量,发生温度为变量进行了试验研究.试验结果表明:当喷射器结构确定时,喷射系数ER、系统性能系数COP和机械性能系数COP_m均不会随着发生温度的升高一直增大,系统必然存在一个最佳的发生温度使其性能达到最佳.研究可为今后最佳发生温度的选择及实际应用中如何维持系统高效运行提供理论指导.     

Thermodynamic analysis of subcooling and superheating effects of alternative refrigerants for vapour compression refrigeration cycles

This paper presents a computer‐based first law and exergy analysis applied to vapour compression refrigeration systems for determining subcooling and superheating effects of environmentally safe new refrigerants. Three refrigerants are considered: R134a, R407c and R410a. It is found that subcooling and superheating temperatures directly influence the system performance as both condenser and evaporator temperatures are affected. The thermodynamic properties of the refrigerants are formulated using artificial neural network (ANN) methodology. Six ANNs were trained to predict various properties of the three refrigerants. The training and validation of the ANNs were performed with good accuracy. The correlation coefficient obtained when unknown data were used to the networks were found to be equal or very near to 1 which is very satisfactory. Additionally, the present methodology proved to be much better than the linear multiple regression analysis. From the analysis of the results it is found that condenser and evaporator temperatures have strong effects on coefficient of performance (COP) and system irreversibility. Also both subcooling and superheating affect the system performance. This effect is similar for R134a and R407c, and different for R410a. Copyright © 2005 John Wiley & Sons, Ltd.     

热回收式CO2制冷系统性能研究

对热回收式CO2制冷系统性能COP进行了计算和分析,结果表明:蒸发温度、气体冷却器出口CO2温度、热水加热器入口水温是影响其COP的主要因素;回热器出口过热度对COP的影响较小,对压缩机的排气温度影响较大;随着排气压力的升高,COP是否出现峰值,取决于气体冷却器入口制冷剂的特征温度;在相同工况下,蒸发温度、气体冷却器出口CO2温度、回热器出口过热度对最佳排气压力的影响较小,热水加热器入口水温是影响最佳排气压力的主要因素。     

回热器对低温空气制冷系统性能影响的实验研究

随着环保问题的日益突出,空气制冷系统的理论和实验研究重新受到重视。通过对开式空气制冷系统的三种回热方案进行实验测试对比,分析了回热器对系统性能及除湿效果的影响。实验结果表明:与无回热的空气制冷系统相比,在相同的工况下,二级回热系统可大幅降低涡轮出口温度,最大降低约8.5℃,并可大幅降低涡轮进口的含湿量,最大降低约35%。同时一级回热系统和二级回热系统均可大幅增加系统的COP和制冷量,但一级回热器对涡轮进口含湿量的影响较小。     

Experimental investigation on subcooling of liquid hydrogen by helium gas injection through evacuation

Subcooling is the process of bringing down the temperature of liquids lower than that of the boiling point of the corresponding vapor pressure. The performance of subcooling of cryogenic liquids mainly depends on the heat-inleak of the system, the helium injection mass flow rate, helium injection temperature, and helium injection nozzle pattern. This paper presents an alternative method, by making use of the least heat in the leakage of the liquid hydrogen storage container, which is quite possible because containers with excellent thermal insulation are commercially available nowadays. The process involved is rapid evacuation through gas ejectors, thus reducing the effect of temperature. The advantage and the process of evacuation leading to subcooling in a unique manner are the objective of this article. The experimental results are discussed in comparison with the thermophysical process involved in the subcooling operation. A comparative study is also carried out with the theoretical heat exchange process in which helium is used as a medium for the economy of the stated process. It is stated that the current process of subcooling through evacuation is superior to the conventional heat exchange process.