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Experimental Investigation of an Advanced Organic Rankine Vapor Compression Chiller

机译:一种先进的有机朗肯蒸汽压缩式冷水机组的实验研究

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摘要

Thermally driven chilling technologies convert heat into cooling. These systems can support increasing cooling demands using waste heat in a variety of applications. Commercial thermally driven chilling technologies suffer from several implementation challenges, including high capital costs, limited equipment lifecycles, rigid working principles, and large physical formats, and thus are not implemented widely. Organic Rankine vapor compression cooling systems are a pre-commercial technology which can address the limitations of commercial alternatives. Organic Rankine vapor compression cooling systems couple an organic Rankine power generation cycle to a standard vapor compression chilling cycle. These systems can use benign, pressurized refrigerants as working fluids which allows for reduced heat exchanger costs over commercial thermally driven alternatives without environmentally impactful fugitive emissions. Refrigerants are released from cooling technologies during charging, leaking connections, and/or improper/unregulated disposal. Furthermore, the coupling of the two individual cycles allows the use of high-speed compression and expansion machinery as well as multiple methods of heat recuperation. High-speed fluid machinery and heat recuperation strategies reduce the format and cost of the technology while simultaneously improving the longevity and operational flexibility.Current organic Rankine vapor compression efforts are limited from an absence of experimental validation. This study aims to fill this research gap through investigating a prototype organic Rankine vapor compression system enhanced with a high-speed, centrifugal turbo-compressor, sub cycle and cross cycle heat recuperation, compact heat exchanger technologies, and benign, next-generation refrigerants at an industry-relevant scale of 300 kW. A thermodynamic model was created and a system heat-to-cooling coefficient of performance (COP) of 0.65 was simulated with 91°C liquid waste heat, 30°C condenser coolant, and 7°C chilled water delivery where a 5°C inlet to outlet temperature difference was specified for each stream. A full-scale prototype was fabricated and tested following standards for performance rating of commercial water chilling technologies to validate the performance simulation. Experimental testing of the prototype yielded a thermal COP of 0.56 and a cooling duty of 264 kW under its baseline operating conditions. The baseline test conditions were identical to the simulated conditions except the temperature difference across the condensers, which was 1.7°C greater due to a 25.6% lower condenser coolant flowrate. The lower condenser coolant flowrate, a vapor compression condenser refrigerant outlet vapor mass quality of 6.2% instead of the modeled 1°C of subcooling, and elevated system pressure losses limited the efficiency and cooling duty of the prototype over the simulated values. A scenario analysis on the test data was complete to show the prototype could surpass the simulated performance prediction with a COP of 0.66 at 300 kW of cooling if the operational limitations associated with prototype were corrected. This performance is competitive with commercial single-effect absorption systems and is possible because the turbomachinery efficiencies were high. The isentropic efficiency values for the turbine and compressor were 76.7% and 84.8% respectively at the baseline conditions during experimentation and the two devices had a 100% power transmission efficiency within experimental error.Following the assessment of baseline performance, operational characteristics of the technology were quantified at off-design boundary conditions and normalized to those of the baseline to identify performance trends. It was shown that prototype thermal performance generally improved with increasing waste heat supply temperature, increasing chilled water delivery temperature, decreasing condenser coolant temperature, and decreasing chilling duty. These tren
机译:热驱动冷却技术将热量转化为冷却。这些系统可以在各种应用中利用废热来支持日益增长的冷却需求。商用热驱动冷却技术面临多项实施挑战,包括高昂的资本成本、有限的设备生命周期、严格的工作原理和大型物理格式,因此没有得到广泛实施。有机朗肯蒸汽压缩冷却系统是一种商业化前技术,可以解决商业替代品的局限性。有机朗肯蒸汽压缩冷却系统将有机朗肯发电循环与标准蒸汽压缩冷却循环相结合。这些系统可以使用良性的加压制冷剂作为工作流体,与商业热驱动替代方案相比,可以降低热交换器成本,而不会对环境造成影响。制冷剂在充气、连接泄漏和/或不当/不受监管的处置过程中从冷却技术中释放出来。此外,两个独立循环的耦合允许使用高速压缩和膨胀机械以及多种热回收方法。高速流体机械和热回收策略减少了技术的格式和成本,同时提高了使用寿命和操作灵活性。由于缺乏实验验证,目前的有机朗肯蒸气压缩工作受到限制。本研究旨在通过研究原型有机朗肯蒸汽压缩系统来填补这一研究空白,该系统采用高速离心式涡轮压缩机、子循环和交叉循环热回收、紧凑型热交换器技术和良性的下一代制冷剂增强,行业相关规模为 300 kW。创建了一个热力学模型,并使用 91°C 液体废热、30°C 冷凝器冷却剂和 7°C 冷冻水输送模拟了 0.65 的系统热冷却性能系数 (COP),其中每个流指定了 5°C 的入口到出口温差。按照商用水冷却技术的性能评级标准制造和测试了全尺寸原型,以验证性能模拟。原型的实验测试在其基准工作条件下产生了 0.56 的热 COP 和 264 kW 的冷却负荷。基线测试条件与模拟条件相同,但冷凝器之间的温差不同,由于冷凝器冷却剂流速降低 25.6%,冷凝器温差增加了 1.7°C。冷凝器冷却液流量较低,冷凝器蒸汽压缩时制冷剂出口的蒸汽质量质量为6.2% 而不是模拟的 1°C 过冷度,并且系统压力损失的增加限制了原型的效率和冷却负荷超过模拟值。对测试数据的情景分析已经完成,表明如果纠正了与原型相关的操作限制,原型可以在 300 kW 冷却下以 0.66 的 COP 超过模拟性能预测。这种性能与商用单效吸收系统相比具有竞争力,并且由于涡轮机械效率很高,因此成为可能。在实验期间,涡轮机和压缩机的等熵效率值分别为76.7%和84.8%,两种装置在实验误差范围内的功率传输效率为100%。在对基线性能进行评估后,在非设计边界条件下量化了该技术的操作特性,并根据基线的特性进行归一化,以确定性能趋势。结果表明,随着余热供应温度的升高、冷冻水输送温度的提高、冷凝器冷却液温度的降低和冷却负荷的降低,原型的热性能普遍得到改善。这些 tren

著录项

  • 作者

    Grauberger, Alex Michael.;

  • 作者单位

    Colorado State University.;

  • 授予单位 Colorado State University.;
  • 学科 Mechanical engineering.;Thermodynamics.;Energy.
  • 学位
  • 年度 2022
  • 页码 260
  • 总页数 260
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Mechanical engineering.; Thermodynamics.; Energy.;

    机译:机械工程。;热力学。;能源。;
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