穿臨界CO2流體應用於熱泵和烘乾機之系統模擬

在本论文中，开发了一种适用于大中型系统应用的无约束跨临界CO2热泵模型和一种用于衣物烘干应用的瞬态热泵。在每个模型上，考虑了主要部件的详细几何特征，并且与适用于CO2系统的文献中存在的现有模型不同，所开发的模型不对模拟施加约束，例如固定操作压力和恒定温度。然而，压力优化也得到了解决，并且通过泊松类型的最近复杂的无量纲无量纲对数线性相关来调节排热压力。该模型针对各种操作条件的实验数据进行测试，结果准确地反映了实际系统，其性能系数和加热能力的最大误差分别为9.6％和3.9％。此外，两个模型的模拟结果在文献报道的实验结果的背景下进行了讨论和证实。然而，压力优化所采用的广义相关性也经过测试，验证和讨论，与实验数据和文献中提供的其他相关性进行了彻底的比较。相关性可准确预测排热压力，平均误差为1.31％，标准偏差为4.26 bar，适用环境温度适用范围为-18至50°C，-7至15°C和10°C蒸发器和气体冷却器出口分别为50°C。一旦跨临界热泵模型，压力优化方法和热泵干燥器模型得到验证，就会开发出一个完全瞬态的热泵干燥器模型，并使用CO2和R-134a进行模拟，以进行比较。在调查影响两种制冷剂的系统整体性能的相关参数的影响时，进行标准性能测试并随后用作参考案例。随后，进行综合参数研究以确定影响系统性能的相关参数。在这方面，为了比较目的，进行两种系统（CO 2和R-134a）的模拟。此外，还提供了优化系统性能和突出跨临界CO2系统优势的指南和控制策略。

關鍵字

跨临界二氧化碳；热泵系统；烘干机；滚筒烘干机；干燥系统；瞬态模型；动态干燥过程；最佳压力；对照；参数研究

並列摘要

In this thesis, a constrains-free transcritical CO2 heat pump model for medium and large system applications and a transient heat pump for clothes drying applications are developed. On each model, the detailed geometric characteristics of the major component are taken into account and, unlike existing models existing in literature applicable for CO2 system, the developed models do not impose constraints upon simulation, such as fixed operating pressures and constant temperatures. Yet, pressure optimization is also addressed and heat rejection pressure is modulated through a recent sophisticated generalized dimensionless log-linear correlation of the Poisson type. The models are tested against experimental data for a wide range of operating conditions and the results accurately reflected an actual system with a maximum error of 9.6% and 3.9% for the coefficient of performance and heating capacity, respectively. Moreover, the simulation results of both models are discussed and substantiated in the context of experimental results reported in literature. Yet, the generalized correlation employed for pressure optimization is also tested, validated and discussed thorough comparison to experimental data and other correlations available from literature. The correlation can accurately predict heat rejection pressure with an average error of 1.31% and a standard deviation of 4.26 bar, with a valid range of applicability for ambient temperatures from -18 to 50 °C, and within -7 to 15 °C and 10 to 50 °C for the evaporator and gas cooler outlet, respectively. Once the transcritical heat pump model, pressure optimization method and heat pump dryer models are validated, a fully transient heat pump dryer model is developed and simulated using CO2 and then R-134a, for comparison purposes. A standard performance test is carried out and employed later as the reference case when investigating the influence of relevant parameters affecting the overall performance of the system for both refrigerants. Subsequently, comprehensive parametric studies are conducted to identify relevant parameters influencing system performance. In this regard, simulations for both systems (CO2 and R-134a) are conducted for comparison purposes. Additionally, guidelines and control strategies to optimize system performance and highlight the advantages of transcritical CO2 systems are provided.

並列關鍵字

Transcritical CO2 ； heat pump system ； tumble dryer ； transient model ； dynamic drying process ； optimal pressure ； R-134a ； comparison ； parametric study

參考文獻

[1] Ciconkov R. Refrigerants: There is still no vision for sustainable solutions. Int J Refrig 2018;86:441–8. doi:10.1016/j.ijrefrig.2017.12.006.

[2] Ciconkov R. Refrigerants: There is still no vision for sustainable solutions. Int J Refrig 2018;86:441–8. doi:10.1016/j.ijrefrig.2017.12.006.

[3] Lorentzen G, Pettersen J. A new, efficient and environmentally benign system for car air-conditioning. Int J Refrig 1993;16:4–12. doi:10.1016/0140-7007(93)90014-Y.

[4] Lorentzen G. Revival of carbon dioxide as a refrigerant. Int J Refrig 1994;17:292–301. doi:10.1016/0140-7007(94)90059-0.

[5] Lorentzen G. The use of natural refrigerants: a complete solution to the CFC/HCFC predicament. Int J Refrig 1995;18:190–7. doi:10.1016/0140-7007(94)00001-E.

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穿臨界CO2流體應用於熱泵和烘乾機之系統模擬

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