Comparative study for CO2 and R-134a heat pump tumble dryer – A rational approach

Sian, Rony A.; Wang, Chi-Chuan

doi:10.1016/j.ijrefrig.2019.05.027

Cited by 23 publications

(5 citation statements)

References 60 publications

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“…As early as the end of the last century, researchers at the University of Essen in Germany found that CO2 was more energy efficient than R134a in drying clothes in a laundry room, with a COP of 5.5 and energy savings of up to 55% [97] . Sian et al [98] also confirmed that a CO2 dryer had higher drum outlet air and clothing temperatures than those of the R134a dryer, improved specific humidity extraction and COP, and reduced drying time by 15%. In addition, Li et al [99] also found that a two-stage drying system had a higher specific humidity extraction rate than that of the single-stage drying CO2 system and a higher energy utilization efficiency than that of the power dryer.…”

Section: Co2 Heat Pump Dryingmentioning

confidence: 93%

Research progress and applications of transcritical carbon dioxide heat pumps: A review

Mei,

Liu,

Liu

2023

Clean Energ. Sci. Tech.

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Heat pump technology is an energy-saving technology that can efficiently utilize low-grade energy. It has broad application prospects in building heating, industrial waste heat utilization, new energy and other fields. However, the refrigerants used in traditional heat pump systems have serious negative impacts on the environment, and there is an urgent need to find a safe, environmentally friendly, and efficient alternative refrigerant. As a natural refrigerant, CO2 has good physical and chemical properties and is very suitable as a working fluid in transcritical cycles, showing great advantages in the field of heat pump technology. At present, research on CO2 heat pumps has made certain progress, but there are few reviews of the research status and development trends of CO2 heat pumps in different applications. Therefore, this article systematically summarizes the latest research results of transcritical CO2 heat pumps in different application fields, pointing out the difficulties such as high pressure and low operating efficiency in system design and operation. It also summarizes the latest optimization research on system components, cycle structure, mixed refrigerants and control strategies. The results show that each optimization method can significantly improve system performance, among which mixed refrigerant is the simplest optimization method. Finally, the outlook for CO2 heat pump technology is put forward. With policy support and technological advancement, more comprehensive, energy-saving, and intelligent CO2 heat pump technology will continue to develop and innovate.

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Section: Co2 Heat Pump Dryingmentioning

confidence: 93%

Research progress and applications of transcritical carbon dioxide heat pumps: A review

Mei,

Liu,

Liu

2023

Clean Energ. Sci. Tech.

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“…进行优化。Chen 等 [90] 针对电动汽车制热的中间冷却双级 CO2 热泵系统提出了一种基于 COP 最优的控制策略。该策略使制热量和 COP 随环境温度降低而显著提高，COP 提高了 18.9%-61.9%。Zhang 等 [91] 采用模型预测控制策略，优化了铁路车辆中超临界 CO2 空调系统的运行，相比 PID 控制策略，平均 COP 提高了 7.4%。Wang 等 [92] 设计了一种新颖的模型预测控制器，用于电动汽车的超临界 CO2 车舱热管理系统，相比于 PI 控制器，能耗降低了 13.33%-20.27%。Wang 等 [93] 提出了一种新颖的无霜控制策略，用于解决电动汽车热泵结霜导致的性能下降问题，发现无霜控制策略在运行时间超过 60 min 时是最佳选择。Yin 等 [94] [95] 。因此，寻找一种更高效、更节能的干燥技术已经成为了一个重要的研究方向。 CO2 跨临界热泵干燥系统具有加热温度高(最高加热温度 110 ℃左右)、系统响应快、高效节能及运行成本低等优势 [96] 。图 14 展示了跨临界 CO2 热泵烘干机的系统原理，通过气体冷却器加热空气，加热了的空气再通入干燥室进行干燥。早在上个世纪末，德国 Essen 大学的研究人员就发现， CO2 在热泵在洗衣房干燥衣物方面比 R134a 更节能，其 COP 达到 5.5，节能率高达 55% [97] 。Sian 等 [98] 等也证实了 CO2 干燥器比 R134a 干燥器有更高的滚筒出口空气温度和衣物温度，且其比湿度提取率和 COP 都有所提高，干燥时间缩短了 15%。此外，Li 等 [99] 也发现两级干燥系统的比湿度提取率高于单级干燥 CO2 系统，能源利用效率高于电力干燥器。研究。周安仁等 [96] 研究了其在烘茶技术方面的性能，发现该技术可以大幅度降低烘茶的负荷和峰值负荷比，同时还能保证茶叶的品质。Zhang 等 [100] 研究了 CO2 热泵烫虾系统，与传统的燃料烫虾系统相比，该系统可以显著降低能耗和运行成本，同时还能提高虾的经济价值。另一方面，夏飞等 [101] 设计了适用于中药材干燥要求的 CO2 热泵干燥装置，该装置不仅环保、节能，适用范围广，而且能满足中药材干燥的特殊要求，保证其有效成分和药效。在仿真研究方面，Sarkar 等 [102] 对 CO2 热泵干燥器的进行了模拟研究，并探讨了各种参数对系统性能的影响。结果表明干燥效率、再循环空气比、环境温度和空气质量流量等参数对系统性能有显著影响，而旁路空气比和环境相对湿度的影响较小。Erdem 等 [103] 建立了一个基于 MATLAB 软件的 CO2热泵滚筒干燥器的理论模型，并分析了不同的工作参数对系统性能的影响。结果表明 CO2作为工质具有良好的物理和环保特性，通过优化参数可以显著降低干燥时间和能耗。Jokiel 等 [104] 基于…”

Section: Co2 混合制冷剂研究unclassified

跨临界二氧化碳热泵研究进展与应用综述

梅申功,

刘中毅,

刘夏

2023

Journal of Clean Energy Science and Technology

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热泵技术是一种能够高效利用低品位能源的节能技术，在建筑供暖、工业余热利用、新能源等领域具有广阔的应用前景。然而，传统的热泵系统使用的制冷剂对环境有着严重的负面影响，亟需寻找一种安全、环保、高效的替代制冷剂。CO2作为一种天然制冷剂，具有良好的物理和化学特性，且非常适合作为跨临界循环的工质，在热泵技术领域显示出了巨大的优势。目前对CO2热泵的研究已经取得了一定的进展，但关于CO2热泵在不同应用场合的研究现状和发展趋势的综述较少，因此，本文系统地总结了跨临界CO2热泵在不同应用领域的最新研究成果，指出其在系统设计和运行过程中存在的压力较高，运行效率低等困难，并总结出最新的系统部件、循环结构、混合制冷剂和控制策略几方面的优化研究，结果表明了各优化方式对系统性能都有明显的提升，其中混合制冷剂是最简单的优化方式。最后，对CO2热泵技术提出展望，随着政策的扶持和技术的进步，更全面、节能和智能的CO2热泵技术将持续地发展和创新。

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“…At the same time, R407C was phased out due to concerns about its environmental impact. Sian and Wang (2019) completed comparative studies of CO 2 and R134a heat pump tumble dryers and showed that heat pumps using CO 2 could be competitive with R134a. They also confirmed the solid prevalence of the CO 2 system over R134a in terms of COP, specific moisture extracted ratio (SMER), and drying time.…”

Section: Introductionmentioning

confidence: 99%

Experimental assessment of a low GWP nonflammable new refrigerant in a closed heat pump drying system

Yang

et al. 2022

J Food Process Engineering

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Low global warming potential (GWP) refrigerants are vital to mitigating the effect of heat systems on climate change. A low GWP mixture, RGT2 (R134a/R1234yf/R161, 54%/43%/3% weight), was proposed as an alternative refrigerant for R134a in heat pump systems. This article presented the results of an experimental investigation evaluating RGT2 as a possible replacement for R134a in a closed heat pump drying (CHPD) system and studying the drying characteristics of fig slices. The experiment concluded that RGT2 has a higher coefficient of performance (COP hp ) value than R134a, on average, by 1.92%, achieving lower discharge temperature and pressure ratio at different condensing temperatures (45 C-70 C). Although the heating capacity of RGT2 was slightly lower, it still met the requirements of HPD. With careful consideration of the environment, performance, and safety, RGT2 was a suitable substitute for R134a in the drying field. In addition, the drying characteristics of fig slices were significantly affected by the air temperature. The effective diffusion coefficient (D eff ) and specific moisture extracted ratio (SMER) are increased by increasing temperature and air flow rate. The two-term model was the better model to accurately predict the fig slices drying process. The highest mean D eff and SMER of CHPDS were obtained as 6.4518 Â 10 À10 m 2 /s and 39.197 g/kWh, respectively, at the highest drying air temperature. Practical ApplicationA mixed refrigerant (RGT2) was proposed to replace R134a, and its GWP value was about 61% lower than that of R134a. Most of the studies on substituting R134a in the literature are simulations. This paper aims to evaluate the substitutions' feasibility theoretically and experimentally. The results have been assessed to provide better information about RGT2 as a potential substitute for R134a with superior comprehensive performance. Drying kinetics has also been determined experimentally, which helped to simulate fig drying. This study will provide a reference for refrigerants replacement in heat pump drying.

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Comparative study for CO2 and R-134a heat pump tumble dryer – A rational approach

Cited by 23 publications

References 60 publications

Research progress and applications of transcritical carbon dioxide heat pumps: A review

Research progress and applications of transcritical carbon dioxide heat pumps: A review

跨临界二氧化碳热泵研究进展与应用综述

Experimental assessment of a low GWP nonflammable new refrigerant in a closed heat pump drying system

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