非共沸工质辅助过冷CO2冷热联供系统的热力学性能分析

doi:10.11949/0438-1157.20221670

摘要/Abstract

摘要：

为满足食品加工领域对高温消毒和冷冻的双重需求，提出了基于非共沸工质辅助过冷的跨临界CO₂冷热联供系统，辅助循环采用低GWP非共沸工质，充分利用冷凝热及气体冷却器放热生产高温热水，并同时进行食品冷冻。以COP为目标函数，对混合工质的组元、组分进行分析，对系统的排气压力和过冷度的影响进行优化。结果表明系统存在最优排气压力和最优过冷度，大温度滑移工质相对小温度滑移工质和纯工质能够显著提升系统性能，降低排气压力。采用R32/R1234ze(Z)(0.4/0.6) 时COP最高为3.45，相对纯工质R32和R1234ze(Z) 分别提高4.77%和5.15%，排气压力降低0.958 MPa和0.910 MPa。CO₂循环对系统整体起主导作用。采用非共沸工质可提高系统效率。可为推广CO₂制冷热泵技术的应用提供理论参考。

关键词: 非共沸工质, 跨临界CO₂, 机械过冷, 冷热联供, 大温度滑移, 双级压缩

Abstract:

In order to meet the requirements of uperization and freezing in the field of food processing, two-stage compression transcritical CO₂ cooling and heating system with dedicated mechanical subcooling using zeotropic refrigerant is proposed. The subcooling cycle that uses low global warming potential (GWP) zeotropic refrigerant makes full use of the heat of the condenser and gas cooler to produce hot water. Additionally, cooling capacity is also generated for food freezing. Setting the coefficient of performance (COP) as the objective function, the component, mass fraction, discharge pressure and subcooling degree of the system are analyzed and optimized. The results show that the system has optimal discharge pressure and subcooling degree. The large temperature glide working fluid can significantly improve the system performance and reduce the discharge pressure comparing with the small temperature glide and pure working fluid. The highest COP of 3.45 is achieved when R32/R1234ze(Z) (0.4/0.6) is utilized, which is 4.77% and 5.15% higher than that of pure R32 and R1234ze(Z), and the discharge pressure drops by 0.958 MPa and 0.910 MPa, respectively. The CO₂ cycle plays a dominant role for the overall system. The system exergy efficiency can also be improved by using zeotropic refrigerant. This study can provide a theoretical reference to widen the application of CO₂ refrigeration and heat pump technology.

Key words: zeotropic refrigerant, transcritical CO₂, mechanical subcooling, combined cooling and heating supply, large temperature glide, two-stage compression

中图分类号:

TK 11⁺4

代宝民, 王启龙, 刘圣春, 张佳宁, 李鑫海, 宗凡迪. 非共沸工质辅助过冷CO₂冷热联供系统的热力学性能分析[J]. 化工学报, 2023, 74(S1): 64-73.

Baomin DAI, Qilong WANG, Shengchun LIU, Jianing ZHANG, Xinhai LI, Fandi ZONG. Thermodynamic performance analysis of combined cooling and heating system based on combination of CO₂ with the zeotropic refrigerant assisted subcooled[J]. CIESC Journal, 2023, 74(S1): 64-73.

图/表 13

图1 机械过冷CO2冷热联供系统图

Fig.1 Diagram of mechanical subcooling CO2 combined cooling and heating system

图2 机械过冷CO2冷热联供系统T-s图

Fig.2 T-s diagram of mechanical subcooling CO2 combined cooling and heating system

表1 制冷剂的物理特性、安全性和环境特性［28］

Table 1 The physical properties， safety and environmental characteristics of refrigerant［28］

工质	物理性质				安全特性		环境特性
工质	分子量	T_b/℃	T_cr/℃	p_cr/MPa	LEL/%	安全等级	大气寿命/a	ODP	GWP
R744	44.01	-78.5	31.1	7.38	—	A1	>50	0	1
R1270	42.08	-47.7	92.4	4.66	2.0	A3	0.001	0	-20
R601	72.15	36.1	196.6	3.37		A3		0	4
R290	44.10	-42.1	96.7	4.25	2.1	A3	0.041	0	约20
R161	48.06	-37.6	102.2	5.09	3.8	—	0.21	0	12
R32	52.02	-51.7	78.1	5.78	14.1	A2	4.9	0	675
R1234ze(Z)	114.04	9.0	153.6	3.97	—	—	—	—	<6
R600	58.12	-0.49	152.0	3.8	1.85	A3	—	0	0.1
R1234yf	114.04	-29.5	94.7	3.38	6.2	A2L	0.029	0	<4.4
R152a	66.05	-24.0	113.3	4.52	4.8	A2	1.4	0	124

图3 温度滑移随第一组元组分的变化

Fig.3 Variation of temperature glide with the mass fraction of the first component

图4 COP随排气压力和过冷度的变化

Fig.4 COP variation with discharge pressure and subcooling degree

图5 系统性能参数随过冷度的变化

Fig.5 Variation of system performance parameters with subcooling degree

图6 COP随第一组元组分的变化

Fig.6 Variation of COP with the mass fraction of the first component

图7 组分对温度匹配的影响

Fig.7 Effect of mass fraction on the temperature matching

图8 采用不同工质时系统最优过冷度

Fig.8 System optimum subcooling degree corresponding to different working fluid pairs

图9 采用不同工质时系统最优排气压力

Fig.9 System optimum discharge pressure corresponding to different working fluid pairs

图10 压缩机功耗比随第一组元质量分数的变化规律

Fig.10 Variation of compressor power consumption ratio with mass fraction of the first component

图11 不同工况下系统COP变化

Fig.11 System COP variation at different working conditions

图12 系统损及效率随第一组元质量分数的变化规律

Fig.12 System exergy loss and exergy efficiency with mass fraction of the first component

参考文献 30

1	董益秀, 王如竹. 高温热泵的循环、工质研究及应用展望[J]. 化工学报, 2023, 74(1): 133-144.
	Dong Y X, Wang R Z. High temperature heat pump: cycle configurations, working fluids and application potentials[J]. CIESC Journal, 2023, 74(1): 133-144.
2	UNEP Ozone Secretariat. In twenty-eighth meeting of the parties to the montreal Protocol on substances that deplete the ozone layer: 10-14 October 2016[R]. Kigali, Rwanda, 2016.
3	Lorentzen G. Revival of carbon dioxide as a refrigerant[J]. International Journal of Refrigeration, 1994, 17(5): 292-301.
4	Song Y L, Cui C, Yin X, et al. Advanced development and application of transcritical CO₂ refrigeration and heat pump technology—A review[J]. Energy Reports, 2022, 8: 7840-7869.
5	Ma Y T, Liu Z Y, Tian H. A review of transcritical carbon dioxide heat pump and refrigeration cycles[J]. Energy, 2013, 55: 156-172.
6	Kim M H, Pettersen J, Bullard C W. Fundamental process and system design issues in CO₂ vapor compression systems[J]. Progress in Energy and Combustion Science, 2004, 30(2): 119-174.
7	Kauf F. Determination of the optimum high pressure for transcritical CO₂-refrigeration cycles[J]. International Journal of Thermal Sciences, 1999, 38(4): 325-330.
8	Llopis R, Cabello R, Sánchez D, et al. Energy improvements of CO₂ transcritical refrigeration cycles using dedicated mechanical subcooling[J]. International Journal of Refrigeration, 2015, 55: 129-141.
9	Llopis R, Nebot-Andrés L, Cabello R, et al. Experimental evaluation of a CO₂ transcritical refrigeration plant with dedicated mechanical subcooling[J]. International Journal of Refrigeration, 2016, 69: 361-368.
10	代宝民, 刘圣春, 孙志利, 等. 机械过冷CO₂跨临界制冷循环性能理论分析[J]. 制冷学报, 2018, 39(1): 13-19.
	Dai B M, Liu S C, Sun Z L, et al. Theoretical performance analysis of CO₂ transcritical refrigeration cycle with mechanical subcooling[J]. Journal of Refrigeration, 2018, 39(1): 13-19.
11	Nebot-Andrés L, Sánchez D, Calleja-Anta D, et al. Experimental determination of the optimum working conditions of a commercial transcritical CO₂ refrigeration plant with a R-152a dedicated mechanical subcooling[J]. International Journal of Refrigeration, 2021, 121: 258-268.
12	Nebot-Andrés L, Calleja-Anta D, Sánchez D, et al. Experimental assessment of dedicated and integrated mechanical subcooling systems vs parallel compression in transcritical CO₂ refrigeration plants[J]. Energy Conversion and Management, 2022, 252: 115051.
13	Liu S C, Lu F P, Dai B M, et al. Performance analysis of two-stage compression transcritical CO₂ refrigeration system with R290 mechanical subcooling unit[J]. Energy, 2019, 189: 116143.
14	Cao F, Cui C, Wei X Y, et al. The experimental investigation on a novel transcritical CO₂ heat pump combined system for space heating[J]. International Journal of Refrigeration, 2019, 106: 539-548.
15	Song Y L, Li D Z, Yang D F, et al. Performance comparison between the combined R134a/CO₂ heat pump and cascade R134a/CO₂ heat pump for space heating[J]. International Journal of Refrigeration, 2017, 74: 592-605.
16	Song Y L, Cao F. The evaluation of the optimal medium temperature in a space heating used transcritical air-source CO₂ heat pump with an R134a subcooling device[J]. Energy Conversion and Management, 2018, 166: 409-423.
17	He Y J, Cheng J H, Chang M M, et al. Modified transcritical CO₂ heat pump system with new water flow configuration for residential space heating[J]. Energy Conversion and Management, 2021, 230: 113791.
18	Cheng J H, He Y J, Zhang C L. New scenario of CO₂ heat pump for space heating: automatic mode switch between modified transcritical and cascade cycle in one system[J]. Applied Thermal Engineering, 2021, 191: 116864.
19	梁坤峰, 冯长振, 王莫然, 等. 非共沸工质换热匹配特性影响热泵性能的高级㶲分析[J]. 化工学报, 2021, 72(4): 2038-2046.
	Liang K F, Feng C Z, Wang M R, et al. Advanced exergy analysis of heat pump performance affected by heat transfer matching characteristics of non-azeotropic refrigerants[J]. CIESC Journal, 2021, 72(4): 2038-2046.
20	Dai B M, Liu S C, Li H L, et al. Energetic performance of transcritical CO₂ refrigeration cycles with mechanical subcooling using zeotropic mixture as refrigerant[J]. Energy, 2018, 150: 205-221.
21	Llopis R, Toffoletti G, Nebot-Andrés L, et al. Experimental evaluation of zeotropic refrigerants in a dedicated mechanical subcooling system in a CO₂ cycle[J]. International Journal of Refrigeration, 2021, 128: 287-298.
22	Yao L, Li M X, Hu Y S, et al. Comparative study of upgraded CO₂ transcritical air source heat pump systems with different heat sinks[J]. Applied Thermal Engineering, 2021, 184: 116289.
23	林励冠, 代彦军, Armin Hafner. 两级R744超市中央制冷系统节能特性[J]. 化工学报, 2018, 69(S2): 394-401.
	Lin L G, Dai Y J, Armin H. Performance of R744 commercial centralized refrigeration systems[J]. CIESC Journal, 2018, 69(S2): 394-401.
24	李敏霞, 詹浩淼, 王派, 等. 一种带引射器和经济器的CO₂跨临界制冷系统[J]. 化工学报, 2021, 72(S1): 146-152.
	Li M X, Zhan H M, Wang P, et al. A CO₂ transcritical refrigeration system with ejector and economizer[J]. CIESC Journal, 2021, 72(S1): 146-152.
25	代宝民, 剧成成, 粱梦桃, 等. 机械过冷跨临界CO₂热泵供暖系统性能分析[J]. 制冷学报, 2019, 40(4): 29-36.
	Dai B M, Ju C C, Liang M T, et al. Performance analysis of a transcritical CO₂ heat pump with mechanical subcooling for space heating[J]. Journal of Refrigeration, 2019, 40(4): 29-36.
26	李小燕, 代宝民, 滑雪, 等. 基于引射器的双温蒸发CO₂热泵系统性能分析[J]. 制冷学报, 2022, 43(2): 54-61.
	Li X Y, Dai B M, Hua X, et al. Performance analysis of CO₂ dual-temperature evaporation heat pump system with an ejector[J]. Journal of Refrigeration, 2022, 43(2): 54-61.
27	Zühlsdorf B, Jensen J K, Cignitti S, et al. Analysis of temperature glide matching of heat pumps with zeotropic working fluid mixtures for different temperature glides[J]. Energy, 2018, 153: 650-660.
28	Calm J M, Hourahan G C. Physical, safety, and environmental data for current and alternative refrigerants[C]//Proceedings of 23rd international congress of refrigeration (ICR2011. Prague, RepublicCzech, 2011: 21-26.
29	代宝民, 张鹏, 刘圣春, 等. 采用非共沸工质机械过冷跨临界CO₂热泵供暖性能分析[J]. 制冷学报, 2021, 42(6): 51-58.
	Dai B M, Zhang P, Liu S C, et al. Performance of transcritical CO₂ air-source heat pump heating system with mechanical subcooling using zeotropic refrigerant[J]. Journal of Refrigeration, 2021, 42(6): 51-58.
30	Liao S M, Zhao T S, Jakobsen A. A correlation of optimal heat rejection pressures in transcritical carbon dioxide cycles[J]. Applied Thermal Engineering, 2000, 20(9): 831-841.

[1]	李沛昀, 李杨, 王文彬, 王文. 三角转子膨胀机在跨临界CO₂制冷循环中的应用分析[J]. 化工学报, 2021, 72(S1): 161-169.
[2]	梁坤峰, 冯长振, 王莫然, 董彬, 王林, 刘瑞见. 非共沸工质换热匹配特性影响热泵性能的高级分析[J]. 化工学报, 2021, 72(4): 2038-2046.
[3]	刘洋, 韩吉田, 游怀亮. 基于SOFC/GT/TCO₂复合动力循环和溴化锂制冷机的冷热电联供系统性能[J]. 化工学报, 2018, 69(S2): 341-349.
[4]	贺素艳, 邵超, 杨玉涛, 王超, 赵有信. 混合工质配比对自复叠制冷循环影响的理论模拟和实验研究[J]. 化工学报, 2018, 69(S1): 108-114.
[5]	黄仁龙, 罗向龙, 梁志辉, 陈颖. 基于分液冷凝的R245fa/pentane混合工质朗肯循环多目标优化[J]. 化工学报, 2018, 69(5): 2040-2048.
[6]	刘剑, 张小松. 基于大滑移温度非共沸工质的双温冷水机组[J]. 化工学报, 2016, 67(4): 1186-1192.
[7]	刘琦, 马国远, 许树学. 单机双级滚动活塞压缩机热泵系统的性能特性[J]. 化工学报, 2013, 64(10): 3599-3605.
[8]	金旭1，王树刚1，张腾飞1，李照义2，祖丰1. 变工况双级压缩中间压力及其对系统性能的影响[J]. 化工学报, 2012, 63(1): 96-102.
[9]	刘兆永，赵力，赵学政. 高温热泵工况下非共沸工质在换热器中的换热特性[J]. CIESC Journal, 2011, 62(12): 3386-3393.
[10]	谢英柏;刘迎福;汤建成;孙刚磊. 中间完全冷却CO₂跨临界双级压缩节流循环 [J]. CIESC Journal, 2010, 61(3): 551-556.

非共沸工质辅助过冷CO₂冷热联供系统的热力学性能分析

Thermodynamic performance analysis of combined cooling and heating system based on combination of CO₂ with the zeotropic refrigerant assisted subcooled

RichHTML

PDF (PC)

可视化

摘要/Abstract

引用本文

使用本文

图/表 13

参考文献 30

相关文章 10

编辑推荐

Metrics

本文评价