STUDY ON THEORETICAL OPTIMAL DEFROSTING QUANTITY OF AIR-SOURCE HEAT-PUMP WITH FLASH-TANK VAPOUR-INJECTION

Liu Xianglong; Yang Hao; Luo Chen; Hu Guang; Liu Zepeng; Zhou Maojun

doi:10.19912/j.0254-0096.tynxb.2023-1915

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Acta Energiae Solaris Sinica ›› 2024, Vol. 45 ›› Issue (7) : 407-414. DOI: 10.19912/j.0254-0096.tynxb.2023-1915

STUDY ON THEORETICAL OPTIMAL DEFROSTING QUANTITY OF AIR-SOURCE HEAT-PUMP WITH FLASH-TANK VAPOUR-INJECTION

Liu Xianglong¹, Yang Hao¹, Luo Chen¹, Hu Guang¹, Liu Zepeng¹, Zhou Maojun²

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Abstract

To address this energy waste, this paper conducts a theoretical analysis by introducing relevant frost formation models and combines experimental data to derive a semiempirical formula for the "theoretically optimal defrosting amount". The formula mainly involves parameters such as cold surface temperature, moisture content of saturated water vapour, time, and wind speed. Moreover, this paper explains why defrosting does not occur during the early stage of frost formation and highlights that this factor has a relatively minor impact on the overall predictive performance. To verify the effectiveness of the formula, this paper conducted experiments on a manufacturer's supplemental gas enthalpy booster-type secondary compression air-source heat pump under various operating conditions. Experimental tests were conducted in a temperature range of -4 ℃ to 4 ℃ at relative humidity levels of 65%, 70%, and 80%. The actual defrosting amount observed under different conditions was compared with the "theoretically optimal defrosting amount" calculated using a semiempirical formula, and it was found that the relative error between the two was relatively small, within ±10%. The study showed that the formula provided a relatively accurate prediction of the frost amount in the later period of frost formation, and it could serve as a reference for designing supplemental heating control and secondary compressor enthalpy for controlling the defrosting time of air-source heat pumps.

Key words

air source heat pumps / vapor injection / defrost / heat transfer characteristics / optimal amount of defrosting / frost model

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Liu Xianglong, Yang Hao, Luo Chen, Hu Guang, Liu Zepeng, Zhou Maojun. STUDY ON THEORETICAL OPTIMAL DEFROSTING QUANTITY OF AIR-SOURCE HEAT-PUMP WITH FLASH-TANK VAPOUR-INJECTION[J]. Acta Energiae Solaris Sinica. 2024, 45(7): 407-414 https://doi.org/10.19912/j.0254-0096.tynxb.2023-1915

References

[1] 王伟, 吴旭, 孙育英, 等. 不同除霜周期对空气源热泵运行性能影响的实测研究[J]. 暖通空调, 2018, 48(6): 1-7, 60.
WANG W, WU X, SUN Y Y, et al.Influence of different defrosting cycles on operating performance of air-source heat pumps[J]. Heating ventilating & air conditioning, 2018, 48(6): 1-7, 60.
[2] 刘西安, 陈海, 冯荣杰, 等. 分段除霜持续供热空气源热泵系统除霜性能研究[J]. 太阳能学报, 2023, 44(11): 1-8.
LIU X A, CHEN H, FENG R J, et al.Defrost performance study of continuous heating air source heat pump system with segmented defrost[J]. Acta energiae solaris sinica, 2023, 44(11): 1-8.
[3] 赵洪运, 宇世鹏, 邱国栋, 等. 可实现“无霜效果” 的蓄热型空气源热泵系统实验研究[J]. 太阳能学报, 2021, 42(4): 61-67.
ZHAO H Y, YU S P, QIU G D, et al.Experimental study on heat storage air source heat pump system with “no frost effect”[J]. Acta energiae solaris sinica, 2021, 42(4): 61-67.
[4] 赵洪运, 邱国栋, 宇世鹏. 可实现快速制热和除霜的蓄能型空气源热泵系统的实验研究[J]. 太阳能学报, 2021, 42(3): 184-190.
ZHAO H Y, QIU G D, YU S P.Experimental study on energy storage air source heat pump system with quick heating and defrosting[J]. Acta energiae solaris sinica, 2021, 42(3): 184-190.
[5] HU W J, FAN J, SONG M J, et al.An experimental study on the frosting characteristic and performance of a micro-channel evaporator in an air source heat pump unit[J]. Energy and buildings, 2020, 224: 110254.
[6] LIANG S M, WANG W, SUN Y Y, et al.A novel characteristic index for frosting suppression based on the configuration and operation of air source heat pumps[J]. International journal of refrigeration, 2020, 109: 161-171.
[7] 刘向龙, 曾智, 王艳, 等. 补气增焓准二级压缩空气源热泵热水器实验测试方法[J]. 湖南工程学院学报(自然科学版), 2020, 30(1): 75-80.
LIU X L, ZENG Z, WANG Y, et al.Experimental methods on air source heat pump water heater of two-stage compression with flash tank vapor-injection[J]. Journal of Hunan Institute of Engineering (natural science edition), 2020, 30(1): 75-80.
[8] 曾智, 刘向龙, 李小华, 等. 补气增焓准二级压缩空气源热泵热水器热力学分析[J]. 制冷技术, 2021, 41(1): 35-40.
ZENG Z, LIU X L, LI X H, et al.Thermodynamic analysis of quasi-secondary compressed enhanced vapor-injection air-source heat pump water heater[J]. Chinese journal of refrigeration technology, 2021, 41(1): 35-40.
[9] LIU X L, HU G, ZENG Z, et al.A novel testing and theoretical approach for air-source heat-pump water heater with flash tank vapor-injection[J]. Engineering research express, 2022, 4(4): 045030.
[10] LIU X L, HU G, ZENG Z.Potential of biomass processing using digester in arrangement with a Brayton cycle, a Kalina cycle, and a multi-effect desalination; thermodynamic/environmental/financial study and MOPSO-based optimization[J]. Energy, 2022, 261(PT. A): 125-222.
[11] LIU X L, HU G, ZENG Z.Performance characterization and multi-objective optimization of integrating a biomass-fueled brayton cycle, a Kalina cycle, and an organic Rankine cycle with a Claude hydrogen liquefaction cycle[J]. Energy, 2023, 263: 125535.
[12] HAYASHI Y, AOKI A, ADACHI S, et al.Study of frost properties correlating with frost formation types[J]. Journal of heat transfer, 1977, 99(2): 239-245.
[13] HERMES C J L, PIUCCO R O, BARBOSA J R J, et al. A study of frost growth and densification on flat surfaces[J]. Experimental thermal and fluid science, 2009, 33(2): 371-379.
[14] LEE J, KIM J, KIM D R, et al.Modeling of frost layer growth considering frost porosity[J]. International journal of heat and mass transfer, 2018, 126(Pt A): 980-988.
[15] XU Z M, WANG Z P, LIANG Z, et al.A frost model based on the frost layer's supporting function[J]. International journal of heat and mass transfer, 2023, 202: 123741.
[16] WESTHAEUSER J, SCHULZE C, ALBRECHT J C, et al.Model for cyclic frosting and defrosting of flat tube heat exchangers: theoretical analysis and experimental validation[J]. Applied thermal engineering, 2023, 225: 120140.
[17] HERMES C J L, LOYOLA F R, NASCIMENTO V S J. A semi-empirical correlation for the frost density[J]. International journal of refrigeration, 2014, 46: 100-104.
[18] KONDEPUDI S N, O'NEAL D L. Performance of finned-tube heat exchangers under frosting conditions: I. Simulation model[J]. International journal of refrigeration, 1993, 16(3): 175-180.
[19] 唐瑾晨. 空气源热泵防融霜过程的热力学与传热特性研究[D]. 长沙: 湖南大学, 2016.
TANG J C.Study of thermodynamics and heat transfer on frost prevention and retardation of air source heat pump[D]. Changsha: Hunan University, 2016.
[20] 陈轶光. 空气源热泵结霜/除霜特性的数值模拟与实验研究[D]. 天津: 天津商学院, 2006.
CHEN Y G.Numerical simulation and experimental study on frosting / defrosting characteristics of air source heat pump[D]. Tianjin: Tianjin University of Commerce, 2006.
[21] 郭宪民, 陈轶光, 汪伟华, 等. 室外环境参数对空气源热泵翅片管蒸发器动态结霜特性的影响[J]. 制冷学报, 2006, 27(6): 29-33.
GUO X M, CHEN Y G, WANG W H, et al.Effects of outdoor air parameters on frosting characteristics of fin-tube evaporator for air source heat pump unit[J]. Journal of refrigeration, 2006, 27(6): 29-33.