Air-side heat transfer characteristics of flat plate finned-tube heat exchangers with large fin pitches under frosting conditions

Lee, Moo‐Yeon; Kim, Yong-Han; Lee, Hosung; Kim, Yongchan

doi:10.1016/j.ijheatmasstransfer.2010.02.047

Cited by 56 publications

(17 citation statements)

References 15 publications

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“…Therefore, boundary layer interruption between fins can occur theoretically for a fin space of 7.0 mm at an air flow rate of 1.0 m 3 /min. That is, the boundary layer interruption for a fin space of more than 7.0 mm can be avoided under the given conditions because the boundary layer interruption is largely dependent on the fin space [25]. This is consistent with the results of Kim [22].…”

Section: Numerical Resultssupporting

confidence: 90%

Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps

Lee

2012

Advances in Mechanical Engineering

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The objective of this study is to provide the numerical model for prediction of the frost growth of the round plate fin for the purpose of using it as a round plate fin-tube heat exchanger (evaporator) under frosting conditions. In this study, numerical model was considering the frost density change with time, and it showed better agreement with experimental data of Sahin (1994) than that of the Kim model (2004) and the Jonse and Parker model (1975). This is because the prediction on the frost height with time was improved by using the frost thermal conductivity reflecting the void fraction and density of ice crystal with frost growth. Therefore, the developed numerical model could be used for frosting performance prediction of the round plate fin-tube heat exchanger.

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Section: Numerical Resultssupporting

confidence: 90%

Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps

Lee

2012

Advances in Mechanical Engineering

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“…The result provided by Kim et al [60] also revealed the above conclusion. They measured the change of sessile droplet temperature with time on a cold surface (its static contact angle was 75 ± 1 • ), when the cold surface temperature, the outdoor air temperature (T a ) and relative humidity (RH) were held constant at-10 ± 0.2 • C, 25 ± 1 • C and Energies 2018, 11, 2642 5 of 36 30 ± 3%, respectively, without forced air flow around the cold surface [60]. The results are showed in Figure 3.…”

Section: Figurementioning

confidence: 99%

“…To promote the rapid development of ASHP technology and the successful implementation of Coal to Electricity policy in China, the anti-frosting and defrosting technologies are focused by researchers worldwide in recent years [14]. According to the references, the anti-frosting technologies include changing the characteristics (temperature, velocity [20], humidity [21], pressure [22] and purified air [23]) of inlet ambient air, changing the cold surface temperature [24], surface treatment [25], changing the structure of air heat exchanger (fin-tube geometry [26][27][28], fin spacing [29,30], fin type [31,32]), changing the interaction between air or frost layer and cold surface (electric field [33], ultrasonic wave [34], magnetic field [35] and low frequency mechanical oscillation [36]). And the defrosting technologies mainly have reverse cycle [37], hot gas bypass [38], electrical heating [19,39,40], warm-air defrosting [41], compressor shutdown [42], hot water spray [43], phase change heat storage, electric field [44], ultrasonic wave [45], magnetic field [46], air-particle jet [47], control strategy [48] and waste heat recovery [49,50].…”

Section: Introductionmentioning

confidence: 99%

“…Finally, combined with the frosting phenomenon, the future researches to develop the frost-free technology for the ASHP system will be given from four aspects: optimization of system performance, new material (liquid/solid desiccant), new method, optimization of the control strategy. [29,30], fin type [31,32]), changing the interaction between air or frost layer and cold surface (electric field [33], ultrasonic wave [34], magnetic field [35] and low frequency mechanical oscillation [36]). And the defrosting technologies mainly have reverse cycle [37], hot gas bypass [38], electrical heating [19,39,40], warm-air defrosting [41], compressor shutdown [42], hot water spray [43], phase change heat storage, electric field [44], ultrasonic wave [45], magnetic field [46], air-particle jet [47], control strategy [48] and waste heat recovery [49,50].…”

Section: Introductionmentioning

confidence: 99%

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Frosting Phenomenon and Frost-Free Technology of Outdoor Air Heat Exchanger for an Air-Source Heat Pump System in China: An Analysis and Review

Zhang

Zhang³

et al. 2018

Energies

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Frost layer on the outdoor air heat exchanger surface in an air-source heat pump (ASHP) can decrease the system coefficient of performance (COP). Although the common defrosting and anti-frosting methods can improve the COP, the periodic defrosting not only reduces the system energy efficiency but also deteriorates the indoor environment. To solve these problems, it is necessary to clearly understand the frosting phenomenon and to achieve the system frost-free operation. This paper focused firstly on the analyses of frosting pathways and frosting maps. Followed by summarizing the characteristics of frost-free technologies. And then the performances of two types of frost-free ASHP (FFASHP) systems were reviewed, and the exergy and economic analysis of a FFASHP heating system were carried out. Finally, the existing problems related to the FFASHP technologies were proposed. Results show that the existing frosting maps need to be further improved. The FFASHP systems can not only achieve continuous frost-free operation but reduce operating cost. And the total COP of the FFASHP heating system is approximately 30–64% higher than that of the conventional ASHP system under the same frosting conditions. However, the investment cost of the FFASHP system increases, and its reliability also needs further field test in a wider frosting environment. In the future, combined with a new frosting map, the control strategy for the FFASHP system should be optimized.

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“…Their investigations revealed that round tube heat exchanger showed the longest refrigeration time due to its larger surface area. Some other researchers have equally examined the frost formation and effect of frost layer on the performance of fin-tube heat exchanger [21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Investigation on thermal-hydraulic performance of outdoor heat exchanger in air sources heat pump

Zhaosong

Cheng

et al. 2017

Experimental Thermal and Fluid Science

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A plethora of findings exists on the decreasing heat transfer performance of ASHP under frosting condition. This study investigates, using field and laboratory experiments, the frosting behavior and heat transfer performance of fin-tube exchangers. Findings from our initial observation revealed the severity of frosting phenomenon during winter in hot summer and cold winter zone of China; for avoiding the lower COP, defrosting period of ASHP was not bigger than 60 min. The results showed that although the basic tube surface temperature decreases with running time and remains stable after 70 min, an adverse pressure drop ensued. The findings, thereby suggests a 70 min defrosting period in ASP. Comparing / and COP between exchangers revealed an improved performance of plain fin-tube exchanger over that of louver fintube exchanger in all the test conditions. Therefore, under frosting condition, plain fin-tube heat exchanger provides a superior thermal-hydraulic performance over louver fin-tube heat exchanger. Findings from this study will help designers and facility managers in taking a more informed decision when selecting heat exchanger types for ASHP.

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Air-side heat transfer characteristics of flat plate finned-tube heat exchangers with large fin pitches under frosting conditions

Cited by 56 publications

References 15 publications

Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps

Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps

Frosting Phenomenon and Frost-Free Technology of Outdoor Air Heat Exchanger for an Air-Source Heat Pump System in China: An Analysis and Review

Investigation on thermal-hydraulic performance of outdoor heat exchanger in air sources heat pump

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