Effects of surface characteristic on frosting and defrosting behaviors of fin-tube heat exchangers

Wang, Feng; Liang, Caihua; Yang, Mingtao; Fan, Chuanjie; Zhang, Xiaosong

doi:10.1016/j.applthermaleng.2014.10.090

Cited by 123 publications

(24 citation statements)

References 17 publications

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“…Their operation conditions are listed in Table 2 and shown in Figure 9, and the corresponding results are shown in Figure 10. It can be seen that although frosting time was much shorter in severe frosting zone than that in other areas, the frost layers were significantly thicker in this zone (case 1-3) than that in the moderate region and the mild frosting region (case 5,8,11,14) [63]. In addition, based on the severe frosting region in Figures 8b and 9, Su and Zhang [73] proposed the suggested operation region, as shown in Figure 11.…”

Section: Ta-rh Frosting Mapmentioning

confidence: 99%

“…The clean heat supply is defined as using one or more clean or renewable energy, such as electricity (including heat pump system [1,2] and electric boiler), natural gas, biomass and solar energy, to achieve low emission and low energy consumption for heat supply process through a system of high efficient transmission and distribution network and buildings of energy-saving. In all the above mentioned clean and renewable energy resources, an air-source heat pump (ASHP) system is a kind of renewable energy device transferring heat energy from a low-temperature heat source to a high-temperature heat source called a heat sink, using a small amount Frost formation will occur inevitably on the surface of the outdoor air heat exchanger for the ASHP system operating in a cold and humid environment, when the surface temperature is below both the dew point and the freezing point [6][7][8]. During the early initial period of frost formation, the frost crystals depositing on the heat transfer surfaces play the roles of increasing surface area and surface roughness [9,10].…”

Section: Introductionmentioning

confidence: 99%

“…This may enhance the heat transfer between the surface and the outdoor air [11,12]. However, with the growth of frost layer, the frost accumulation may cause two problems as follows: (1) an increase in heat transfer resistance between the air and the cold surface and a decrease in heat transfer efficiency [8]; (2) an increase in the resistance of air flowing through the heat exchanger, a reduction of air mass flow rate and an increase of pressure drop in the air-side and power consumption [13,14]. As a result, the COP of the ASHP system is significantly degraded [15].…”

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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Section: Ta-rh Frosting Mapmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…The outdoor thermal parameters all cases but most of them, the air condition defrosts at a period between 50 and 70 min [26,35].…”

Section: Tablementioning

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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“…Los parámetros considerados para el estudio involucran temperaturas de almacenamiento de agua en el generador, temperaturas del refrigerante en el evaporador y condensador, temperatura de subenfriamiento de hielo, espesor de hielo y velocidad de liberación y extracción de calor de forma natural. Fue importante estudiar la generación de hielo, tomando en cuenta que, al aumentar el espesor aumenta la resistencia de transferencia de calor [22,23]. El equipo utilizado para el estudio paramétrico está conformado por una unidad condensadora L'UNIQUE HERMETIQUE CAJ2428ZBR de 1/2 HP de capacidad, que utiliza R404a como refrigerante, una válvula de expansión TES 2 -0,45, filtro A-TD -132 SAE, visor de líquidos SGI-10, válvula solenoide TR ¼ 032F8107, presóstato, manómetros, tablero de control, conjunto tanque-reservorio, sistema de aire para agitación de agua y un evaporador alojado en el tanque (Figura 1), que está conformado por dos serpentines de cobre tipo L de 15,88 mm (1/2 pulg) de diámetro, cada uno de 3 metros de longitud.…”

Section: Introductionunclassified

Estudio paramétrico para optimización de un generador de hielo tubular de laboratorio

Guapulema

Hidalgo²

2019

ings

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En Ecuador existe un gran consumo energético por climatización y refrigeración en los sectores industrial, comercial y residencial. Un método para reducir la demanda eléctrica máxima es incorporar un sistema óptimo de almacenamiento de energía térmica de refrigeración. Este trabajo tiene por objetivo realizar el estudio paramétrico de un generador de hielo tubular de laboratorio para su posterior optimización. Se estudiaron los principales parámetros que intervienen en la formación de hielo como temperatura del agua en el reservorio, temperaturas del refrigerante en el evaporador y condensador, temperatura de subenfriamiento del hielo y velocidad de formación de hielo. Los parámetros destacados que intervinieron en el proceso fueron las condiciones ambientales del lugar y la temperatura del agua utilizada. Al disminuir la temperatura ambiental, disminuye la carga térmica y mejora la eficiencia del condensador, el cual influye directamente sobre la eficiencia del equipo. La inestabilidad observada en la primera hora de prueba intervino en la temperatura final del agua, la misma que varió en el rango de 1,1 °C a –0,4 °C en 3 horas.

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Effects of surface characteristic on frosting and defrosting behaviors of fin-tube heat exchangers

Cited by 123 publications

References 17 publications

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

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

Estudio paramétrico para optimización de un generador de hielo tubular de laboratorio

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