An experimental study on convective boiling of R-22 and R-410A in Horizontal smooth and micro-fin tubes

Kim, Yong Chan; Lee, Kyu Jung; Park, Youn Cheol

doi:10.1007/bf03185095

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…Можно усомниться в достоверности экспериментальных данных, полученных разными специалистами. Например, в опытах по кипению R410A при одинаковой температуре t о = 5 о С получен градиент давления (dР/dz) э = 7100 Па в статье [4] и 4750 Па в статье [13]. Расчетные их значения различаются несущественно и по методике [12] составили 2706 и 3209 Па, соответственно.…”

Section: обсуждение результатовunclassified

“…Расчетные их значения различаются несущественно и по методике [12] составили 2706 и 3209 Па, соответственно. Различие условий кипения характеризуется значениями d o = 9,52 мм, wρ = 250 кг/ (м•с 2 ), q = 12500 Вт/м 2 в статье [4], а в статье [13] шению градиента давления, то уменьшение диаметра d o с 9,52 до 7 мм, наоборот, вызывает рост градиента давления. Уменьшение теплового потока с 12500 до 5000 Вт/м 2 приводит к увеличению длины зоны кипения l к , что сопровождается ростом как падения давления, так и среднего его градиента.…”

Section: обсуждение результатовunclassified

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Refrigerant R410A pressure drop in the coils of air-cooler with internal micro-fins

Koshelev¹,

Eideyus²,

Slastikhin³

2018

Journal IAR

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Калининградский государственный университет Балтийская государственная академия рыбопромыслового флота Проведен анализ данных по эффективности внутреннего микрооребрения в испарителях, экспериментально определено падение давления хладагента в змеевиках канального воздухоохладителя, работающего на хладагенте R410A. Во время теплотехнических испытаний холодильной машины со змеевиковым воздухоохладителем измерялось падение давления хладагента R410A на четырех участках трех змеевиков. Измерения проводились в установившихся режимах поочередно по участкам каждого змеевика. Для каждого режима определялись основные параметры холодильной машины. Измеренные падения давления оказались существенно выше расчетных значений, полученных по компьютерной программе для змеевиков из гладких труб. Осуществлено сопоставление полученных данных с результатами расчета по доступным методикам. Осредненные градиенты давления по участкам испытуемого воздухоохладителя, охватывающим 3, 5, 7 и 8 труб длиной 0,855 м, сравнивались с результатами расчета по упомянутым методикам. Расчетные значения опять оказались заметно ниже осредненных по опытным данным градиентов давления. Отчасти это объясняется наличием калачей и местного сопротивления на входе образующегося в змеевиках пара в вертикальный коллектор. Несовпадение расчетных и экспериментальных данных указывает на необходимость углубленного исследования гидродинамики и теплообмена при движении двухфазных потоков в трубах с микрооребрением.

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Section: обсуждение результатовunclassified

Refrigerant R410A pressure drop in the coils of air-cooler with internal micro-fins

Koshelev¹,

Eideyus²,

Slastikhin³

2018

Journal IAR

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“…The flow regime was annular except the entrance region of the test section. Enhancement of heat transfer coefficient was not found although D/B is less than 1.5.Seo et al [18] studied, the evaporation heat transfer coefficients and pressure drops for R-22 and R-410A were measured and analyzed as a function of heat flux, mass flux, evaporating temperature, and tube diameter. The experiments were conducted for the smooth and micro-fin tubes with outside diameters of 9.52 mm and 7.0 mm.…”

Section: Individual Refrigerantsmentioning

confidence: 99%

Review of Nucleate Pool Boiling Heat Transfer using Refrigerant

Ray¹,

Bhaumik²

2017

International Journal of Applied Engineering Research

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Nucleate pool boiling has an important place in refrigeration industries. The pool boiling process occurs in the shell side of flooded evaporators and low pressure refrigerants are proposed for industry applications. Enhancement of heat transfer rate depends on different design of heating surface, type of refrigerant and operating parameters like heating surface roughness, surface orientation, operating pressure & temperature. Refrigerant plays a crucial role in the study of nucleate pool boiling heat transfer. Various inferences have been drawn based on the existing parameters by different researchers for enhancement of heat transfer rate. In this paper a detailed study has been carried out using different refrigerants on different surfaces to investigate the optimum value of heat transfer coefficients (HTC). The process could be further investigated using heat transfer enhancement particles such as nanofluids and modification of the heating surface. The surfaces are characterized with contact angle, roughness, film thickness and scanning electron microscopy (SEM) & atomic force microscopy (AFM) etc. The surface modification can be done by nanocoating or polishing the surface area. The addition of lubricant to individual or binary or ternary refrigerants can significantly alter the boiling phenomena for accumulating lubricant at the nanocoating heat transfer surface. Many researchers explained the heat transfer enhancement techniques by the passive methods. Many authors gave empirical correlations (dimensional and nondimensional) for heat transfer coefficient in terms of surface roughness factor, vapour density, liquid density, etc from their experimental results. But there was no theoretical method to get the value of HTC which is a function of bubble density, surface roughness factor, bubble growth, etc.

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“…Both the local evaporating and condensing heat transfer coefficients of hydrocarbon refrigerants were higher than R-22. [30][31][32]. Higher values of pressure drop were also observed for hydrocarbon refrigerants than R-22.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Using R-410A, R-407C, R-22, and R-134a as Cooling Medium in the Condenser of a Steam Power Plant

Yousef

Hegazy

Engeda

2014

Journal of Engineering for Gas Turbines and Power

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A step-by-step technique has been implemented in the analytical study of heat transfer and pressure gradient characteristics of refrigerants R-410A, R-407C, R-22, and R-134a used as cooling media in the condenser of a steam power plant. Refrigerants are optimized to replace water/air as coolant in the condenser of a steam power plant. Refrigerants have much lower temperatures and much higher heat transfer rates than water or air. The thermal resistances that affect heat transfer characteristics and surface condenser performance are included. The effect of inlet refrigerant temperature and mass flow rate are reported for the four refrigerants. Calculations are performed at two inlet refrigerant temperatures À21 C and À30 C and mass flow rate ranging from 92.905 to 132.905 kg/s. The results revealed that the overall heat transfer coefficient, heat transfer rate, and condensation rate increased with refrigerant mass flow rate, with higher values at lower inlet refrigerant temperatures. For a given refrigerant mass flow rate and inlet temperature, the analytical study indicated that R-410A has higher values of overall heat transfer coefficient, heat transfer rate and condensation rate than R-407C, R-22, and R-314a, respectively. Moreover, it is found that R-410A, at À30 C and 132.905 kg/s, is superior in condensing all steam entering the condenser than the other refrigerants; this corresponds to higher exergy efficiency. The condenser pressure was observed to be slightly higher for R-410A than the other refrigerants.

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An experimental study on convective boiling of R-22 and R-410A in Horizontal smooth and micro-fin tubes

Cited by 7 publications

References 5 publications

Refrigerant R410A pressure drop in the coils of air-cooler with internal micro-fins

Refrigerant R410A pressure drop in the coils of air-cooler with internal micro-fins

Review of Nucleate Pool Boiling Heat Transfer using Refrigerant

Comparative Study of Using R-410A, R-407C, R-22, and R-134a as Cooling Medium in the Condenser of a Steam Power Plant

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