Experimental study on condensation heat transfer of R32, R152a and R22 in horizontal minichannels

Liu, Na; Li, Junming

doi:10.1016/j.applthermaleng.2015.07.062

Cited by 34 publications

(11 citation statements)

References 25 publications

(20 reference statements)

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“…The R32 heat transfer characteristics (largest liquid thermal conductivity) are better than those of R22 [44], and the friction pressure drops are very similar (R32 and R22 show almost equivalent pressure gradients) [45].…”

Section: Condensationmentioning

confidence: 95%

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Mota-Babiloni

Navarro-Esbrí

Makhnatch

et al. 2017

Renewable and Sustainable Energy Reviews

111

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Because air conditioning and heat pump systems contribute greatly to greenhouse gas emissions, equipment with both lower global warming potential (GWP) working fluids and a higher level of performance should be used. R32 (difluoromethane) has been proposed to substitute R410A, particularly in residential air conditioning (RAC) systems. This study collected the most relevant and recent researches into R32 as a refrigerant so as to assess its viability in RAC systems in both Europe and the USA, as compared to R410A and other lower GWP RAC alternatives.The R32 value of GWP is 677, which is below the F-gas regulation limit in RAC equipment (750). According to ASHRAE standard 34, R32 is less flammable than hydrocarbons, and the amount of charge permitted for R32 is above the necessary level in RAC equipment. It can be concluded that R32 has significantly good heat transfer characteristics and a level of performance that make it acceptable at low condensing temperatures, thereby avoiding overly high compressor discharge temperatures. Its performance is very similar to that of R410A across the entire operating range, and it is therefore believed that R32 will be utilized in RAC systems in the remaining countries that prioritize lower GWP fluids but are less strict in their security regulations.To replace R410A under extreme conditions, some system modifications can be conducted, or R32 mixtures with hydrofluoroolefins (HFOs) can be used. Such mixtures achieve a lower performance than R32, but are acceptable replacements when considering their lower GWP compared to that of R32, and similar level of flammability. Finally, other (R32-based) alternative mixtures have also been developed and their behaviours studied under a wide range of operating conditions.

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Section: Condensationmentioning

confidence: 95%

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Mota-Babiloni

Navarro-Esbrí

Makhnatch

et al. 2017

Renewable and Sustainable Energy Reviews

111

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“…The results showed that R152a had better heat transfer performance than R22 and R134a. The experimental research of Liu and Li (2015) also showed that the heat transfer coefficients during condensation of R152a were greater than those of R22. Although R152a is a potential substitute for R22, no experimental study has been carried out on the flow regimes during the entire condensation process in minichannels.…”

Section: Introductionmentioning

confidence: 93%

Flow Regimes and Transitions for Two-Phase Flow of R152a During Condensation in a Circular Minichannel

2021

Self Cite

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Two-phase flow regimes were experimentally investigated during the entire condensation process of refrigerant R152a in a circular glass minichannel. The inner and outer diameters of the test minichannel were 0.75 and 1.50 mm. The channel was 500 mm long to allow observation of all the two-phase flow regimes during the condensation process. The experiments used saturation temperatures from 30 to 50°C, a mass flux of 150 kg/(m2·s) and vapor qualities from 0 to 1. The annular, intermittent and bubbly flow regimes were observed for the experimental conditions in the study. The absence of the stratified flow regime shows that the gravitational effect is no longer dominant in the minichannel for these conditions. Vapor-liquid interfacial waves, liquid bridge formation and vapor core breakage were observed in the minichannel. Quantitative measurements of flow regime transition locations were carried out in the present study. The experiments also showed the effects of the saturation temperature and the cooling water mass flow rate on flow regime transitions. The results show that the annular flow range decreases and the intermittent and bubbly flow ranges change little with increasing saturation temperature. The cooling water mass flow rate ranging from 38.3 kg/h to 113.8 kg/h had little effect on the flow regime transitions.

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“…The two-phase flow and heat transfer characteristics inside the mini/microchannels differ significantly from those inside the macrochannels, which have been extensively researched. Liu et al, [10] experimentally studied the condensing flow characteristics of R32, R152a, and R22 in round and square minichannels and found that R32 and R152a can replace the R22 and have a good heat exchange capacity. Hossain et al, [11] experimentally measured the pressure difference and heat transfer for a new refrigerant, R1234ze, inside the 4.35 mm levelling tube and evaluated the well-known correlations.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analysis of Condensation Heat Transfer and Pressure Drop of Refrigerant R22 in Minichannels of a Printed Circuit Heat Exchanger

Zhao

Zhang

et al. 2020

Energies

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A Printed Circuit Heat Exchanger (PCHE) is a type of highly complete and efficient heat exchanger that consists of numerous mini/micro-channels and has been successfully applied to the Liquefied Natural Gas (LNG) regasification project. During the research presented in this paper, the condensation flow and heat transfer performance of the R22 in PCHE hot side minichannels are analyzed via experiments and numerical simulations, respectively. A liquid nitrogen–R22 experimental loop is established to examine the pressure difference and heat transfer coefficient of R22 in the minichannels of the PCHE hot side. The inlet pressures of the R22 range from 0.5 MPa to 0.65 MPa, the mass flux values are changed from 10.52 kg m−2s−1 to 109.42 kg m−2s−1, and the inlet temperatures vary from 273 K to 289 K. The differences between experiments and simulations are analyzed by comparing the experimental values of the Nusselt number (Nu) and the friction pressure gradient with the numerical ones. Furthermore, the influences of pressure and mass flux on the Nu, as well as the friction pressure gradient, are analyzed in depth through condensation flow regimes to explore the underlying mechanism giving the results.

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Experimental study on condensation heat transfer of R32, R152a and R22 in horizontal minichannels

Cited by 34 publications

References 25 publications

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Flow Regimes and Transitions for Two-Phase Flow of R152a During Condensation in a Circular Minichannel

Experimental and Numerical Analysis of Condensation Heat Transfer and Pressure Drop of Refrigerant R22 in Minichannels of a Printed Circuit Heat Exchanger

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