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Journal articles on the topic 'Zeotropic refrigerant'

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Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Nowak, Bernard, and Piotr Życzkowski. "THE EFFECT OF TEMPERATURE GLIDE OF R407C REFRIGERANT ON THE POWER OF EVAPORATOR IN AIR REFRIGERATORS / WPŁYW POŚLIZGU TEMPERATURY CZYNNIKA CHŁODNICZEGO R407C NA MOC PAROWNIKA CHŁODZIARKI POWIETRZA." Archives of Mining Sciences 58, no. 4 (December 1, 2013): 1333–46. http://dx.doi.org/10.2478/amsc-2013-0092.

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Abstract The article discusses the effect of the phenomenon of temperature glide of zeotropic refrigerants on thermal power of an evaporator in an air compression refrigerator. Zeotropic mixtures are subject to phase transitions, the process of which significantly differs from that of homogeneous refrigerants. In contrast to homogeneous refrigerants, where boiling and condensing processes take place at a constant temperature, for the zeotropic mixtures it is essential to know the vapor quality to unambiguously determine the temperature at which the evaporation process is initiated. The R407C refrigerant serves as an example to describe the method of determining the initial temperature of the evaporation process taking into account the effect of temperature glide. The developed formula (7) has been based on a proven linear course of isobars in the two-phase region (Fig. 5) and thus determining a polynomial describing their angle of inclination (8). In addition, temperature calculation formulas (9) and specific enthalpy (10) of dry saturated vapor of the R407C refrigerant have been presented as well. This approach allows to determine the temperature of the R407C refrigerant at the inlet to the evaporator without the required knowledge of its vapor quality. The previously used simplified methods for determining the temperature of a refrigerant at the inlet to the evaporator result in considerable deviations in calculated power of the evaporator compared with its actual value. The presented calculation example involving mine air compression refrigerator of TS-450P type shows that relative deviations of the evaporator thermal power may even exceed 20%. This example compares two simplified methods for determining zeotropic evaporating temperature of a refrigerant used in comparative calculations of refrigerants with the method presented in this article.

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2

Saengsikhiao, Piyanut, and Juntakan Taweekun. "The Data Mining Technique Using RapidMiner Software for New Zeotropic Refrigerant." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, no. 1 (June 3, 2021): 70–90. http://dx.doi.org/10.37934/arfmts.83.1.7090.

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This research presents the development of environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration systems that new azeotropic refrigerant mixture of hydrofluorocarbons and hydrocarbon that can retrofit in the refrigeration system using R404A. The medium back pressure refrigeration testing standard that follow CAN/ANSI/AHRI540 standard air-conditioning, heating, and refrigeration institute (AHRI) and The properties of refrigerants and refrigeration simulation system that used national institute of standards and technology (NIST) reference fluid thermodynamic and transport properties database (REFPROP) software and NIST vapor compression cycle model accounting for refrigerant thermodynamic and transport properties (CYCLE_D-HX) software. The methodology uses decision tree function in datamining by rapid minor software that first of KDnuggets annual software poll that showed new azeotropic refrigerant mixture had cooling capacity, refrigerant effect, GWP and boiling point were lower than R404A but work and pressure for medium temperature refrigeration system of azeotropic refrigerant mixture were higher than R404A. The artificial intelligence (AI) by data mining technic can predictive environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration. The result of refrigerant mixed by R134A, R32, R125 and R1270 and is consistent with the evolution of fourth-generation refrigerants that contain a mixture of HFCs and HCs which are required to produce a low-GWP, zero-ozone-depletion-potential (ODP), high-capacity, low-operating-pressure, and nontoxic refrigerant.

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3

Anusha Peyyala, M. Naga Swapna, B. Purna Chandra Sekhar, and B. Sunil. "Experimental investigation of cop for an air conditioner using zeotropic blend." Global Journal of Engineering and Technology Advances 6, no. 3 (March 30, 2021): 014–23. http://dx.doi.org/10.30574/gjeta.2021.6.3.0028.

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In this project an air conditioner was fabricated using R-410a as refrigerant and its COP is calculated. CFCs have been phased out, except for essential users, and HCFCs are to be eliminated by 2020, because of their ozone depletion potential.This generates a need for the investigation of zero ozone depletion potential (ODP) refrigerants or refrigerant blends.R410A is among newer brand of refrigerant blend, with zero ODP. The biggest difference to R22 is the pressure levels generated which are more than50% higher. The refrigerant R410A operates at higher pressure at the same saturated temperatures than R22, therefore system should be re designed. The overall COP of the system is 5 to 6% more than the R22. We also calculated the relative humidity of room air after it gets cooled, heat removed from the air by considering the input data from weather online which provides us the day to day climatic conditions. Present work provides us regarding performance of an self fabricated zeotropic air conditioner.

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4

Sivakumar, Mayilsamy, and Periasamy Somasudaram. "Thermodynamic investigations of Zeotropic mixture of R290, R23 and R14 on three-stage auto refrigerating cascade system." Thermal Science 20, no. 6 (2016): 2073–86. http://dx.doi.org/10.2298/tsci140103091s.

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The zeotropic mixture of environment friendly refrigerants (hydrocarbons and hydrofluorocarbons) being the only alternatives for working fluid in low temperature refrigeration system. Hence, three-stage auto refrigerating cascade system was studied for the existence using four combinations of three-component zeotropic mixture of six different refrigerants. The exergy analysis confirmed the existence of three-stage auto refrigerating cascade system. The performances of the system like coefficient of performance, exergy lost, exergic efficiency, efficiency defect, and the evaporating temperature achieved were investigated for different mass fractions in order to verify the effect of mass fraction on them. In accordance with the environmental issues and the process of sustainable development, the three-component zeotropic mixture of R290/R23/R14 with the mass fraction of 0.218:0.346:0.436 was performing better and hence can be suggested as an alternative refrigerant for three-stage auto refrigerating cascade system operating at very low evaporating temperature in the range of ?97?C (176 K), at coefficient of performance of 0.253 and comparatively increased exergic efficiency up to 16.3% (58.5%).

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5

Chen, J., and H. Kruse. "Calculating Circulation Concentration of Zeotropic Refrigerant Mixtures." HVAC&R Research 1, no. 3 (July 1, 1995): 219–31. http://dx.doi.org/10.1080/10789669.1995.10391320.

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6

El-Sayed, A. R., M. El Morsi, and N. A. Mahmoud. "A Review of the Potential Replacements of HCFC/HFCs Using Environment-Friendly Refrigerants." International Journal of Air-Conditioning and Refrigeration 26, no. 03 (September 2018): 1830002. http://dx.doi.org/10.1142/s2010132518300021.

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The adequate and efficient performance of HVAC systems are signs of luxury and human comfort, and the improvement of their performance has been the target of continuous researches. Choosing the suitable refrigerant is the main parameter in matching the system components, selecting the type of heat exchangers, the compressor, the expansion device and the suitable lubricant. The theoretically ideal refrigerant is the one having zero ozone depletion potential (ODP), low global warming potential (GWP), nontoxic, nonflammable, has appropriate thermodynamic and heat transfer properties and is compatible with any type of lubricating oil. Chlorinated, fluorinated refrigerants, zeotropic and azeotropic mixtures satisfy many requirements, but have high ODP and GWP and are not compatible with all types of oil. Hydrocarbons (HCs) satisfy all the requirements except being highly flammable. This work reviews previous research aiming to find substitutes for the environmentally harmful refrigerants by other environmentally friendly ones and compare their performance in various HVAC appliances.

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7

Hambarde, M. D., Ramakant Shrivastava, S. R. Thorat, and O. P. Dale. "Experimental investigation on evaporation of R407C in a single horizontal smooth tube." IRA-International Journal of Technology & Engineering (ISSN 2455-4480) 7, no. 2 (S) (July 10, 2017): 266. http://dx.doi.org/10.21013/jte.icsesd201726.

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Due to higher ozone layer depletion potential of HCFC refrigerant, R22 which has been mostly used in house hold refrigeration will be phased out by 2020 as per Montreal Protocol and UNFCCC Regulations. R407C, a zeotropic refrigerant from HFC category is a promising refrigerants in place of R22. Performance evaluation of R407 is required to enhance its application in house hold refrigeration. Hence an experimental investigation is carried out to understand the heat transfer characteristics during flow boiling of R407C in a smooth horizontal tube of 13.386 mm inner diameter and 2m length. The experiment is performed under the operating conditions; (i) mass flux range 100 to 300 kg s-1m-2; (ii) heat flux within range 2 to 7 kWm-2; (iii) temperature range at inlet to test section -100C to +100C; (iv) average vapor quality within test section from 0.05 to 0.95.The effect of heat flux, mass flux, vapor quality, temperature glide on heat transfer coefficient, during evaporation of R407C are examined.

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8

Ardita, I. Nengah, I. Gusti Agung Bagus Wirajati, I. Dewa Made Susila, and Sudirman Sudirman. "Performance analysis of retrofit R410a refrigerant with R32 refrigerant on a split air conditioner." Journal of Applied Mechanical Engineering and Green Technology 2, no. 1 (March 31, 2021): 1–4. http://dx.doi.org/10.31940/jametech.v2i1.2459.

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Split air conditioning (AC) is the most widely used in the community for both commercial and domestic utilities. At the present refrigerant which used in Split AC is mostly common group of HFCs, such as R410a. R410a is a zeotropic refrigerant and if there is a leak in the system, it cannot be added this refrigerant. This will increase the cost of maintenance. The aims of this research is to investigate the retrofit of R410a with R32 on the Split AC system. The R32 is chosen because it has higher latent evaporation heat at the same temperature and has less effect on global warming. The refrigeration effect, the power consumption and the system performance are the main three quantities that want to be examined in this research which are observed before and after retrofit. Experimental investigation conducted during this research, including design and manufacture of experimental equipment, calibration and tools installment, collecting the experimental data and analysis by quantitative description method before and after retrofit. The results informed that cooling effect increased during the research, but the COP system has a slight decrease about 4%. R32 refrigerant is quite feasible as a retrofit refrigerant to R410a refrigerant.

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9

Smit, F. J., J. R. Thome, and J. P. Meyer. "Heat Transfer Coefficients During Condensation of the Zeotropic Refrigerant Mixture HCFC-22/HCFC-142b." Journal of Heat Transfer 124, no. 6 (December 1, 2002): 1137–46. http://dx.doi.org/10.1115/1.1484108.

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Heat transfer coefficients during condensation of zeotropic refrigerant mixtures were obtained at mass fractions of 90 percent/10 percent, 80 percent/20 percent, 70 percent/30 percent, 60 percent/40 percent, and 50 percent/50 percent for HCFC-22/HCFC-142b and for pure HCFC-22 in a horizontal smooth tube at a high saturation pressure of 2.43 MPa. The measurements were taken in a series of eight 8.11 mm inner diameter smooth tubes with lengths of 1 603 mm. At low mass fluxes, from 40 kg/m2s to 350 kg/m2s where the flow regime is predominately stratified wavy, the refrigerant mass fraction influenced the heat transfer coefficient by up to a factor of two, decreasing as the mass fraction of HCFC-142b is increased. At high mass fluxes of 350 kg/m2s and more, the flow regime was predominately annular and the heat transfer coefficients were not strongly influenced by the refrigerant mass fraction, decreasing only by 7 percent as the refrigerant mass fraction changed from 100 percent HCFC-22 to 50 percent/50 percent HCFC-22/HCFC-142b. The results also indicated that of three methods tested to predict heat transfer coefficients, the flow pattern correlation of Dobson and Chato (1998) gave the best results for pure HCFC-22 and for the mixtures utilizing the Silver-Bell-Ghaly method (1964).

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10

Bohdal, Tadeusz, Katarzyna Widomska, and Małgorzata Sikora. "The analysis of thermal and flow characteristics of the condensation of refrigerant zeotropic mixtures in minichannels." Archives of Thermodynamics 37, no. 2 (June 1, 2016): 41–69. http://dx.doi.org/10.1515/aoter-2016-0012.

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Abstract The paper presents the results of experimental heat transfer and pressure drop during condensation of the single component refrigerant R134a and zeotropic mixtures R404A, R407C, and R410A in tube minichannels of internal diameter from the range 0.31-3.30 mm. The local values and the average of heat transfer coefficient and pressure drop in the whole range of the change in mass quality were measured. On the basis of the obtained test results there was illustrated the influence of the change of mass vapor quality, the mass flux density, and the inner diameter of channel on the studied parameters. These results were compared with the calculation results based on the relations postulated by other authors. The discrepancy range was ± 50%. On the basis of given test results own correlation was developed to calculate the heat transfer coefficient and pressure drop of tested refrigerants which presents the obtained results in a range of discrepancy of ±25%.

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11

Rajapaksha, Leelananda. "Zeotropic Refrigerant Mixtures in Vapour Compression Refrigeration Systems - Issues and Implications." Engineer: Journal of the Institution of Engineers, Sri Lanka 38, no. 4 (October 22, 2005): 52. http://dx.doi.org/10.4038/engineer.v38i4.7228.

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12

Kim, M. S., and D. A. Didion. "Simulation of Isothermal and Adiabatic Leak Processes of Zeotropic Refrigerant Mixtures." HVAC&R Research 1, no. 1 (January 1, 1995): 3–20. http://dx.doi.org/10.1080/10789669.1995.10391305.

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13

Del Col, D., A. Cavallini, and J. R. Thome. "Condensation of Zeotropic Mixtures in Horizontal Tubes: New Simplified Heat Transfer Model Based on Flow Regimes." Journal of Heat Transfer 127, no. 3 (March 1, 2005): 221–30. http://dx.doi.org/10.1115/1.1857951.

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The need for optimal design of heat exchangers with in-tube condensation of zeotropic refrigerant mixtures has pushed the research of predictive methods in the last years. Some procedures have been developed, based on the Colburn and Drew (1937, Trans. AIChemE 33, pp. 197–215) analysis, that require significant numerical effort and the diffusivity properties of the mixture to calculate the mass transfer resistance in the process and, hence, are rarely used for heat exchanger design. Proposing a modified version of the well-known simplified approach of Silver (1947, Trans. Inst. Chem. Eng. 25, pp. 30–42) and Bell and Ghaly (1973, AIChE Symp. Ser. 69, pp. 72–79) to include the effects of interfacial roughness and nonequilibrium effects, the present study extends the flow-pattern-based model of Thome, El Hajal, and Cavallini (2003, Int. J. Heat Mass Transfer 46, pp. 3365–3387) for condensation of pure fluids and azeotropic mixtures to zeotropic mixtures. By implementing this within the above flow-pattern-based heat transfer model, it leads to an improved method for accurately predicting local mixture heat transfer coefficients, maintaining a clear relationship between flow regime and heat transfer, and achieving both the goals of higher prediction accuracy and low calculation effort. The method has been verified for refrigerant mixtures (both halogenated and hydrocarbon) having temperature glides of 3.5–22°C, that is temperature differences between the dew point and bubble point temperatures (at a fixed pressure and bulk composition).

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14

Venkatarathnam, G., Girish Mokashi, and S. Srinivasa Murthy. "Occurrence of pinch points in condensers and evaporators for zeotropic refrigerant mixtures." International Journal of Refrigeration 19, no. 6 (July 1996): 361–68. http://dx.doi.org/10.1016/s0140-7007(96)00023-0.

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15

Yilmaz, Mehmet. "Performance analysis of a vapor compression heat pump using zeotropic refrigerant mixtures." Energy Conversion and Management 44, no. 2 (January 2003): 267–82. http://dx.doi.org/10.1016/s0196-8904(02)00054-7.

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16

Bamorovat Abadi, Gholamreza, and Kyung Chun Kim. "Enhancement of phase-change evaporators with zeotropic refrigerant mixture using metal foams." International Journal of Heat and Mass Transfer 106 (March 2017): 908–19. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.10.039.

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17

Wang, Baolong, Zuo Cheng, Wenxing Shi, and Xianting Li. "Optimal volume ratio of two-stage vapour compression system using zeotropic refrigerant." International Journal of Refrigeration 98 (February 2019): 343–53. http://dx.doi.org/10.1016/j.ijrefrig.2018.11.021.

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18

Jerald. "INVESTIGATIONS ON THE PERFORMANCE OF VAPOUR COMPRESSION SYSTEM RETROFITTED WITH ZEOTROPIC REFRIGERANT R404A." American Journal of Environmental Sciences 10, no. 1 (January 1, 2014): 35–43. http://dx.doi.org/10.3844/ajessp.2014.35.43.

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19

WAKUI, Tetsuya, Hiroaki OKAMURA, and Ryohei YOKOYAMA. "Performance Analysis of Vapor-Compression Type Air-Conditioning Systems Using Zeotropic Refrigerant Mixture." Proceedings of the Symposium on Environmental Engineering 2019.29 (2019): J410. http://dx.doi.org/10.1299/jsmeenv.2019.29.j410.

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20

Jacob, Tabeel A., and Brian M. Fronk. "In-Tube condensation of zeotropic refrigerant R454C from superheated vapor to subcooled liquid." Science and Technology for the Built Environment 26, no. 9 (August 18, 2020): 1177–90. http://dx.doi.org/10.1080/23744731.2020.1804281.

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21

Smit, F. J., and J. P. Meyer. "R-22 and Zeotropic R-22/R-142b Mixture Condensation in Microfin, High-Fin, and Twisted Tape Insert Tubes." Journal of Heat Transfer 124, no. 5 (September 11, 2002): 912–21. http://dx.doi.org/10.1115/1.1484394.

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Using mixtures of the zeotropic refrigerant mixture R-22/R-142b, a series of experiments was performed to determine the sectional and average heat transfer coefficients. Experiments were also conducted to compare three different heat transfer enhancement methods to that of smooth tubes. They were microfins, twisted tapes, and high fins. Measurements at different mass fluxes were obtained at six refrigerant mass fractions from 100 percent R-22 up to a 50 percent/50 percent mixture of R-22/R-142b. All condensation measurements were conducted at an isobaric inlet pressure of 2.43 MPa. This pressure corresponds to a saturation temperature of 60°C for R-22. The measurements were taken in 9.53 mm outer diameter smooth tubes and microfin tubes with lengths of 1603 mm. The heat transfer coefficients were determined with the Log Mean Temperature Difference equations. It was found that microfins were more suitable as an enhancement method than twisted tubes or high fins. Also, that the heat transfer coefficients and pressure drops decrease as the mass fraction of R-142b increases.

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22

Fiorelli, F. A. S., and O. M. Silvares. "EXPERIMENTAL VALIDATION OF A CAPPILARY TUBE SIMULATION MODEL WITH REFRIGERANT MIXTURES FLOW." Revista de Engenharia Térmica 3, no. 1 (June 30, 2004): 15. http://dx.doi.org/10.5380/reterm.v3i1.3485.

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This paper presents the experimental validation of a simulation model for refrigerant mixtures flow through capillary tubes. To perform such validation it was built an experimental apparatus using a blow-down process. It was carried out preliminary tests for characterization of experimental parameters: actual capillary tube diameters; relative roughness; and the heat losses in subcooling/quality control system. It was obtained almost 200 experimental points for R-407C (a zeotropic mixture) and R-410A (a near azeotropic mixture). Complete data set for each point consists of the measured pressure and temperature profiles, mass flow rate and mixture composition, as well as subcooling/quality control system inlet and outlet temperatures and heater electric power consumption for tests with two-phase flow capillary tube inlet conditions. Comparison of simulation and experimental data show a good agreement. Main deviations are connected with the delay of vaporization phenomenon occurrence, experimentally verified by the authors.

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23

Mulroy, W. J., P. A. Domanski, and D. A. Didion. "Glide matching with binary and ternary zeotropic refrigerant mixtures Part 1. An experimental study." International Journal of Refrigeration 17, no. 4 (January 1994): 220–25. http://dx.doi.org/10.1016/0140-7007(94)90037-x.

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24

Domanski, P. A., W. J. Mulroy, and D. A. Didion. "Glide matching with binary and ternary zeotropic refrigerant mixtures Part 2. A computer simulation." International Journal of Refrigeration 17, no. 4 (January 1994): 226–30. http://dx.doi.org/10.1016/0140-7007(94)90038-8.

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25

Sobieraj, Michał. "Experimental Investigation of the Effect of a Recuperative Heat Exchanger and Throttles Opening on a CO2/Isobutane Autocascade Refrigeration System." Energies 13, no. 20 (October 12, 2020): 5285. http://dx.doi.org/10.3390/en13205285.

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An experimental evaluation of an autocascade refrigeration (ACR) system was carried out. A zeotropic mixture of isobutane and CO2 was employed as a working fluid in an autocascade refrigeration (ACR) system. An experimental system was designed and built to study the influence of the recuperative heat exchanger (RHX) and openings of the throttle valves on the system performance. The use of RHX facilitated the condensation process and improved the cycle characteristics. The working mass concentration of CO2 was higher, as it was closer to the nominal concentration and the discharge pressure was lower by 19% to even 39% when the RHX was employed in the system. An increase of up to 20% in the coefficient of performance (COP) was observed. Furthermore, the effects of the openings of the throttle valves on the system characteristics were studied. The change in the openings of the expansion valves affected the mass flows and the working mixture composition. The working CO2 mass fraction increased with higher openings of the evaporator throttle. The subcooling degree of liquid CO2-rich refrigerant increased with higher openings of the expansion valve under the phase separator. The results of the present work should be helpful for design and optimization of autocascade systems working with natural and synthetic refrigerants.

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26

Honda, H., N. Takata, H. Takamatsu, J. S. Kim, and K. Usami. "Effect of Fin Geometry on Condensation of R407C in a Staggered Bundle of Horizontal Finned Tubes." Journal of Heat Transfer 125, no. 4 (July 17, 2003): 653–60. http://dx.doi.org/10.1115/1.1560153.

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Experimental results are presented that show the effect of fin geometry on condensation of downward flowing zeotropic refrigerant mixture R407C in a staggered bundle of horizontal finned tubes. Two types of conventional low-fin tubes and three types of three-dimensional-fin tubes were tested. The refrigerant mass velocity ranged from 4 to 23 kg/m2 s and the condensation temperature difference from 3 to 12 K. The measured condensation heat transfer coefficient was lower than the previous results for R134a, with the difference being more significant for smaller mass velocity. The effect of fin geometry on the condensation heat transfer coefficient was less significant for R407C than for R134a. The effect of condensate inundation was more significant for the three-dimensional-fin tubes than for the low-fin tubes. By using the dimensionless heat transfer correlation for the condensate film that was based on the experimental data for R134a, a superficial vapor-phase heat transfer coefficient was obtained for condensation of R407C. The vapor-phase heat transfer coefficient showed characteristics similar to the vapor-phase mass transfer coefficient that was obtained in the previous study for R123/R134a.

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27

Dai, Baomin, Shengchun Liu, Hailong Li, Zhili Sun, Mengjie Song, Qianru Yang, and Yitai Ma. "Energetic performance of transcritical CO2 refrigeration cycles with mechanical subcooling using zeotropic mixture as refrigerant." Energy 150 (May 2018): 205–21. http://dx.doi.org/10.1016/j.energy.2018.02.111.

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28

Honda, H., H. Takamatsu, and N. Takata. "Condensation of Downward-Flowing Zeotropic Mixture HCFC-123/HFC-134a on a Staggered Bundle of Horizontal Low-Finned Tubes." Journal of Heat Transfer 121, no. 2 (May 1, 1999): 405–12. http://dx.doi.org/10.1115/1.2825993.

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Experiments were conducted to obtain row-by-row heat transfer data during condensation of downward-flowing zeotropic refrigerant mixture HCFC-123/HFC-134a on a 3 × 75 (columns × rows) staggered bundle of horizontal low-finned tubes. The vapor temperature and the HFC-134a mass fraction at the tube bundle inlet were maintained at about 50°C and nine percent, respectively. The refrigerant mass velocity ranged from 9 to 34 kg/m2 s, and the condensation temperature difference from 3 to 12 K. The measured distribution of the vapor mass fraction in the tube bundle agreed fairly well with that of the equilibrium vapor mass fraction. The vapor phase mass transfer coefficient was obtained from the heat transfer data by subtracting the thermal resistance of the condensate film. The heat transfer coefficient and the mass transfer coefficient decreased significantly with decreasing mass velocity. These values first increased with the row number up to the third (or second) row, then decreased monotonically with further increasing row number, and then increased again at the last row. The mass transfer coefficient increased with condensation temperature difference, which was due to the effect of suction associated with condensation. On the basis of the analogy between heat and mass transfer, a dimensionless correlation of the mass transfer coefficient for the 4th to 14th rows was developed.

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29

Jin, Xing, and Xiaosong Zhang. "A new evaluation method for zeotropic refrigerant mixtures based on the variance of the temperature difference between the refrigerant and heat transfer fluid." Energy Conversion and Management 52, no. 1 (January 2011): 243–49. http://dx.doi.org/10.1016/j.enconman.2010.06.062.

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30

Shao, David, and Eric Granryd. "Flow Pattern, Heat Transfer and Pressure Drop in Flow Condensation Part II: Zeotropic Refrigerant Mixtures (NARMs)." HVAC&R Research 6, no. 2 (April 1, 2000): 197–209. http://dx.doi.org/10.1080/10789669.2000.10391257.

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31

Deethayat, Thoranis, Attakorn Asanakham, and Tanongkiat Kiatsiriroat. "Performance analysis of low temperature organic Rankine cycle with zeotropic refrigerant by Figure of Merit (FOM)." Energy 96 (February 2016): 96–102. http://dx.doi.org/10.1016/j.energy.2015.12.047.

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32

Johansson, A., and P. Lundqvist. "A method to estimate the circulated composition in refrigeration and heat pump systems using zeotropic refrigerant mixtures." International Journal of Refrigeration 24, no. 8 (December 2001): 798–808. http://dx.doi.org/10.1016/s0140-7007(00)00061-x.

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33

Smit, F. J., and J. P. Meyer. "Condensation heat transfer coefficients of the zeotropic refrigerant mixture R-22/R-142b in smooth horizonal tubes." International Journal of Thermal Sciences 41, no. 7 (June 2002): 625–30. http://dx.doi.org/10.1016/s1290-0729(02)01356-x.

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34

Hewitt, N. J., J. T. McMullan, B. Mongey, and R. H. Evans. "From pure fluids to zeotropic and azeotropic mixtures: The effects of refrigerant-oil solubility on system performance." International Journal of Energy Research 20, no. 1 (January 1996): 57–67. http://dx.doi.org/10.1002/(sici)1099-114x(199601)20:1<57::aid-er240>3.0.co;2-b.

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35

Venkatarathnam, G., and S. Srinivasa Murthy. "Effect of mixture composition on the formation of pinch points in condensers and evaporators for zeotropic refrigerant mixtures." International Journal of Refrigeration 22, no. 3 (May 1999): 205–15. http://dx.doi.org/10.1016/s0140-7007(98)00056-5.

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36

Afroz, Hasan M. M., Anowar Hossain, and Akio Miyara. "F226 Analysis of condensation heat transfer characteristics of zeotropic refrigerant mixture R1234ze/R32 inside a Horizontal Smooth tube." Proceedings of the Thermal Engineering Conference 2013 (2013): 387–88. http://dx.doi.org/10.1299/jsmeted.2013.387.

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37

Yoon, Seok Ho, and Min Soo Kim. "Investigation of Circumferential Variation of Heat Transfer Coefficients During In-Tube Evaporation for R-22 and R-407C Using Liquid Crystal." Journal of Heat Transfer 124, no. 5 (September 11, 2002): 845–53. http://dx.doi.org/10.1115/1.1484110.

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Heat transfer coefficients during evaporation in a horizontal smooth tube for R-22 and R-407C (R-32/125/134a, 23/25/52 wt.%) have been measured using thermochromic liquid crystal. Focus has been put on the circumferential variation of heat transfer coefficients at several cross-sections of the test tube with inner diameter of 11.3 mm for several vapor qualities of refrigerant. The inner wall temperatures were calculated by one dimensional heat conduction equation from the measured outer wall temperatures, which were obtained using an image processing technique with thermochromic liquid crystal (TLC). The relation between measured temperature and color information (Red-Green-Blue values) of thermochromic liquid crystal was calibrated by a neural network method. Results show that circumferential variation of heat transfer coefficients for R-22 is quite large with the highest heat transfer coefficient at the top of the tube. For zeotropic mixture of R-407C, similar trend has been observed with less difference between the heat transfer coefficients at the top and bottom than that of R-22.

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38

Lee, Jangho, Young-Chul Kwon, and Moo Hwan Kim. "An improved method for analyzing a fin and tube evaporator containing a zeotropic mixture refrigerant with air mal-distribution." International Journal of Refrigeration 26, no. 6 (September 2003): 707–20. http://dx.doi.org/10.1016/s0140-7007(03)00023-9.

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39

Dang, Chao, Li Jia, Mingchen Xu, Qian Huang, and Qi Peng. "Experimental study on flow boiling characteristics of pure refrigerant (R134a) and zeotropic mixture (R407C) in a rectangular micro-channel." International Journal of Heat and Mass Transfer 104 (January 2017): 351–61. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.08.067.

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Ma, Xuelian, Yufeng Zhang, Xiaoqiong Li, Hongfu Zou, Na Deng, Jinzhe Nie, Xiaohui Yu, Shengming Dong, and Wei Li. "Experimental study for a high efficiency cascade heat pump water heater system using a new near-zeotropic refrigerant mixture." Applied Thermal Engineering 138 (June 2018): 783–94. http://dx.doi.org/10.1016/j.applthermaleng.2017.12.124.

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41

Meyer, J. P., J. M. Bukasa, and S. A. Kebonte. "Average Boiling and Condensation Heat Transfer Coefficients of the Zeotropic Refrigerant Mixture R22/R142b in a Coaxial Tube-in-Tube Heat Exchanger." Journal of Heat Transfer 122, no. 1 (October 1, 1999): 186–88. http://dx.doi.org/10.1115/1.521455.

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Average boiling and condensation heat transfer coefficients were determined experimentally for a coaxial tube-in-tube heat exchanger used in hot water heat pumps. During manufacturing, the heat exchanger geometry used for the experiments changed from round tubes to elliptical tubes as no spacers were used to keep the inner tube from touching the outer tube. The refrigerant used was two different mixtures of R22 with R142b in mass ratios of 80 percent/20 percent and 60 percent/40 percent. The results were compared to theoretical results for straight tubes. It was concluded that the theoretical modes do not predict the heat transfer coefficients very well in coaxial tube-in-tube heat exchangers where the annulus touches the inside of the outer tube. [S0022-1481(00)01001-X]

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42

Rajapaksha, Leelananda. "Influence of special attributes of zeotropic refrigerant mixtures on design and operation of vapour compression refrigeration and heat pump systems." Energy Conversion and Management 48, no. 2 (February 2007): 539–45. http://dx.doi.org/10.1016/j.enconman.2006.06.001.

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43

Zhang, Zhengguo, Qianxia Li, Tao Xu, Xiaoming Fang, and Xuenong Gao. "Condensation heat transfer characteristics of zeotropic refrigerant mixture R407C on single, three-row petal-shaped finned tubes and helically baffled condenser." Applied Thermal Engineering 39 (June 2012): 63–69. http://dx.doi.org/10.1016/j.applthermaleng.2012.01.021.

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44

Nozu, Shigeru, Hiroshi Honda, and Shin Nishida. "Condensation of a zeotropic CFC 114-CFC 113 refrigerant mixture in the annulus of a double-tube coil with an enhanced inner tube." Experimental Thermal and Fluid Science 11, no. 4 (November 1995): 364–71. http://dx.doi.org/10.1016/0894-1777(95)00059-3.

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45

Chen, J. "Zeotropic refrigerants and the special characteristics." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 219, no. 2 (May 1, 2005): 183–86. http://dx.doi.org/10.1243/095440805x8629.

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Zeotropic refrigerants, compared with conventional refrigerants, have different characteristics during evaporation and condensation. This article summarizes the special characteristics of zeotropic refrigerants in five aspects: fractionation behaviour; non-leakage-related concentration change; leakage-associated concentration change; gliding temperature and the limitation on media flow rate; and degradation in heat transfer. The relevant thermo-dynamic performance has been analysed. Newly developed technology for improving system efficiency and reliability has been incorporated in the discussion.

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46

Nozu, Shigeru, Hiroshi Honda, and Shin Nishida. "An Experimental Study of Heat Transfer and Pressure Drop in a Double-Pipe Condenser with U-Bends. Experiments with a Zeotropic Refrigerant Mixture R-114/R113." Transactions of the Japan Society of Mechanical Engineers Series B 60, no. 575 (1994): 2472–78. http://dx.doi.org/10.1299/kikaib.60.2472.

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47

Wang, Linlin, Pengfei Jiao, Chaobin Dang, Eiji Hihara, and Baomin Dai. "Condensation heat and mass transfer characteristics of low GWP zeotropic refrigerant mixture R1234yf/R32 inside a horizontal smooth tube: An experimental study and non-equilibrium film model development." International Journal of Thermal Sciences 170 (December 2021): 107090. http://dx.doi.org/10.1016/j.ijthermalsci.2021.107090.

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48

Tarrad, Ali Hussain, and Ayad Khudhair Al-Nadawi. "Modeling of Finned-Tube Evaporator using Pure and Zeotropic Blend Refrigerants." Athens Journal of Τechnology & Engineering 2, no. 4 (November 30, 2015): 263–82. http://dx.doi.org/10.30958/ajte.2-4-4.

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49

Garimella, Srinivas, Jeffrey Milkie, and Malcolm Macdonald. "Condensation of zeotropic mixtures of low-pressure hydrocarbons and synthetic refrigerants." International Journal of Heat and Mass Transfer 162 (December 2020): 120301. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2020.120301.

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Kundu, A., R. Kumar, and A. Gupta. "Performance Comparison of Zeotropic and Azeotropic Refrigerants in Evaporation Through Inclined Tubes." Procedia Engineering 90 (2014): 452–58. http://dx.doi.org/10.1016/j.proeng.2014.11.755.

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