ABSTRACT
This research establishes 5 mm 3-D flow and heat transfer microfin tube theoretical models with three different geometric structures. Using these models, the thermal-hydraulic performances of supercritical CO2/R32 in microfin tubes with different structures at various working conditions were investigated. The influences of each of three factors (pressure, mass-flow, and microfin tube structures) on the thermal-hydraulic performance of CO2/R32 were evaluated, respectively. Furthermore, orthogonal tests were undertaken to obtain the optimized combination of overall thermal-hydraulic performance. Results indicate that: the more the temperature of working media approximates to the critical temperature, the bigger the local convective heat transfer coefficient (CHTC). Compared to non-critical temperatures, the CHTC at critical temperature shows an eight-fold increase. The closer the pressure of the mixed working media is to the critical pressure, the greater the maximum CHTC and the lower the temperature corresponding to the peak point, among which, the maximum CHTC under 7.5 MPa is three times as large as that at 8.5 MPa. The CHTC increases with increasing mass velocity, generally showing a linear relationship. Through calculating the most optimal combination of thermal-hydraulic performance evaluation using orthogonal tests, the maximum CHTC is determined to be 96 kW/m2K.
KEYWORDS
PAPER SUBMITTED: 2022-08-19
PAPER REVISED: 2022-09-30
PAPER ACCEPTED: 2022-10-26
PUBLISHED ONLINE: 2022-12-17
THERMAL SCIENCE YEAR
2023, VOLUME
27, ISSUE
Issue 4, PAGES [2665 - 2676]
- Kim N. H., Evaporation Heat Transfer and Pressure Drop of R-410A in a 5.0 mm O.D. Smooth and Microfin Tube, International Journal of Air-Conditioning and Refrigeration, 23(2015), pp.1550004-1-15
- Lin Y., et al., Numerical investigation on thermal performance and flow characteristics OFZ and S shape PCHE using S-CO2, Thermal Science, 23(2019), Suppl.3,pp. 757-764
- Lorentzen G. Revival of carbon dioxide as a refrigerant, International Journal of Refrigeration, 17(1994), 5, pp. 292-301
- Kalair N A, Kalair A R, Khan N, et al. Natural and synthetic refrigerants, global warming: A review, Renewable and Sustainable Energy Reviews, 90(2018), pp. 557-569
- Bruch A, Bontemps A, Colasson S. Experimental investigation of heat transfer of supercritical carbon dioxide flowing in a cooled vertical tube, International Journal of Heat & Mass Transfer, 52(2009), 11-12, pp. 2589-2598
- Dang C, Hihara E. In-tube cooling heat transfer of supercritical carbon dioxide. Part 1. Experimental measurement. International Journal of Refrigeration, 27(2004), 7, pp.736-747
- Dai B., Dang C., et al., Thermodynamic performance assessment of carbon dioxide blends with low-global warming potential (GWP) working fluids for a heat pump water heater, International Journal of Refrigeration, 56(2015), pp.1-14
- Hakkaki-Fard A., Aidoun Z., Ouzzane M., Applying refrigerant mixtures with thermal glide in cold climate air-source heat pumps, Applied Thermal Engineering, 62(2014), 2, pp. 714-722
- Niu B., Zhang Y., Experimental study of the refrigeration cycle performance for the R744/R290 mixtures, International Journal of Refrigeration, 30(2007), 1, pp. 37-42
- Cavallini A., Del Col D., Doretti L., et al., Heat Transfer and Pressure Drop During Condensation of Refrigerants Inside Horizontal Enhanced Tubes, International Journal of Refrigeration, 23(2000),1,pp. 4-25
- Cho J M., Kim M S., Experimental Studies on the Evaporative Heat Transfer and Pressure Drop of CO2 in Smooth and Micro-Fin Tubes of the Diameters of 5 and 9.52 mm. International Journal of Refrigeration, 30(2007), 6, pp. 986-994
- Dai R., Xu X., Wang Y., et al., Comprehensive evaluation on the thermal-hydraulic performance of supercritical CO2/R41 in a micro-fin tube, Thermal Science, (2022), OnLine-First
- Lee E J, Kim N H, Byun H W. Condensation heat transfer and pressure drop in flattened microfin tubes having different aspect ratios, International Journal of Refrigeration, 38(2014), pp. 236-249
- MH Kim, S. Shin, Evaporating heat transfer of R22 and R410A in horizontal smooth and microfin tubes, International Journal of Refrigeration, 28(2005), 6, pp. 940-948
- Passos J. C., Kuser V. F., Haberschill P., et al., Convective boiling of R-407c inside horizontal microfin and plain tubes, Experimental Thermal & Fluid Science, 27(2003), 6, pp. 705-713
- Akhavan-Behabadi M. A., Mohseni S. G., Razavinasab S. M., Evaporation heat transfer of R-134a inside a microfin tube with different tube inclinations, Experimental Thermal & Fluid Science, 35(2011), 6, pp. 996-1001
- Wu Z, Wu Y, B Sundén, et al. Convective vaporization in micro-fin tubes of different geometries, Experimental Thermal & Fluid Science, 44(2013), pp. 398-408
- Qu J., Li X., Wang Q., et al. Heat transfer characteristics of micro-grooved oscillating heat pipes, Experimental Thermal and Fluid Science: International Journal of Experimental Heat Transfer, Thermodynamics, and Fluid Mechanics, 85(2017), pp.75-84.
- Kim D E, Kim M H. Two layers heat transfer model for supercritical fluid flow in a vertical tube, The Journal of Supercritical Fluids, 58(2011), pp. 15-25
- Webb R. L. Prediction of condensation and evaporation in micro-fin and micro-channel tubes, Heat transfer enhancement of heat exchangers, Springer, Dordrecht, (1999), pp. 529-550
- Zhang J., Li W., Minkowycz W. J., Numerical simulation of R410A condensation in horizontal microfin tubes, Numerical Heat Transfer Part A Application, An International Journal of Computation & Methodology, 71(2017),4,pp.361-376
- Wang Y., Liu D., et al. Optimized Design of Micro-channel Heat Sinks with Orthogonal Simulation, Chinese Journal of Lasers, 38(2011), 7, pp. 6-11
