Horizontal convective boiling of R1234yf, R134a, and R450A within a micro-fin tube

Abstract

This paper presents local convective boiling heat transfer and Fanning friction factor measurements in a micro-fin tube for R134a and two possible low global warming potential (GWP) refrigerant replacements for R134a, namely R1234yf and R450A. Test section heating was achieved with water in either counterflow or in parallel flow with the test refrigerant to provide for a range of heat fluxes for each thermodynamic quality. An existing correlation from the literature for single and multi-component mixtures was shown to not satisfactorily predict the convective boiling measurements for flow qualities greater than 40%. Accordingly, a new correlation was developed specifically for the test fluids of this study so that a fair comparison of the heat transfer performance of the low GWP refrigerants to that of R134a could be made. The new correlation was used to compare the heat transfer coefficient of the three test fluids at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux. The resulting example comparison, for the same operating conditions, showed that the heat transfer coefficient of the multi-component R450A and the single-component R1234yf were, on average, 15% less and 5% less, respectively, than that of the single-component R134a. Friction factor measurements were also compared to predictions from an existing correlation. A new correlation for the friction factor was developed to provide a more accurate prediction. The measurements and the new models are important for the evaluation of potential low-GWP refrigerants replacements for R134a.

Update of legacy NIST horizontal micro-fin tube convective boiling measurements and model with current fluid property values

“…Considering that Kedzierski and Kang (2018) provide a detailed description of the test apparatus and the measurement technique, it will be briefly described here. Figure 1 shows a sketch of the experimental apparatus that was used in all five NIST studies to establish and measure convective boiling heat transfer coefficients.…”

“…NIST (2021) provides an online database that contains the complete corrected flow boiling heat transfer measurements of the Hamilton et al (2008), the Kedzierski and Park (2013), the Kedzierski and Kang (2016), and the Kedzierski and Kang (2018). The data presented in Domanski et al (2021) is also included in the database; however, it did not require correction.…”

“…The third NIST study (Kedzierski and Kang, 2016) contains the refrigerants R448A, R449A, and R452B. Finally, the fourth NIST study (Kedzierski and Kang, 2018) contains the refrigerants R1234yf, R134a, and R450A. The fifth study are measurements for R513A, R515B, and R450A that were analyzed with the current REFPROP and presented without the raw measurements in Domanski et al (2021).…”

Evaporation Heat Transfer and Pressure Drop of Low-Global Warming Potential Refrigerant HFO-1234yf in 6.95-mm Horizontal Smooth Tube

“…In addition, it was revealed that the heat transfer coefficients of R-134a and R-1234yf were similar. Kedzierski et al [9] studied the local convective heat transfer of R-1234yf and R-134a in microfin tubes with an inner diameter of 8.8 mm. The comparison results showed that the heat transfer performance of R-1234yf was 5% lower than that of R-134a.…”

Modeling and multi-objective optimization of an R450A vapor compression refrigeration system

“…Electric energy consumption with R450A was between 1.3% and 5.8% higher than that of R134a in a single-stage refrigeration system with a semi-hermetic compressor connected to a commercial vertical cabinet with doors placed inside a climatic chamber (Llopis et al, 2017). Additionally, Kedzierski and Kang (2018) studied the local convective boiling heat transfer in micro-fin tubes resulting, on an average, 15% lower for R450A in comparison with R134a.…”