Effect of IF-WS2 nanolubricant on R134a boiling on a reentrant cavity surface:

Abstract

This report quantifies the influence of inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles on the pool-boiling performance of R134a/polyolester mixtures on a commercial (Turbo-ESP) boiling surface. Tungsten disulfide nanoparticles, of roughly 150 nm, were used at a 15 % mass fraction in a base polyolester lubricant to produce the test nanolubricant. The nanolubricant was mixed with R134a at a 1 % mass fraction. The study showed that the nanolubricant caused an average 37 % degradation in the boiling heat flux as compared to R134a/neat-lubricant boiling on a reentrant cavity surface at the same superheat. Similarly, boiling with R134a/neat-lubricant caused, on average, a 27 % degradation in the boiling heat flux as compared to pure R134a boiling and the same superheat. An analysis was presented which showed that the nanoparticles were too large and too dense to promote a boiling enhancement. In addition, the fullerene-like structure and the large size encouraged nanoparticle settling, which presumably filled cavities of the boiling surface leading to additional boiling degradations.

Pool Boiling of R514A, R1224yd(Z), and R1336mzz(E) on a Reentrant Cavity Surface; Extensive Measurement and Analysis

“…TN.2125 Considering that R514A is 74.7/25.3 by mass mixture of R1336mzz(Z) and R1130, Fig. 4 compares the present pool-boiling measurements for R514A to the means of the R1336mzz(Z) pool boiling measurements from Kedzierski and Lin (2019) Being that R514A is a replacement for R123, Fig. 4 provides the mean boiling curve for R123 at a saturation temperature of 277.6 K, as taken from and shown as a long-dashed black line.…”

“…They presented an analysis that showed that the nanoparticles were too large and too dense to promote a boiling enhancement. In other work, Kedzierski and Lin (2019) quantified the pool boiling performance of R1336mzz(Z) on the Turbo-ESP surface and showed that the boiling performance of R1336mzz(Z) did not differ statistically from that of R123 for heat fluxes between 13 kWm -2 and 59 kWm -2 . For heat fluxes larger than 59 kWm -2 , the R123 boiling heat flux was up to 5 % larger than the heat flux for R1336mzz(Z).…”

“…Kedzierski and Lin (2020a) updated their pool boiling model for pure and mixed refrigerants for the Turbo-ESP surface and showed that the vapor Prandtl number and the product of the latent heat and vapor density significantly influenced the boiling heat flux. More boiling measurements were made on the Turbo-ESP surface by Kedzierski and Lin (2020b) in a study of the influence of inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles on the pool-boiling performance of R134a/polyolester mixtures. The study showed that the nanolubricant caused an average 37 % degradation in the boiling heat flux as compared to R134a/neat-lubricant boiling on the Turbo-ESP surface at the same superheat.…”