| description abstract | In the paper [1], the author presented heat transfer coefficients during pool boiling of five different refrigerants (R123, R245fa, R236fa, R134a, and R22) on the outside surface of a horizontal smooth tube. The boiling heat transfer coefficients were derived from the measured overall water-refrigerant heat transfer coefficients, with the water-side single-phase convection heat transfer coefficients calculated by using the Sieder-Tate correlation [2] Display FormulaNuD=0.027 ReD0.8Pr1/3(μμwall)0.14 (1) in which NuD , ReD , and Pr are, respectively, the Nusselt number, Reynolds number, and Prandtl number of the fluid; μ and μwall are the dynamic viscosities of the bulk fluid and the fluid near the wall. According to Bejan [3], the Petukhov and Popov correlation [4] seems to be a more accurate correlation, which has been recommended through the author’s communication with the Technical Editor. The Petukhov and Popov correlation is reproduced in Eq. 2Display FormulaNuD=(f/2)ReDPr1.07+900/ReD-0.63/(1+10Pr)+12.7(f/2)1/2(Pr2/3-1) (2) for the flow conditions of 4 × 103 ≤ ReD ≤ 5 × 106 and 0.5 ≤ Pr ≤106 . The friction factor in Eq. 2 is estimated by using the correlation f=0.078ReD-1/4 for ReD < 8 × 104 . | |
