Condensation of pure and near-azeotropic refrigerants in microfin tubes: A new computational procedure

Heat transfer during condensation of HFC-134a and R-404A inside of a horizontal smooth and micro-fin tube

“…Only predicted correlation shows good association with experimental data for all range of temperatures of HFC-134a and R-404A. For micro-fin tube, only values from Cavalini et al [38] and Jonathan et al [37] fall above 50% for HFC-134a, but for R-404A only values from Luu and Bergles [7], Kedzierski and Goncalves [9], and Cavallini et al [38] fall within 20%, rest all values fall above 50%. Like smooth tube, predicted correlation shows good accuracy with experimental data for all range of temperatures of HFC-134a and R-404A.…”

In-tube performance evaluation of an air-cooled condenser with liquid–vapor separator

“…Although the inlet mass flux was fixed for the three condensers in the experiments, only the refrigerant in the SC had unchanged mass flux along the whole route because it had only one pass. The theoretical AHTCs in the SC calculated using the model proposed by Cavallini et al [16] under the constant wall temperature had maximum over prediction of 24.1% and 17.0% than the experimental ones at 45°C and 50°C, respectively. However, the mass flux increased as the pass number in the PFC increased because the tube number decreased as the pass number increased.…”

Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes

“…A clear effect of both mass velocity and vapor quality is visible: the higher the mass velocity and the vapor quality, the higher the heat transfer coefficient, due to the diminishing liquid film thickness. According to the flow regime map developed by Doretti et al [25] and reported by Cavallini et al [26], all the experimental data fall in the ∆T-independent zone, i.e., annular flow, except data at G = 200 kg m −2 s −1 up to a mean vapor quality of 0.5, which fall into the ∆T-dependent zone, i.e., they are in stratified flow regime. Data at higher mass velocity shows a higher slope of the heat transfer coefficient trend, highlighting a higher convective effect as the mass velocity increases.…”