Analytical Model With Nonadiabatic Effects for Pressure Drop and Heat Transfer During Boiling and Condensation Flows in Conventional Channels and Minichannels

Calculation Method for Flow Boiling and Flow Condensation of R134a and R1234yf in Conventional and Small Diameter Channels

“…Several publications, namely by Ribatski [27], Tibirçá and Ribatski [28], Sardeshpande and Ranade [29], and Alagesan [30] analyse the experimental data for validation of heat transfer coefficient predictions using correlations available in the literature. In the present paper, the experimental results collected from the literature are compared with the predictions of the model [31,32]. Based on the evidence of comparison with the abovementioned experimental data, a correction making use of the reduced pressure effect has been applied to the authors' model to provide feasibly the best consistency of the predictions with the experiments.…”

“…The versatile semi-empirical model to calculate flow boiling and flow condensation due to D. Mikielewicz et al [31,32] has been tested for a significant number of experimental data and has returned satisfactory results for cases of flow boiling processes in numerous fluids. The fundamental hypothesis of the model is the fact that heat transfer during flow boiling with bubble generation can be modelled as a sum of two contributions constituting the total energy dissipation in the flow, namely the energy dissipation due to shearing flow without bubbles and the dissipation resulting from bubble generation.…”

“…For that purpose, two models were introduced into Equation (1), namely the Muller -Steinhagen and Heck correlation [33]. Additionally, the calculation procedure includes the so called blowing parameter B, which is responsible for evaluation of the nonadiabatic effects appearing due to shear stress modification on the liquid-vapour interface [32].…”

“…The modified two-phase multiplier R B , inclusive of nonadiabatic effects, has the following form [32]:…”

The performance of H2O, R134a, SES36, ethanol, and HFE7100 two-phase closed thermosyphons for varying operating parameters and geometry

“…There are not many studies during the two-phase flow of new perspectives dielectric fluids such as HFE-7100, SES36 [24,25]. Those fluids are more environmentally friendly compared to R134a or R404a.…”