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Homotopy perturbation method with trefftz functions and simcenter star-ccm+ used for the analysis of flow boiling heat transfer

Pawińska Anna, Hożejowska Sylwia, Piasecki Artur, Dadas Norbert, Piasecka Magdalena

Acta Mechanica et Automatica

2024

Vol. 18, no. 2

233--243

This work presents experimental and numerical studies of heat transfer during cooling fluid flow in a group of five minichannels 1 mm deep. The main purpose was to determine the heat transfer coefficient on the contact surface between the fluid and the heated wall of the selected minichannel at subcooled boiling. The temperature distribution on the outer surface of the heated plate was measured by means of an infrared camera. Thermal and flow parameters were monitored by an appropriate data-acquisition system. The test section was placed horizontally with fluid flowing above the heated wall. The HFE-649, HFE-7100 and HFE-7200 working fluids were examined in the experiments. Simcenter STAR-CCM+ software was used for numerical analysis of heat transfer in the test section. Furthermore, a simplified two-dimensional (2D) model was proposed that designates subcooled boiling heat transfer during fluid flow in a central minichannel. The heat-transfer process in the heated plate and the working fluid was described using indicated partial differential equations with appropriate boundary conditions. The solution to the proposed system of equations led to the solving of two more inverse Cauchy-type problems. The classical Trefftz method (TM) and the homotopy perturbation method (HPM) combined with the TM allowed for obtaining temperature distributions in the heater and the fluid and consequently, the heat transfer coefficient at the heater–fluid interface from the Robin boundary condition. Comparison of the results from numerical simulation due to Simcenter STAR-CCM+ showed similar temperature distributions at the heated surface. The calculated heat transfer coefficients, by HPM and Simcenter STAR-CCM+, were validated using the 1D approach. Furthermore, the results from simulations in Simcenter STAR-CCM+ in the form of local temperatures of the heater were confronted with experimental data for comparison. Similar results were achieved.

On the mechanistic modeling of forced-convection low-quality boiling

Podowski M. Z.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

1999

Z. 67

97--111

Practical applications of forced-convection boiling encompass a wide spectrum of industrial systems, including but not limited to, thermal energy generation systems, because of the complexity of phenomena governing boiling heat transfer in general, and subcooled boiling in particular, a commonly used approach to both fundamental and practical problems has traditionally been based on experimental correlations rather than mechanistic models. The recent progress in computational fluid dynamics (CFD), combined with improved experimental techniques in two-phase flow and heat transfer, makes the use of rigorous physically-based models a realistic alternative to the simplistic phenomenological approach which dominated the field in the past. The objective of this paper is to discuss some of the recent accomplishments in the mechanistic modeling of forced-convection low-quality boiling, including both the nucleate boiling regime and the mechanisms governing the departure from nucleate boiling (critical heat flux - CHF).