Evaporation, Condensation and Heat Transfer

A special issue of Fluids (ISSN 2311-5521). This special issue belongs to the section "Heat and Mass Transfer".

Deadline for manuscript submissions: 31 December 2024 | Viewed by 516

Special Issue Editors


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Guest Editor
Department of Mechanical Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Interests: two phase flow heat transfer; system thermal/cooling design; refrigeration and air condition

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Guest Editor
School of Mechanical Engineering, University of Adelaide, Adelaide, SA 5005, Australia
Interests: computational fluid dynamics (CFD); renewable energy including solar hybrid systems, and geothermal systems; solar cars design/build and simulations; combustion/gasification including fire simulations, coal combustion/gasification, MILD combustion; multiphase flows particularly particle-laden flows

Special Issue Information

Dear Colleagues,

Improvements to the energy utilization efficiency in various engineering systems are receiving ever-increasing worldwide attention in light of their importance in reducing the release of CO2(g), a global weather-warming gas, during the burning of fossil fuels to produce the necessary energy. Recently, the use of variable-frequency, instead of ON/OFF, compressors in various air conditioning and refrigeration systems to meet the temporally changing thermal loads has been found to significantly augment the energy efficiencies of these systems. It is important to note that in these systems, the refrigerant flow rate varies with time, and the systems are subjected to changing thermal loads. How this time-dependent refrigerant flow rate and heat flux affect the characteristics of boiling and condensation processes in the refrigeration cycles employed in these air-conditioning and refrigeration systems remains largely unexplored. In cooling future ultra-high-component density electronic devices, methods based on phase change heat transfer are often considered. Moreover, the power dissipated in these devices is also time-dependent, hence the cooling load. The associated time-dependent two-phase flow and heat transfer processes in electronics cooling are also poorly understood.

Dr. Chien-An Chen
Dr. Zhao Tian
Guest Editors

Manuscript Submission Information

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Keywords

  • two-phase flow and heat transfer
  • transient flow boiling
  • flow boiling and evaporation heat transfer
  • time periodic evaporating flow
  • evaporation/evaporative heat transfer
  • flow rate oscillation
  • flow pattern characteristics
  • unsteady heat transfer
  • subcooled flow boiling
  • oscillating refrigerant flow rate
  • triangular oscillation
  • intermittent nucleate boiling
  • amplitude and period
  • energy efficiency
  • saturated flow boiling

Published Papers (1 paper)

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Research

13 pages, 5184 KiB  
Article
Circular Fluid Heating—Transient Entropy Generation
by Fikret Alic
Fluids 2024, 9(5), 119; https://doi.org/10.3390/fluids9050119 - 18 May 2024
Viewed by 303
Abstract
A technical issue with fluid flow heating is the relatively small temperature increase as the fluid passes through the heating surface. The fluid does not spend enough time inside the heating source to significantly raise its temperature, despite the heating source itself experiencing [...] Read more.
A technical issue with fluid flow heating is the relatively small temperature increase as the fluid passes through the heating surface. The fluid does not spend enough time inside the heating source to significantly raise its temperature, despite the heating source itself experiencing a substantial increase. To address this challenge, the concept of the multiple circular heating of air was developed, forming the basis of this work. Two PTC heaters with longitudinal fins are located within a closed channel inside housing composed of a thermal insulation material. Air flows circularly from one finned surface to another. Analytical modeling and experimental testing were used in the analysis, with established restrictions and boundary conditions. An important outcome of the analysis was the methodology established for the optimization of the geometric and process parameters based on minimizing the transient thermal entropy. In conducting the analytical modeling, the temperature of the PTC heater was assumed to be constant at 150 °C and 200 °C. By removing the restrictions and adjusting the boundary conditions, the established methodology for the analysis and optimization of various thermally transient industrial processes can be applied more widely. The experimental determination of the transient thermal entropy was performed at a much higher air flow rate of 0.005 m3s−1 inside the closed channel. The minimum transient entropy also indicates the optimal time for the opening of the channel, allowing the heated air to exit. The novelty of this work lies in the controlled circular heating of the fluid and the establishment of the minimum transient thermal entropy as an optimization criterion. Full article
(This article belongs to the Special Issue Evaporation, Condensation and Heat Transfer)
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