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evaporation-and-condensation
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Experimental Investigation of an Evaporative Condenser-Based Combined Heat Pump and Humidification-Dehumidification Desalination System
, Ph.D. Dissertation Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
The present thesis aimed to study a novel heat pump integrated humidification-dehumidification (HDH-HP) desalination system. A theoretical outline was proposed for the first time to examine the design and off-design performance of HDH-HP cycles via the compressor characteristics method. In this regard, the variations in heat pump performance were modeled in different operating conditions for a fixed-size system. To fabricate a compact HDH-HP system, an evaporative condenser was designed and used instead of a separate humidifier, heater, and air/water-cooled condensers find in previous HDH-HP systems. Meanwhile, the air dehumidification process in this work directly occurred inside the heat...
Modeling and Conceptual Design of Solar Water Desalination System with Ground Condenser
, Ph.D. Dissertation Sharif University of Technology ; Kazemzadeh Hannani, Siamak (Supervisor) ; Hakkaki Fard, Ali (Supervisor)
Abstract
Providing fresh water for domestic and agricultural purposes has become one of the most pressing issues of the present century. Due to the dependency of conventional desalination on fossil fuels, these methods are associated with carbon dioxide and other greenhouse gas emissions. Therefore, renewable energy-based desalination systems have come to the fore. This study scrutinizes the performance of the solar Humidification-Dehumidification (HDH) desalination systems with subsurface condensers. In this system, solar energy evaporates water, and subsurface condensers condense water vapor into fresh water. Therefore, this system uses two renewable solar and geothermal energy. Due to the lack of...
Influence of liquid density variation on the bubble and gas dynamics of a single acoustic cavitation bubble
, Article Ultrasonics ; Volume 102 , March , 2020 ; Pasandideh, K ; Navid, H. A ; Sadighi Bonabi, R ; Sharif University of Technology
Elsevier B.V
2020
Abstract
The effects of liquid density variation at the bubble surface on the dynamics of a single acoustic cavitation bubble are numerically studied. The Gilmore model together with a comprehensive hydrochemical model is used. The evaporation and condensation of water vapor are included in the hydrochemical model. The simulation results are compared to those resulting from the widely known Keller-Miksis model, which assumes a constant liquid density at the bubble surface. The numerical results for a single argon bubble in water reveal that the pressure and the temperature inside the bubble in collapse phase significantly increase, when the non-constant liquid density is used. These differences...
A comparative study of various machine learning methods for performance prediction of an evaporative condenser
, Article International Journal of Refrigeration ; Volume 126 , 2021 , Pages 280-290 ; 01407007 (ISSN) ; Faegh, M ; Shafii, M. B ; Khiadani, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Evaporative condensers are regarded as highly-efficient and eco-friendly heat exchangers in refrigeration systems. Data-driven methods can play a key role in performance prediction of evaporative condensers, conducted without the complexity of theoretical analysis. In this study, four machine learning models including multi-layer perceptron artificial neural network (ANNMLP), support vector regression (SVR), decision tree (DT), and random forest (RF) models have been employed to predict heat transfer rate and overall heat transfer coefficient of a small-scale evaporative condenser functioning under a wide range of working conditions. A set of experimental tests were conducted, where inlet...
The effect of variable temperature and location on relative thermal conductivity (RTC) on the heat pipe in the presence of AL2O3 nanoparticles: Numerical and optimization approaches
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 124 , 2021 , Pages 132-149 ; 18761070 (ISSN) ; Mohammadiun, H ; Alizadeh, R ; Mesgarpour, M ; Younesian, A ; Jowkar, S ; Sharif University of Technology
Taiwan Institute of Chemical Engineers
2021
Abstract
Background: The cooling system is one of the important parts of new devices such as smartphones, servers, and other electrical devices. By employing the almost all heat transfer methods such as conduction, evaporation and condensation, heat pipes are the best choice to increase the heat transfer. The thermal conductivity of heat pipe is much higher than fins because they benefit from condensation and evaporation simultaneously. Methods: This study tries to present relative thermal conductivity base on temperature and length of a heat pipe in optimized geometry. To achieve this aim, unsteady, multiphase fluid was considered inside the heat pipe. Evaporation, condensation, and conduction were...
Effect of working fluid inventory and heat input on transient and steady state behavior of a thermosyphon
, Article Journal of Thermal Analysis and Calorimetry ; Volume 143, Issue 5 , 2021 , Pages 3825-3834 ; 13886150 (ISSN) ; Forootan, D ; Farajimoghaddam, F ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
The effect of working fluid inventory and heat input on the performance of thermosyphon is investigated in this paper. First, a thermosyphon with diameter of 16 mm made of steel with toluene as working fluid and the length of the evaporator, adiabatic and condenser section 10, 23 and 17 cm was considered, respectively. The working fluid inventory was considered 0.1, 0.14, 0.18 and 0.24 of total volume of thermosyphon and in each case 54–235 W of heat input applied to the evaporator area also. In order to evaluate the transient behavior of the thermosyphon, in any amount of working fluid, 28 W of heat input was considered and temperature of the evaporator area were recorded at different...
Interface formation and bond strength in 3Y-TZP/Cr composite bilayers produced by sinter-joining
, Article Materials Science and Engineering A ; Volume 527, Issue 3 , 2010 , Pages 449-453 ; 09215093 (ISSN) ; Simchi, A ; Hokamoto, K ; Tanaka, S ; Sharif University of Technology
Abstract
The mechanism of interface formation during sinter-joining of nanostructured yttria stabilized zirconia (27 nm) compacts with chromium powder was investigated. The effect of sintering atmosphere, i.e. argon or vacuum, was studied. Microstructural evaluation and phase formation was examined by scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), and micro-focused X-ray diffraction (MFXRD) methods. It is shown that spreading and evaporation-condensation mechanisms are responsible for the interface formation. An improved joint shear-strength was obtained after sintering in vacuum (74 MPa) compared with argon (41 MPa). The result of MFXRD indicated formation of Cr-island at...
Thermal performance assessment of an evaporative condenser-based combined heat pump and humidification-dehumidification desalination system
, Article Desalination ; Volume 496 , 2020 ; Shafii, M. B ; Sharif University of Technology
Elsevier B.V
2020
Abstract
A new design for heat pump integrated humidification-dehumidification (HDH-HP) desalination cycles was proposed in the current experimental study. An evaporative condenser was designed and fabricated instead of a separate humidifier, heater, and air/water-cooled condensers find in previous HDH-HP systems. Meanwhile, the air dehumidification process in this work directly occurred inside the heat pump evaporator. The effect of several operating parameters such as ambient wet-bulb temperature, spraying saline water and airflow rates, compressor speed, superheat, and evaporator saturation temperature control modes of the electronic expansion valve (EEV) on freshwater production and GOR were...
Effect of working fluid inventory and heat input on transient and steady state behavior of a thermosyphon
, Article Journal of Thermal Analysis and Calorimetry ; 2020 ; Forootan, D ; Farajimoghaddam, F ; Sharif University of Technology
Springer Netherlands
2020
Abstract
The effect of working fluid inventory and heat input on the performance of thermosyphon is investigated in this paper. First, a thermosyphon with diameter of 16 mm made of steel with toluene as working fluid and the length of the evaporator, adiabatic and condenser section 10, 23 and 17 cm was considered, respectively. The working fluid inventory was considered 0.1, 0.14, 0.18 and 0.24 of total volume of thermosyphon and in each case 54–235 W of heat input applied to the evaporator area also. In order to evaluate the transient behavior of the thermosyphon, in any amount of working fluid, 28 W of heat input was considered and temperature of the evaporator area were recorded at different...