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    Ferrofluidic open loop pulsating heat pipes: Efficient candidates for thermal management of electronics

    , Article Experimental Heat Transfer ; Vol. 27, issue. 3 , Dec , 2014 , p. 296-312 ; ISSN: 08916152 Mohammadi, M ; Taslimifar, M ; Saidi, M. H ; Shafii, M. B ; Afshin, H ; Hannani, S. K ; Sharif University of Technology
    Abstract
    Thermal management of electronic devices is presently a serious concern. This article investigates the thermal performance of a five-turn open-loop pulsating heat pipe in both start-up and steady thermal conditions. The effects of working fluid, namely water and ferrofluid, heat input, charging ratio, ferrofluid concentration, orientation, as well as application of magnetic field, are explored. Experimental results show that using ferrofluid enhances the thermal performance in comparison with the case of distilled water under certain conditions. In addition, applying a magnetic field on the open-loop pulsating heat pipe charged with ferrofluid improves its thermal performance. Charging... 

    Experimental study of the startup performance of ferrofluidic open loop Pulsating Heat Pipes

    , Article ASME 2012 Heat Transfer Summer Conference Collocated with the ASME 2012 Fluids Engineering Div. Summer Meeting and the ASME 2012 10th Int. Conf. on Nanochannels, Microchannels and Minichannels, HT 2012, Rio Grande, 8 July 2012 through 12 July 2012 ; Volume 2 , 2012 , Pages 585-591 ; 9780791844786 (ISBN) Maziar, M ; Mehdi, T ; Siamak, K. H ; Mohammad Hassan, S ; Hossein, A ; Mohammad Behshad, S ; Sharif University of Technology
    2012
    Abstract
    Pulsating Heat Pipes (PHPs) are new and promising heat transfer devices. To implement the novel idea to vary the startup performance of a PHP using ferrofluid with and without the application of magnetic field, an experimental investigation is conducted. The effects of several important parameters including working fluid, charging ratio, heat input, ferrofluid concentration, internal pressure, and application of magnetic field on the startup performance of Open Loop Pulsating Heat Pipes (Open Loop PHPs) have been considered and described in detail. Obtained results show that using ferrofluid instead of distilled water can improve the startup performance of PHPs in certain conditions.... 

    Experimental investigation of the thermal characteristics of single-turn pulsating heat pipes with an extra branch

    , Article International Journal of Thermal Sciences ; Volume 134 , 2018 , Pages 258-268 ; 12900729 (ISSN) Sedighi, E ; Amarloo, A ; Shafii, M. B ; Sharif University of Technology
    Elsevier Masson SAS  2018
    Abstract
    In addition to some approaches such as changing the working fluid or number of turns in a pulsating heat pipe (PHP), geometrical changes are also appealing for enhancing the thermal performance of this type of heat pipes. The main idea of this investigation is to increase heat transfer rate by increasing flow circulation of working fluid. By placing an additional branch in the evaporator section, a secondary bubble pump was created which improved the circulation of fluid inside PHP. In order to investigate the impact of this additional branch, two similar one-turn copper heat pipes were fabricated. One of them was the conventional PHP and the other had an additional branch and is named... 

    Experimental and Analytical Investigation on Power Generation from Pulsating Heat Pipe

    , M.Sc. Thesis Sharif University of Technology Moazami Goudarzi, Hossein (Author) ; Shafii, Mohammad Behzad (Supervisor)
    Abstract
    Recently pulsating heat pipe have been used efficiently for heat transfer appications especially for heat excretion. As the name speaks, a pulsating movement of the fluid exists in the device and the principal aim of this research is to utilize this potential mechanical work ability of this movement and convert it to electrical energy. In this system slug-plug pulsating movement paradigm has been used in a U-shape pipe for supplying electromagnetic energy generator. The magnet positioning between hot and cold sources is moved in a pulsating form by the fluid and therefore electrical force is induced in the form of pulsating voltage difference. Fluid current is modeled by governing equations... 

    Experimental Investigation of Effect of Nanofluid Stability on Thermal Performance and Flow Regimes in Pulsating Heat Pipe

    , M.Sc. Thesis Sharif University of Technology Akbari, Ali (Author) ; Saeedi, Mohammad Hassan (Supervisor)
    Abstract
    Pulsating heat pipe (PHP) is a type of wickless heat pipe that has a simple structure and an outstanding thermal performance. Nanofluid is a type of fluifid in which nanoparticles are dispersed in a base fluid and has a better thermal conductivity in comparison with its base fluid. In this article, the performance of a nanofluid PHP is investigated. In order to simultaneously investigate the thermal performance and flow regimes in the PHP, a one-turn copper PHP with a Pyrex glass attached to its adiabatic section was used. A one-turn Pyrex PHP was also used to fully visualize flow patterns in the PHP. Our results showed that the material that a PHP made of and temperature of working fluid... 

    Design and performance of a novel hybrid photovoltaic–thermal collector with pulsating heat pipe (PVTPHP)

    , Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; Volume 43 , 2019 , Pages 371-381 ; 22286187 (ISSN) Kavoosi Balotaki, H ; Saidi, M. H ; Sharif University of Technology
    Springer International Publishing  2019
    Abstract
    Hybrid photovoltaic–thermal collectors (PVT) are cogeneration components that convert solar energy into both electricity and heat. Pulsating heat pipe (PHP) is a fast-responding, flexible and high-performance thermal-conducting device. The aim of this work is design and performance of a novel hybrid photovoltaic–thermal collector with pulsating heat pipe (PVTPHP) for improving the electrical efficiency, by reducing the photovoltaic panel’s temperature, as well as taking advantage of the thermal energy produced. An experimental setup of PVTPHP is constructed, and its operating parameters are measured. The measured parameters include solar radiation intensity, ambient temperature, filling... 

    Experimental Investigation of Pulsating Heat Pipe Using Nano-Fluid

    , M.Sc. Thesis Sharif University of Technology Taslimifar, Mehdi (Author) ; Saidi, Mohammad Hassan (Supervisor) ; Afshin, Hossain (Supervisor) ; Shafiee, Mohammad Behshad (Supervisor)
    Abstract
    Considerable increase in speed and decrease in size of electronic devices results in increase of heat flux, so there is a need to enhance efficiency of cooling electronic devices. In the present research two sets of OLPHPs with five turns for two different magnetic nano-fluids were fabricated and the effects of working fluid (water, and two types of magnetic nano-fluids), working pressure, concentration, magnetic field, magnets location, and inclination angle on the thermal performance of OLPHPs have been considered in both startup and steady thermal conditions.
    Experimental results show that magnetic nano-fluids can improve thermal performance of the OLPHPs. Application of magnetic... 

    Experimental Investigation ofClosed-loop Pulsating Heat-pipe with an Additional Branch in the Evaporator Section

    , M.Sc. Thesis Sharif University of Technology Sedighi, Erfan (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    The main idea of this investigation is to increase heat transfer rate by increasing flow circulation of working fluid. By placing additional branches in the evaporator section, secondary bubble pumps were created which improved the circulation of fluid inside PHP. This research was implemented in two distinct phases. In the first phase, the novelty was implemented on a single turn PHP and in the second phase, the same procedure was implemented on a 4-turn PHP. In order to investigate the impact of these additional branches, two similar heat pipes were fabricated. One of them was the conventional PHP and the other had additional branches and is named additional branch PHP (AB-PHP). Thermal... 

    Experimental investigation on performance of a rotating closed loop pulsating heat pipe

    , Article International Communications in Heat and Mass Transfer ; Volume 45 , 2013 , Pages 137-145 ; 07351933 (ISSN) Aboutalebi, M ; Nikravan Moghaddam, A. M ; Mohammadi, N ; Shafii, M. B ; Sharif University of Technology
    2013
    Abstract
    Pulsating heat pipes (PHPs) are interesting heat transfer devices. Their simple, high maintaining, and cheap arrangement has made PHPs very efficient compared to conventional heat pipes. Rotating closed loop PHP (RCLPHP) is a novel kind of them, in which the thermodynamic principles of PHP are combined with rotation. In this paper, effect of rotational speed on thermal performance of a RCLPHP is investigated experimentally. The research was carried out by changing input power (from 25. W to 100. W, with 15. W steps) and filling ratio (25%, 50%, and 75%) for different rotational speeds (from 50. rpm to 800. rpm with an increment of 125. rpm). The results presented that at a fixed filling... 

    Promising technology for electronic cooling: Nanofluidic micro pulsating heat pipes

    , Article Journal of Electronic Packaging, Transactions of the ASME ; Volume 135, Issue 2 , 2013 ; 10437398 (ISSN) Jahani, K ; Mohammadi, M ; Shafii, M. B ; Shiee, Z ; Sharif University of Technology
    2013
    Abstract
    Currently, the thermal management of microelectromechanical systems (MEMS) has become a challenge. In the present research, a micro pulsating heat pipe (MPHP) with a hydraulic diameter of 508 lm, is experimented. The thermal performance of the MPHP in both the transient and steady conditions, the effects of the working fluid (water, silver nanofluid, and ferrofluid), heating power (4, 8, 12, 16, 20, 24, and 28 W), charging ratio (20, 40, 60, and 80%), inclination angle (0 deg, 25 deg, 45 deg, 75 deg, and 90 deg relative to horizontal axis), and the application of magnetic field, are investigated and thoroughly discussed. The experimental results show that the optimum charging ratio for water... 

    Overall thermal performance of ferrofluidic open loop pulsating heat pipes: An experimental approach

    , Article International Journal of Thermal Sciences ; Volume 65 , 2013 , Pages 234-241 ; 12900729 (ISSN) Taslimifar, M ; Mohammadi, M ; Afshin, H ; Saidi, M. H ; Shafii, M. B ; Sharif University of Technology
    2013
    Abstract
    Pulsating heat pipes (PHPs) are simple, cheap, and efficient heat transfer devices. They have applications in electronic cooling. In the present research, an experimental investigation is conducted on startup and steady thermal performances of open loop pulsating heat pipes (OLPHPs). Effects of working fluid, heat input, non-condensable gases (NCGs), ferrofluid concentration, magnets location, and inclination angle on the thermal performance of OLPHPs have been considered. Obtained results show that using ferrofluid can improve the thermal performance in steady state condition. Furthermore, applying a magnetic field enhances the heat transfer characteristics of ferrofluidic OLPHPs in both... 

    Thermal performance of an open loop pulsating heat pipe with ferrofluid (Magnetic Nano-Fluid)

    , Article ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012 ; 2012 , Pages 185-190 ; 9780791854778 (ISBN) Taslimifar, M ; Mohammadi, M ; Saidi, M. H ; Afshin, H ; Shafii, M. B ; Kazemzadeh Hannani, S ; Sharif University of Technology
    Abstract
    In the present research an experimental investigation is performed to explore the effects of working fluid, heat input, ferrofluid concentration, magnets location, and inclination angle on the thermal performance of an Open Loop Pulsating Heat Pipe (OLPHP). Obtained results show that using ferrofluid can improve the thermal performance and applying a magnetic field on the water based ferrofluid decreases the thermal resistance. It shows that at an inclination angle of the OLPHP to be zero, the thermal performance of the present OLPHP reduces. Best heat transfer capability was achieved at 67.5 degree relative to horizontal axis for all of working fluids. Variation of the magnets location... 

    Experimental study of the effects of ferrofluid on thermal performance of a pulsating heat pipe

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011 ; Volume 1 , 2011 , Pages 435-440 ; 9780791844632 (ISBN) Maziar, M ; Mohammad, M ; Amir, R. G ; Shafii, M. B ; Sharif University of Technology
    2011
    Abstract
    In this work, a four-turn Pulsating Heat Pipe (PHP) is fabricated and tested experimentally. The novelty of the present PHP is the capability of obtaining various thermal performances at a specific heat input by changing the magnetic field. The effects of working fluid (water and ferrofluid), charging ratio (25%, 40%, and 55%), heat input (25, 35, 45, 55, 65, 75, and 85 W), orientation (vertical and horizontal heat mode), and magnetic field on the thermal performance of PHPs are investigated. The results showed that applying the magnetic field on the water based ferrofluid reduced the thermal resistance of PHP by a factor of 40.5% and 38.3% in comparison with the pure water case for the... 

    Experimental investigation of nanofluid stability on thermal performance and flow regimes in pulsating heat pipe

    , Article Journal of Thermal Analysis and Calorimetry ; 25 May , 2018 , Pages 1-13 ; 13886150 (ISSN) Akbari, A ; Saidi, M. H ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    Pulsating heat pipe (PHP) is a type of wickless heat pipe that has a simple structure and an outstanding thermal performance. Nanofluid is a type of fluid in which nanoparticles are dispersed in a base fluid and have generally a better thermal conductivity in comparison with its base fluid. In this article, the performance of a nanofluid PHP is investigated. Graphene/water nanofluid with a concentration of 1 mg mL−1 and TiO2 (titania)/water nanofluid with a concentration of 10 mg mL−1 are used as the working fluids. To simultaneously investigate the thermal performance and flow regimes in the PHP, a one-turn copper PHP with a Pyrex glass attached to its adiabatic section is used. A one-turn... 

    Experimental investigation of nanofluid stability on thermal performance and flow regimes in pulsating heat pipe

    , Article Journal of Thermal Analysis and Calorimetry ; Volume 135, Issue 3 , 2019 , Pages 1835-1847 ; 13886150 (ISSN) Akbari, A ; Saidi, M. H ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    Pulsating heat pipe (PHP) is a type of wickless heat pipe that has a simple structure and an outstanding thermal performance. Nanofluid is a type of fluid in which nanoparticles are dispersed in a base fluid and have generally a better thermal conductivity in comparison with its base fluid. In this article, the performance of a nanofluid PHP is investigated. Graphene/water nanofluid with a concentration of 1 mg mL −1 and TiO 2 (titania)/water nanofluid with a concentration of 10 mg mL −1 are used as the working fluids. To simultaneously investigate the thermal performance and flow regimes in the PHP, a one-turn copper PHP with a Pyrex glass attached to its adiabatic section is used. A... 

    Experimental Investigation of Pulsating Heat Pipe

    , M.Sc. Thesis Sharif University of Technology Jamshidi, Hamed (Author) ; Shafiee, Mohammad Behshad (Supervisor)
    Abstract
    Pulsating heat pipes (PHP) are complex heat transfer devices which unlike conventional heat pipes do not contain any wick in their structure. The effective parameters consist of; working fluid, volumetric filling ratio, operational orientation and input heat power have been investigated here. The experimental set-up we have contemplated, fabricated and tested included five turns, made of copper tube coupled with two glass tube of internal diameter 1.8 mm. The height of evaporator, condenser and adiabatic section was 60, 60 and 150 mm, respectively. The evaporator was heated with electrical element connected to an AC variant power supply and the condenser was connected to a constant... 

    Design and Fabrication of a Fluid Oscillation Micro-Power Generator in a Pulsating Heat Pipe and its Performance Experimental and Theoretical Investigation

    , M.Sc. Thesis Sharif University of Technology Zia Oleslami, Naser (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    Pulsating heat pipes have been more studied in recent two decades as effective tools in dissipating waste heat from electronic components. Due to oscillating fluid flow model, these tubes have the potential of converting waste energy to power. This research presents a system that makes this potential to act. In this system, the oscillating slug-plug fluid flow pattern in an open-looped pulsating heat pipe makes a permanent magnet which is levitated in Ferrofluid to vibrate in an electromagnetic vibration-based generator in order to induce electro motive force. The fluid flow regime in pulsating heat pipe has been simulated numerically with finite element scheme. The model results for fluid... 

    Exergy analysis of a flat plate solar collector in combination with heat pipe

    , Article International Journal of Environmental Research ; Vol. 8, Issue. 1 , 2014 , Pages 39-48 ; ISSN: 17356865 Kargarsharifabad, H ; Shafii, M. B ; Rahni, M. T ; Abbaspour, M ; Sharif University of Technology
    Abstract
    The use of solar collectors in combination with heat pipes is rapidly growing in recent years. Heat pipes, as heat transfer components, have undeniable advantages in comparison with other alternatives. The most important advantage is their high rate of heat transfer at minor temperature differences. Although there have been numerous studies on the heat analysis or first thermodynamic analysis of flat plate solar collectors in combination with heat pipes, the exergy analysis of these collectors is needed to be investigated. In this work, energy and exergy analysis of a flat plate solar collector with a heat pipe is conducted theoretically. Next, the exergy efficiency of pulsating heat pipe... 

    Experimental investigation of thermal resistance of a ferrofluidic closed-loop pulsating heat pipe

    , Article Heat Transfer Engineering ; Vol. 35, issue. 1 , 2014 , pp. 25-33 ; ISSN: 01457632 Mohammadi, M ; Mohammadi, M ; Ghahremani, A. R ; Shafii, M. B ; Mohammadi, N ; Sharif University of Technology
    Abstract
    For the present article, a pulsating heat pipe (PHP) is fabricated and tested experimentally by bending a copper tube. The effects of working fluid, heat input, charging ratio, inclination angle, magnets location, and ferrofluid (magnetic nanofluid) volumetric concentration have been investigated on the thermal performance of this PHP. Experimental results show that using ferrofluid as a working fluid improves the thermal performance of the PHP significantly. Moreover, applying a magnetic field on a ferrofluidic PHP reduces its thermal resistance. By changing the inclination angle of the PHP from vertical mode to angles close to the horizontal mode, the present PHP has a constant and... 

    Open-loop pulsating heat pipes charged with magnetic nanofluids: powerful candidates for future electronic coolers

    , Article Nanoscale and Microscale Thermophysical Engineering ; Volume 18, Issue 1 , 2014 , Pages 18-38 ; ISSN: 15567265 Mohammadi, M ; Taslimifar, M ; Haghayegh, S ; Hannani, S. K ; Shafii, M. B ; Saidi, M. H ; Afshin, H ; Sharif University of Technology
    Abstract
    The present research proposes an effective method to enhance the heat transport capability of conventional electronic coolers and improve their thermal management. Pulsating heat pipes (PHPs) are outstanding heat transfer devices in the field of electronic cooling. In the present study, two sets of open-loop pulsating heat pipes (OLPHPs) for two different magnetic nanofluids (with and without surfactant) were fabricated and their thermal performance was experimentally investigated. Effects of working fluid (water and two types of magnetic nanofluids), heating power, charging ratio, nanofluid concentration, inclination angle, application of a magnetic field, and magnet location are described....