scholarly journals Performance and impact of cryogenic pulsating heat pipe using a different number of turns and helium gas

2021 ◽  
pp. 210-210
Author(s):  
Arunkumar Munimathan ◽  
Mohanavel Vinayagam ◽  
Prabhu Rajalingam ◽  
Ganesamoorthy Raju ◽  
Suban Kaveripakkam

The present work involves the development of helium based Pulsating heat pipe (PHP), which containing 48 parallel tubing parts. Pulsating heat pipe (PHP) is considered as one of the best alternatives for conducting metals and it is used for long distance heat transfer process. Their heat transfer capability and efficient thermal conductivity are the prominent properties which considered for applications. The region of the condenser was thermally sealed to the giffored mcmohanon cryo-cooler [gm-cryo cooler] using a cooling cap of 1.49 W at 4.2 K while 1.1 W of heat are allowed to the evaporator section at a filling rate of 70%, through comparing the 48-turn PHP and 8-turn PHP, a most intense efficient thermal conductivity of 12329 W/ mK was achieved in the 48 turn PHP. The influence of no turns of warm movement execution was observed with the same operating parameters and topographical parameters. Observations revealed that the temperature variations of PHP 48-turn was significantly less than that of PHP 8-turn. It exhibited efficient thermal conductivity, high capacity heat transfer and a good dry-out temperature response. Thus PHP 48-turn of series and parallel configurations are defined as excellent system designs and are accessible to the PHP cryogenics framework architecture.

Author(s):  
K. C. Giri

Abstract: Pulsating heat pipe is a heat transfer device which works on two principles that is phase transition and thermal conductivity which transfer heat effectively at different temperatures. Different factors affect the thermal performance of pulsating heat pipe. So, various researchers tried to enhance thermal conductivity by changing parameters such as working fluids, filling ratio, etc. Analysis of heat transfer characteristics of closed loop pulsating heat pipe (CLPHP) is to be carried out by using Computational Fluid Dynamics. The CLPHP is to be modelled on ANSYS Workbench, the flow of CLPHP is to be observed under specific boundary conditions by using ANSYS Fluent software. Acetone and Water are taken as the working fluid with 70% filling ratio at ambient temperature 30° C and the heat flux of 200 W is supplied at evaporator. Also, the analysis has been done to know the behaviour of PHPs under varying supply of heat flux at evaporator (inlet), the output heat flux is obtained at condenser (outlet) and find out how the heat flux is varying at different temperatures. CFD results shows the heat transfer characteristics observing the performance of CLPHP is a numerical manner. The obtained CFD results are compared with the experimental. The outputs of the simulations are plotted in graphs and outlines. Keywords: Closed Loop Pulsating Heat Pipe, CFD, Heat Transfer, ANSYS.


Author(s):  
Mustafa Özçatalbaş ◽  
Ramazan Aykut Sezmen

Abstract Heat pipes are passive two-phase heat transfer devices that used in various heat transport applications because of their high thermal conductance capacities with low temperature differences. One of these applications is aerospace avionics that heat pipes are exposed to transient heat loads. Although heat pipes have been one of the heat removal alternatives for compact electronic devices, they have some restrictions during the usage in such high heat flux areas. In order to use heat pipes as effective heat removal devices, operating heat load range should not be exceeded during the operation of avionics or electronic devices. Out of these operating range, heat pipes no longer perform as effective heat removal devices because of phenomena called dry-out. In this study, a novel Finite Element (FE) Analysis Method was developed to model transient heat transfer behavior in heat pipes including dry-out phenomenon. Transient heat transfer analysis using Finite Element Method (FEM) was conducted to investigate heat pipe thermal performance considering heat flux dependent thermal conductivity under randomly varying heat inputs, which were assumed as heat dissipation of an electronic device. Validation of the FE model was done by using the results given in the literature. Heat pipe was made of Al with a length of LHP = 200 mm. Heat flux and convective heat transfer boundary conditions were used at the evaporator and condenser sections, respectively. Effective thermal conductivity of heat pipe, keff, was calculated by using the heat input depended thermal resistance, Rth, values given in literature. Under transient heat loads, heat flux dependent effective thermal conductivity was defined using user defined subroutines to simulate the dry-out. The transient heat transfer analysis was conducted using ABAQUS commercially available software. Temperature differences between evaporator and condenser sections, ΔT = Te−Tc, and thermal resistance, Rth, values are calculated for varying heat input values and compared with the results that provided in literature.


Author(s):  
Bhawna Verma ◽  
V. L. Yadav ◽  
K. K. Srivastava

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Masao Furukawa

The state of the art of thermally self-excited oscillatory heat pipe technology is briefly mentioned to emphasize that there exists no oscillating/pulsating heat pipe (OHP/PHP) suited to long-distance heat transport. Responding to such conditions, this study actively proposes a newly devised conceptually novel type of OHP/PHP. In that heat pipe, the adiabatic section works as it were the dream pipe invented by Kurzweg. This striking quality of the proposed new-style OHP/PHP produces high possibilities of long-distance heat transport. To support such optimistic views, an originally planned mathematical model is introduced for feasibility studies. Hydraulic considerations have first been done to understand what conditions are required for sustaining bubble-train flows in a capillary tube of interest. Theoretical analysis has then been made to solve the momentum and energy equations governing the flow velocity and temperature fields in the adiabatic section. The obtained analytical solutions are arranged to give algebraic expressions of the effective thermal diffusivity, the performance index combined with the tidal displacement, and the required electric power. Computed results of those three are displayed in the figures to demonstrate the realizability of that novel OHP.


Author(s):  
Dongwei Zhang ◽  
Erhui Jiang ◽  
Zhuantao He ◽  
Chao Shen ◽  
Junjie Zhou

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