scholarly journals EFFECT OF WATER BATH TEMPERATURE ON EVAPORATOR AND CONDENSER TEMPERATURE OF CLOSED LOOP PULSATING HEAT PIPE WITH ACETONE AS WORKING FLUID

2015 ◽  
Vol 04 (02) ◽  
pp. 383-387
Author(s):  
Roshan D.Bhagat .
Keyword(s):  
Heat Pipe ◽  
Closed Loop ◽  
Bath Temperature ◽  
Water Bath ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Effect Of Water ◽  
Condenser Temperature

Modeling for Fluid Flow and Heat Transfer in Closed Loop Pulsating Heat Pipe

2020 ◽  
pp. 1-34
Author(s):  
Radhakanta Sarangi ◽  
Satya Prakash Kar ◽  
Abhilas Swain ◽  
Lalit Kumar Pothal
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Vapor Bubble ◽  
Closed Loop ◽  
Working Fluid ◽  
Vapour Bubble ◽  
Pulsating Heat Pipe ◽  
Time Step ◽  
Liquid Plug ◽  
Evaporation And Condensation

Abstract Numerical modelling of multi turn Closed Loop Pulsating Heat Pipe (CLPHP) is presented in this paper for ethanol as working fluid. Modelling is carried out for 1mm and 2mm ID PHP for different number of turns, different orientations and at constant wall temperature boundary conditions. Momentum and heat transfer variations with time are investigated numerically solving the one dimensional governing equations for vapor bubble and liquid plugs. Evaporation and condensation takes place by heat transfer through liquid film present around the vapour bubble. The code takes into account the realistic phenomena such as vapour bubble generation, liquid plug merging and super heating of vapor bubbles above its saturation temperature. During merging of liquid plugs, a time step adaptive scheme is implemented and this minimum time step was found to be 10−7 s. Nature of flow is investigated by momentum variation plot. Model results are compared with the experimental results from literature for nine different cases. Maximum variation in heat transfer for all these cases is found to be below ±34%. Keywords: Closed Loop Pulsating Heat Pipe, Liquid Plug, Plug momentum, Vapor Bubble, Heat Transfer, Thin Film Evaporation and Condensation

Thermal Resistance of a Rotating Closed-Loop Pulsating Heat Pipe: Effect of Centrifugal Accelerations

2016 ◽  
Vol 851 ◽  
pp. 292-298
Author(s):  
Niti Kammuang-Lue ◽  
Deuansavanh Phommavongsa ◽  
Kritsada On-Ai ◽  
Phrut Sakulchangsatjatai ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Working Fluid ◽  
Outer Side ◽  
Gravitational Acceleration ◽  
Pulsating Heat Pipe ◽  
Centrifugal Acceleration ◽  
Condenser Section ◽  
Evaporator Section

Objective of this study is to experimentally investigate the effect of centrifugal accelerations on thermal resistance of the rotating closed-loop pulsating heat pipe (RCLPHP). The RCLPHPs were made of a copper tube with internal diameter of 1.50 and 1.78 mm and bent into flower’s petal-shape and arranged into a circle with 11 turns. The evaporator section located at the outer end of the bundle while the condenser section placed around the center of the RCLPHP with no adiabatic section. Both sections had an identical length of 50 mm. R123, and ethanol was filled as working fluid respectively. The RCLPHP was installed on the test rig and it was rotated by the DC motor at the centrifugal acceleration of 0.5, 1, 3, 5, 10, and 20 times of the gravitational acceleration considering at the connection between the evaporator and condenser section. Heat input was generated by electrical annular-plate heaters and varied from 30 to 50, 100, 150, and 200 W. Ceramic papers, wooden plate, and insulation sheet were consecutively attached on the outer side of the heaters in order to prevent the heat loss from the heater. It can be concluded that when the centrifugal acceleration increases, the thermal resistance continuously decreases since the condensate flows back to the evaporator section more rapidly.

Experimental Investigation of a Flat-Plate Closed-Loop Pulsating Heat Pipe

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Wessel W. Wits ◽  
Gerben Groeneveld ◽  
Henk Jan van Gerner
Keyword(s):  
Experimental Investigation ◽  
Flat Plate ◽  
Heat Pipe ◽  
Closed Loop ◽  
Electronics Cooling ◽  
Power Input ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Thermo Electric ◽  
Temperature And Pressure

The thermal performance and operating modi of a flat-plate closed-loop pulsating heat pipe (PHP) are experimentally observed. The PHP is manufactured through computer numerical controlled milling and vacuum brazing of stainless steel 316 L. Next to a plain closed-loop PHP, also one that promotes fluid circulation through passive Tesla-type valves was developed. Each channel has a 2 × 2 mm2 square cross section, and in total, 12 parallel channels fit within the 50 × 200 mm2 effective area. During the experimental investigation, the power input was increased from 20 W to 100 W, while cooling was performed using a thermo-electric cooler (TEC) and thermostat bath. Three working fluids were assessed: water, methanol, and ammonia. The PHP was charged with a 40% filling ratio. Thermal resistances were obtained for different inclination angles. It was observed that the PHP operates well in vertical evaporator-down orientation but not horizontally. Moreover, experiments show that the minimum operating orientation is between 15 and 30 deg. Two operating modi are observed, namely, the thermosyphon modus, without excessive fluctuations, and the pulsating modus, in which both the temperature and pressure responses oscillate frequently and violently. Overall thermal resistances were determined as low as 0.15 K/W (ammonia) up to 0.28 and 0.48 K/W (water and methanol, respectively) at a power input of 100 W in the vertical evaporator-down orientation. Infrared thermography was used to visualize the working fluid behavior within the PHPs. Infrared observations correlated well with temperature and pressure measurements. The experimental results demonstrated that the developed flat-plate PHP design, suitable for high-volume production, is a promising candidate for electronics cooling applications.

Experimental Investigation and Performance Evaluation of a Multi Turn Closed Loop Pulsating Heat Pipe

2014 ◽  
Vol 592-594 ◽  
pp. 1554-1558 ◽  
Author(s):  
N. Narendra Babu ◽  
Rudra Naik
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Closed Loop ◽  
Experimental Result ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Working Fluids

Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region to another with exceptional heat transfer capacity. It utilizes the latent heat of vaporization of the working fluid as well as the sensible heat. As a result, the effective thermal conductivity is higher than that of the conductors. An experimental study on three turn closed loop pulsating heat pipe with three different working fluids viz., Acetone, Methanol, Heptane and distilled water were employed. The PHP is made up of brass material with an inner diameter of 1.95mm, with a total length of 1150 mm for different fill ratios (FR) was employed .The PHP is tested for the thermal resistance and the heat transfer coefficient. The experimental result strongly demonstrates that acetone is a better working fluid among the working fluids considered in terms of higher heat transfer coefficient and lower thermal resistance.

scholarly journals Effect of Working Fluid on Thermal Performance of Closed Loop Pulsating Heat Pipe

2019 ◽  
Vol 9 (2) ◽  
pp. 953-956
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Filling Ratio ◽  
Working Fluid ◽  
External Diameter ◽  
Pulsating Heat Pipe ◽  
Condenser Section ◽  
Heat Transfer Efficiency ◽  
Bottom Heat

The pulsing heat pipe (PHP) is an technology that is increasingly capable of applying many manufacturing areas, but a thorough knowledge of its thermo-hydrodynamic There's far from enough system. This research explored the features of oscillation and the heat transfer efficiency of a closed-loop PHP using an internal and external diameter copper tube with 2.0 and 3.0 mm respectively. For all experimentation, filling ratio (FR) was 40%, five turns and different heat inputs of 20 to 80 W was supplied to PHP. The position of the PHP was vertical bottom heat type. 52 mm, 170 mm,60 mm was retained for the duration of the evaporator, adiabatic and condenser section. Water, Ethanol are chosen as working liquids. To understand, thermal resistance features and median evaporator pressures for multiple operating liquids at distinct heat inputs. An significant consideration for the results of PHPs is the research on PHP stated operating fluid. The result demonstrates that, with the rise of the heating output from 20 to 80 W, where as steadily increases above 80W, the thermal resistance reduces faster. By comparing Water , Ethanol working fluids, Ethanol provides the highest heat performance . The simulation is performed in Mat lab and the results have been contrasted

scholarly journals Nonlinear Analysis of Chaotic Flow in a Three-Dimensional Closed-Loop Pulsating Heat Pipe

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
S. M. Pouryoussefi ◽  
Yuwen Zhang
Keyword(s):  
Lyapunov Exponent ◽  
Heat Pipe ◽  
Closed Loop ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Periodic Behavior ◽  
Working Fluids ◽  
Chaotic Flow ◽  
Temperature Oscillations

Numerical simulation has been conducted for the chaotic flow in a 3D closed-loop pulsating heat pipe (PHP). Heat flux and constant temperature boundary conditions were applied for evaporator and condenser sections, respectively. Water and ethanol were used as working fluids. Volume of fluid (VOF) method has been employed for two-phase flow simulation. Spectral analysis of temperature time series was carried out using power spectrum density (PSD) method. Existence of dominant peak in PSD diagram indicated periodic or quasi-periodic behavior in temperature oscillations at particular frequencies. Correlation dimension values for ethanol as working fluid were found to be higher than that for water under the same operating conditions. Similar range of Lyapunov exponent values for the PHP with water and ethanol as working fluids indicated strong dependency of Lyapunov exponent on the structure and dimensions of the PHP. An O-ring structure pattern was obtained for reconstructed 3D attractor at periodic or quasi-periodic behavior of temperature oscillations. Minimum thermal resistance of 0.85 °C/W and 0.88 °C/W were obtained for PHP with water and ethanol, respectively. Simulation results showed good agreement with the experimental results from other work under the same operating conditions.

Parametric Behaviour of Closed Loop Pulsating Heat Pipe in the Presence of Water As a Working Fluid

2019 ◽  
Author(s):  
Nagendra P. Yadav ◽  
Madhuri ◽  
Anil Kumar
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Integrated Circuit ◽  
Closed Loop ◽  
Electronic Devices ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Power Inputs ◽  
Variable Power ◽  
Circuit Technology

Abstract This paper focuses on the parametric behavior of a closed loop pulsating heat pipe in the presence of water as a working fluid. The experimental study was done in the presence of different vacuum pressures inside the heat pipe with 50 percent filling ratio. The temperature was measured through the DAQ system with help of Lab VIEW 15.1 software at 12 locations of heat pipe at variable power inputs (10W–70W). Thermal resistance and variation of temperature are used to predict the performance of the heat pipe. Thermal resistance of heat pipe decreases with decrease in vacuum pressure inside the heat pipe. This work is useful for the transfer of heat of electronic devices and integrated circuit technology due to the high coefficient of convective heat transfer in the presence of phase change of working fluid inside the heat pipe.

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