scholarly journals A SINGLE LOOP PULSATING HEAT PIPE IN VARYING GRAVITY CONDITIONS: EXPERIMENTAL RESULTS AND NUMERICAL SIMULATIONS

2018 ◽  
Author(s):  
Luca Pietrasanta ◽  
Daniele Mangini ◽  
Davide Fioriti ◽  
Nicolas Miche ◽  
Manolia Andredaki ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Heat Pipe ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Single Loop

Experimental Study on Flow Visualizing and Heat Transfer Characteristic of Pulsating Heat Pipe

2007 ◽  
Author(s):  
Li Jia ◽  
Dayan Yin
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Flow Patterns ◽  
Bulk Flow ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Transition Flow ◽  
Fill Ratio

The flow of looped pulsating heat pipe was studied by a visualizing experiment, and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The experimental results indicate that bulk flow, transition flow and annular flow are the major flow patterns in PHP. Under different fill ratios and heat transfer rate, the flow pattern in PHP is transferred form bulk flow to semi-annual flow and annual flow, and the performance of heat transfer is improved. In the experiment, nuclear boiling, the convergence and break up of liquid-plug and vapor-slug were observed. The influence characterization has been done for the variation of fill ration, heat transfer rate, non-condensable gas and inclination angle. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%; the heat resistance is decreased with heat transfer rate, and non-condensable gas also has significant influence on it. The temperature of tubes in heating, condensing and observe sections were recorded, The fluctuation of heat pipe wall temperature was analysed, and the phenomena of suddently increase or decrease of temperature, the unregular fluctuation of temperature were analyzed. Otherwise the response time under different conditions was also analyzed.

Experimental Research on Heat Transfer Characteristics of Pulsating Heat Pipe

2008 ◽  
Author(s):  
Li Jia ◽  
Yan Li
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Experimental Research ◽  
Transfer Rate ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Fill Ratio ◽  
Transfer Characteristics

Experimental research was conducted to understand heat transfer characteristics of pulsating heat pipe in this paper. The PHP is made of high quality glass capillary tube. The heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage under different fill ratio. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appeares in top heating condition. The flow pattern in PHP is transferred form bulk flow to semi-annual flow and annual flow, and the performance of heat transfer is improved for down heating case under different fill ratios and heat transfer rate. The experimental results show that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

Heat Transfer Characteristics of a 3-D Printed Pulsating Heat Pipe: Fundamental Experiments Using Water As a Working Fluid

2017 ◽  
Author(s):  
Yasushi Koito ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Cooling Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transient Temperature ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Condenser Section ◽  
Heater Power ◽  
Cooling Water Temperature

This paper describes extended experiments on a pulsating heat pipe (PHP) fabricated by using a 3-D printer and a graphene-laden PLA (PolyLactic Acid) filament. Water was used as a working fluid. To maintain airtightness, the 3-D printed PHP was electroplated by copper since the graphene in the filament allows electric currents to pass through. The PHP had ten square channels. A cross section and a length of the square channel were 1.5 mm × 1.5 mm and 80 mm, respectively. Ends of each channel were connected to form a single serpentine channel. A filling ratio of the working fluid was 50%. In experiments, an evaporator section of the PHP was heated by a heater and a condenser section was cooled using a water-cooling jacket. The heater power was increased stepwise from 2.0 W to 7.0 W while the cooling water temperature and its flow rate were maintained at 4.0 °C and 0.25 LPM, respectively. Transient temperature distributions of the PHP were measured by K-type thermocouples. From the experimental results, steady-state two-phase heat transport operation of the PHP was confirmed for the heater power between 3.0 W and 6.0 W. Moreover, the present experimental results were compared with the previous ones, where ethanol was used as the working fluid. It was also confirmed that the thermal resistance of the PHP with ethanol was slightly smaller than that with water.

On Application of Looped Pulsating Heat-Pipe in High-Power LED for Street Light

2013 ◽  
Vol 732-733 ◽  
pp. 265-269 ◽  
Author(s):  
Wen Wu Tang ◽  
Guang Xiao Kou ◽  
Liang Liang Hu ◽  
Hui Wen Zhou ◽  
Bo Feng
Keyword(s):  
Thermal Analysis ◽  
Heat Pipe ◽  
High Power ◽  
Thermal Condition ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Loop Heat Pipe ◽  
Pulsating Heat Pipe ◽  
Temperature Distributions ◽  
Simulation Results

The ANSYS-ICEPAK is used to establish and analyze the thermal condition of the cooling modular of the looped pulsating heat pipe in the street light, the reliability is proved by experimental results of thermal analysis. The experimental results show that: the temperature distributions on the surface of the lamp shell and loop heat pipe are uniform, and the average temperatures of them are about 40°Cand 43°C; while the maximum temperature of the chip base reaches 67.5°C. Through comparison, the simulation results are close to the actual measured results.

Numerical Analysis of Effects of Surface Tension and Viscosity on 3 Dimensional Pulsating Heat Pipe

2018 ◽  
Author(s):  
Durga Bastakoti ◽  
Hongna Zhang ◽  
Weihua Cai ◽  
Fengchen Li
Keyword(s):  
Surface Tension ◽  
Numerical Analysis ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Input ◽  
Lower Surface ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Lower Surface Tension

Since the development of Pulsating Heat Pipe (PHP), it has gained a lot of attention in the field of thermal management. Flow inside multi-turn PHP is dominated by the capillary action mostly driven by the surface tension and drag force. Cetyltrimethyl ammonium chloride (CTAC) surfactant solution has lower surface tension and higher viscosity values compared to water, its base fluid. Experimental results have proven that the thermal resistance of PHP has increased its thermal performance at higher fill ratios and higher heat input, however the operational mechanism is not yet understood. Vapor formation, its movement and flow pattern of phases of working fluid can be well analyzed by the computational approach. In this paper, results of numerical analysis of 3-D PHP with working fluids that has values of surface tension and viscosity equal to that of 2000 ppm of CTAC are presented to validate the experimental results, thereby explain the thermodynamic reason of decreased thermal resistance. Moreover, the reasons for degraded performance of PHP with CTAC solutions at lower fill ratio and lower heat inputs are explained based on the vapor generation and flow of liquid-vapor inside the capillary tube. The numerical investigation was carried out for the case of 35%, 50% and 65% Fill Ratios (FR) at heat supply of 20, 30, 40 and 50 Watts. Lower surface tension promoted the phase change by rapid formation of vapor from liquid phase. Higher viscosity decreased the velocity of the fluid within the pipe. Influence of surface tension and viscosity on the thermal performance of PHP varied with different fill ratios and heat input.

Characterisation of a Novel Pulsating Heat Pipe Cooler for Power Electronics at Extreme Ambient Temperatures

2015 ◽  
Author(s):  
Daniele Torresin ◽  
Mathieu Habert ◽  
Violette Mounier ◽  
Francesco Agostini ◽  
Bruno Agostini
Keyword(s):  
Heat Pipe ◽  
Low Cost ◽  
Saturation Temperature ◽  
Open Loop ◽  
Experimental Results ◽  
Fluid Distribution ◽  
Pulsating Heat Pipe ◽  
Ambient Temperatures ◽  
Air Temperatures ◽  
Thermo Physical Properties

A compact and low cost pulsating heat pipe cooler (PHP) based on automotive technology is presented. This technology uses numerous aluminium MultiPort Extruded (MPE) tubes with capillary sized channels disposed in parallel to achieve the desired compactness. The sub-channels of the MPEs are connected in a serpentine manner by means of fluid distribution elements integrated in the evaporator and condenser manifolds. This configuration enables the oscillation of liquid slugs and elongated bubbles between the evaporator and the condenser areas. In the present paper the experimental results of an open loop type PHP with refrigerants fluids R134a and R245fa are presented. Tests have been carried out for air temperatures ranging between −60 and 60 °C at a fixed air flow rate of 480 m3/h and heat loads from 3 to 13 W/cm2. The experimental results show the different thermo-physical properties effect of the two tested fluids on the cooler performances: R134a is more adapted to low saturation temperature than R245fa and the contrary has been observed at high saturation temperatures. This is due to the fact that R245fa reaches its viscous limit at low temperatures while at high temperatures R134a reaches its critical temperature.

scholarly journals Study on oscillatory heat transfer performance of single loop pulsating heat pipe

2021 ◽  
Vol 680 (1) ◽  
pp. 012049
Author(s):  
Zhuang Zhi ◽  
Su Lei ◽  
Dingming Zheng
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Pulsating Heat Pipe ◽  
Single Loop

Numerical Study of a Novel Single-loop Pulsating Heat Pipe with Separating Walls within the Flow Channel

2021 ◽  
pp. 117246
Author(s):  
Zhanxiao Kang ◽  
Dahua Shou ◽  
Jintu Fan
Keyword(s):  
Heat Pipe ◽  
Numerical Study ◽  
Flow Channel ◽  
Pulsating Heat Pipe ◽  
Single Loop
Sign in / Sign up

Export Citation Format

Share Document