Thermal Characteristics Of Heat Pipe Research Articles

Thermal Characteristics of a Cylindrical Heat Pipe using Multi-Layer Screen Mesh Wick

Heat pipe is the most widely used heat exchanging device in removal of heat from any given system at a faster rate. The thermal characteristics of heat pipe with single and multi-layered screen mesh wicks have been observed with two working fluids water and acetone. Heat pipe of length 250 mm and 12.7 mm outer diameter, made of copper material is used in all the trials of with and without wick structure. A 100 mesh stainless steel screen wire mesh is chosen as wick structure. Experiments were conducted at different heat loads and various inclinations with 100% fill ratio in evaporator. The performance is measured based on total thermal resistance and overall heat transfer coefficient. The heat pipe is found effective at 60o inclination with acetone as a working fluid and with four layered screen mesh wick. Uncertainty in thermal resistance and heat transfer coefficient is calculated for a heat input of 10W at 0ï‚° and 60ï‚° inclinations.

Numerical Simulation Study of the Heat Transfer Performance in Ω-Shape Grooved Heat Pipes

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. An experimental investigation and CFD simulation of thermal characteristics of heat pipe were presented in the present work. It can be found that using FLUENT can simulate the evaporation and condensation in heat pipe. With the increase of slit width, thermal resistance and the maximum heat transfer capacity of the heat pipe have a decline trend, while the equivalent thermal conductivity of the heat pipe increases gradually. With the increase of channel diameter, thermal resistance and the maximum heat transfer capacity of the heat pipe have an upward trend, while the equivalent thermal conductivity of the heat pipe reduces gradually. Results in the present work can provide guidance to further research of grooved heat pipe.

Numerical simulation study of the heat transfer characteristic in Ω-shape grooved heat pipes

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. An experimental investigation and CFD simulation of thermal characteristics of heat pipe was presented in the present work. It can be found that using FLUENT can simulate the evaporation and condensation in heat pipe. With the increase of chamber diameter, the equivalent thermal conductivity and maximum heat transfer capacity of heat pipe are both on an increasing trend, however, the thermal resistance reduces gradually. With the increase of channel number, the thermal resistance and maximum heat transfer capacity of heat pipe are both on an increasing trend, however, the equivalent thermal conductivity reduces gradually. Results in the present work can provide guidance to further research of grooved heat pipe.

Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a “segmented” thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed “segmented” model shows more precise than the “non-segmented” model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the “segmented” model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

Study on Heat Transfer Characteristics of Heat Pipe with Axial “Ω”-Shaped Microgrooves

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. Heat pipe with axial ‘‘Ω”-shaped grooves combines a high capillary pumping pressure with a low axial pressure drop in the liquid. An experimental investigation of thermal characteristics of heat pipe with axial ‘‘Ω”-shaped grooves was presented in this paper. The experimental results showed that the work temperatures affect the equivalent heat transfer coefficients obviously, and 20 °C is chosen to be the most appropriate working temperature for heat pipe in present study. The working temperature affects the operational characteristic of heat pipe significantly. When the working temperature is 20 °C, the most efficient working input power is from 80 to 140W. The tilt angles affect the equivalent heat transfer coefficients not so obviously.

Experimental Research and Simulation in a Thermosyphon

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. An experimental investigation and CFD simulation of thermal characteristics of heat pipe was presented in this paper. It can be found that UDF in FLUENT can simulate the evaporation and condensation in heat pipe. The pressure difference between evaporation section and condenser ensure the vapor can flow successfully from the evaporation section to condenser. In steady state, the fluctuation of axial velocity is very small in the most area in heat pipe. In general, the magnitudes of velocity vary from 0 to maximum from the end of both evaporation section and condenser, and the maximum value was maintained in the adiabatic section.

An Investigation of the Thermal Performance of a Novel Axial Grooved Heat Pipe

Heat pipes are devices capable of very high heat transfer and have been widely used in many thermal management applications. An experimental investigation of thermal characteristics of heat pipe with axial ‘‘Ω”-shaped grooves was presented in this paper. The effects of angle of inclination and input power on thermal performance of heat pipe were investigated, the surface tension and gravity both impacted the fluid flow in heat pipe, and which one was dominating was analyzed. Experimental results indicate that the working temperature of heat pipe, the axial temperature differences and the maximum axial temperature differences increase when increasing the input heat flux. The total thermal resistances become smaller with the input power increasing, but become bigger with the angle of inclination increasing. And the trend of the thermal coefficient of heat pipe reverses that of the total thermal resistance. The influence of gravity on thermal performance is weaker than that of the surface tension.

Thermal Characteristics of Heat Pipe with Axially Swallow-tailed Microgrooves

A thermal model for a heat pipe with axially swallow-tailed microgrooves is developed and analyzed numerically to predict the heat transfer capacity and total thermal resistance. The effect of heat load on the axial distribution of capillary radius, and the effect of working temperature and wick structure on the maximum heat transfer capability, as well as the effect of the heat load and working temperature on the total thermal resistance are all investigated and discussed. It is indicated that the meniscus radius increases non-linearly and slowly at the evaporator and adiabatic section along the axial direction, while increasing drastically at the beginning of the condenser section. The pressure difference in the vapor phase along the axial direction is much smaller than that in the liquid phase. In addition, the heat transfer capacity is deeply affected by the working temperature and the size of the wick. A groove wick structure with a wider groove base width and higher groove depth can enhance the heat transfer capability. The effect of the working temperature on the total thermal resistance is insignificant; however, the total thermal resistance shows dependence upon the heat load. In addition, the accuracy of the model is also verified by the experiment in this paper.