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This paper presents a 1-D modeling approach for conventional heat pipes, incorporating various variables and validated against experimental results. The model utilizes AMESim software to simulate thermal resistance and two-phase flow inside the heat pipe. By employing this efficient modeling technique, the study comprehensively explores the behavior of heat pipes under different operating conditions. The validated model serves as a valuable tool for predicting thermal performance and optimizing heat pipe design. The paper discusses the methodology, including the formulation of thermal resistance and two-phase flow models, and describes the experimental setup used for validation. Results show good agreement between simulations and experiments, indicating the accuracy of the model. The study emphasizes the practicality and time efficiency of 1-D modeling for evaluating different design configurations and parameters in heat pipe systems. [ABSTRACT FROM AUTHOR]

Heat pipes have been extensively studied using various methods, such as MATLAB, AMESIM, and commercial CFD software. Early numerical models employed the thermal conductance approach, which oversimplified the characteristics and performance of heat pipes. Newer models comprise the thermal resistance model, which emphasizes two-phase heat transfer, AI-based approaches for predicting flow patterns and thermal characteristics, and the CFD model, which accounts for phase changes and two-phase flow utilizing the VoF and phase change models. Although the thermal resistance model demands fewer computing resources, it has limited visualization of the flow pattern and wick structure. In contrast, CFD models offer advantages in visualizing the flow pattern and thermal characteristics but have limitations in terms of consuming computing resources and considering heat transfer from wick structures and mass transfer rates caused by phase changes. Consequently, most simulations are validated with experimental results. Innovative approaches for phase changes in heat pipes and wick structures are necessary to address these challenges. [ABSTRACT FROM AUTHOR]

This study presents experimental investigations on the optimal design and operating conditions of pulsating heat pipe (PHP) cooling systems for cylindrical 18650 cells in electric vehicles with a special top heating mode. The research explores the effects of various parameters, including the number of turns, working fluid, filling ratio, coolant temperature, and condenser length, on the PHP system's performance. A cylindrical 3D PHP module was designed based on the flat-type PHP experimental results and evaluated as a cooling system for 18650 cells. The study highlights that the number of turns and working fluid significantly influence the PHP system's performance, with methanol identified as the most suitable working fluid. The optimal number of turns for continuous operation was determined to be 8 to 9. The condenser length was found to play a crucial role in enhancing heat transfer efficiency. The PHP system's continuous flow of working fluid ensured stable temperature profiles and prevented overheating. The research recommends a 9-turn PHP system with methanol as the working fluid and 10 %–15 % filling ratio for cooling two 18650 cylindrical cells. Maintaining cooling water temperature below 25 °C and considering specific orientation angles further improved the PHP system's cooling performance. Overall, these findings provide valuable insights into the optimal design and operating conditions of PHP cooling systems for electric vehicle batteries, leading to stable and efficient cooling, prolonged battery life, and improved electric vehicle efficiency. These results are vital for researchers and engineers working in the field of electric vehicle battery cooling systems and can serve as a foundation for future studies in this area. [ABSTRACT FROM AUTHOR]

Numerical simulation of the in-cylinder flow for internal combustion (IC) engine with different bowl shapes has been performed. The LES models are applied to a piston-cylinder assembly with a stationary valve and a harmonically moving piston. Gas motion inside the engine cylinder determines the thermal efficiency of an IC engine, and combustion chamber geometry affects the performance of the IC engine. Comparison of the flow characteristics inside the engine cylinder equipped with different piston geometries shows that the squish flow affects the turbulence generation process near the top dead center during compression stroke. The A-type combustion chamber with reentrant shape is shown to have higher radial velocity and turbulence intensity in the piston bowl compared with other types. Results of these simulations aid in the improved understanding of the effect of intake and compression process of piston geometry on the in-cylinder flow. The detailed flow characteristics inside the in-cylinder for different piston bowl shapes can offer basic guidelines to improve the combustion process. [ABSTRACT FROM AUTHOR]

The present study used TiO-nanofluid with different volume ratios as the working fluids of a therrmosyphon and grooved heat pipe and investigated various parameters such as volume concentration of nanoparticles, orientation, heat flux, and cooling media. Further, the present study used nanofluids and dispersed TiO-nanoparticles into pure water with each cross-blended concentration of 0.05%, 0.1%, 0.5%, and 1%. The authors observed the best heat transfer performance in the 0.05% concentration with thermosyphon. The present study presents the enhancement of heat transfer performance with TiO-nanofluids, and fabricated a heat pipe from a straight stainless steel tube with an outer diameter and length of 10 and 500 mm, respectively. At the optimum condition for the pure refrigerant, the thermosyphon with 0.05% TiO-nanoparticle concentration gave 1.40 times higher efficiency than that of pure water. [ABSTRACT FROM AUTHOR]

The temperature uniformity on a heat pipe hot chuck (HPHC) during semiconductor wafer processing has been an important factor to critical dimension (300 mm) uniformity as the feature size of semiconductors decreases and productivity density increases due to the new process of nano size special manufacturing technology. To design the present heat pipe hot chuck system, which has enhanced temperature uniformity for the wafer process, the heat distribution of the system was analyzed experimentally with various working fluids such as water, TiO2, ATO, ITO, Al2O3, and Ag-nanofluids and 8 cell structures. Unlike the conventional solid state chuck, the present heat pipe hot chuck system consists of a heat pipe containing specially charged working fluid. Various working fluids have been tested to find best temperature uniformity feature on the top surface of hot chuck. TiO2-nanofluid was used and tested as the working fluid of the heat pipe hot chuck system in this paper. The temperature uniformity of upper surface was sustained in the range of ±1°C. A nano-porous layer was observed on the surface with the good result of surface temperature uniformity compared with distilled water. [ABSTRACT FROM AUTHOR]

The instability of two-phase loop thermosyphons was investigated experimentally and analytically. Three orifice type inserts were used to study the effect of change in the pressure drop in the flow channel of the TLT on the flow instability and temperature fluctuation. It is observed that a decrease in the size of the orifice insert from 3.7 mm (no insert) to 0.71 mm drastically reduced the fluctuation of the temperature, especially at the evaporator section of the TLT. With the orifice type insert of 0.71 mm for the TLT, the overall temperature fluctuation was almost completely eliminated, especially at higher power input to the TLT. The analysis based on the Kelvin-Helmholtz instability theory seems to predict reasonable well the loop stability state of the TLT with experimentally determined constant factors. [ABSTRACT FROM AUTHOR]

The present study is concerned with a cooling package system for electronic components such as multichip modules (MCM) which are used in many electronic system. The im of the cooling capacity up to heat flux of 4 W/cm2 was achieved. A heat flux of 4 W/cm2 is about two to three times of the value generally accepted as the limit by forced air cooling together with heat pipes (Kishimoto et al., 1994). The data obtained from the experimental program was used to manifest the deficiency and inaccuracies of multitude of the empirical correlations for various heat transfer modes involved in the computer simulation of the proposed system. The dominant role of the temperature distributions in the system and the related two-phase flow heat transfer have been quantitatively identified and the limit of the computer simulation for such system as proposed in the present study has been advanced. [ABSTRACT FROM AUTHOR]

computer simulation is performed for a two-phase loop thermosyphon for the B-ISDN telecommunications. The aim of this code development is to provide capabilities to predict the affects of many variables on the performance of the proposed TLT system using different empirical correlations obtained from the literature for the evaporation and condensation, and the shape factors available. In the present study, the simulation code is based on the sectorial thermal resistance network built on the flow regimes of the two-phase flows involved. The nodal resistances are solved by the typical Gauss-Seidal iteration method. The code can predict whether the proposed design is possible based on the Hooding limit calculation of the system and its results are compared with the experimental results. [ABSTRACT FROM AUTHOR]