Integrated Heat Pipe Research Articles

Experimental and numerical investigation on the performance of binary solid-solid phase change materials with integrated heat pipe and aluminium foam based heat sink for thermal management of electronic systems

Phase change material (PCM) is widely utilised in thermal management systems (TMS), however its low thermal conductivity inhibits performance. Heat pipe and porous materials are incorporated into PCM due to their high thermal conductivities to form a hybrid system that substantially enhances PCM's heat transfer capability. This study investigates experimentally and numerically, the cooling performance of heat sink by integrating aluminium foam and heat pipe (HP) with binary Neopentyl glycol (NPG)/Trihydroxy methyl-aminomethane (TAM) solid-solid phase change material (SS_PCM) obtained at 90/10 wt% (N9T1), 70/30 wt% (N7T3) and 50/50 wt% (N5T5). Compared to pure NPG thermal conductivity, N9T1, N7T3, and N5T5 samples demonstrated relative enhancement ratios of 0.017, 2.46, and 2.84. Different heat sink configurations are examined at three constant power levels 15, 17 and 19 W for the same charging period of 10000 s to determine the optimal cooling arrangement. During the charging period, hybrid cooling (PCM-Foam-HP) system with fan in contrast to an empty sink achieved the highest temperature reduction of 58.31 %, 58.99 % and 59.89 % at power levels of 15, 17 and 19 W, respectively. N9T1, N7T3 and N5T5 combinations lowered temperature by 4.6 %, 5.9 % and 10.8 %, respectively, when compared to NPG. Furthermore, all configurations performed better at lower heat generation rates by extending the safe operational period (SOP).The investigation concluded that N5T5 SS_PCM-aided heat sinks with integrated aluminium foam and heat pipe with fan reduced temperatures the most and performed best in all aspects. Finally, the experimental results for TMS were numerically validated using COMSOL software.

Comprehensive energy, exergy, and environmental evaluation of integrated heat pipe photovoltaic/thermal systems using multi-objective optimization

The depletion of fossil fuels and their environmental emissions have led to a tendency toward the implementation of sustainable energy sources. This study aims to evaluate the energy, exergy, and environmental performance of photovoltaic/thermal systems-based heat pipes. Furthermore, the electrical exergy and thermal efficiency of the photovoltaic/thermal system are analyzed. In this regard, two methods of multi-objective evolutionary algorithm based on non-dominated sorting genetic algorithm II (NSGA II) and multi-objective particle swarm optimization (MOPSO) are utilized. The simulated heat pipes are regarded as thermosyphon and pulsating type with water and acetone as the working fluid. The novelty of this study lies in the comparative analysis of thermosyphon and pulsating heat pipes with water and acetone as working fluids in PV/T systems, combined with the application of advanced multi-objective optimization algorithms, offering a comprehensive. The result demonstrates that acetone, as a working fluid, can help achieve better performance compared towater, and also pulsating heat pipe illustrates greater performance rather than the thermosyphon heat pipe. Moreover, the result reveals that the electrical exergy efficiency of the photovoltaic panel equipped with thermosyphon heat pipe with acetone has increased by 14.2 % compared to the photovoltaic panels without the heat pipe. In addition, utilizing thermosyphon base photovoltaic/thermal system with acetone reduces the production of greenhouse gases by 894.5 CO2eqkg/m2.year, which is a further reduction of 156.8 CO2eqkg/m2.year compared to the photovoltaic panel without a heat pipe.

Digital twin-driven energy consumption management of integrated heat pipe cooling system for a data center

The energy consumption management (ECM) for the integrated heat pipe cooling (IHPC) systems has become a significant cost-cutting strategy, given the growing demand for the decreased cooling and maintenance costs in data centers. However, the traditional ECM strategies lack an integration with the real-time information and the automatic feedback control, causing the risks of system operation difficult to diagnose and the potential for energy saving hard to exploit. In this respect, a digital twin approach was proposed to efficiently and automatically implement the ECM strategy for an IHPC system. First, a digital twin architecture was established to enable seamless integration and real-time interaction between the physical system and the digital twin. Secondly, the digital twin models of monitoring, simulation, energy evaluation and optimization were developed to drive the corresponding services. Finally, the approach was verified on an IHPC system operating in a real-life data center. It is found that the approach can automatically detect and justify the abnormal states of the IHPC system. Moreover, the approach can reduce the power consumption by 23.63% while meeting the production requirements. The mean relative errors of the supply air temperature and the cooling capacity between the digital twin simulated and the on-site records are 1.43% and 1.46%, respectively. In summary, the proposed approach provides a digital twin workflow that can significantly improve the efficiency of the ECM strategy deployed on an IHPC system.

Thermal Management System for an Electric Machine With Additively Manufactured Hollow Conductors With Integrated Heat Pipes

Thermal Management System for an Electric Machine With Additively Manufactured Hollow Conductors With Integrated Heat Pipes

Performance improvement of the automotive thermoelectric generator by extending the hot side area of the heat exchanger through heat pipes

In pursuit of enhancing the utilization of exhaust heat in the automotive thermoelectric generator (ATEG), this study introduces a novel heat exchanger with integrated heat pipes to extend the effective hot-side surface area. Meanwhile, a numerical model containing multiphysical fields is developed, and the quantity and arrangement of heat pipes are optimized based on this model. Results suggest that (i) The incorporation of heat pipes markedly enhances the recovery of heat energy from the ATEG, leading to a substantial increase in its output power; (ii) With an increasing heat pipe quantity, the ATEG’s output power exhibits a continuous upward trend before eventually reaching stability; (iii) The arrangement of heat pipes also influences system performance, and through optimizations, the optimal quantity of heat pipes is determined to be N = 11 and toleration to be d = 1 mm. At an exhaust temperature of 550 K and a mass flow rate of 60 g/s, the ATEG achieves an output power of 213.19 W and a heat absorption of 4318.02 W, which increased by 42.95 % and 55.6 % respectively, compared with the traditional structure without heat pipes. This structural optimization concept for the heat exchanger provides a new approach to performance improvements of ATEGs. This study provides a design basis and guidance for optimizing the design of ATEG systems with integrated heat pipes.

Research Progress of Enhanced Thermal Evacuation and Cooling Technology for High-Speed Motors

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle.

Towards zero-carbon solar heating in severe cold and cold regions of China by building integrated heat pipes

As a climate-responsive building, the building integrated heat pipes (BIHP) can greatly improve the indoor thermal environment during the local heating season, utilizing the thermal diode characteristic and ultrahigh equivalent thermal conductivity of the L-shaped flat gravity heat pipe. The thermophysical properties of the internal envelope greatly influence the heating effect, and the utilization potentiality of BIHP varies in locations with diverse climate resources. In this paper, the utilization effects of BIHP at 61 locations in severe cold and cold regions of China are investigated. Improved backtracking search and particle swarm optimization are used to obtain the optimal heating effect and the corresponding thermophysical properties of the internal envelope at zero-carbon heating locations and non-zero-carbon heating locations, respectively. The relationship between the improvement degree of thermal discomfort and the solar radiation over temperature difference is studied, and the utilization potentiality map and zoning of BIHP are obtained. This study is of great significance for promoting the application of climate-responsive BIHP to effectively and efficiently utilize solar energy to reach zero-carbon heating.

Optimization Design of Closed-Loop Thermosyphons: Experimentation and Computational Fluid Dynamics Modeling

The well-established practice of integrating heat pipes into thermosyphons is recognized for its efficacy in achieving energy savings. This integration facilitates heat transfer and fluid circulation without requiring additional pumps or energy input, resulting in reduced consumption, lowered operational costs, and an overall improvement in system efficiency. This research explores the energy-saving potential of closed-loop thermosyphons, with a specific focus on their integration in latent heat-based heat pipe technologies in industrial settings. The study systematically investigates the influence of thermosyphon orientation on energy efficiency through a combination of experiments and computational fluid dynamics (CFD) simulations. Thereby, it results in superior heat transfer rates in forced convection scenarios. A closed-loop thermosyphon heat exchanger undergoes evaluation in three panel installation configurations relative to the ground, taking into consideration factors including copper diameters, coolants (with or without R410a), and temperature conditions. CFD validation identifies an efficient thermosyphon design—a panel oriented perpendicularly to the ground and filled with R410a refrigerant at 90 °C. It utilizes a 19.05 mm copper tube for forced convection. This optimized design demonstrates a commendable heat transfer rate of 1485 W and a heat transfer coefficient of 1252 W/(m2·K), significantly enhancing thermal process efficiency and resulting in notable energy savings.

Experimental study on the thermal performance of a liquid-cooled heat sink integrating heat pipes for dual CPU servers

The increasing power consumption of server CPUs poses a challenge for data center cooling. In this work, a liquid-cooled heat pipe heat sink (LHPHS) with compactly arranged heat pipes is designed and fabricated for CPU cooling in dual CPU servers. Water is selected as the working fluid in the heat pipes. Experiments are conducted to explore the heat dissipation potential of LHPHS under high inlet coolant temperature and high heat load conditions, and to investigate the operational stability of LHPHS under the conditions of uneven heat generation between two CPUs. Furthermore, a one-dimensional thermal resistance network and numerical model of the LHPHS are established to quantitatively analyze the thermal resistance distribution of LHPHS and the variation of thermal resistance with coolant flow rate. The results show that, firstly, the LHPHS operates stably under high inlet coolant temperature and high heat load conditions, meeting the heat dissipation requirements of up to 37.5 W/cm2 with a coolant flow rate of 1 L/min and inlet coolant temperature of 35℃. Secondly, the LHPHS exhibits excellent performance in controlling temperature difference between CPUs and even when there is discrepant heat generation between them. Thirdly, the LHPHS performs a low thermal resistance, measuring 0.044 ℃/W at a coolant flow rate of 0.5 L/min, and this resistance further decreases as the flow rate increases. Additionally, it is observed that the thermal resistance of the liquid-cooled plate decreases with the increasing flow rate, and heat transfer within the heat pipes becomes a critical aspect under high coolant flow rates. Therefore, reducing the thermal resistance of the heat pipe is crucial for the thermal performance improvement of the LHPHS.

Experimental investigation of nanoparticle enhanced polyol solid–solid phase change material aided heat sink with integrated heat pipe for electronic cooling application

Solid Solid phase change materials (SS_PCM) based thermal management systems (TMS) integrated with heat pipe are considered as excellent passive thermal management solution for electronic packages. To enhance the thermal conductivity of SS_PCM, nano-enhanced solid–solid phase change material (NE_SSPCM) samples were prepared by incorporating Neopentyl Glycol (NPG) with 1 wt% of Graphene nanoplatelets (GnP), Copper oxide (CuO) and Aluminium oxide (Al2O3) nanoparticles separately and its thermophysical characterisation study was performed. NE_SSPCM packed heat sink integrated with heat pipe was tested at different power levels from 9 to 13 W and its thermal performance was compared with TMS based on Empty heat sink, PCM-packed heat sink and PCM-packed finned heat sink configurations. TGA and FTIR characterisation techniques revealed good thermal and chemical stability for all NE_SSPCM without affecting the structure of NPG. DSC showed reduction in phase transition enthalpy for NE_SSPCM than SS_PCM. Thermal conductivities of NPG with 1 wt% of GnP, CuO and Al2O3 nanoparticles improved with relative enhancement ratios of 1.8, 1.5 and 0.8, respectively. From the experimental analysis, NE_SSPCM with heat pipe configuration showed outstanding average improvement by 7, 4.3 and 4.2 times at 9–13 W. Additionally, by extending safe operational period, all configurations were more effective at lower heat generation rates. In contrast to three nanoparticles, GnP based NE_SSPCM showed outstanding average improvement of 1.8 over NPG for PCM-based configurations. The study concluded that implementation of GnP in SS_PCM assisted heat sinks with heat pipe exhibited maximum enhancement ratio of 11.3 and demonstrated remarkable efficacy in all aspects.

Study of the thermal expansion effects of a space nuclear reactor with an integrated honeycomb core design using OpenMC and ANSYS

The negative reactivity feedback in the nuclear fuel plays an important role in maintaining the stable operation of nuclear reactors. For heat pipe cooled space reactors using highly enriched U, the fuel temperature reactivity feedback mainly due to Doppler effect and the thermal expansion of solid fuel. In this paper, based on an integrated heat pipe space reactor design, a one-way coupling of the Monte Carlo code OpenMC and finite element method ANSYS is used to evaluate the reactor expansion and the impacts to the reactor reactivity. The average expansion was 0.126 cm for the fuel block from cold state to full power operation state. The fuel thermal expansion introduces a negative reactivity feedback of −59 pcm, and the reflector expansion introduces another −675 pcm, resulting a temperature coefficient of −0.638 pcm/K.

Experimental and numerical investigation of solid-solid phase change material assisted heat sink with integrated heat pipe for electronic cooling

Advancements in phase change materials (PCM) technology offer adaptable solutions for challenging high heat dissipation problems in electronic devices. In this work, the influence of Neopentyl Glycol (NPG) as PCM having solid-solid phase transition on the functioning of heat pipe assisted heat sink is studied. Experimental and numerical investigation was performed on the transient thermal performance of heat pipe integrated PCM-assisted heat sink application with forced air cooling. The heat pipe's evaporator section is in contact with PCM- assisted heat sink, while condenser section is exposed to the ambient. Investigations were carried out at power levels of 9–13 W, corresponding to an equivalent heat flux range of 2.5–3.5 kW/m2 and with PCM filling of 33, 66 and 99 % of the heat sink volume where without integration of PCM and heat pipe in heat sink as the reference configuration. PCM-assisted heat sink and heat pipe configurations outperformed other configurations based on charging period for all experimental parameters with a maximum enhancement ratio of 3.29. Heat sink assembly comprising 99 % PCM with heat pipe gives the most significant results on comparison with all other configurations, whereas the assembly without heat pipe showed the best results for 66 %.

Performance Analysis of Solar Water Heater with Various Working Fluids

Optimized design of a solar water heater for effective heat transfer and the performance analysis was carried out in the present study. An experimental and theoretical performance of the system with an integrated heat pipe is evaluated for the same. The system uses a heat pipe with a wick to transmit heat from evaporator to the tank. The thermal behaviour of different parts of the system is analyzed. A sequence of tests are done on the heat pipe solar water heating system and thermosyphon water heating system to stimulate better configuration. The thermal efficiency of the system is optimized for maximum heat transfer using analytical techniques. Results show good thermal performance characteristics. Computation of various design parameters of heat pipe system related to the collection and consumption of solar energy are also conducted. Further, the exergy analysis and comparison of performance analysis of solar heat pipe collector with flat plate collector is also done.

Solar application potential and thermal property optimization of a novel zero-carbon heating building

Building Integrated Heat Pipes (BIHP), specifically a novel passive solar house integrated with gravity heat pipes, realizes envelopes with variable thermal properties and makes effective and efficient use of solar energy to reach zero-carbon heating, and can greatly improve the indoor thermal environment in winter. In this paper, an efficient method based on particle swarm optimization for the optimization of thermal properties of the BIHP interior envelope is proposed. The key thermal properties of the heat pipe and the exterior and interior envelopes are optimized, and the solar application potential of improving indoor thermal discomfort by BIHP in five representative cities of northern China is obtained. The results show that the equivalent thermal conductivity of the heat pipe is suggested to be greater than 2 × 104 W/(m·K). The optimal BIHP should have exterior envelopes with high thermal resistance and interior envelopes with large thermal capacity. In the selected areas, the optimal BIHP improves indoor thermal discomfort by 36 %–100 % and increases the minimum indoor operative temperature by 5.1–10.5 °C compared to the reference building. BIHP is recommended in areas with the ratio of radiation to temperature difference greater than 5 W/(m2·K) and can reach zero-carbon heating in Lhasa and Yinchuan. This research provides a global matching and optimization method for the effective and efficient utilization of solar energy to reach zero-carbon heating and evaluates the application potential of BIHP.

Experimental study of cell integrated heat pipe cooling with a lithium-ion cell emulator

Novel switchable cells challenge conventional thermal management approaches in battery electric vehicles. The study introduces a novel hybrid cooling approach based on liquid bottom cooling and cell integrated heat pipes. For the experimental investigation a thermal cell emulator is developed and the environmental conditions of a cell in an automotive battery system are reproduced. The validation of the cell emulator reveals almost similar behavior compared to a real prismatic 25 Ah cell with additional access to the internal temperature distribution. Thus, a flexible research tool is introduced for thermal investigations of lithium-ion cells. The subsequent investigation of the cell integrated heat pipes is performed for a switchable cell as an essential part of novel intelligent battery systems. As a result of the experimental investigation a reduction of the core temperature of 2 K during 3C cycling is found using integrated heat pipes. Furthermore, in a case study for fast charging the heat pipes enable consistent temperatures within the cell core, while the charging time is decreased by 12%.

Innovative Passive and Environmentally Friendly System for Improving the Energy Performance of Buildings.

The aim of the study is to develop a system for converting, accumulating, and delivering solar energy that is based on the development of an innovative solar panel with heat pipes and a heat storage wall, for the construction of passive structures. The novel aspect of this experiment is the utilization of concrete walls that have different recyclable materials added to their structure in various proportions. The solar energy from the sunny façades is transformed by this system into thermal energy, which is then transferred by integrated heat pipes in a massive element with high thermal inertia. Using insulated shutters, thermal energy can be stored during the day and released at night to keep the room at a comfortable temperature. In order to integrate the modules into the solar recovery system, four concrete samples were cast with a blend of standard and waste aggregates. Four heat fluxes of 100 W/m2, 150 W/m2, 200 W/m2, and 250 W/m2 were applied to each global system. Thermal imaging data and numerical simulations both supported the findings of temperature sensors. The most effective mixture, fly ash and chopped PET, delivered temperatures that were, on average, 3.3% higher at the end of the charging cycle than those measured for the control sample. The discharging cycle of the concrete block with fly ash and sawdust was the most effective, with an average temperature loss of 5.0 °C as compared to 5.5 °C for the control sample, on average.

Comparison, advancement, and performance evaluation of heat exchanger assembly in solid-state hydrogen storage device

Despite myriads of mathematical and experimental studies using various heat exchanger-metal hydride assemblies, an adept comparison of reactors on standard performance defining parameters, i.e., reactor weight, external energy utilization, and alloy material, are not studied or reported for industrial storage containers and onboard applications. This lacuna is a critical barrier in developing efficacious hydrogen storage reactors for various applications. This article chronicles the 3-D design and optimization of three basic heat exchanger setups of solid-state hydrogen storage systems (shell and tube, spiral tube, and tubular) on critical parameters. For 5 kg LaNi5, a tubular design with small tube diameters has resulted in a shorter reaction time (120 s) for 90% saturation at 303 K and 15 bar inlet conditions; however, the reactor's gravimetric density was exceptionally high. In contrast, the reactor with three spiral tubes accomplished an exemplary reaction rate at a reasonable gravimetric density. This spiral arrangement became the base for developing a novel reactor that integrated heat pipes to reduce the sorption time. The proposed design achieved a specific output energy rate of 527 W/kg for 90% saturation in 366 s at a supply pressure of 15 bar, which is 23.7% higher than the reactor without heat pipes.

Improvements on permanent magnet synchronous motor by integrating heat pipes into windings for solar unmanned aerial vehicle

The successful market uptake of all-electric propulsion systems is closely related to the performance metrics of the electrical motor used within. In light of this, various road-maps have been set for the next two decades by aerospace and automotive bodies targeting ambitious future targets of the motor's power densities and efficiencies. In achieving motors with such step-improvement performance metrics, often the thermal management is a key challenge. In this paper, a cooling structure for a propulsion motor of solar unmanned aircraft is proposed which combines the stator windings with heat pipes, and which is shown to simultaneously improve the heat dissipation as well as the efficiency. This paper firstly determines the heat transfer characteristic of the heat pipe experimentally which is then used in the development of a bespoke thermal network model of the motor. The effects of the cooling structure on the motor's temperature rise, copper losses, torque, and efficiency are studied in detail. Finally, a prototype is developed and a test platform is built. The experimental results are consistent with the analytical result, verifying the correctness of the thermal network model and the benefits of the proposed mechanism. Compared to the motor without heat pipes, the temperature rise of the motor is reduced by 35%, while its efficiency is improved by a significant 1.5%.

Visualization research on influencing factors of flat heat pipes

Flat heat pipes can effectively spread a concentrated high power heat source in a small region into a larger heat dissipation area, which is widely used in the thermal management of electronic devices. In this paper, two different sintered copper powder wick structures are designed to study the effect of porous column height on the heat transfer performance. The results show that the best performance is achieved at the 30% filling ratio under the 15 ℃ cooling water with all the porous columns contacting with the condenser. The heat power is 312.7 W and the thermal resistance is 0.192 ℃/W. As the cooling water temperature increases, the evaporation rate increases, resulting in a decrease in the thermal resistance. But the decrease in temperature difference causes the decline in heat dissipation power. Through the visual observation, it is found that the porous column contacting with the condenser can not only play the role of support and liquid reflow pathway, but also serve as an effective evaporation area to improve the heat transfer performance. While the low porous column cannot transport the condensed liquid and is completely immersed by the liquid under the high filling ratio, which is difficult to promote evaporation rate. In order to improve the performance at air cooling situation, an integrated heat pipe combined the flat heat pipe and fin tubes is designed, which can achieve a heat power of 259.8 W and present excellent temperature uniformity. This research provides the guidelines to optimize the heat transfer performance of porous column wick structures.

Mathematical Modeling and Optimization Heat Pipe Systems

The results of optimization of the supporting structure of a block of onboard electronic equipment with a built-in single flat heat pipe in the supporting structure with an integrated heat pipe system are presented, using the example of solving a model problem with a single heat source. The comparison was carried out at an equal temperature, occupied volume and for a certain maximum temperature of electrical radio products. The results of computational modeling are presented, demonstrating a comparison of the characteristics of a single flat heat pipe with a system of sequentially located flat heat pipes. Ultimately, the studies carried out have determined the limiting values of the removed thermal power of a single heat pipe, two-level and three-level heat pipe systems with different heat carriers. The versatility of the mathematical model, supplemented by the optimization method, has been confirmed