PCM-based Heat Sink Research Articles

Characterisation of heat dissipation from PCM based heat sink using Mach–Zehnder Interferometry

Characterisation of heat dissipation from PCM based heat sink using Mach–Zehnder Interferometry

Numerical study of nanocomposite phase change material-based heat sink for the passive cooling of electronic components

The current two-dimensional (2D) numerical study presents the melting phenomenon and heat transfer performance of the nanocomposite phase change material (NCPCM) based heat sink. Metallic nanoparticles (copper: Cu) of different volume fractions of 0.00, 0.01, 0.03, and 0.05 were dispersed in RT–28HC, used as a PCM. Transient simulations with conjugate heat transfer and melting/solidification schemes were formulated using finite–volume–method (FVM). The thermal performance and melting process of the NCPCM filled heat sink were evaluated through melting time, heat storage capacity, heat storage density, rate of heat transfer and rate of heat transfer density. The results showed that with the addition of Cu nanoparticles, the rate of heat transfer was increased and melting time was reduced. The reduction in melting time was obtained of − 1.36%, − 1.81%, and − 2.56% at 0.01, 0.03, and 0.05, respectively, compared with 0.00 NCPCM based heat sink. The higher heat storage capacity enhancement of 1.87% and lower reduction of − 7.23% in heat storage density was obtained with 0.01 volume fraction. The enhancement in rate of heat transfer was obtained of 2.86%, 2.19% and 1.63%; and reduction in rate of heat transfer density was obtained of − 6.33%, − 21.05% and − 31.82% with 0.01, 0.03, and 0.05 volume fraction of Cu nanoparticles, respectively. The results suggest that Cu nanoparticles of 0.01 volume fraction has the lower melting rate, higher heat storage capacity and heat transfer rate, lower heat storage density and heat transfer rate density which is preferable for passive cooling electronic components.

A novel phase change material-based heat sink with an orthotropic plate to enhance the temperature field uniformity for avionics

In this study, an orthotropic plate arranged at the bottom of the phase change material (PCM) -based heat sink is employed to enhance the temperature field uniformity (TFU) in the heat sink. The performance of the orthotropic plate in enhancing the TFU is numerically studied during the melting process of the PCM. The effects of the orthotropic conductivity (R) are examined at R = 10 Rb, 5 Rb, 0.2 Rb and 0.1 Rb. The configuration including a copper plate is also taken into consideration as a contrast to achieve a more objective and deeper insight. It is found that the orthotropic plate can significantly enhance the TFU by up to 4 times in the PCM regions; it can also narrow down the temperature range in the heat sink region. When the orthotropic conductivity is greater than Rb, it can even benefit in improving the performance of thermal management of the heat sink. Principles about the orthotropic conductivity are drawn and comprehensive evaluations are conducted to guide in designing PCM-based heat sink for thermal management of avionics.

Temperature Regulation of Photovoltaic Cells using Phase Change Material Heat Sinks Integrated with Metal Foam

This article investigates the cooling performance of Phase Change Material “PCM”-heat sinks integrated with porous metal that are attached to PV cells. Numerical simulations were carried out for a 2-dimensional configuration of a PCM-based heat sink subjected to uniform heat flux of 900W/m2 on the upper side and heat convection takes place at all other sides with a uniform convective heat transfer coefficient of 10 W/m2.°C. Two different PCMs were considered (n-Eicosane and RT44HC) and three values of metal foam porosity “e” were chosen as well (ε = 1.00, 0.97 and 0.90, where ε = 1.00 refers to no-metal foam case). Results showed that addition of metal foam enhances the cooling performance of PCM-based heat sinks. In the n-Eicosane based heat sinks, the PV-surface temperature was reduced by 6.31 °C and 7.00 °C for the 97% and 90% porosities respectively when compared to the no-metal foam case (100% porosity). On the other hand, in the RT44HC based heat sinks the PV-surface temperature was reduced by 5.50 °C and 6.15 °C for the 97% and 90% porosities respectively when compared to the no-metal foam case (100% porosity).

Sensitivity analysis on thermophysical properties efficacy on PCM-based heat sink usefulness: effects of solid particles versus liquid phase fraction

In this study, PCM-based heat sink effectiveness was investigated to examine the role of thermophysical properties. Through sensitivity analysis, the PCM thermophysical properties were changed to investigate the efficacy of each parameter on the objective function. For this purpose, the conservation equations for the PCM filled heat sink were solved using the Green-Gauss finite volume method. There were two interfaces within the PCM-based heat sink. The interface between solid nano-particles and liquid phases was tracked using the enthalpy-porosity approach, while the interface between air and PCM was located using the two-phase VOF technique. It was found that increasing the melting temperature diminished the PCM-filled heat sink effectiveness (keeping the base temperature low). As the thermal conductivity doubled, the PCM-filled heat sink ability in lowering the base temperature was slightly improved. The increase in latent heat led to an increase in melting time and consequently improved the effectiveness.

Introducing a novel heat sink comprising PCM and air - Adapted to electronic device thermal management

With the introduction of PCM-based heat sinks, the cooling of the electronic components in transient applications has been developed. The PCM-based heat sink effectiveness is acceptable only within the melting time, so that in the post-melting stage, the electronic component temperature increases significantly. In this study, a novel hybrid heat sink filled with PCM and air was introduced. This heat sink uses the PCM and air potentials simultaneously to neutralize the effects of the incoming heat flux to keep low the electronic device temperature. Incorporation of air into the PCM-based heat sink leads to acceleration in the heat rejection to the ambient (positive effect) and reduces the PCM volume fraction (negative effect). Based on the results, the positive effect outweighed the negative one and consequently, the cooling ability of the novel heat sink was better than the PCM-based as well as air-cooled heat sinks. As the convective coefficient increases, the positive effect strengthened and hybrid heat sink effectiveness become more apparent. It was found that the novel heat sink (with 50 W.m−2.K−1) can compete with air-cooled heat sinks with much higher convective heat transfer coefficient (100 W.m−2.K−1).

Experimental study on the thermal response of PCM-based heat sink using structured porous material fabricated by 3D printing

Phase change material (PCM) based heat sink has the potential to be applied for the thermal management of electronic devices. Whereas, PCM suffers from a low thermal conductivity, which results in local overheating at the base of heat sink. To enhance thermal performance of heat sink, a structured porous material (SPM) used as thermal conductivity enhancer (TCE) is designed and fabricated, where 3D printing technique is adopted to achieve the fast and precise manufacture of SPM. The thermal response of heat sink using SPM with different porosities (80%, 85%, 90%, and 95%) is experimentally investigated at various heating power levels (8 W, 10 W, and 12 W). Results show that the use of SPM has a significant effect on thermal response of heat sink for electronic cooling system. Furthermore, the thermal behavior of heat sink can be further heightened by reducing the porosity of SPM, e.g., the heat sink using SPM with 80% porosity shows the highest enhancement ratio in all cases of present study. The increase of power level can result in the reduction of operation time of PCM-based heat sink. This study is of great significance for the design and application of SPM used in thermal management unit.

Thermal performance of phase change material–based heat sink for passive cooling of electronic components: An experimental study

SummaryPresent paper reports the thermal performance of various phase change material (PCM)‐based heat sinks during melting process for cooling of portable electronic devices through experimental investigations. Heat sink configurations include unfinned with pure PCM, finned with pure PCM, unfinned with metallic foam (MF)–PCM composite, and finned with MF–PCM composite. Paraffin wax is used as PCM, and tests have been carried out for various input heat flux values (1.3, 2.0, and 2.7 kW/m2) at different volume fractions of PCM (0, 0.50, 0.86, and 1). The effect of various parameters such as PCM volume fraction, heat sink type, and heat flux on the stretching of operating time to achieve a set point temperature (SPT) is studied. Results obtained from the current experimental investigation are compared with the existing test results. Also, unfinned heat sink without and with PCM is used for baseline comparison. The evolution and propagation of melt front inside the heat sink are studied through photographic observation. The enhancement in operating time is found to vary with the SPT and heat flux values. MF–PCM‐based heat sinks are more advantageous for higher value of input heat flux (2.0 and 2.7 kW/m2). For q″ = 1.3 and 2.0 kW/m2, four‐finned MF–PCM‐based heat sink exhibits better performance; while three‐finned MF–PCM‐based heat sink shows best performance at q″ = 2.7 kW/m2. The highest enhancement ratio of ~2.97 is obtained at 1.3 and 2.7 kW/m2 for four‐finned MF–PCM heat sink and three‐finned MF–PCM heat sink, respectively. Also, three‐finned heat sink provides higher heat transfer rate and highest thermal conductance at q″ = 2.7 kW/m2.

An efficient reliability-based design optimization study for PCM-based heat-sink used for cooling electronic devices

Nowadays, development of new technologies requires efficient mechatronic components which needs more sophisticated cooling systems. Furthermore, phase change material (PCM) based heat sinks presents an appropriate technique for electronic devices. Then, the aim of this work is to propose an efficient methodology that determines an optimal design of such a PCM-based cooling system. Despite of the satisfaction of the optimal solution founded by the deterministic design optimization (DDO), the reliability level is not controlled. For this reason, reliability-based design optimization (RBDO) studies were performed. In fact, RBDO approaches aim to find the best compromise between safety and cost by taking into consideration uncertainties for the studied model. Therefore, several methods are studied, such as the optimum safety factor approach and the hybrid method. Yet, the application of these methods is limited only to linear materials. Hence, this study presents an extension in the case of nonlinear materials. In addition, to overcome problems of the classical hybrid approach, a Robust Hybrid Method (RHM) is proposed. A numerical application is used to study the different DDO and RBDO methods. Then, the efficiency of the RHM method for PCM-based heat sinks is verified.

Design optimization of PCM-based finned heat sinks for mechatronic components: A numerical investigation and parametric study

This paper presents an efficient numerical investigation of a PCM-based heat sink for the purpose of thermal management, that leads to determine its optimal configuration. This study is based on experimental results, where a comparison between heat sink with and without phase change material (PCM) was carried out. Furthermore, a detailed analysis of various parameters’ effects of the studied PCM-based heat sink in relation with geometry, boundary conditions and material parameters were studied. Numerical results show that n-Eicosane increases clearly the thermal performance of the studied cooling system, comparing with other studied PCMs. In addition, increasing the volume fraction of PCM leads to delay the latent heating phase and then increase the thermal management behavior. Also, as expected, increasing the input power level leads to increase the melting rate of PCM. The parametric analysis lead finally to define an optimal design with an efficient thermal performance, for both charging and discharging phases.

Thermal Performance of a Phase Change Material-Based Heat Sink Subject to Constant and Power Surge Heat Loads: A Numerical Study

Abstract A power surge is a frequent phenomenon that occurs in electronics. Inadequate and improper cooling during power surges results in a rapid increase in operating temperatures that may lead to failure of the electronics. In the present investigation, the thermal characteristics of a phase change material (PCM)-based heat sinks, having different configurations and orientations of fins, subject to (i) constant heat load and (ii) heat load with a power surge, are studied numerically. Preliminary investigations showed that a heat sink with PCM gets heated at a much lower temperature than an air cooled heat sink. Following this, four finned heat sinks are considered for further investigations. The heat sink with PCM, sans fins, is used for baseline comparison. The orientation of fins in the other four heat sinks is either vertical or horizontal with square and rectangular cross sections. The heat sink and fins are made of aluminum, and the PCM used is n-eicosane (C20 H42). The enthalpy-porosity method is used to model the solid–liquid phase change in the PCM. All the transient three-dimensional numerical simulations are carried out using ansys fluent 15.0. For a constant heat load of 5 W and power surges of various magnitudes at different time instants, the heat sink with vertical square fins shows superior performance. However, the performance variation among the heat sinks with different fin configurations is insignificant for constant heat load. Even so, for power surges, the location and the configuration of fins have a significant effect on the heater temperature. Cases with high power surge and shorter duration of the surge were also considered to critically examine the effect of fins in controlling the maximum temperature in the heat sink. The numerical results of the best-performing heat sink, i.e., the heat sink with vertical square fins, are finally validated against in-house experiments.

Incorporation of Horizontal Fins into a PCM-Based Heat Sink to Enhance the Safe Operation Time: Applicable in Electronic Device Cooling

In this study, the effect of the presence of horizontal fins on the safe operating time (SOT) of the PCM filled heat sink was examined. The effects of the number of horizontal fins, as well as fins length on SOT at different aspect ratios, was investigated. Horizontal fins, owing to their high thermal conductivity, cause uniformity in temperature distribution and improve the heat sink thermal conductivity (positive effect). Incorporating horizontal fins reduces the PCM volume fraction which consequently diminishes the ability of the heat sink to absorb the thermal energy (negative effect). The competition between the former effect and the latter determines the efficacy of adding horizontal fins in the PCM filled heat sinks. As the number of horizontal fins increases up to five, the positive effect is superior to the negative one which in turn enlarges the safe operation time. By the further increase in the number of fins, the negative effect prevailed over the positive effect and therefore the safe operation time diminished. As the heat sink aspect ratio increased, convection heat transfer efficacy becomes more apparent. In this case, it is recommended to use horizontal fins with shorter lengths so that the PCM movement is not disturbed.

Evaluation of heat sink performance using PCM and vapor chamber/heat pipe

This paper presents a numerical study on heat sink thermal performance using phase change materials (PCM) and a vapor chamber for heat source cooling. Heat sink performance in both natural and forced convection heat transfer modes is investigated. The influence of various geometrical parameters such as number, height and thickness of fins for three different modes of conventional heat sink, PCM-based heat sink and heat sink integrated with vapor chamber is studied. Numerical results showed that the number of fins and fin height were more effective than the fin thickness in reducing heat source temperature. Furthermore, in natural convection, the addition of PCM and vapor chamber to the heat sink reduces the heat source temperature by a maximum of 33.1% and 9.5%, respectively, compared to a conventional heat sink. But in forced convection, the use of vapor chamber reduces the heat source temperature by 7.9% while the addition of PCM to the heat sink affects its performance adversely. In fact when fresh air is blown to the heat sink, it provides a higher temperature potential at all the surfaces.

Experimental and numerical studies on heat transfer from a PCM based heat sink with baffles

The goal of this paper is to focus on a strategy to reduce the discharge time for a heat sink filled with a Phase Change Material (PCM). Reducing the heat discharge time is one of the key criteria in the design of a PCM based heat sink used in electronics cooling. To date, almost all of the studies have focused on the improvement of charging time for continuous operation under heavy computational loads. However, when intermittent operations are considered, which are most likely to be encountered in practice, a reduction in the heat discharge time from the heat sink is as important as that of improvement in the charging time. This work reports the results of detailed experimental studies carried out to improve the performance of a PCM based heat sink in the discharging cycle using baffles. Baffles are horizontal plate fins made of aluminum, and the PCM used is n-eicosane. Among different fill ratios and orientations considered, the heat sink with a 99% fill ratio at 0∘ orientation offered the best performance. A numerical study is also performed on the best performing heat sink to ascertain the actual causes for the lower discharge time.

Numerical investigation on conventional and PCM heat sinks under constant and variable heat flux conditions

In this study, a numerical model is developed to study the behaviour of conventional heat sink and phase change material (PCM) heat sink for electronics cooling applications. Two different PCMs, RT35HC (ΔTm = 34–36 °C and ΔH = 240 kJ/kg) and RT44HC (ΔTm = 41–44 °C and ΔH = 250 kJ/kg), are selected for the analysis. A comparison has been made between conventional heat sink and PCM-based heat sink under constant and variable heat flux conditions. Further, four different hybrid heat sink design configurations are studied during the cooling period (solidification) and compared with PCM-based heat sink. During the heating period, the conventional heat sink is subjected to different convective cooling environments (h = 10–50 W/m2-K). The results showed that the PCM heat sink achieved base temperature equivalent to the conventional heat sink with the heat transfer coefficient between 30 and 40 W/m2-K under the constant heat flux condition. Under the variable heat flux condition, the base temperature of the PCM heat sink is very much less than the conventional heat sink subjected to 50 W/m2-K. During the cooling period, hybrid heat sinks reduced the heat transfer coefficient by ten times less than that of the PCM heat sink.

Experimental study on melting performance of phase change material-based finned heat sinks by a comprehensive evaluation

Efficient thermal management has become an important challenge for the integration and miniaturization of electronic devices with high power density. Phase change material (PCM)-based finned heat sink is an efficient passive cooling technology for an intermittent-use electronic device with high power density. The present work reports an experimental study on the transient thermal performance of PCM-based finned heat sinks for thermal management of electronic devices, with particular emphasis on the roles of heat load and PCM volumetric fraction. The temperature response and melting front evolution in heat sinks are analyzed and compared with the corresponding cavity. Moreover, the effects of heat load, fin geometry and PCM volumetric fraction on the melting performance of heat sinks are discussed. The results indicate the presence of fins effectively improves the thermal performance of PCM-based heat sinks, and a more fin number leads to a lower operating temperature and hence the duration of electronic devices is longer in an accepted temperature. Moreover, a higher input heat flux results in a higher operating temperature and a shorter duration of low operating temperature. The increase in PCM volumetric fraction enhances the thermal storage capacity of finned heat sinks and reduces the operating temperature. Therefore, the finned heat sinks filled with PCM ensure sufficiently low operating temperature for perfect reliability and duration of high-power-density electronic devices.

Effect of Nano-Sized Heat Transfer Enhancers on PCM-Based Heat Sink Performance at Various Heat Loads.

Many passive heat controlling technologies are based on the use of phase change materials. As a rule, at low operation temperatures, close to environmental conditions, paraffins or fatty acids with melting points of 20–90 °C are used. However, the low thermal conductivity of these materials requires the development of various heat transfer enhancers satisfying technical requirements. In this work, the possibility of nanoparticle application to the heat transfer augmentation inside a closed copper radiator filled with pure n-octadecane, depending on the thermal conditions of the local heater and other system parameters, are numerically investigated.

Thermal state-of-expansion or melting of phase change material based heat sink for underwater battery power system

Abstract This paper introduces a phase change material (PCM) based heat sink (PCMHS) to reduce the idle and operating temperature of a direct current (DC)/DC converter in an underwater battery power system. The developed macro-encapsulated PCM enclosure features a dampening assembly that maximizes thermal contact and eliminates void space catered for volumetric expansion of the PCM during melting. The operating temperature of the DC/DC converter at steady-state (both idle and full-load cycle condition) is estimated via a validated thermal model. A percentage improvement of at least 27% can be achieved by PCMHS at different load cycle conditions tested. The PCM's volume expansion of approximately 6.4% corresponds to the measured cover movement of around 3 mm. The relationship between the state of expansion (or melt state) to solid-state of the PCM is also established.

Characterization of natural convection in a PCM-based heat sink with novel conductive structures

This paper numerically investigated the effect of natural convection on the thermal behaviour of a PCM-based heat sink with novel tree shape conductive structures and conventional plate fin structures. Simulations were realized using a CFD model based on the enthalpy-porosity and VOF methods. Results showed that the influence of natural convection was related to the applied metal structure, orientation and metal volume fraction. Among them, orientation expressed the most significant impact on the natural convection heat transfer by affecting the flow pattern and in return the fin efficiency. Increasing metal volume fraction tended to weaken the influence of natural convection ascribed to the enhanced heat conduction and restricted convection flow. The optimized tree shape structure with a better heat conduction path and curvilinear interface promoted natural convection, by which the better thermal mixing and higher fin efficiency were achieved, and thus enhanced heat transfer. When natural convection was negligible, the tree shape structure design initially performed a better but subsequently worse heat transfer due to its higher fin efficiency but shorter contact lines. It is suggested that the optimized tree shape structure is more superior in applications where minimum conductive material is necessary and natural convection is significant.

Combined effects of inclination angle and fin number on thermal performance of a PCM-based heat sink

Combined effects of fin number and inclination angle on the thermal performance of a PCM-based heat sink with longitudinal plate fins are investigated experimentally. Five different heat sink geometries with one, two, three, four and five fins are tested under different inclination angles varied from 0° to 90° at a constant thermal load of 16 W for the cases of with and without PCM inclusion. N-eicosane is used as the phase change material. Simultaneous temperature measurements and solid-liquid interface imaging are made to evaluate cooling performance of each heat sink configuration. The results reveal that the inclination angle and fin number plays a critical role on the formation of convective cells in the liquid PCM domain and consequently on the heat transfer and operating time. It is disclosed that the heat sink configuration with an inclination angle of 60° and three fins performs the optimal result in terms of operating time.