Change Material Based Heat Sink Research Articles

Experimental and numerical investigations on the intermittent heat transfer performance of rectangular cavity plate fin phase change material based heat sink

Thermal management of equipment in confined spaces is of great importance for the safe operation of equipment. Solid-liquid phase change materials (PCM) can be applied to the thermal management of intermittent electronic equipment because of their large isothermal latent heat absorption capacity. In this paper, experimental and numerical research on the thermal performance of an intermittent rectangular cavity plate fin PCM-based heat sink is carried out, which can be applied to heat dissipation in narrow spaces with high heat flow. The optimal PCM-based heat sink structure is obtained by numerical simulation based on the Taguchi method, and the enthalpy method is used to model the phase change process. Temperature testing and visualization experiments are used to visually present the PCM-based heat sink's internal temperature distribution and validate the numerical model. The effects of fin structure parameters, heating power, cooling air speed and number of intermittent cycles on thermal performance (base temperature, liquid fraction and operating time) are analyzed for different structured PCM-based heat sinks. The results show that the PCM-based heat sink with 8 fins, 15 mm fin height and 2 mm fin thickness has the longest stage C at the critical base temperature of 348 K and reaches the maximum operating time of 1193 s during the charging cycle. The natural convection in stage C of the charging cycle plays a crucial role in prolonging the operating time. Meanwhile, increasing the number of intermittent cycles can result in longer operating time and lower critical base temperature. As the number of intermittent cycles increases from 1 to 8, the temperature difference between the maximum and minimum temperature of the base during the whole cycle is reduced from 48 K to 25 K, and the temperature fluctuations gradually decrease.

Numerical investigation of a novel phase change material based heat sink with double sided spiral fins

Poor solidification or energy release rate from PCM has been a long-withstanding problem of PCM heat sinks which prevents their application to wide range of problems. The present study aims to simultaneously improve the energy release and storage rate of PCM by employing a novel PCM heat sink with double-sided spiral fins. The novel configuration optimizes the energy stored by the module in latent and sensible form thus improving both energy storage and release rate in successive operating cycles, unlike previous studies which solely focuses on either of these rates. Such a configuration will ensure that the system reaches the initial conditions before the start of successive cycle. The effect of various parameters of spiral fins on the heat sink's performance is numerically investigated and it is observed that increasing fin diameter (2 mm ≤ dfin ≤ 4 mm) and fin length (1 mm ≤ Lfin ≤ 3 mm) reduces the critical temperature of source and the time taken by the system to reach initial conditions. Best configuration of spiral fins is then compared with traditional pin fins to highlight that the critical temperature and time taken to reach initial conditions reduces by 7 K (2%) and 19 mins (38%) respectively.

Heat transfer augmentation of porous media (metallic foam) and phase change material based heat sink with variable heat generations: An experimental evaluation

The operation of electronic devices generates a significant amount of heat. Thermal management is critical for the safe operation and reliability of these machines. In the present experimental research, various configurations of the phase change material (PCM) based heat sink is analyzed with aim of thermal management of electronic particularly computer chips. Nickel foam is employed with paraffin wax because nickel foam is less prompted to latent heat reduction when integrated with PCM. The three-dimensional porous structure of nickel foam drastically enhances the surface area subjected to heat flow. Results revealed that nickel foam impregnated with PCM decreased base temperature up to 25% in comparison to the sink having no PCM as well as foam. Three critical temperatures (45-65⁰C) are also analyzed for PCM volume fractions ranging 0.6–0.8. It was noticed that PCM fraction 0.8 integrated with nickel foam enhanced the operation time of the sink by 4 times. Temperature profiles demonstrated that PCM-foam based sinks obstructed the sudden upsurge of temperature with no considerable cost.

Thermal performance of phase change material–based heat sink with hybrid fin‐metal foam structure under hypergravity conditions

The thermal management systems or heat sinks are an integral part of electronic devices for aerospace applications. The heat transfer characteristics of the widely used phase change material (PCM)-based heat sinks under hypergravity conditions are essential in the designation of the heat sink. The current study conducts a systematic evaluation on the thermal characteristics of PCM coupled with hybrid fin-metal foam (FMF) structure under variable hypergravity conditions. A validated two-dimensional transient melting heat transfer model of the designed system is proposed, and the influences of enclosure orientation, fin height, PCM slab thickness, and the distribution of fin and metal foam under different hypergravity conditions are investigated. Results show that with the decrease in inclination angle, the melting time and the heating wall temperature become lower, and the optimal inclination angle is 0°. As the PCM slab thickness gets larger, natural convection is enhanced, while the heating wall temperature and melting time become larger. With the rise of hypergravity value, the effect of inclination angle strengthens, while the influence of PCM slab thickness weakens. Furthermore, with the rise of the copper foam fraction in the hybrid FMF structure, the melting time and the heating wall temperature firstly decrease and increase afterward. The optimal copper foam fraction is 58.62%. This study guides the optimal design of the PCM-based heat sink in aerospace applications.

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.

Experimental and Numerical Investigations on a Phase Change Material Based Heat Sink with Symbiotically Joined Heat Pipe

This paper reports the results of experimental and numerical investigations on a phase change material based heat sink, with a compact heat pipe as the thermal performance enhancer. The evaporator of heat pipe is placed in such a way that, it is in symbiotic association with the phase change material in the heat sink. Visualization studies and numerical simulations are carried out using a digital camera and enthalpy porosity formulation with equivalent thermal conductivity model respectively. Parametric studies are carried out at 33, 66 and 99% fill ratios of phase change material and at power levels of 6, 8 and 10 W. The heat sink with heat pipe shows superior performance at all fill ratios of the phase change material and for all input power levels over the heat sink without the heat pipe. Experiments are also conducted on a heat sink with radial plate fins as an embedded thermal performance enhancer. Results are very encouraging with the heat sink coupled with the heat pipe showing an enhancement up to 30% and 175% in the time to reach set points during charging and discharging cycles respectively, and in overall effectiveness, it shows 3.58 times enhancement over the heat sink with embedded thermal performance enhancers.

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.

Thermal Performance of Phase Change Material Based Heat Sink for Solar Photovoltaic Cooling

Solar photovoltaic panels can receive only eighty percent of total incident solar radiation. A small amount of incident energy is transformed into electrical energy based on the efficiency of the photovoltaic (PV) cell. The remaining energy leads to an increase in photovoltaic cell operating temperature which affects its life and power output. Cooling of PV panel is the best way to improve the efficiency either by passive or active cooling methods. PV cooling by Phase change materials (PCM) is the best effective technique. Paraffin wax is a non toxic material having high latent heat of fusion used for many thermal applications. In this study, paraffin wax is taken as phase change material in aluminum heat sink with fins. Using DSC, the melting point of paraffin wax is analysed. The flat plate heater is used instead of solar PV panel. Different wattages are used for the experiments. Different inclinations such as horizontal (00), vertical (900) and intermediate (450) were taken in to consideration. The melting starts at 50oC and complete melting occurs at a temperature around 60oC for the paraffin based heat sink. The heat sink surface temperatures, fin temperatures and PCM temperatures are measured. The transient temperature distribution of heat sink, PCM is analysed at different wattage inputs. The total thermal performance of this paraffin PCM based heat sink was analysed experimentally. This infers that the cooling of high temperature of PV panels can be done by using paraffin based PCM to increase the efficiency and life of the panels.

Thermal Performance Evaluation of a Phase Change Material Based Heat Sink: A Numerical Study

This paper numerically investigates the thermal performance of a portable electronic device using PCM based heat sink. The phase change material used in the present study is n-eicosane with a melting point of 36.50C. Considering the current trend in portable electronic devices, a group of smart phones were taken and an average dimension was selected for designing a PCM based heat sink. A constant heat flux is provided at the heat sink bottom for simulating the heat generation by the electronic circuit board. Numerical analysis were performed for a constant heat input of 4 to 6W in steps of 0.5W on this heat sink to study its effect in conjunction with PCM in the efficient cooling of these devices. The effect of natural convention within the melt is also discussed in this paper. All the numerical computations were performed using ANSYS FLUENT 14.0.

Thermal analysis of a phase change material based heat sink for cooling protruding electronic chips

This work aims to numerically study the melting natural convection in a rectangular enclosure heated by three discreet protruding electronic chips. The heat sources generate heat at a constant and uniform volumetric rate. A part of the power generated in the heat sources is dissipated to a phase change material (PCM, n-eicosane with melting temperature, Tm = 36°C). Numerical investigations were carried out in order to examine the effects of the plate thickness on the maximum temperature of electronic components, the percentage contribution of plate heat conduction on the total removed heat and temperature profiles in the plate. Correlations for the dimensionless secured working time (time to reach the threshold temperature, Tcr = 75°C) and the corresponding liquid fraction were derived.