This paper reports the results of an experimental investigation of the performance of finned heat sinks filled with phase change materials for thermal management of portable electronic devices. The phase change material (PCM) used in this study is n-eicosane and is placed inside a heat sink made of aluminium. Aluminium acts as thermal conductivity enhancer (TCE), as the thermal conductivity of the PCM is very low. The heat sink acts as an energy storage and a heat-spreading module. Studies are conducted for heat sinks on which a uniform heat load is applied for the unfinned and finned cases. The test section considered in all cases in the present work is a 80 × 62 mm 2 base with TCE height of 25 mm. A 60 × 42 mm 2 plate heater with 2 mm thickness is used to mimic the heat generation in electronic chips. Heat sinks with pin fin and plate fin geometries having the same volume fraction of the TCE are used. The effect of different types of fins for different power level (ranging from 2 to 7 W) in enhancing the operating time for different set point temperatures and on the duration of latent heating phase were explored in this study. The results indicate that the operational performance of portable electronic device can be significantly improved by the use of fins in heat sinks filled with PCM. © 2011 Elsevier Ltd. All rights reserved.

C. Balaji

Department of Mechanical Engineering

ELECTRONIC CHIPS

Experimental investigations

HEATING PHASE

N-EICOSANE

OPERATING TIME

Operational performance

Phase Change

Pin-fins

PLATE FINS

PLATE HEATER

PORTABLE ELECTRONIC DEVICES

Power levels

Set-point temperatures

Test sections

Aluminum

Amplifiers (electronic)

Buoyancy

DISTRICT HEATING

Electronic cooling

Fins (heat exchange)

Forced convection

Heat sinks

Oscillators (electronic)

Paraffins

Portable equipment

Temperature control

Thermal conductivity

Thermoelectric equipment

Phase change materials

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

International Journal of Heat and Mass Transfer

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. © 2019, © 2019 Taylor & Francis Group, LLC.

Heat Transfer Engineering

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

In photovoltaic (PV) cells, a large portion of the solar-irradiance becomes heat which shoots the cell temperature up and decreases its electrical efficiency. The heat can be removed using phase-change-material (PCM) at the rear of the PV. In literature, the researchers have reported the performance of PV-PCM for their respective locations. However, selection criteria for climates suitable for PCM integration are not reported yet. Thus, it has been carried out in the current work. The model has been validated against the experimental measurements. It has been concluded that (i) the climates having less variations in the ambient temperature are more suitable for PCM integration. The electricity enhancement achieved by PV cooling is 9.7%. It reduces to 6.6% for the climate having large variations, (ii) Heat extraction by PCM-systems is more effective in warm climates in comparison to cold climates, (iii) PCM integration performs better in climates with low wind-speed, (iv) PCM is more effective for the climates where wind-flow is across the PV and (v) Climates having high solar-radiation is better for heat removal by PCM. © 2018 The Authors

Fulltext

Energy Conversion and Management

Climatic behaviour of solar photovoltaic integrated with phase change material

Heat generation during the operation of the photovoltaic (PV) cell raises its temperature and results in reduced electrical output. The heat produced in the process can be removed by attaching phase change material (PCM) at the back of the PV panel which can contain the PV temperature substantially and increase its efficiency. Fins can be used inside the PCM container to enhance the heat transfer. In literature, it is observed that as soon as PCM is melted completely, the heat extraction rate of PCM reduces which again leads to increase in PV temperature. However, the study carrying out the optimization of Finned-PV-PCM system to keep PV temperature low during operation for different solar irradiance levels is not available in literature. Thus, in the current study, the most suitable depth of PCM container is calculated for different solar irradiance levels. In addition, how it is affected with spacing between successive fins, fin length and fin thickness has been studied. The best fin dimensions are also calculated. The results show that the most suitable depth of PCM container is 2.8 cm for ∑IT = 3 kWh/m2/day and 4.6 cm for ∑IT = 5 kWh/m2/day for the chosen parameters. The best spacing between successive fins (to keep PV temperature low) is 25 cm, best fin thickness is 2 mm and best fin length is the one when it touches the bottom of the container. PV, PV-PCM and Finned-PV-PCM systems are also compared. For PV-PCM system (without fins), the most suitable depth of PCM container is 2.3 cm for ∑IT = 3 kWh/m2/day and 3.9 cm for ∑IT = 5 kWh/m2/day. © 2018 The Authors

International Journal of Thermal Sciences

Optimization of finned solar photovoltaic phase change material (finned pv pcm) system

This paper reports the results of an experimental investigation of the heat transfer performance of a phase change material (PCM) based composite 72 pin fin heat sink subjected to individual heat loading of 4 discrete heaters of equal area. The investigation is then followed by multi objective optimization of the individual heat inputs, wherein the total power of the heaters is fixed. The PCM used is n-eicosane and the heat sink is made of aluminium. First, in house experiments are conducted for different combinations of power. The hotspots imposed by spatially non uniform heat flux are seen to have a considerable effect on the melting and solidification cycle and hence on the thermal performance of the heat sink. The diversity in the performance of heat sink motivates us to perform a multi objective optimization using Non-dominated sorting genetic algorithm (NSGA-II) to determine the optimum combination of the discrete power levels, that stretches the charging period and minimizes the discharging period of the heat sink simultaneously. The solutions obtained thus obtained are validated by conducting in house experiments. This study establishes the fact that discrete heating scenarios have to be considered in the future optimization of the heat sinks. © 2016 Elsevier Masson SAS

Experimental investigation on the heat transfer performance of a PCM based pin fin heat sink with discrete heating

Transient three-dimensional simulations are done for a phase-change material (PCM)-based heat sink subjected to constant heat flux of 1.59 kW/m2 with commercially available FLUENT software. Numerically obtained temperature-time histories are matched up with experimental results obtained earlier by our group to determine the overall heat transfer coefficient from the geometry that reconciles the differences between simulations and experiments. For a constant power level and fixed volumes of heat sink material (aluminum) and PCM (n-eicosane), simulations were done for 30 different geometric configurations to determine the time to reach complete melting. A feed-forward back-propagation neural network was then used in conjunction with a genetic algorithm to perform an exhaustive search and estimate the dimensions of the heat sink cavity for which the melt time and hence the thermal performance of the heat sink is maximum. © 2016 Taylor and Francis Group, LLC.

Geometric Optimization of a PCM-Based Heat Sink-A Coupled ANN and GA Approach

Use of composite heat sinks (CHS), constructed using a vertical array of 'fins' (or elemental composite heat sink, ECHS), made of large latent heat capacity phase change materials (PCM) and highly conductive base material (BM) is a much sought cooling method for portable electronic devices, which are to be kept below a set point temperature (SPT). This paper presents a thermal design procedure for proper sizing of such CHS, for maximizing the energy storage and the time of operation until all of the latent heat storage is exhausted. For a given range of heat flux, q″, and height, A, of the CHS, using a scaling analysis of the governing two dimensional unsteady energy equations, a relation between the critical dimension for the ECHS and the amount of PCM used (φ) is determined. For a φ, when the dimensions of the ECHS are less than this critical dimension, all of the PCM completely melts when the CHS reaches the SPT. The results are further validated using appropriate numerical method solutions. A proposed correlation for chosen material properties yields predictions of the critical dimensions within 10% average deviation. However, the thermal design procedure detailed in this paper is valid, in general, for similar finned-CHS configurations, composed of any high latent heat storage PCM and high conductive BM combination. © 2005 Elsevier Ltd. All rights reserved.

Method to improve geometry for heat transfer enhancement in PCM composite heat sinks

Building roof with conical holes containing PCM to reduce the cooling load: Numerical study

Applied Thermal Engineering

Experimental investigations on heat transfer in phase change materials (PCMs) embedded in porous materials

One thousand thermal cycles of magnesium chloride hexahydrate as a promising PCM for indoor solar cooking

Active cooling of a mobile phone handset

Experimental investigations on phase change material based finned heat sinks for electronic equipment cooling

Journal	International Journal of Heat and Mass Transfer
ISSN	00179310
Open Access	No