Heat pipe with nano enhanced-PCM for electronic cooling application (original) (raw)
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IOP Conference Series: Materials Science and Engineering
The paper presents experimental investigations to evaluate thermal performance of heat pipe using Nano Enhanced Phase Change Material (NEPCM) as an energy storage material (ESM) for electronic cooling applications. Water, Tricosane and nano enhanced Tricosane are used as energy storage materials, operating at different heating powers (13W, 18W and 23W) and fan speeds (3.4V and 5V) in the PCM cooling module. Three different volume percentages (0.5%, 1% and 2%) of Nano particles (Al 2 O 3) are mixed with Tricosane which is the primary PCM. This experiment is conducted to study the temperature distributions of evaporator, condenser and PCM during the heating as well as cooling. The cooling module with heat pipe and nano enhanced Tricosane as energy storage material found to save higher fan power consumption compared to the cooling module that utilities only a heat pipe.
Experimental and Numerical Investigations on Al2O3–Tricosane Based Heat Pipe Thermal Energy Storage
International Journal of Engineering, 2018
The enhancement of operating life cycle of electronic devices necessitates the development of efficient cooling techniques. Therefore, in the present work the effects of employment of Phase Change Material, in the adiabatic section of heat pipe for electronic cooling applications were experimentally and numerically investigated. Tricosane (100 ml) is chosen as PCM in this study, where Al2O3 nanoparticles were dispersed in PCM by an ultrasound mechanism with volume fractions of 0.5, 1 and 2%. Transient thermal behavior of the evaporator, energy storage materials and condenser were studied during the charging process with heating powers of 13, 18 and 23W. The performance of system with Tricosane and nanoparticles improved for 1% concentration and reduced for 2% concentration; which concludes for the optimized doping of nanoparticles. In addition, CFD simulation of heat pipe is carried out for the above mentioned opertating conditions. The experimental and simulation results were compa...
A medium of storing thermal energy from Solar, Exhaust gases and waste heat from solar, exhaust gas and waste heat from industries, is the usage of Low Temperature Energy Storage System (LTESS). In order to achieve the storage of energy, Phase Change Materials (PCM) is adopted. PCM is most preferred because of their high storage density, with lesser volume. A drawback of the system is that the thermal conductivity of PCM is very less and requires more time and surface area for loading and unloading of thermal conductivity. To overcome the problem, an attempt was made in the heat exchanger to incorporate Al micro particles in the paraffin PCM in order to increase its thermal conductivity. Both analytically and experimentally, the thermal conductivity of LTESS is determined. Maxwell-Garnett equation is used to determine the thermal conductivity of PCM and Transient Hot Wire Thermal Conductivity Measuring Apparatus KD2 probe is utilized to determine the thermal conductivity experimentally. There is significant change in values of both sensible heat and latent heat, by which, through the use of Al-PCM combination, the thermal conductivity has been seen to be increased to 1.904 W/mK, in contrast to the thermal conductivity of paraffin wax of 0.214 W/mK.
Enhancement of Heat Transfer in Heat Pipes using Al 2 O 3 /Benzene Based Nano-coolants
Nowadays, the world is experiencing many challenges in solving heat transfer issues in various engineering systems. However, limited approaches are available to solve such challenges. To increase heat transfer, many researchers found that the Nanofluid is one of the feasible coolant which increase the working efficiency of many engineering devices. Electronic equipment dissipates enormous amount of heat while in operation which directly affect the work efficiency. To increase the efficiency it is mandatory to remove the heat by using proper coolant. Hence, the heat pipes are employed in electronic devices to remove the heat. To enhance the heat transfer in heat pipe nano-coolants may be used. In this present work, thermophysical properties of different types of base fluids with Aluminium oxide (Al 2 O 3) Nanoparticles have been investigated with different concentrations of Nanoparticles (1-5 % by volume) at 300K temperature. The effective thermal conductivity of Nanofluids is compared with the base fluid and the results show enhancement in thermal conductivity. The thermal conductivity of Nanofluid is increased up to 3% at 300K with 1 % by volume concentration of nanoparticles and 15% at 5% by volume of concentration as compared to Benzene (C 6 H 6) base fluid.
2019
Present experimental investigation focuses on implementing passive cooling thermal management technique using heat sinks filled with paraffin wax as phase change material (PCM). Al2O3 nanoparticles are dispersed as thermal conductivity enhancer (TCE) in different weight fractions (φ) for improved performance in the PCM. Unfinned and two finned heat sinks are used in this investigation. Experimental analysis is performed on different configurations of heat sinks and nano-enhanced phase change materials (NePCMs) consisting various weight fraction of Al2O3 nanoparticles (φ=0%, 0.5%, 4%, and 6%) for a constant heat flux of 2.0 kW/m 2. Results show that latent heat and specific heat capacity decreases with increase in the Al2O3 nanoparticle loading. Addition of Al2O3 nanoparticles in the PCM results in the reduced melting time of PCM. While, pure PCM based heat sinks keeps heat sink base temperature lower for longer time duration. Keywords: Thermal Management, nanoenhanced phase change material (NePCM), Thermal conductivity enhancer (TCE) NOMENCLATURE φ Weight fraction of nanoparticles ρ Density Cp Specific heat capacity SPT Set point temperature Subscripts p Phase change material n nanoparticles np NePCM
MINI HEAT EXCHANGER USING Al2O3-WATER BASED NANO FLUID
Cooling is indispensable for maintaining the desired performance and reliability very huge variety of product like car, computer, high power laser system. Whenever there is a increase the heat load and heat fluxes caused by more power and smaller size for these product cooling is one of the technical challenge faced by the industries like as a microelectronics, transportation, manufacturing. There are many single-phase liquid cooling techniques such as micro channel heat sink and two-phase liquid cooling technology like heat pipes, thermosyphones, direct immersion cooling and spray cooling. Development of the nano materials technology has made it possible to structure a new type of heat transfer fluid formed by suspending nanoparticles ( dia. < 100 nm ).In conventional base fluid like water and ethylene glycol choi coined the term NANO FLUID to refer the thermal properties superior to those of their base fluids. Due to rapid fluid mixing effects strengthens the energy transport inside the nano fluids by modifying the temperature profiles. Experimental data indicates that particle size, volume fraction and properties of the nanoparticles influence the heat transfer characteristics of nano fluids. This paper shows the research work on Mini heat exchanger using Al2O3- Water Based nano fluid
Experimental Heat Transfer, 2020
In this experimental study, the effect of natural convection during the melting and solidification process on nano-enhanced phase change material in a designed cylindrical thermal energy storage system has been investigated. The temperature variations at both axial and radial locations are measured for stearic acid PCM with variation in mass fractions (0.1%, 0.3%, and 0.5%) of Al 2 O 3 nano-additives. Impacts of Rayleigh number, Fourier number, and Nusselt number, as well as heat transfer coefficient, heat transfer rate, and total energy stored, have been considered. Results revealed that the charging time of stearic acid with 0.3% mass fraction of nanoparticles is 16.6%, 12%, and 15% lower compared to stearic acid, 0.1%, and 0.5% mass fraction-based nanoenhanced phase change materials. Also, the natural convection occurs in the designed thermal energy storage system based on the Rayleigh number, Fourier number, and Nusselt number. Stearic acid based 0.3% of mass fraction nano-additive has an increment of 11.08% in energy storage rate compared to stearic acid PCM-based TES system within a time interval of 10min. It also revealed that an increment in axial height from 2.33 to 4.66cm, the total energy stored would be decreased by 8.6%, 12.2%, 12.5%, and 7.9%, respectively, with 0-5% variation of nano-additive in stearic acid PCM. Thus, nano-enhanced PCM has been considered as better thermal storage compared to pure PCM.
2017
Latent heat thermal energy storage (LHTES) system uses a phase change material (PCM) to store or release thermal energy, thus reducing the overall consumption of energy in a system. But, the problem with the PCM is their low thermal conductivity that increases the melting and solidification time, which is not suitable for specific application areas, such as, battery thermal management, electronic cooling etc. To increase the thermal conductivity of PCM, different studies examine different approaches including extension of the heat transfer area using fins and honeycombs, thin metal strips, porous metals, copper chips, metal foam matrices, metal screens and spheres, carbon fiber brushes and chips, graphite matrices, microencapsulated PCM, multiple PCMs, carbon-based nanostructures graphene flakes, carbon nano-tubes, metallic nanoparticles, silver nano-wires, and bio-based composite PCM. The current study incorporates nanoparticle in PCM (nano-PCM) to increase the thermal conductivity of the PCM. Experimental studies are performed using Copper Oxide (50nm) and Aluminum Oxide (50nm) nanoparticles supplied by Sigma Aldrich and Rubitherm (RT-18) as base PCM, supplied by Rubitherm GmbH. The vertical cylindrical LHTES is composed of two concentric pipes; with the inner one carrying a heat transfer fluid at a constant temperature and the annular space containing a nano-PCM. The initial temperature of the nano-PCM is 5 C while the temperature of the heat transfer fluid is 40 C. The experimental results show that using nano-PCM reduces the melting time when compared to base PCM, but enhanced melting is observed when Copper Oxide nanoparticle is used.
Case Studies in Thermal Engineering, 2020
Thermal storage materials considering phase-changing materials (PCM) have attracted many researchers for thermal management of energy crises due to better temperature range to suit the thermal storage applications. However, the effectiveness of PCMs is affected by very low thermal conductivity and this deficiency limits the use of PCMs as an efficient thermal storage material. To increase the thermal conductivity of PCM, different nanoparticles (NPs) with a higher value of thermal conductivity are added which are called nano PCM. This paper presents the preparation and characterization of phase change material enhanced by metallic NPs alumina (Al 2 O 3) and nonmetallic NPs multiwall carbon nanotubes (MWCNTs). The aim of this study is to create the nano PCM by adding Al 2 O 3 & MWCNTs NPs in Paraffin wax at 2 wt%,4 wt% and 6 wt%. The results showed that in the case of pure paraffin wax, the maximum peak temperature obtained after 90 min is 61.53 • C. In the case of alumina oxide maximum peak temperature obtained at top layer for all three samples is as follows; for 2 wt% is 62.65 • C, 4 wt% is 63 • C and 6 wt% is 64 • C and in the case of MWCNTs maximum peak temperature obtained at top layer for all three samples is as follows; for 2 wt% is 68 • C, 4 wt% is 69.86 • C and 6 wt% is 70.55 • C. The maximum peak temperature was increased by an increment of NPs concentration results in better charging and discharging of PCM. It was observed that composite of paraffin wax having 6 wt% of MWCNTs NPs shows the best results as compared to other prepared samples.
IJERT-Experimental Investigation of Enhancement in Heat Transfer using Nano - Mixed PCM
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/experimental-investigation-of-enhancement-in-heat-transfer-using-nano-mixed-pcm https://www.ijert.org/research/experimental-investigation-of-enhancement-in-heat-transfer-using-nano-mixed-pcm-IJERTV3IS110819.pdf Efficient and reliable thermal storage systems are required for solar applications to overcome their existing discontinuous nature and abrupt change in weather conditions. Thermal storage units that utilize Phase Change Material (PCM) as latent heat storage material have received greater attention in recent years. It has larger heat storage capacity and isothermal nature during charging and discharging process. Besides having high energy density most of the PCMs have an unacceptable low thermal conductivity. To conquer this drawback heat transfer enhancement techniques are required for any Latent Heat Thermal Storage (LHTS) application comprises with PCMs. One of the best suited technique is the addition of nanoparticles into base PCM to enhance its thermal performance. In present work, Al 2 O 3 n a n o p a r t i c l e s were added in 0.5%, 1% and 2% into base PCM to enhance its thermal performance. Solar water heating system is considered as LHTS. Experiments were carried out with both base and nano mixed PCM to ensure the enhancement in heat transfer. Keywords-Phase Change Material (PCM); LHTS; Nanoparticles. I. INTRODUCTION Day by day there are increase in greenhouse gas emissions and rise in fuel prices. These are the main driving forces behind efforts to more effectively utilize various sources of renewable energy [1]. The scientists all over the world have been in search of some new and renewable energy sources since long. It is found that one of the alternatives is to develop energy storage devices, which is having same importance as that of developing novel sources of energy. Solar energy is a major renewable energy resource which can be used to generate electricity, provide hot water and for air conditioning system etc. It is of intermittent nature and its effective utilization is dependent on efficient and effective energy storage systems. If no energy storage is used in solar systems, the major part of energy demand will be met by the back up or auxiliary energy due to which annual solar load fraction will be very low. The thermal energy can be stored when energy is abundantly available and used when required. Thermal storage has been characterized as a kind of thermal battery; however it is clear that if solar energy becomes an important energy source efficient, economical and reliable solar Thermal Energy Storage (TES) devices and methods will have to be developed.