Novel heat transfer fluids for direct immersion phase change cooling of electronic systems

2012 ◽  
Vol 55 (13-14) ◽  
pp. 3379-3385 ◽  
Author(s):  
Pramod Warrier ◽  
Aravind Sathyanarayana ◽  
Dadasaheb V. Patil ◽  
Stefan France ◽  
Yogendra Joshi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Electronic Systems ◽  
Heat Transfer Fluids ◽  
Direct Immersion

scholarly journals Phase change dispersion, potentially a new class of heat transfer fluids

2016 ◽  
Vol 745 ◽  
pp. 032133 ◽  
Author(s):  
L J Fischer ◽  
S von Arx ◽  
U Wechsler ◽  
S Züst ◽  
J Worlitschek
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Heat Transfer Fluids ◽  
New Class

scholarly journals Application of Phase Change Material in Sustainable Cooling of Data Centers

2013 ◽  
Author(s):  
Nikhil Dhiman ◽  
Jeet Shah ◽  
Dereje Agonafer ◽  
Naveen Kannan ◽  
James Hoverson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Hot Water ◽  
Shear Stresses ◽  
Heat Transfer Fluids ◽  
Data Center Cooling ◽  
Heat Transfer Phenomenon ◽  
Pipe Joints ◽  
Change Material

The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a result of this phase change, in the heat transfer phenomenon. The composition of phase change material used in slurry greatly affects its efficiency, If not selected properly it can cause serious damage, e.g. agglomeration and clogging of pipes. The main objective of this work is to develop standalone pumpable microencapsulated phase change slurry that is able to withstand shear stresses of the pump and other course surfaces of pipe and pipe joints. In this study, experiments were performed, to determine performance of microencapsulated phase change slurry over conventional heat transfer fluids. After certain pumping cycles, scanning electron microscopy (SEM) has been done to analyze the conditions of shell material of polymeric capsule. Results obtained from SEM show that centrifugal pump is compatible with mPCM particle size upto 3 μm. It is true that selected mPCS have shown better performance over water in hot water bath in case of thermal storage. Also, closed loop final testing has shown that heat flux is about 2–3 times higher with mPCS than water.

Thermal Analysis of Encapsulated Phase Change Materials for Energy Storage

2011 ◽  
Author(s):  
Weihuan Zhao ◽  
Alparslan Oztekin ◽  
Sudhakar Neti ◽  
Kemal Tuzla ◽  
Wojciech M. Misiolek ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
Solar Power ◽  
Solar Thermal Energy ◽  
Heat Transfer Fluids ◽  
Change Material

Concentrating solar power technology is recognized as an attractive option for solar power. A major limitation however is that solar power is available for only about 2,000 hours a year in many places. Therefore it is critical to find ways to store solar thermal energy for the off hours and it is better to store the energy at high temperatures. The present work deals with certain aspects of storing solar thermal energy at high temperatures with phase change materials (PCM) in the range of 275°C to 425°C. NaNO3 is selected as a phase change material encapsulated by stainless steel. The objective is the storage of hundreds mega-watt-hours equivalent of solar energy in systems using encapsulated phase change materials (EPCM). Numerical predictions of conduction and phase change processes are reported here in the form of transient temperature profiles in the PCM and encapsulation materials of EPCM capsules for convective boundary conditions outside EPCM. The time for heating and melting during charging (storage of thermal energy into encapsulated phase change material) and the time for cooling and solidification during discharging (discharge/retrieval of thermal energy) are predicted for NaNO3 PCM in encapsulation. For a temperature range of about 125°C around melting/freezing temperature of the PCM the time it takes to melt/freeze the PCM during storage/retrieval is much longer than the time it takes for diffusion (sensible heat) storage alone. Depending on the properties of the PCM, the energy associated with the latent heat of melting can be a significant leading to smaller thermal energy storage systems and lower costs. As can be expected, the time for heat transfer is much shorter for liquid heat transfer fluids compared to those for gaseous heat transfer fluids that transport the energy to the EPCM.

scholarly journals High Temperature Thermal Energy Storage Utilizing Metallic Phase Change Materials and Metallic Heat Transfer Fluids

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Johannes P. Kotzé ◽  
Theodor W. von Backström ◽  
Paul J. Erens
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Metallic Phase ◽  
High Thermal Conductivity ◽  
Heat Transfer Fluids

Cost and volume savings are some of the advantages offered by the use of latent heat thermal energy storage (TES). Metallic phase change materials (PCMs) have high thermal conductivity, which relate to high charging and discharging rates in TES system, and can operate at temperatures exceeding 560 °C. In the study, a eutectic aluminium–silicon alloy, AlSi12, is identified as a good potential PCM. AlSi12 has a melting temperature of 577 °C, which is above the working temperature of regular heat transfer fluids (HTFs). The eutectic sodium–potassium alloy (NaK) is identified as an ideal HTF in a storage system that uses metallic PCMs. A concept is presented that integrates the TES-unit and steam generator into one unit. As NaK is highly reactive with water, the inherently high thermal conductivity of AlSi12 is utilized in order to create a safe concept. As a proof of concept, a steam power-generating cycle was considered that is especially suited for a TES using AlSi12 as PCM. The plant was designed to deliver 100 MW with 15 h of storage. Thermodynamic and heat transfer analysis showed that the concept is viable. The analysis indicated that the cost of the AlSi12 storage material is 14.7 US$per kWh of thermal energy storage.

Phase-Change Nanofluids With Enhanced Thermophysical Properties

2009 ◽  
Author(s):  
Zenghu Han ◽  
Bao Yang ◽  
Yung Y. Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Effective Heat Capacity ◽  
Heat Transfer Fluids ◽  
Effective Heat ◽  
Indium Nanoparticles

The colloidal dispersion of solid nanoparticles (1–100nm) has been shown experimentally to be an effective way to enhance the thermal conductivity of heat transfer fluids. Moreover, large particles (micrometers to tens of micrometers) of phase-change materials have long been used to make slurries with improved thermal storage capacity. Here, a hybrid concept that uses nanoparticles made of phase-change materials is proposed to simultaneously enhance the effective thermal conductivity and the effective heat capacity of fluids. Water-in-perfluorohexane nanoemulsion fluids and indium-in-polyalphaolefin nanofluids are examples of fluids that have been successfully synthesized for experimental studies of their thermophysical properties (i.e., thermal conductivity, viscosity, and heat capacity) as functions of particle loading and temperature. The thermal conductivity of perfluorohexane was found to increase by up to 52% for nanoemulsion fluids containing 12 vol. % water nanodroplets with a hydrodynamic radius of ∼10 nm. Also observed in water-in-perfluorohexane nanoemulsion fluids was a remarkable improvement in effective heat capacity, about 126% for 12 vol. % water loading, due to the melting-freezing transitions of water nanodroplets to ice nanoparticles and vice versa. The increases in the thermal conductivity and dynamic viscosity of these nanoemulsion fluids were found to be highly nonlinear against water loading, indicating the important roles of the hydrodynamic interaction and the aggregation of nanodroplets. For indium-in-polyalphaolefin nanofluids, the thermal conductivity enhancement increases slightly with increasing temperature (i.e., about 10.7% at 30°C to 12.9% at 90°C) with a nanoparticle loading of 8 vol. %. The effective volumetric heat capacity can be increased by about 20% for the nanofluids containing 8 vol. % indium nanoparticles with an average diameter of 20 nm. Such types of phase-change nanoemulsions and nanofluids possess long-term stability and can be mass produced without using as-prepared nanoparticles. The observed melting-freezing phase transitions of nanoparticles of phase-change materials (i.e., water nanodroplets and indium nanoparticles) considerably augmented the effective heat capacity of the base fluids. The use of phase-change nanoparticles would thus provide a way to substantially enhance the thermal transport properties of conventional heat transfer fluids. Future development of these phase-change nanofluids is expected to open new opportunities for studies of thermal fluids.

scholarly journals State of the Art in PEG-Based Heat Transfer Fluids and Their Suspensions with Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 86
Author(s):  
Alina Adriana Minea
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Polyethylene Glycol ◽  
Phase Change ◽  
Phase Change Materials ◽  
State Of The Art ◽  
Short Review ◽  
Numerical Work ◽  
Heat Transfer Fluids ◽  
Improved Performance

Research on nanoparticle enhanced fluids has increased rapidly over the last decade. Regardless of several unreliable reports, these new fluids have established performance in heat transfer. Lately, polyethylene glycol with nanoparticles has been demarcated as an innovative class of phase change materials with conceivable uses in the area of convective heat transfer. The amplified thermal conductivity of these nanoparticle enhanced phase change materials (PCMs) over the basic fluids (e.g., polyethylene glycol—PEG) is considered one of the driving factors for their improved performance in heat transfer. Most of the research, however, is centered on the thermal conductivity discussion and less on viscosity variation, while specific heat capacity seems to be fully ignored. This short review abridges most of the recent investigations on new PEG-based fluids and is dedicated especially to thermophysical properties of the chemicals, while a number of PEG-based nanofluids are compared in terms of base fluid and/or nanoparticle type and concentration. This review outlines the possibility of developing promising new heat transfer fluids. To conclude, this research is in its pioneering phase, and a large amount of experimental and numerical work is required in the coming years.

Nanostructured phase-changeable heat transfer fluids

2013 ◽  
Vol 2 (3) ◽  
pp. 289-306 ◽  
Author(s):  
Jiajun Xu ◽  
Bao Yang
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Phase Change ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Metallic Phase ◽  
Effective Heat Capacity ◽  
Heat Transfer Fluids ◽  
Effective Heat ◽  
Solid Liquid

AbstractCooling is one of the most important technique challenges faced by a range of diverse industries and military needs. There is an urgent need for the innovative heat transfer fluids with improved thermal properties over the currently available. This review paper discusses the concept of using phase-changeable nanoparticles to increase the effective heat capacity and the heat transfer rate of the fluid. A large amount of heat can be absorbed or released when these nanoparticles undergo phase transition from solid to liquid or liquid to gas or vice versa and, thus, enhancing the heat transfer rate. Two types of phase-change fluids are introduced: one contains liquid nanodroplets that will evaporate at elevated temperatures or solidifies at reduced temperatures, called “nanoemulsion fluids”; the other is suspensions of solid-liquid metallic phase-change nanoparticles. The material synthesis and property characterizations of these phase-changeable fluids are two main aspects of this paper. The explosive vaporization of the dispersed nanodroplets would significantly improve the heat transfer in the nanoemulsion fluid. The solid-liquid metallic phase-change nanoparticles will increase the effective heat capacity and thermal conductivity of the base fluids simultaneously. This paper also identifies the several critical issues in the phase-changeable fluids to be solved in the future.

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