Experimental investigation on thermal conductivity and specific heat capacity of magnetic microencapsulated phase change material suspension

2009 ◽  
Vol 479 (4-6) ◽  
pp. 264-269 ◽  
Author(s):  
Yimin Xuan ◽  
Yong Huang ◽  
Qiang Li
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Heat Capacity ◽  
Phase Change ◽  
Specific Heat ◽  
Phase Change Material ◽  
Specific Heat Capacity ◽  
Microencapsulated Phase Change Material ◽  
Change Material

Fluid Flow and Heat Transfer Characteristics of Microencapsulated Phase Change Material Slurry in Turbulent Flow

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Hessam Taherian ◽  
Jorge L. Alvarado ◽  
Kalpana Tumuluri ◽  
Curt Thies ◽  
Chan-Hyun Park
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Fluid Flow ◽  
Turbulent Flow ◽  
Phase Change ◽  
Phase Change Material ◽  
Flow Conditions ◽  
Microencapsulated Phase Change Material ◽  
Change Material ◽  
Turbulent Flow Conditions

Microencapsulated phase change material (MPCM) slurry is consisted of a base fluid in which MPCM is dispersed. Due to apparent high heat capacity associated with phase change process, MPCM slurry can be used as a viable heat transfer fluid (HTF) for turbulent flow conditions. Heat transfer and fluid flow properties of the slurry in turbulent flow (3000 < Re < 6000) were determined experimentally. Dynamic viscosity of the MPCM slurry was measured at different temperatures close to the melting point of the material (20–30 °C). Pressure drop measurements under turbulent flow conditions were recorded for 6 MPCM samples at various concentrations. The pressure drop of the MPCM slurry was comparable to that of water despite the higher viscosity of the slurry. The effect of heat flux, MPCM mass concentration, flow rate and the type of phase change material was investigated. The effective heat capacity of slurry at the location where phase change occurs was found to be considerably higher than that of water. A nondimensional Nusselt number correlation was proposed in order to facilitate design of heat transfer loops with MPCM slurries as working fluid.

Characterization of Thermal Properties and Heat Transfer Behavior of Microencapsulated Phase Change Material Slurry and Multiwall Carbon Nanotubes in Aqueous Suspension

2007 ◽  
Author(s):  
Jorge L. Alvarado ◽  
Charles Marsh ◽  
Curt Thies ◽  
Guillermo Soriano ◽  
Paritosh Garg
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Heat Transfer Coefficient ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Effective Thermal Conductivity ◽  
Phase Change Material ◽  
Microencapsulated Phase Change Material ◽  
Change Material

In the last decade, microencapsulated phase change material (MPCM) slurries have been proposed and studied as novel coolants for heat transfer applications. Such applications include electronics cooling, and secondary coolants in air conditioning systems among others. Experiments have shown that MPCM’s increase the overall thermal capacity of thermal systems by taking advantage of the phase change material’s latent heat of fusion. However, research has also shown that the overall heat transfer coefficient is diminished due to a reduction in the effective thermal conductivity and increased viscosity of the slurry. For this reason, there is an urgent need to modify the content of microcapsules containing phase change material to increase their effective thermal conductivity and the overall heat transport process. Our solution consists of increasing the thermal conductivity of MPCM by adding carbon nanotubes to the shell and core of the microcapsules. Carbon nanotubes have shown to increase the thermal conductivity of liquids by 40% or more in recent experiments. In this paper, MPCM slurry containing octadecane as phase change material and multi-wall carbon nanotubes (MWCNTs) embedded in the capsule material and core are compared with pure water as heat transfer fluid. Thermal and physical properties of MPCM slurry containing carbon nanotubes were determined using a differential scanning calorimeter and concentric viscometer, respectively. Experimental convective heat transfer coefficient data for MWCNT aqueous suspensions under laminar flow and constant heat flux were determined using a bench-top heat transfer loop. Experimental heat transfer results are presented.

Modeling and Simulations of Laminar Mixed Convection in a Vertical Pipe Conveying Slurries of a Microencapsulated Phase-Change Material in Distilled Water

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
David A. Scott ◽  
Alexandre Lamoureux ◽  
Bantwal R. Baliga
Keyword(s):  
Mathematical Model ◽  
Experimental Investigation ◽  
Mixed Convection ◽  
Phase Change ◽  
Specific Heat ◽  
Bulk Temperature ◽  
Distilled Water ◽  
Microencapsulated Phase Change Material ◽  
Laminar Mixed Convection ◽  
Change Material

Steady, laminar, mixed convection in a straight and vertically oriented pipe conveying slurries of a microencapsulated phase-change material (MCPCM) suspended in distilled water (flowing upwards), with essentially uniform heat flux imposed on its outside surface, are considered. A cost-effective homogenous mathematical model is proposed and shown to be applicable to the aforementioned mixed convection phenomena with slurries of a sample MCPCM. Correlations for the effective properties of the sample MCPCM slurries and procedures for their implementation are presented. The energy equation, in which the latent-heat effects are handled using an effective specific heat, is cast in a form akin to that of a general advection-diffusion transport equation. Difficulties with the standard definition of bulk temperature when the specific heat of the fluid changes significantly with temperature are elaborated, and a modified bulk temperature that overcomes these difficulties is proposed. A finite volume method (FVM) was used to solve the mathematical model. The proposed model and FVM were validated by using them to solve problems involving slurries of the sample MCPCM, and comparing the results to those of a complementary experimental investigation. The numerical results compare very well with those of the complementary experimental investigation. They also demonstrate the need for optimizing the various parameters involved, if full benefits of the MCPCM slurries are to be achieved for specific applications.

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