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.

Computational Investigation of Laminar Mixed Convection in a Vertical Pipe With Slurries of a Microencapsulated Phase-Change Material in Distilled Water

2010 ◽  
Author(s):  
David A. Scott ◽  
Alexandre Lamoureux ◽  
B. Rabi Baliga
Keyword(s):  
Mathematical Model ◽  
Mixed Convection ◽  
Phase Change ◽  
Bulk Temperature ◽  
Distilled Water ◽  
Computational Investigation ◽  
Vertical Pipe ◽  
Microencapsulated Phase Change Material ◽  
Laminar Mixed Convection ◽  
Change Material

A computational investigation of steady, laminar, mixed convection in a vertical pipe, with essentially uniform heat flux imposed on its outer surface and slurries of a microencapsulated phase-change material (MCPCM) particles suspended in distilled water as the working fluid flowing upwards, is presented. The MCPCM particles considered here have a core of solid-liquid PCM contained in a thin solid shell. The mean effective diameter of these particles is 2.5μm; the melting of the core PCM takes place primarily in the temperature range 26°C to 30°C; and the latent heat of fusion of this PCM is 129.5kJ/kg. The total length of the pipe is 2.2479m; and its inside and outside diameters are 0.01257m and 0.01588m, respectively. The main contributions of this paper are the following: i) a homogenous mathematical model is shown to be applicable to the aforementioned mixed convection phenomena; ii) correlations for the effective properties of the MCPCM slurries and procedures for their implementation are presented; iii) difficulties with the standard definition of bulk temperature when the specific heat of the fluid changes significantly with temperature are elaborated; iv) a modified bulk temperature that overcomes these difficulties is proposed; v) a finite volume method (FVM) for the solution of the proposed mathematical model is described briefly; and vi) the numerical results are presented, compared to complementary experimental data, and discussed. These comparisons show that proposed model and FVM allow cost-effective computer simulations of the problems of interest.

Experimental Study of a Closed-Loop Thermosyphon Operating With Slurries of a Microencapsulated Phase-Change Material

2013 ◽  
Author(s):  
Alexandre Lamoureux ◽  
B. Rabi Baliga
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Closed Loop ◽  
Effective Density ◽  
Heat Of Fusion ◽  
Bulk Temperature ◽  
Effective Diameter ◽  
Distilled Water ◽  
Microencapsulated Phase Change Material ◽  
Change Material

An experimental investigation of steady, laminar, fluid flow and heat transfer in a vertical closed-loop thermosyphon operating with slurries of a microencapsulated phase-change material (MCPCM) suspended in distilled water is presented. The MCPCM particles consisted of a solid-liquid phase-change material (PCM) encapsulated in a thin polymer resin shell. Their effective diameter was in the range 0.5 to 12.5 micrometers, and had a mean value of 2.5 micrometers. The melting and freezing characteristics and the latent heat of fusion of the PCM were determined using a differential scanning calorimeter. The effective density of the MCPCM was measured, and the effective thermal conductivity of the slurries was determined using a published correlation. In the range of parameters considered, it was determined that the slurries exhibit non-Newtonian behavior. The closed-loop thermosyphon consisted of two vertical straight pipes, joined together by two vertical semi-circular 180-degree bends made of the same pipe. An essentially constant heat flux was imposed on a portion of one of the vertical pipes. The wall temperature of a portion of the other vertical pipe was maintained at a constant value. The outer surfaces of the entire thermosyphon were very well insulated. Calibrated thermocouples were used to measure the outer-wall-surface temperature at numerous points over the heated portion and the bulk temperature of the slurry at four different locations. A special procedure was formulated, benchmarked, and used to deduce the mass flow rate of the slurries in the thermosyphon. The investigation was conducted with slurries of MCPCM mass concentration 0% (pure distilled water), 7.471%, 9.997%, 12.49%, 14.95%, and 17.5%. The results are presented and discussed.

Heat Transfer Enhancement Analysis of Microencapsulated Phase Change Suspension

2013 ◽  
Vol 361-363 ◽  
pp. 239-243
Author(s):  
Wen Bo Fang ◽  
Chong Jie Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Theoretical Analysis ◽  
Phase Change ◽  
Specific Heat ◽  
Heat Transfer Enhancement ◽  
Dsc Analysis ◽  
Transfer Enhancement ◽  
Microencapsulated Phase Change Material ◽  
Change Material

This paper investigates heat transfer enhancement of the microencapsulated phase change material (MPCM) suspension. The specific heat of tested sample is measured by A Differential Scan Calorimeter (DSC) analysis. The corrected factor of sample is obtained by theoretical analysis and DSC measurement. The thermal conductivity is obtained by theoretical analysis and verified by previous works.

scholarly journals Determining the Heat of Fusion and Specific Heat of Microencapsulated Phase Change Material Slurry by Thermal Delay Method

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 179
Author(s):  
Krzysztof Dutkowski ◽  
Marcin Kruzel ◽  
Bartosz Zajączkowski
Keyword(s):  
Phase Change ◽  
Specific Heat ◽  
Phase Change Material ◽  
Water Solution ◽  
Heat Of Fusion ◽  
Main Peak ◽  
Liquid Form ◽  
Microencapsulated Phase Change Material ◽  
Thermal Delay ◽  
Change Material

This paper details an experimental study that was performed to investigate the specific heat of microencapsulated phase change material (mPCM) slurry and its heat of fusion at the PCM phase change transition temperature. Six samples (mPCM slurry concentrate with the water solution of propylene glycol used as a main base liquid) were prepared. As the concentrate contains 43.0% mPCM, the actual mass fraction amounts to 8.6, 12.9, 17.2, 21.5, 25.8, and 30.1 wt%, respectively. The thermal delay method was used. Samples were cooled from 50 °C to 10 °C. A higher concentration of microcapsules caused a proportional increase in the specific heat of slurry at the main peak melting temperature. The maximum value of the specific heat changed from 9.2 to 33.7 kJ/kg for 8.6 wt%, and 30.1 wt%, respectively. The specific heat of the mPCM slurry is a constant quantity and depends on the concentration of the microcapsules. The specific heat of the slurry (PCM inside microcapsules in a liquid form) decreased from 4.0 to 3.8 kJ/(kgK) for 8.6 wt%, and 30.1 wt% of mPCM, respectively. The specific heat of the slurry (PCM inside microcapsules in a liquid form) was higher than when the PCM in the microcapsules is in the form of a solid and increased from 4.5 to 5.2 kJ/(kgK) for 8.6 wt% and 30.1 wt% of mPCM, respectively.

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