Preparation of Silica Microcapsules Containing Phase Change Paraffin Wax

2007 ◽  
Vol 561-565 ◽  
pp. 631-634
Author(s):  
Chun Yan Miao ◽  
Gang Lü ◽  
Ke Cao ◽  
You Wei Yao ◽  
Guo Yi Tang ◽  
...  
Keyword(s):  
Phase Change ◽  
Cell Model ◽  
Silica Shell ◽  
Paraffin Wax ◽  
Maximum Difference ◽  
Sorbitan Monooleate ◽  
Two Samples ◽  
Emulsion Systems ◽  
Tetraethyl Silicate

This paper deals with the preparation of silica microcapsules containing phase change paraffin wax for thermal energy storage and the determination of their thermal properties. The spherical microcapsule samples respectively containing two types of paraffin wax (with peak melting temperature of 29.3 °C (type P1) and 35.5 °C (type P2), and the fusion heat of 140 J/g (type P1) and 153 J/g (type P2)) as core and chemically and thermally stable silica as shell, were prepared from O/W emulsion systems in the presence of polyvinyl alcohol as stabilizer, and sorbitan monooleate and poilyoxyethylene(20) sorbitan monooleate as emulsifiers. The silica shell formed via hydrolysis and condensation from tetraethyl silicate with acetate acid as catalyst. The fusion heat of the two samples is 101 J/g and 112 J/g respectively. Property of adaptable temperature of the as-made microcapsules is measured through a self-made cell model. The maximum difference between the temperature of the cell with PCM wallpaper and that of the cell with controlled wallpaper is about 1.1 °C.

scholarly journals Thermal Dynamic Behavior in Bi-Zone Habitable Cell with and without Phase Change Materials

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 41
Author(s):  
Hanae El Fakiri ◽  
Lahoucine Ouhsaine ◽  
Abdelmajid El Bouardi
Keyword(s):  
Thermal Behavior ◽  
Thermal Comfort ◽  
Phase Change ◽  
Dynamic Behavior ◽  
Phase Change Materials ◽  
Energy Performance ◽  
High Energy ◽  
Water Heater ◽  
Simplified Modeling

The thermal dynamic behavior of buildings represents an important aspect of the energy efficiency and thermal comfort of the indoor environment. For this, phase change material (PCM) wallboards integrated into building envelopes play an important role in stabilizing the temperature of the human comfort condition. This article provides an assessment of the thermal behavior of a “bi-zone” building cell, which was built based on high-energy performance (HEP) standards and heated by a solar water heater system through a hydronic circuit. The current study is based on studying the dynamic thermal behavior, with and without implantation of PCMs on envelope structure, using a simplified modeling approach. The evolution of the average air temperature was first evaluated as a major indicator of thermal comfort. Then, an evaluation of the thermal behavior’s dynamic profile was carried out in this study, which allowed for the determination of the PCM rate anticipation in the thermal comfort of the building cell.

scholarly journals Reviewing the Exergy Analysis of Solar Thermal Systems Integrated with Phase Change Materials

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 724
Author(s):  
Macmanus Chinenye Ndukwu ◽  
Lyes Bennamoun ◽  
Merlin Simo-Tagne
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Second Law Of Thermodynamics ◽  
Heat Transfer Fluid ◽  
Solar Still ◽  
Thermal Systems ◽  
Solar Systems ◽  
Exergy Balance ◽  
Change Material

The application of thermal storage materials in solar systems involves materials that utilize sensible heat energy, thermo-chemical reactions or phase change materials, such as hydrated salts, fatty acids paraffin and non-paraffin like glycerol. This article reviews the various exergy approaches that were applied for several solar systems including hybrid solar water heating, solar still, solar space heating, solar dryers/heaters and solar cooking systems. In fact, exergy balance was applied for the different components of the studied system with a particular attention given to the determination of the exergy efficiency and the calculation of the exergy during charging and discharging periods. The influence of the system configuration and heat transfer fluid was also emphasized. This review shows that not always the second law of thermodynamics was applied appropriately during modeling, such as how to consider heat charging and discharging periods of the tested phase change material. Accordingly, the possibility of providing with inappropriate or not complete results, was pointed.

Cryoscopy of Milk: Effect of Variations in the Method

1966 ◽  
Vol 49 (3) ◽  
pp. 511-515 ◽  
Author(s):  
R W Henningson
Keyword(s):  
Statistical Analysis ◽  
Sample Size ◽  
Freezing Point ◽  
Collaborative Study ◽  
Sample Temperature ◽  
Milk Samples ◽  
Two Samples ◽  
Temperature Rate

Abstract Bath level, sample temperature, rate of stirring, degree of supercooling, sample size, sample isolation, and refreezing of the sample were the variables in the thermistor cryoscopic method for the determination of the freezing point value of milk chosen for study. Freezing point values were determined for two samples of milk and two secondary salt standards utilizing eight combinations of the seven variables in two test patterns. The freezing point value of the salt standards ranged from –0.413 to –0.433°C and from –0.431 to –0.642°C. The freezing point values of the milk samples ranged from –0.502 to –0.544°C and from –0.518 to –0.550°C. Statistical analysis of the data showed that sample isolation was a poor procedure and that other variables produced changes in the freezing point value ranging from 0.001 to 0.011°C. It is recommended that specific directions be instituted for the thermistor cryoscopic method, 15.040–15.041, and that the method be subjected to a collaborative study.

Convection Oven Determination of Loss of Mass on Drying of Quick Frozen French Fried Potatoes: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 635-636 ◽  
Author(s):  
David O Biltcliffe ◽  
Hillary J Judd ◽  
Roger Wood ◽  
◽  
A C Bushnell ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Frozen Foods ◽  
Codex Alimentarius Commission ◽  
Convection Oven ◽  
Economic Commission ◽  
Two Samples ◽  
Repeatability And Reproducibility ◽  
Loss Of Mass ◽  
Fried Potatoes

Abstract A collaborative study was carried out on one of the methods submitted to the Joint Economic Commission for Europe (ECE)/Codex Alimentarius Commission Group of Experts on the Standardization of Quick Frozen Foods for the determination of moisture in quick frozen french (fried potatoes. The method was based on the determination of loss of mass of the sample on drying in a convection oven 16 h at 103±2°C. Two samples of uncooked quick frozen french fried potatoes and 2 samples of oven quick frozen french fried potatoes were analyzed by 14 and 13 laboratories, respectively. The method is simple and was found to be analytically satisfactory with repeatability and reproducibility values of 0.21 and 2.00 g/100 g french fried potatoes, and 0.29 and 3.00 g/100 g oven french fried potatoes, respectively. The method was adopted by the Group of Experts in preference to other proposed procedures for this determination. The method has been adopted official first action by AOAC.

Determination of readiness for laying based on material moisture, corresponding relative humidity, and water release

2020 ◽  
Vol 62 (10) ◽  
pp. 1033-1040
Author(s):  
Christoph Strangfeld ◽  
Sabine Kruschwitz
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Embedded Sensors ◽  
Residual Water ◽  
Floor Covering ◽  
Water Release ◽  
Content Determination ◽  
Two Samples ◽  
Moisture Content Determination

Abstract The moisture content of the subfloor has to be determined before installation to avoid damage to the floor covering. Only if readiness for layering is reached, can an installation without damage be expected in all cases. In general, three approaches exist to measure residual water content: determination of moisture content, determination of water release, or determination of the corresponding relative humidity. All three approaches are tested under laboratory conditions at eight screed types including two samples thicknesses in each case. Moisture content and water release are measured by sample weighing, the corresponding relative humidity is measured by embedded sensors. All three approaches are compared and correlated. The evaluations show only a weak correlation and, in several cases, contradicting results. Samples are considered ready for layering and not ready for layering at the same time, depending on the chosen approach. Due to these contradicting results, a general threshold for a risk of damage cannot be derived based on these measurements. Furthermore, the experiment demonstrates that the measurement of corresponding relative humidity is independent of the screed type or screed composition considered. This makes humidity measurement a potentially very promising approach for the installation of material moisture monitoring systems.

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