Wednesday, May 19, 2010

DSC

In the Course of our work , sometimes we might need to identify unknown samples. One of the best way thus far in fulfilling this was the use of DSC, Differential scanning calorimetry.
Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. Generally, the temperature program for a DSC analysis is designed such that the sample holder temperature increases linearly as a function of time. The reference sample should have a well-defined heat capacity over the range of temperatures to be scanned.

Wikipedia provide a very in depth explaination regarding this subject: the link can be sort at the following:
DSC

Tuesday, May 11, 2010

Quality Control for Glass

There is a series of test that undergoes to ensure solar glass can perfomed to spec
-Light transmittance Test
-impact Test
-Boil Test
-Loading Test
-Bow Measurement
-Dimension Measurement
-Diagonal Line measurement
-Arch Measurement
-Fragment measurement
-surface checking
-resistance measurement

Quality Control Specification and Picture

Normal CLear Float Glass

Common Clear Float Tempered Glass

What is Clear Float Tempered/Toughened Glass?
Clear float glass, it is molten glass floats on the tin and
spreads out thus seeking a controlled level. Control heating will then allows the glass to flow and form a float ribbon of uniform thickness while on the tin bath. Glass is then slowlycooled and fed off from the molten tin into the annealing lehr for further cooling.
Clear float tempered/toughened glass is float glass that has been processed through a tempering oven to
increase its strength to resist impact, mechanical loads and thermal
stress breakage.
Glass is heat-treated by heating annealed glass to a temperature of approximately 1,150°F (621°C), then rapidly cooling it. The glass is cooled by a carefully controlled airflow (also known as quenching), which uniformly cools all glass surfaces simultaneously.
It is approximately four times stronger than annealed glass of the same thickness and configuration. When it is broken, tempered glass fractures into small fragments that reduce the probability of serious injury as compared to annealed glass.

Characteristics
It is smooth without any pattern on glass surface.
The energy transmittance about 88%
It is of less cost compare to low iron glass
It is a little green seen from edges.

Where to use it?
· Substrate of semiconductor of thin film photovoltaic technology, including amorphous silicon (aSi), cadmium telluride (CdTe) and copper indium diselenide (CIS).
· Thermal Collector.

Low Iron Float Glass/ Ultra Clear glass

What is Low Iron Float Tempered Glass?

Low iron float glass also named Ultra-clear glass. It is made by matured technical operation norm. It looks just like colorless crystal with higher transmittance.
Compare to common float glass, it is with outstanding characteristics of the high solar lights transmittance, the low reflectance, the low iron, the high mechanical strength and the high flatness, it is the ideal encapsulation material for thin solar modules and thermal collectors.
Low iron float tempered glass is low iron float glass that


has been processed through a tempering oven to increase its strength to resist impact, mechanical loads and thermal stress breakage. It is approximately four times stronger than annealed glass of the same thickness and configuration. When it is broken, tempered glass fractures into small fragments that reduce the probability of serious injury as compared to annealed glass.

Characteristics
It is of higher energy transmittance about 91%
It is expensive compare to clear float glass
It is highly smooth without patterned which more suitable for thin film solar modules and thermal collectors.

Where to use it?
· Front cover glass of of thin film photovoltaic technology, including amorphous silicon (aSi), cadmium telluride (CdTe) and copper indium diselenide (CIS).
· Front cover glass of thermal collectors.

Low Iron Pattered Glass

Low Iron Patterned Tempered Glass

What is Low Iron Patterned Tempered Glass?
Low iron patterned glass, also called low iron figured glass or low iron rolled glass or low iron textured glass, is made by a continuous roll-impressed process. Low iron patterned glass with excellent performance on high solar transmittance, low absorbance, low reflectance and low iron content, is the ideal encapsulationmaterial for solar thermal and photovoltaic modules.Low iron patterned tempered glass is low ironpatternedglass that has been processed through a
tempering ovento increase its strength to resist impact, mechanical loads and thermal stress breakage. Glass is heat-treated by heating annealed glass to a temperature of approximately 1,150°F (621°C), then rapidly cooling it. The glass is cooled by a carefully controlled airflow (also known as quenching), which uniformly cools all glass surfaces simultaneously.
It is approximately four times stronger than annealed glass of the same thickness and configuration. When it is broken, tempered glass fractures into small fragments that reduce the probability of serious injury as compared to annealed glass.
Specifications and Properties of Raw Glass:

1、Glass Thickness:3.2m &4mm;
2、Tolerance of thickness:±0.15mm
3、Max. Size:1650mm×2440mm
4、Light transmittance(3.2mm):≥91.6%
5、Content Iron:≤150ppmFe2O3
6、Specific Heat at 32° -212°F (0° -100°C):0.2
7、Density:2.5g/cc
8、(Young's) Modulus of Elasticity :73GPa
9、Tensile Strength :42 MPa
10、Hemispherical Emissivity at 0° -150° (-18° -66°C):0.84
11、Expansion Coefficient :9.03x10-6/℃
12、Softening Point:720 ℃
13、Annealing Point:550 ℃
14、Strain Point:500 ℃


Characteristics
It is of higher energy transmittance about 91.5%
It is expensive compare to clear float glass
It has two types of surface patterns, prismatic/matt-finished (SM) and matt-finished/matt-finished (MM).

Series of low iron patterned glass:
· Raw glass without tempered
· Tempered with designed sizes

Where to use it?
· Front cover glass of Crystalline silicon (cSi) including monocrystalline solar panels, polycrystalline solar panels.