TRX Evacuated tubes

Home

TRX Solar

Collector Evacuated Tube Type

Collector Flat Plate Type

DHW System Components

Thermosyphon Type Water Heater

Evacuated Tubes

Cu-N/AL Selective Coating

Installation Photos

Co-Chance

Sun Cruiser Tracking System

Alpheus A*PEX

PEX Tubing

Water Solutions

Others

Solar Electric Panels

Rechargeable Battery packs

Technical Support

Engineering Data

Insolation Data

TRX Evacuated Tubes with TRX Selective Coating

Descriptions

Specifications

Accelerated Aging Test

Aging Test Report

Conclusions

Descriptions

Made of high strength boron silicate glass tubes with high vacuum in between the tubes . The outer wall of the inner tube is coated with TRX's proprietary CU-N/AL selective coating . Mo-Al₂O₃ is available for higher temperature application ,
Cu-A/AL selective coating allows 94 to96% of solar radiation energy to be absorbed while emit less than 7% of heat through Black body radiation.
Life span of coating is much longer than other equivalent system .
Efficiency of energy conversion maintains throughout the working life

Specifications

Coating type	Cu-N/AL		Mo-Al₂O₃
Absorption（am=1.5）	92-96%		92-96%
Emissivity（150°C）	≤7%		≤6%
Inner & outer tube size (mm)	37/47 47/58 54/65
Tube length (mm)	Factory standard: 300、500、1000、1200、1500、1800、2000 Odd size tubes may be produced .
Suggested working temperature °C	≤330		≤450
Vacuum in the tube	≤2.5×10^-3Pa
Coefficient of heat loss	≤0.8W/m²*°K
Material of glass	Very high strength well tempered Boron Silicate glass
Transmittance of light	≥91%
Life expectancy	>15 years	>30 years Go Top

Accelerated Aging Test

Test Procedures

1. Place the evacuated tube horizontally , insert a hot air heating tube in the middle with the hot air blowing at temperature capable of above 500 deg C ( 932 deg F ). The temperature of the tube is measured by placing 3 thermocouples in inner wall of the tubes and one at the outlet .

2. Temperature of the tube were raised to a constant 420 deg C (788 deg F ) It is maintained for the duration of the test ( 30 minutes and 60 minutes )

3. Any change in the color of the thin film coated tube was recorded , as well as the color of the end of the evacuated tube ( Silver color Barium coating , the silver color will turn white if the vacuum of the tube is lost .)

4. At the end of high temperature exposure , the evacuated tube was cracked to retrieve the inner Thin Film coated tube . Heat Absorption and Emission tests were carried out . Test data of before and after heat exposure were recorded and compared .

5. 30 minutes of 420 deg C ( 788 deg F ) high heat exposure is equivalent to 8 years of normal operating life ( under normal operation the inner tube wall temperature is about 250 deg C, or 482 deg F ) Go Top

Aging Test Results

	TRX with CU-N/AL		TRX with CU-N/AL		Other maker with Al-N/AL
Test sample markings	200407020103		200409250117		China made evacuated tube
Test date	2004 07 03		2004 09 28		2005 03 03
Heat Exposure Time(420 C)	60 minutes		60 minutes		30 minutes
Observation	After	Before	After	Before	After	Before
Color of Barium coating	No Change		No Change		No Change , but the barrier coating was reduced by 10 mm
Color of inner coated tube	No Change		No Change		No Change
Heat Absorption	94.5%	95.9%	95.2%	95.2%	82.0%	93.6%
Heat Emissivity ( loss)	6.9%	5.3%	5.9%	5.6%	22 %	8.5%

Go Top

Conclusions

1. After 60 minutes exposure to 420 deg C , ( equivalent to 16 years of working life ) TRX evacuated tubes shows little degradation of thermal absorption and heat emission efficiency.

2. Competitive evacuated tubes with AL-N/AL coating suffers significant degradation of efficiency after just 30 minutes of exposure . ( 8 years of working life ) . The heat absorption efficiency drops by 13 percents and the heat loss through emission increased by 250 percents .

Go Top