Technical Parameter

Solar water heater knowledge Evacuated Tube Heat Pipe Vacuum Tube

The economic benefit is prominent. Once-off investment and long-term profit is the prominent character of solar water heater system. After our many years' practice and test, in general solar water heaters can win all investment during 2-3 years. Generally speaking, per square meter of collector of solar water heater can generate 50~60 liters of hot water above 40~50^o every day and can generate heat about 600000~700000 kcal. in a whole year. The contrast between solar energy and common energy sources (counting according to average 300 days of sunlight all year): taking heating 14 tons water to up net 30^o daily by the solar water heater project of 245,000 Yuan as comparative object. Industrial electricity is 0.80 Yuan/kw., the efficiency of electric water heater is 95%; natural gas is 2.5 Yuan/m3, when the quality of heat is 37000KJ/ m3, the efficiency of gas-fired water heater is 85%; diesel oil is 4.5 Yuan/kg, when quality of heat is 46040KJ/kg, the efficiency of oil-fired boiler is 80%.

Item of hot water equipment	10t solar water heater collector	Oil boiler with 300 thousand kcal	Gas boiler with 300 thousand kcal	Electrical boiler with 300 thousand kcal
Investment for equipment (yuan)	245000	30000	35000	24000
Life-span of equipment (year)	15	5	5	5
Daily hot water output(t/^o)	14t/55^o	14t/55^o	14t/55^o	14t/55^o
Fuel expense every year (300 days)	0	48kg4.5yuan300days =64800	56 m32.5yuan300days =42000	513kilowatt 0.8yuan 300days=123120
Total investment for equipment in 15 years (yuan)	245000	90000	105000	72000
The needs of wage pay in 15 years (yuan)	0	6000	6000	0
Total expanse in 15 years (yuan)	245000	1052000	735000	1918800
accident	no	yes	yes	yes
Environment pollution	no	yes	yes	a little
remark	(1)Data in the table is theoretic; (2)expense of water is not included; (3)from the table, we can calculate that by using solar water heater, we can get back the investment within 4 years

From the comparison of the results in the above table, all of the investment on solar water heater can be got back in 2~4 years. After 2~4 years, we can use hot water free. That's to say, we can save 123120 yuan from expense of electricity, or we can save 42000 yuan from expense of expenses of gas fuel, or we can save 64800 yuan from expense of oil fuel.
Another kind of way also can show the same result:
1, only use coal boiler water heater:
If the demand of the hot water is 8000KGS every day and the unit price of coal is 600RMB/T, the hot water supply fee will be 1172360/4300/60%*0.6*365=99514.2RMB per year.
2, only use fuel gas water heater:
If the demand of the hot water is 8000KGS every day and the unit price of gas is 2.2RMB/M3, the hot water supply fee will be 1172360/8600/75%*2.2*365=145954.3RMB per year
3, use solar water heater add fuel gas water heater:
In changzhou, there are about 280-300 days available for us to choose solar water heater to supply hot water each year, so that other about 85 days depend on fuel gas water heater., the fee is 1172360/8600/75%*2.2*86=33989.4RMB
The solar water heater project price for 8000KGS hot water is 120000RMB
We can see from the above calculate that the cost of using solar water heater add fuel gas water heater is the lowest, then the coal boiler water heater, and the cost of the fuel gas water heater is the highest. Since the recycling time of using coal boiler and gas water heater system making hot water is about 1-2years, while the life time of the solar water heater is 15years, as a result, install and use the solar water heater system is both economical, energy save and environmental protection.

Evacuated tubes are the absorber of the solar water heater. They absorb solar energy converting it into heat for use in water heating. Evacuated tubes have already been used for years in Germany, Canada, China and the UK. There are several types of evacuated tubes in use in the solar industry. Huihao collectors use the most common "twin-glass tube". This type of tube is chosen for its reliability, performance and low manufacturing cost.

Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures. This "evacuation" of the gasses forms a vacuum, which is an important factor in the performance of the evacuated tubes.
Please
Why a vacuum? As you would know if you have used a glass lined thermos flask, a vacuum is an excellent insulator. This is important because once the evacuated tube absorbs the radiation from the sun and converts it to heat, we don't want to lose it!! The vacuum helps to achieve this. The insulation properties are so good that while the inside of the tube may be 150oC / 304oF , the outer tube is cold to touch. This means that evacuated tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta-T conditions).
In order to maintain the vacuum between the two glass layers, a barium getter is used (the same as in television tubes). During manufacture of the evacuated tube this getter is exposed to high temperatures which causes the bottom of the evacuated tube to be coated with a pure layer of barium. This barium layer actively absorbs any CO, CO2, N2, O2, H2O and H2 out-gassed from the evacuated tube during storage and operation, thus helping to maintaining the vacuum. The barium layer also provides a clear visual indicator of the vacuum status. The silver coloured barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition. See picture below.

The Getter is located at the bottom of the evacuated tube

Left Tube = Vacuum Present Right Tube = Faulty

Evacuated tubes are aligned in parallel, the angle of mounting depends upon the latitude of your location. In a North South orientation the tubes can passively track heat from the sun all day. In an East West orientation they can track the sun all year round.
The efficiency of a evacuated water heater is dependent upon a number of factors, one important one being the level of evacuated radiation (insolation) in your region.

Evacuated Tube Basic Specifications
Length (nominal)
1500mm /1800mm
Outer tube diameter
58mm
Inner tube diameter
47mm
Glass thickness
1.6mm
Thermal expansion
3.3x10-6 ^oC
Material
Borosilicate Glass 3.3
Absorptive Coating
Graded Al-N/Al
Absorptance
>92% (AM1.5)
Emittance
<8% (80^oC)
Vacuum
P<5x10-3 Pa
Stagnation Temperature
>200^oC
Heat Loss<0.8W/ ( m2 ^oC )
Maximum Strength
0.8MPa

Huihao three target vacuum tube assimilate the advanced 12 layers of spattering deposition of trivalent element technology, high borosilicate glass, gradual change of ALN/ALN-SS/CU selective complex absorptive coating. And these make vacuum tubes have high performance of absorptance and low reflection ratio. Through the interlayer vacuum has a unique effect of thermo, with its temperature up to 380^oC, of idle suning, performing a strong heating ability.

Models	φ47*150	φ58*180
Weight	1.35±0.12kg	2.29±0.18kg
Structure	All glass coaxial double-layer tubes	All glass coaxial double-layer tubes
Outer tube diameter	φ47±0.7mm	φ58±0.7mm
Inner tube diameter	φ37±0.7mm	φ47±0.7mm
Outer Tube thickness	1.6±0.15mm	1.8±0.15mm
Inner tube thickness	1.6±0.15mm	1.6±0.15mm
Tubes length	1542±4mm	1812±4mm
Material of coating	AlN/AIN-SS/Cu	AlN/AIN-SS/CU
Absorptance	0.94~0.96	0.94~0.96
Emittance	0.04~0.06	0.04~0.06
Vacuum	P≤5 * 10-3pa	P≤5 * 10-3pa
Transmittance of Outer Tube	0.91	0.91
Stagnation temperature (height)	270~300φ	270~300^oC
Heat-loss coefficient	≤0.6w/ m2*^o)	≤0.6 w/ (m2*^o)
Bearing hailstone ability	hailstone diameter φ25mm	hailstone diameter φ25mm
Pressure-endure ability	1MPa	1MPa

♦Feature:
A perfect combination of the vacuum tube and the heat pipe
1) Higher heat efficiency: advanced heat transferring style of the heat pipe, excellent selective absorbent coating and perfect combination with high vacuum heat preservation.
2) Wide applicable range: as the heat pipe has less heat capacity, it can be started quickly even under cloudy fine day and collect heat effectively. It can work normally even-30 below degree. As no water in the vacuum tube. It can effectively prevent lowing of heat efficiency due to frost cracking or scaling.
3) Each individual tube can work independently, and the whole machine can still work if individual tube is damaged. The service life of the heat pipe can be longer than 15 years.
4) The unique connection between the heat pipe and the vacuum tube can ensure both sealing and replace of damaged glass vacuum tube.

♦Specifications

Working principle:
The selective coating on the inner cover of the evacuated tubes converts solar energy into heat energy and transfers heat to the heat pipes by aluminum fins. The liquid in the heat pipe changes into vapour which rises to rises to the condenser. The heat then passes through the heat exchanger.

The heat conduction through the pipe is by the way of exchage of liquid and gas.The temperature difference is very low.Because of its high heat conduction feature and efficency,the pipe is used popularly in solar industry.
1.High heat conduction coefficient:is 2000-5000 times of matal materials.
2.High quantity of heat conduction:is 1000times od metal materials.
3.Low temperature difference:less than 4鈩?difference in 2 meter long pipe.

Product	Type	Type	Wall Thickness
Horizontal pipe	ø24mm	ø14mm	0.7mm
Gravity pipe	ø14mm	ø18mm	0.7mm

♦Technical Specifications

Item	Measured Value
Heat conduction coefficient	>99%
Axial heat transition auantity	0.93-2.49kw/cm²
Heat conduction speed	>200mm/s
Axial temperature difference	1-2°C/m
Starting temperature	20°C
Starting speed	2min
Working temperature range	30°C~300°C
Life	>10years
wall thickness	0.7mm

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Pre-heated Pressure Solar Water Heater
Integrative Pressurized Solar Water Heater
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Solar Heater Accessories
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CONTACT US

Haining Huihao Solar Energy Technology Co., Ltd.
Tel:0086-57387862598
Fax:0086-57387863811
Email:supersky2010@yahoo.cn
Web:http://www.solarwaterheaterfactory.com
Add:South of Xiaohong Bridge,North of Yuanhua Town, Haining City ,Zhejiang Province,China.

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Project Solar Heating System

Solar Collector Manifold System

Non-Pressure Solar Collector

Compact Non-Pressure Solar Water Heater

Pressure Solar Collector

Split Pressurized Solar Water Heater

Pre-heated Pressure Solar Water Heater

Integrative Pressurized Solar Water Heater

Flat Plate Solar Water Heater

Solar Heater Accessories

New Products