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Inner Light-Focusing Vacuum Tube U Pipe Solar Collector

Inner Light-Focusing Vacuum Tube U Pipe Solar Collector

Demax Inner Light-Focusing Vacuum Tube U Pipe Solar Collector

A mid-temperature solar collector mainly used for space heating, domestic hot water, or preheating (eg, for solar air conditioning).

It is a mid-temperature collector that generates 90℃ hot water.

An off-center vacuum tube (not concentric) with a built-in parabolic reflector.

The collector can be installed solely or connected together to meet larger heat demand.

Introduction
Structure and Working Principle
Technical Parameter
RFQ
Application Case
Recommended

Pressurized Inner-lighting U-Pipe Solar Thermal Collector

Reliable Solar Thermal Solution for Residential & Commercial Applications

As a trusted one-stop provider of new energy products and solutions, we engineer our U-Pipe Solar Thermal Collectors for high efficiency, all-weather reliability, and long-term performance. Designed for pressurized solar hot water systems, this collector delivers consistent heat output for residential complexes, hotels, hospitals, and industrial process heating (IPH) projects worldwide.

Core Advantages

Exceptional Thermal Efficiency
- Selective absorption coating with solar absorptance ≥0.956 and thermal emittance ≤0.049; minimal performance decay (≤2.1% after 2000 hours of aging).
- Aluminum 3003 fin with high thermal conductivity ensures rapid heat transfer from the evacuated tube to the U-pipe.
- Delivers 68%–73% instantaneous efficiency under standard test conditions, outperforming traditional flat-plate collectors by 5–8 percentage points.
Robust Freeze & Leak Protection
- Dry-tube design: No water inside the evacuated tubes—eliminates freezing risks in low temperatures and scaling issues that reduce efficiency over time.
- Compatible with antifreeze heat transfer fluids for stable operation in cold climates.
- Rigid welded copper connections (no silicone gaskets) prevent leaks and aging-related failures, ensuring a 10-year+ service life.
System Reliability & Easy Maintenance
- Independent U-pipe circuits: The system continues operating even if one evacuated tube is damaged, reducing downtime for maintenance.
- Pressurized operation (up to 6 bar) for stable water pressure and consistent hot water supply.
- Modular design allows flexible parallel/series connection to scale for projects of any size.
Versatile Installation
- 0–90° installation flexibility: Suitable for roof mounting, ground mounting, and balcony wall mounting (vertical/horizontal).
- Lightweight aluminum alloy frame with corrosion resistance for outdoor use in harsh environments.
- Pre-assembled manifolds reduce on-site installation time and errors.

Structure

Working Principle

The sunligh shines on the outer wall of the vacuum tube as well as the built-in mirror to reflect back

onto the outer wall of the vacuumm tube.Sunlight is then absorbed by the all glass vacuum tube and

converted into heat energy which is then transfered to the U pipe via fin in order to heat transmission

medium inside the U pipe.The heat energy is then conveyed to the water in the water tank.

The parameter of vacuum tube & Solar collector

Length	2100MM
Diameter of outer tube	84MM
Thickness of outer tube	2.0MM
Diameter of inner tube	47MM
Thickness of inner tube	1.6MM
Material	High borosilicate glass 3.3
Solar transmission ratio	≥92%
Selective coatring type	AlN/AlN-SS/Cu
Absorptance ratio	≥94%
Vacuum degree(Pa)	≦5.0X10^-4
Maxium temperature	250-320℃
Heat loss(W/㎡.℃)	≦0.65
Rated Pressure	0.6Mpa

Specification of collector	DMJUS 14-84/47	DMJUS 16-84/47	DMJUS 20-84/47
Specification of vacuum tube	Ф84/47X2100MM	Ф84/47X2100MM	Ф84/47X2100MM
No.of vacuum tubes	14	16	20
Weight	50KG	59KG	76KG
Outline dimension	1554X2200X158MM	1754X2200X158MM	2154X2200X158MM
Capacity of collector	2.59L	2.95L	3.69L
Flow L/(min.㎡)	0.6-1.2	0.6-1.2	0.6-1.2
Collector type	Aluminium U pipe	Aluminium U pipe	Aluminium U pipe
Insulation material	Fiber glass	Fiber glass	Fiber glass
Working medium	Propylene glycol	Propylene glycol	Propylene glycol
Reted pressure	0.6Mpa	0.6Mpa	0.6Mpa
Total area	3.42㎡	3.86㎡	4.74㎡
Aperature area	2.27㎡	2.60㎡	3.25㎡
Absorber area	1.336㎡	1.526㎡	1.908㎡
Shell material	Aluminium profile	Aluminium profile	Aluminium profile
Frame material	Galvanized steel plate	Galvanized steel plate	Galvanized steel plate
Tailstock material	Nylon	Nylon	Nylon
Collector interface	3/4" coupling nut	3/4" coupling nut	3/4" coupling nut
Maximum working temperature	240℃	240℃	240℃

RFQ

1.What is an Inner Light-Focusing Solar Collector and what core components does it consist of?

It is a mid-temperature solar collector mainly used for space heating, domestic hot water, or preheating (e.g., for solar air conditioning). Its core components include a header, inner light-focusing vacuum tubes, U pipes, mounting frames, and a tube bottom rack.

2.What are the key specifications of the vacuum tube in this collector?

The vacuum tube has an outer tube diameter of 84mm, an inner tube diameter of 47mm, and a length of 2100mm. It is made of Borosilicate Glass 3.3, with a solar transmission rate ≥0.92, an absorptance ratio ≥0.94, a vacuum degree <5.0×10⁻⁴ Pa, and a maximum temperature resistance of 250–320℃.

3.How does the Inner Light-Focusing Solar Collector work to heat water?

Sunlight hits the outer wall of the vacuum tube; meanwhile, sunlight on the built-in coated reflector (parabolic mirror) is reflected onto the vacuum tube’s outer wall. The all-glass vacuum tube absorbs sunlight and converts it into heat, which is transferred to the U pipe via fins. The heat then warms the heat-transmission medium (propylene glycol) in the U pipe, and finally, the heat energy is conveyed to the water in the storage tank.

4.What temperature range can this collector reach, and what makes it efficient?

It is a mid-temperature collector that generates 80–90℃ hot water. Its high efficiency comes from two key features: 1) Built-in coated reflectors in the vacuum tube that focus sunlight to the inner tube, improving heat absorption; 2) U-pipe heat transfer technology that reduces heat loss, with a heat efficiency of up to 60% at 90℃ (triple that of ordinary vacuum tubes) and a concentration ratio of 2.2.

5.What advantages does it have over traditional all-glass evacuated tube collectors?

Structural difference: It is an off-center vacuum tube (not concentric) with a built-in parabolic reflector, while traditional ones are concentric without reflectors.
Performance: No water in the vacuum tube (avoids fouling/breaking), faster temperature rise, and higher heat efficiency.
Installation: No restriction on installation height, supports pressurized operation for a better bathing experience.

6.What are the available models of the Inner Light-Focusing Solar Collector and their main differences?

Three main models are available: JUS 14-84/47, JUS 16-84/47, and JUS 20-84/47. Their key differences lie in the number of vacuum tubes (14, 16, 20 respectively), weight (50kg, 59kg, 76kg), outline dimensions, collector capacity (2.59L, 2.95L, 3.69L), and total/aperture/absorber areas (e.g., total area: 3.42㎡, 3.86㎡, 4.74㎡).

7.What environmental conditions can this collector withstand?

It has strong environmental adaptability: 1) Anti-cold resistance down to -40℃ and air drying temperature resistance not lower than 400℃; 2) Anti-hail impact (resists hail with a diameter of 2.5cm or less); 3) The shell and frame are made of galvanized steel, and the tailstock is nylon, ensuring good aging resistance.

8.Can multiple Inner Light-Focusing Solar Collectors be used together, and what working medium does it use?

Yes, the collector can be installed solely or connected together to meet larger heat demand. Its working medium is propylene glycol, which is used in the U pipe to transfer heat efficiently, and the system operates at a rated pressure of 0.6MPa.

Core Technology Support:
The internal focusing vacuum tube has a special structure, increasing the heat collection area by about 20% compared to ordinary vacuum tubes. With the combined effect of the internal focusing mirror surface, heat loss is reduced by 1/3, so the temperature under direct sunlight can exceed 330 ℃.

1.Industrial Thermal Oilfield Application Case Study

1.1 Shengli Oilfield Solar Thermal Application – Replacing 20kW Electric Heating Furnace

1.2 Shengli Oilfield Solar Thermal Application

1.3 Shengli Oilfield and Liaohe Oilfield Solar Thermal Application – Replacing 20kW Electric Heating Furnace

2.Qingdao Enliwang Precision Industrial Heating Project-Replacement for 100kW Electromagnetic Heating Furnace

Two production lines operate 24 hours a day using heat, primarily to ensure the hot water tank remains at 65±2 degrees ℃ Water temperature: 12 hot water exchange tanks per production line, total volume 4500 liters; total volume of tanks for two production lines is 9000 liters, heating load 60 kW/hour;

Add 6.5m3 of hot water (15m3 of cold water) every day ℃ Temperature rises to 65 ℃ ), heating load 16 kW/hour;

The water in the production line sink is changed once a week, 9000L15 ℃ Cold water temperature rises to 65 ℃ The heating duration does not exceed 4 hours (the original process used an electromagnetic heating furnace from Party A, but after upgrading, hot water is supplied directly to the hot water exchange tank), with a heating load of 523 kWh per cycle. The average daily heating power is 100 kW, and the daily electricity consumption is >2400 kWh.

The project was put into operation in October 2024, with a system configuration of 110 units of 28-tube concentrated U-shaped tube collectors, with a total collector area of 708.4. ㎡ After the project implementation, the energy-saving effect is significant, with an energy substitution rate >60%.

Note: The second phase project was shipped on January 26, 2026, and is currently under construction.

3.China Academy of Agricultural Sciences Greenhouse Heating Industrial Thermal Project

Solar + phase change energy storage industrial heating project, providing hot water above 70 degrees Celsius to the phase change storage tank, generating phase change heat storage to solve the winter heating problem for greenhouse orchids

48 sets of concentrating solar collectors at the Taiyuan base 60 sets of concentrating solar collectors at the Beijing base

Enable remote real-time monitoring of mobile phones, as well as the detection of various data such as heat generation and energy consumption, allowing customers to directly experience the energy-saving effects.