Solar Heating Tubes

Product Definition

Solar Heating Tubes are high-efficiency solar thermal components, typically evacuated glass tubes, designed to capture solar radiation and convert it into usable heat for water heating and thermal energy systems, offering stable performance across diverse climatic and installation conditions.

Technical Parameters and Specifications

Solar heating tubes are manufactured according to standardized thermal and mechanical performance requirements to ensure long-term reliability.

• Tube type: Evacuated tube / Heat pipe tube

• Outer diameter: 47 mm / 58 mm

• Tube length: 1500 mm / 1800 mm / 2000 mm

• Glass material: Borosilicate 3.3

• Vacuum degree: ≤5×10⁻³ Pa

• Solar absorption rate: ≥93%

• Emissivity: ≤6%

• Operating temperature: -40°C to 200°C

• Design service life: ≥15 years

Structure and Material Composition

Solar heating tubes feature a layered and highly engineered structure:

• Outer glass tube: High-transparency borosilicate glass

• Inner absorber tube: Selective-coated glass layer

• Selective coating: Aluminum-nitride or copper-based coating

• Vacuum layer: Thermal insulation to minimize heat loss

• Heat pipe (optional): Copper pipe with working fluid

• Sealing end cap: Barium getter and vacuum seal

Manufacturing Process

The production of solar heating tubes follows strict industrial procedures:

1. Glass tube forming and annealing

2. Selective coating deposition via magnetron sputtering

3. Inner and outer tube assembly

4. Vacuum extraction and getter activation

5. Heat pipe insertion and sealing (if applicable)

6. Thermal shock and vacuum retention testing

Core equipment includes coating chambers, vacuum pumps, annealing furnaces, and automated inspection systems.

Industry Comparison

Application Scenarios

Solar heating tubes are widely specified by EPC contractors, system integrators, and distributors in the following projects:

• Residential solar water heating systems

• Hotels, hostels, and resorts

• Hospitals and healthcare facilities

• School and university campuses

• Industrial process water preheating

• District heating and hybrid solar systems

Core Pain Points and Engineering Solutions

• Heat loss in low temperatures: Vacuum insulation minimizes convection losses

• System scalability: Modular tube arrays enable flexible capacity expansion

• Tube breakage concerns: Borosilicate glass improves impact resistance

• Uneven heat transfer: Heat pipe designs enhance thermal consistency

Risk Warnings and Mitigation Recommendations

Engineering risk control is essential for long-term system stability:

• Vacuum degradation → specify certified vacuum retention tests

• Overheating risk → integrate pressure relief and heat dump systems

• Hail or impact damage → select reinforced tube thickness

• Improper installation angle → follow manufacturer tilt guidelines

Procurement and Selection Guide

1. Define daily hot water or thermal load requirements

2. Evaluate local solar irradiation and climate conditions

3. Select tube diameter and length based on output targets

4. Decide between direct-flow or heat pipe tubes

5. Verify coating technology and vacuum standards

6. Confirm compatibility with storage tanks and manifolds

7. Review supplier certifications and project references

Engineering Case Example

A hospital hot water retrofit project utilized 300 sets of 58×1800 mm solar heating tubes integrated with a 5000-liter storage system. The installation supplied approximately 62% of annual hot water demand, reduced fossil fuel consumption, and achieved system payback within five years under continuous operation.

Frequently Asked Questions (FAQ)

• Q1: What is the main advantage of solar heating tubes?
  A: High efficiency and excellent cold-weather performance.

• Q2: Are solar heating tubes suitable for freezing climates?
  A: Yes, especially heat pipe configurations.

• Q3: What is the typical lifespan?
  A: 15 years or more with proper installation.

• Q4: Do tubes require frequent maintenance?
  A: No, routine inspection is sufficient.

• Q5: Can individual tubes be replaced?
  A: Yes, modular replacement is possible.

• Q6: How do they compare to flat plate collectors?
  A: Higher efficiency and better low-temperature performance.

• Q7: What tilt angle is recommended?
  A: Typically 30°–45°, depending on latitude.

• Q8: Are they compatible with hybrid systems?
  A: Yes, widely used with gas or electric backup.

• Q9: Is vacuum loss detectable?
  A: Yes, via visual indicators or thermal output decline.

• Q10: Can systems be expanded later?
  A: Yes, additional tubes can be integrated.

Call to Action

For project-specific quotations, detailed technical datasheets, or engineering consultation on solar heating tube systems, please submit your requirements to receive professional support, configuration recommendations, and sample solutions.

E-E-A-T Author Credentials

This content is prepared by solar thermal engineers and project consultants with extensive experience in collector component manufacturing, EPC system integration, and lifecycle performance analysis for commercial and infrastructure-scale solar heating projects.

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