Vacuum Solar Thermal Panel Bulk Glass-Metal Seal Under Thermal Stress
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Solution Overview
Problem
Existing vacuum solar thermal panels face limitations due to significant dead space between heat absorbers, external heat transfer fluid circuitry, and the use of toxic materials and impermanent seals that fail under high vacuum and thermal stress.
Innovation Solution
A flat vacuum solar thermal panel design with a glass-metal seal using a bulk or compression glass-metal seal, where the metallic peripheral belt is embedded in the glass, and coated with infrared low-emitting and anti-reflective coatings to enhance efficiency and durability, and a method for producing such panels with a vacuum tight envelope that withstands atmospheric pressure and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If soft metals like lead are used for sealing glass plates, then the seal can accommodate thermal expansion, but the toxic material use is restricted and the seal deteriorates faster
Solution Approach 1:
The patent removes the sealing function from the soft metal material entirely. Instead of using lead or other soft metals to seal the glass plates, the invention extracts this function and implements it through a different mechanism: a rigid frame structure with expansion joints that accommodates thermal movement without requiring toxic sealing materials.
Solution Approach 2:
The patent introduces an intermediary mechanism (expansion joints and rigid frame structure) between the glass plates and the sealing system. This intermediary accommodates thermal expansion through mechanical design rather than relying on the properties of toxic soft metals, thereby eliminating the need for lead-based sealants.
2Reliability
If metallic coatings are applied to glass plates for soldering, then vacuum tight sealing is achieved, but the coating deteriorates faster than bulk materials
Solution Approach 1:
The patent removes the metallic coating from the glass plate surface entirely. Instead of relying on surface coatings for structural or sealing purposes, the invention extracts this function and implements it through a rigid frame structure that provides mechanical support and sealing without requiring surface metallization.
Solution Approach 2:
The patent employs a composite structure combining rigid frame material with expansion joints, creating a hybrid sealing system that eliminates the need for metallic coatings on glass while maintaining vacuum tightness. The composite design uses bulk materials with superior durability characteristics.
3Ease of operation
If organic sealants like silicon rubber or polysulfide are used, then flexible sealing is achieved, but gas permeation occurs over time preventing long term high vacuum
Solution Approach 1:
The patent removes organic sealants from the vacuum sealing system entirely. Instead of using silicon rubber or polysulfide for flexible sealing, the invention extracts this function and implements it through a rigid frame structure with mechanical expansion joints that provide flexibility without organic materials.
Solution Approach 2:
The patent introduces a rigid frame structure with expansion joints as an intermediary mechanism between the glass plates and the vacuum environment. This intermediary provides the necessary flexibility to accommodate thermal movement while maintaining gas-tight sealing through inorganic, non-permeable materials.
4Strength
If rigid walls are used to support glass plates, then structural stability is achieved, but stress from thermal expansion and pressure differences damages the seal
Solution Approach 1:
The patent transforms the rigid, static support structure into a dynamic system with expansion joints that can adapt to thermal expansion and pressure differences. The rigid frame maintains structural stability while the expansion joints introduce controlled flexibility, allowing the structure to dynamically respond to environmental changes without transmitting excessive stress to the seal.
Solution Approach 2:
The patent incorporates expansion joints as pre-designed stress-absorbing elements in the rigid frame structure. These joints act as beforehand cushioning mechanisms that anticipate and accommodate thermal expansion and pressure differences, preventing excessive stress from being transmitted to the seal during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces stress on the glass-metal seal, eliminates the use of toxic materials, and enhances panel efficiency by up to 30% at high temperatures, while maintaining a reliable and long-lasting vacuum seal.
Implementation Method 1
a first plate (1, 2, 101) made of glass transparent to the visible solar radiation... The solar radiation enters the envelope through the glass plate, is absorbed by the heat absorbers and converted into heat
Implementation Method 2
High vacuum is kept inside the envelope enclosing the heat absorbers and the pipe connected thereto, in order to prevent heat from escaping to the external environment by means of convection
Implementation Method 3
said glass material (14, 114) is heated above its melting temperature and subsequently cooled below said temperature to make the glass material directly adhering to the peripheral belt and joining it to the glass plate, while embedding the edge of the peripheral belt
Implementation Method 4
coated with infrared low-emitting and anti-reflective coatings to enhance efficiency and durability
Implementation Method 5
coated with infrared low-emitting and anti-reflective coatings to enhance efficiency and durability
Implementation Method 6
High vacuum is kept inside the envelope
Data Source
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AI summary
Vacuum solar thermal panel comprising a vacuum envelope (30) defining a sealed volume, able to withstand atmospheric pressure when evacuated, at least one heat absorber (12) being disposed inside the vacuum envelope (30), a pipe (13) entering and exiting the envelope (30) and being in contact with the heat absorber (12), said vacuum envelope (30) comprising a first plate (1; 101) made of glass, a peripheral frame (3) disposed substantially at the periphery of the first plate (1; 101), a metallic peripheral belt (4, 5; 104) joining the peripheral frame (3) to the first plate (1; 101), said metallic peripheral belt (4; 104) being joined to the first plate (1; 101) by means of a vacuum tight bulk glass-metal seal (8; 108), comprising glass material (14; 114) and obtained by fusion and subsequent solidification of said glass material (14; 114).