Movable Cooling Plates for Large Silicon Ingots
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Solution Overview
Problem
Existing directional solidification furnaces are unable to produce multi-crystalline silicon ingots with masses greater than 600 kg due to limitations in heat management and cooling control, resulting in ingots with defects such as dislocations that affect photovoltaic device efficiency.
Innovation Solution
A directional solidification furnace with a crucible support system that includes a cooling plate lift mechanism and control system to precisely manage heat transfer and cooling rates, allowing for the production of ingots exceeding 1000 kg by adjusting the position and force of cooling plates and insulating members to control the solidification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mass of silicon ingots is increased to improve efficiency and reduce production cost, then productivity and cost-effectiveness are improved, but heat management and cooling control become insufficient, resulting in ingots with defects such as dislocations
Solution Approach 1:
The heat exchanger is designed with movable components including extendable cooling plates and adjustable insulation members that can dynamically change position during the solidification process. This allows the cooling system to adapt to different ingot sizes and stages of solidification, maintaining effective heat transfer even as the ingot mass increases beyond 600 kg.
Solution Approach 2:
The system enables dynamic adjustment of cooling parameters by moving heat exchanger components to different positions and configurations. The extendable cooling plates can increase surface area contact, while adjustable insulation members can modify thermal gradients, allowing optimization of cooling rates for larger ingot masses to prevent defect formation.
2Reliability
If fixed heat exchangers are used in conventional furnaces, then device complexity is reduced, but the ability to control cooling rates and produce defect-free large ingots is limited
Solution Approach 1:
The heat exchanger incorporates movable cooling plates and adjustable insulation members that can be positioned at different locations around the crucible. This dynamic configuration allows precise control of heat extraction rates from different regions of the ingot, improving cooling control precision while the controlled movement mechanisms keep added complexity manageable.
Solution Approach 2:
The movable heat exchanger system serves multiple functions: it can adjust to different ingot sizes, modify cooling rates dynamically, and prevent various types of defects. The same adjustable components that increase control precision also provide versatility for producing different ingot specifications, justifying the increased device complexity.
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 system enables the production of large, high-quality multi-crystalline silicon ingots with reduced dislocation density, enhancing the efficiency of photovoltaic devices by precisely controlling the solidification rate and heat transfer, thereby overcoming previous limitations in ingot size and defect formation.
Implementation Method 1
a cooling plate positioned beneath the base of the crucible support
Implementation Method 2
The controlled rate of cooling is established by any combination of reducing the amount of heat applied by the heaters, movement of or opening of insulation surrounding the crucible, and/or the circulation of a cooling medium through a heat exchanger disposed adjacent the crucible
Data Source
AI summary
A directional solidification furnace includes one or more movable cooling plates disposed beneath a crucible. In a first position, the cooling plates are free from contact with a crucible support positioned adjacent the crucible. In a second position, the cooling plates are in contact with the crucible support. A control system is used to control the amount of force exerted by the cooling plates against the crucible.