Refurbishing non-convective zone in a solar pond
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Solution Overview
Problem
Existing methods for maintaining the salinity gradient in Salinity Gradient Solar Ponds (SGSPs) are inefficient, leading to significant heat and water loss, and are not practical for large-scale commercialization due to land and cost requirements, particularly the Surface Wash method.
Innovation Solution
The Pond Rolling Method, which involves draining and storing the upper and lower convective zones in surrounding ponds, refurbishing the non-convective zone, and returning them to minimize heat and water loss, allowing for controlled salinity gradient maintenance and efficient land use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Surface Wash method is used to maintain the salinity gradient, then the gradient can be maintained, but significant heat and water loss occurs and land requirements increase
Solution Approach 1:
The invention extracts the upper convective zone (UCZ) and lower convective zone (LCZ) from the solar pond as separate entities, storing them in external tanks. This allows the non-convective zone (NCZ) to be refurbished independently without losing the valuable UCZ and LCZ, thereby preventing heat and water loss that would occur in traditional methods where the entire pond must be drained and refilled.
Solution Approach 2:
The invention recovers and stores the UCZ and LCZ in external tanks during the NCZ refurbishment process, then returns them to the pond after refurbishment. This prevents the discarding of valuable thermal energy and water that would otherwise be lost during gradient maintenance operations, directly addressing the heat and water loss problem of traditional methods.
2Reliability
If the Surface Wash method is used to maintain the salinity gradient, then the gradient can be maintained, but land requirements and costs increase
Solution Approach 1:
The invention transitions from a two-dimensional surface wash approach to a three-dimensional storage system by using vertical tanks to store the UCZ and LCZ. This allows the same volume of water to be stored in a compact vertical space rather than requiring additional horizontal land area, reducing the land footprint while maintaining the ability to perform complete gradient maintenance.
3Ease of repair
If traditional draining and refilling methods are used, then the non-convective zone can be refurbished, but heat and water loss increases
Solution Approach 1:
The invention extracts and stores the UCZ and LCZ in external tanks before refurbishing the NCZ, then returns them after refurbishment. This prevents water loss by maintaining the water inventory outside the pond during the refurbishment process, allowing complete NCZ renovation without the need to drain and refill the entire pond.
Solution Approach 2:
The invention recovers the UCZ and LCZ that would otherwise be lost during traditional draining operations. By storing these zones in external tanks and returning them after NCZ refurbishment, the system prevents both water and thermal energy loss, enabling easy NCZ repair without substance loss.
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
This method reduces heat and water loss, minimizes land requirements, and lowers costs compared to previous methods, enabling reliable and efficient operation of SGSPs for commercial-scale renewable energy production.
Implementation Method 1
storing the upper convective zone and the lower convective zone in a corresponding zone of at least one surrounding ponds
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
A Salinity Gradient Solar Pond (SGSP) has saturated salt water in the bottom zone of the pond and nearly fresh water at the top zone, with a gradient zone between the top and bottom. Due to this salinity stratification the upward diffusion of salt is a natural consequence in SGSP's. Controlling the salinity gradient in SGSP systems is vital to their reliable operation. The method for controlling the salinity gradient disclosed in this application, coined the "Pond Rolling Method" by the authors, rapidly drains the pond's non-gradient zones, refurbishes the gradient, and restores the non-gradient zones of the SGSP system, in a manner that minimizes land use, water and heat loss. The salt in the pond is allowed to diffuse upward over time and, on condition as needed to restore the gradient, the Pond Rolling Method is used to completely rebuild the gradient and the SGSP zones.