Vacuum-Insulated Solar Water Heater With Phase-Change Storage
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Solution Overview
Problem
Conventional solar water heating systems face challenges in low insolation regions due to excessive heat loss, especially at night or during non-collection periods, making them less viable economically, and are often prohibitively expensive for regions requiring freeze protection.
Innovation Solution
A solar water heating apparatus featuring concentrically arranged vessels with a partially evacuated cavity containing a phase change material, wicking material, and a heat exchanger, which enhances heat retention and reduces heat loss through strategic insulation and condensation management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional solar water heating systems are used, then solar energy collection is achieved, but excessive heat loss occurs during non-collection periods especially at night
Solution Approach 1:
The patent applies parameter changes by evacuating the cavity between the inner and outer vessels to create a vacuum environment. This fundamentally changes the thermal conduction parameter from normal atmospheric conditions to near-zero conduction, dramatically reducing heat loss during non-collection periods while maintaining the solar collection function.
Solution Approach 2:
The patent employs composite material structures by combining the inner vessel containing water, the evacuated cavity space, and the outer vessel with insulation layer. This multi-layer composite structure integrates different functional materials (conductive water, insulating vacuum, protective outer shell) to simultaneously achieve heat collection and heat retention.
2Ease of manufacture
If integrated collector storage solar water heater is used, then construction and installation simplicity is achieved, but heat losses to ambient especially at night-time are excessive
Solution Approach 1:
The patent maintains the simple integrated structure of the ICSSWH while adding the vacuum-evacuated cavity between the inner and outer vessels. This parameter change (creating vacuum insulation) significantly reduces ambient heat loss without complicating the basic integrated design, allowing the system to retain both simplicity and thermal efficiency.
3Productivity
If solar water heating system is used in low insolation regions, then solar energy collection is attempted, but the system becomes economically unviable due to excessive heat loss
Solution Approach 1:
By evacuating the cavity to create a vacuum environment, the patent dramatically reduces the thermal conduction parameter between the inner and outer vessels. This enables the system to maintain higher water temperatures for longer periods, improving the solar fraction and economic viability even in regions with lower insolation levels where every unit of captured energy is more valuable.
4Reliability
If conventional solar collector with water store is used, then solar water heating function is achieved, but system complexity and cost increase due to twin coil hot water cylinder requirement
Solution Approach 1:
The patent merges the collector and storage functions into a single integrated unit where the inner vessel serves as both the heat collection chamber and the water storage container. The evacuated cavity provides insulation without requiring separate insulation components or twin coil cylinders, simplifying the overall system while maintaining reliable heating function.
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 apparatus effectively maintains water temperature during non-collection periods, reduces energy requirements, and provides a cost-effective solution by integrating with existing hot water systems without the need for additional components like twin coil cylinders, thus improving the solar fraction and economic viability.
Implementation Method 1
the cavity is partially evacuated
Implementation Method 2
a phase change material provided in the cavity
Implementation Method 3
wicking material located in the cavity
Implementation Method 4
a solar radiation absorbent coating is provided on an outer face of the outer vessel
Data Source
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AI summary
The present invention provides a solar water heating apparatus which includes concentric inner and outer vessels defining an annular cavity therebetween, within which cavity a phase change material is located, and which is vaporised when solar radiation is incident on the outer vessel, in order to transfer heat to a water store contained in the inner vessel, this water store being fed fresh unheated water while the heated water is extracted therefrom for domestic or other purposes.