Evacuated Solar Thermal Loop With Phase Change for Low-Loss Building Energy
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Solution Overview
Problem
Existing solar thermal systems are inefficient in providing simultaneous space heating, space cooling, water heating, and electricity generation due to the conflict between maintaining high solar collector temperatures for efficient heat collection and minimizing heat loss, leading to insufficient energy delivery to buildings.
Innovation Solution
A closed-loop conduit network with full surface contact and phase change capabilities, evacuated to minimize temperature differentials, combined with an impermeable housing for vacuum insulation, and integrated heat transfer devices for efficient energy distribution and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If solar collector temperature is increased to collect more heat energy, then heat collection efficiency is improved, but heat loss to environment increases
Solution Approach 1:
The patent changes the physical state of the working fluid from liquid to vapor through phase change, enabling heat transfer at constant temperature. This parameter change allows the system to operate at higher temperatures without increasing temperature differentials, thereby collecting more heat energy while minimizing heat loss to the environment.
Solution Approach 2:
The patent utilizes phase transition of the working fluid (liquid to vapor and back) as the primary heat transfer mechanism. During evaporation, the working fluid absorbs heat at constant temperature from the solar collector, and during condensation, it releases heat at constant temperature to the end use. This phase change mechanism enables efficient heat collection and transfer while maintaining minimal temperature differentials.
2Temperature
If working fluid temperature is increased above ambient to enable heat transfer, then heat transfer capability is improved, but heat loss to environment increases
Solution Approach 1:
The patent employs phase transitions of the working fluid to achieve heat transfer at constant temperature. The working fluid evaporates at a specific temperature determined by the ambient pressure, absorbs heat during this phase change, and then condenses at the same temperature to release heat. This eliminates temperature differentials during heat transfer processes, minimizing heat loss to the environment while maintaining effective heat transfer capability.
Solution Approach 2:
The patent creates a vacuum environment around the solar collector and working fluid system, eliminating air convection and reducing radiative heat loss. This inert environment (vacuum) prevents heat loss to the surrounding atmosphere, allowing the system to operate at higher temperatures without proportionally increasing heat loss.
3Device complexity
If conventional solar thermal systems are used for single-purpose applications, then system simplicity is maintained, but ability to provide multiple services simultaneously is insufficient
Solution Approach 1:
The patent designs a solar thermal system that can simultaneously provide multiple services including space heating, space cooling, domestic hot water, and electricity generation. The phase-change working fluid system can be configured to serve different thermal loads concurrently, making a single system versatile enough to meet all building energy needs without requiring multiple separate systems.
Solution Approach 2:
The patent segments the thermal energy distribution into different temperature levels and applications. The system divides heat transfer into distinct pathways: high-temperature heat for electricity generation via heat engine, medium-temperature heat for domestic hot water, and low-temperature heat for space heating. This segmentation allows simultaneous fulfillment of multiple energy demands from a single solar thermal source.
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 achieves high efficiency and cost-effectiveness by reducing temperature differentials, minimizing energy consumption, and preventing heat loss, enabling simultaneous provision of space heating, cooling, hot water, and electricity generation.
Implementation Method 1
the working fluid experiences phase change whenever heat energy is added or removed
Implementation Method 2
the working fluid received by the heat transfer interface obtains heat energy from the solar absorber, evaporates
Implementation Method 3
an impermeable housing enveloping the closed-loop conduit network and forming a high vacuum located between and defined by the outer surface of the closed-loop conduit network and the inner surface of the impermeable housing such that the working fluid is adiabatically isolated
Implementation Method 4
provides vacuum insulation to greatly reduce heat energy lost from conduction and convection
Implementation Method 5
the working fluid releases heat energy, condenses, and collects at a liquid reservoir
Implementation Method 6
The thermal energy of solar radiation is absorbed by an absorber body in a solar thermal collector
Implementation Method 7
a heat engine coupled with a generator to provide electricity
Data Source
AI summary
A building-integrated solar energy system that concurrently provides space heating, space cooling, hot water, and electricity to commercial and residential buildings. The solar energy system comprises an evacuated closed-loop conduit network circulating a working fluid through a solar thermal collector and at least one heat usage device, wherein the effective entirety of the surfaces of the closed-loop conduit network are in contact with the working fluid such that phase change occurs whenever heat energy is added by the solar thermal collector or removed by a heat usage device. The solar energy system further comprises an impermeable outer housing enveloping the closed-loop conduit network and forming an evacuated space located between and defined by the outer surface of the closed-loop conduit network and the inner surface of the impermeable housing such that the working fluid is adiabatically isolated. As a result, the full surface contact and low-pressure isolation of the working fluid dramatically reduces temperature differentials and energy losses, allowing for highly efficient and cost-effective heat collection and distribution.