Phase Change Thermal Valve for Solar Photobioreactor Temperature Control
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Solution Overview
Problem
Closed photo-bioreactors with direct sunlight capture face excessive heating issues, leading to temperature control challenges, which can be detrimental to microorganisms, and existing solutions like water spraying or immersion consume water and reduce light capture efficiency, or require energy for cooling/heating.
Innovation Solution
A photo-reactor with a confined reaction chamber featuring a thermal valve composed of a phase change material and a heat exchanger, which passively regulates temperature by maintaining it below a threshold, eliminating the need for energy or water, using materials like paraffin with a phase change temperature range between 25°C and 40°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water spraying or immersion is used for thermal regulation, then temperature control is improved, but water consumption increases and light capture efficiency decreases
Solution Approach 1:
The patent applies phase transition of phase change material (PCM) to achieve thermal regulation. The PCM absorbs excess heat during daytime when it melts (solid to liquid transition) and releases heat when it freezes (liquid to solid transition), maintaining optimal temperature without water consumption. This directly resolves the contradiction by replacing water-based cooling with phase transition-based thermal management.
Solution Approach 2:
The thermal regulation system is self-regulating through the inherent properties of phase change material. The PCM automatically absorbs or releases heat based on temperature conditions without requiring external control systems, water supply, or energy input. This eliminates water consumption while maintaining effective temperature control.
2Temperature
If water spraying is used for thermal regulation, then temperature control is improved, but light capture efficiency decreases due to fouling of light-capturing surfaces
Solution Approach 1:
The phase change material provides thermal regulation through solid-liquid phase transition without involving water spray. This eliminates mineral salt deposition on light-capturing surfaces, maintaining high light transmission efficiency while achieving effective temperature control through the PCM's latent heat absorption and release.
Solution Approach 2:
The phase change material acts as an intermediary thermal management component positioned between the reaction chamber and the external environment. It mediates heat transfer without requiring direct water contact with light-capturing surfaces, thus preserving optical properties while achieving thermal regulation.
3Temperature
If active cooling or heating systems are used, then temperature control is improved, but energy consumption increases
Solution Approach 1:
The phase change material provides passive thermal regulation through its inherent phase transition properties. During daytime, the PCM absorbs heat during melting without requiring energy input. During nighttime or cooler periods, it releases stored heat during freezing. This passive operation eliminates the need for energy-consuming active cooling or heating systems.
Solution Approach 2:
The thermal regulation system operates autonomously using the natural phase transition properties of the PCM. No external power source, control system, or active intervention is required. The system self-regulates temperature by absorbing heat when temperature rises and releasing heat when temperature drops, eliminating energy consumption entirely.
4Temperature
If immersion in water pool is used, then temperature control is improved, but light capture efficiency decreases due to reflection-absorption of light flux
Solution Approach 1:
The phase change material provides thermal regulation through phase transition without requiring water immersion. The PCM is positioned as a thermal management layer that does not interfere with light transmission to the reaction chamber, maintaining high light capture efficiency while achieving effective temperature control through latent heat storage and release.
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
Effectively maintains the temperature within the reaction chamber below the threshold, reducing energy and water consumption, and enhancing light capture efficiency by preventing overheating without the need for external cooling or heating systems.
Implementation Method 1
the thermal valve being composed of a phase change material and a heat exchanger
Implementation Method 2
the thermal valve being composed of a phase change material and a heat exchanger
Implementation Method 3
the thermal valve being composed of a phase change material and a heat exchanger
Implementation Method 4
the thermal valve being composed of a phase change material and a heat exchanger
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5d
AI summary
The invention relates to a photoreactor (1) comprising a contained reaction chamber (15), wherein the chamber (15) is separated from the exterior by a light-capturing wall (11) and another wall (12), the capturing wall and the other wall being parallel to one another; characterized in that the photoreactor (1) additionally comprises a thermal valve (13) placed against the other wall (12) for passively controlling the increase in heat inside the chamber (15) due to the radiation passing through the capturing wall (11) in order to maintain the temperature in at least one part of the chamber (15) under a threshold temperature (Ts), the thermal valve (13) being made of a phase-change material.