Apparatus for membrane distillation using solar absorber and heat pump
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Solution Overview
Problem
Existing membrane distillation processes using solar collectors suffer from low heat collection efficiency and are significantly affected by weather conditions, leading to reduced treatment efficiency, especially as sunset approaches when sunlight weakens.
Innovation Solution
An apparatus combining a solar absorber and a heat pump to maintain a consistent temperature difference between raw water and coolant, utilizing a phase change material to store and release heat when sunlight is scarce, ensuring prolonged membrane distillation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If solar collectors are used to heat raw water for membrane distillation, then renewable energy is utilized to reduce energy costs, but heat collection efficiency is low and treatment efficiency decreases as sunset approaches
Solution Approach 1:
The solar absorber pre-heats the raw water to a high temperature during the day when sunlight is available. The phase change material (paraffin wax) absorbs and stores excess thermal energy during peak sunlight hours, preparing the system for sustained operation into the evening when solar input decreases. This preliminary energy storage action maintains the temperature difference across the membrane, preserving treatment efficiency beyond sunset.
Solution Approach 2:
The patent utilizes the phase transition of paraffin wax (solid-liquid transition at approximately 47-49°C) as a thermal energy storage mechanism. During the day, the phase change material absorbs latent heat from the solar-heated raw water, melting from solid to liquid state. At night, it releases this stored latent heat as it solidifies, maintaining raw water temperature and the temperature gradient necessary for membrane distillation, thereby extending productive operation into the evening.
2Reliability
If existing solar collectors are used for membrane distillation, then solar heat is utilized, but heat collection efficiency is low and the system is heavily affected by weather conditions
Solution Approach 1:
The patent employs a composite structure combining a solar absorber (with selective coating for maximum solar radiation absorption), a metal plate (for thermal conduction), and phase change material (paraffin wax, for thermal energy storage). This composite system captures solar energy efficiently, transfers it effectively, and stores it reliably, reducing sensitivity to weather variations and maintaining operational stability even when solar input fluctuates.
Solution Approach 2:
The system changes the thermal parameters of the raw water by pre-heating it to a higher temperature using the solar absorber. This temperature elevation increases the temperature difference across the membrane, enhancing the driving force for vapor transport. The phase change material dynamically adjusts the thermal energy storage capacity based on solar input intensity, maintaining stable operation under varying weather conditions.
3Use of energy by stationary object
If solar heat alone is used for membrane distillation, then energy costs are reduced, but membrane distillation efficiency drops significantly after sunset
Solution Approach 1:
The solar absorber and phase change material perform preliminary energy capture and storage during daylight hours, building up a thermal reservoir before sunset. This stored thermal energy extends the membrane distillation process into the evening, increasing the operational duration without requiring additional energy input after sunset.
Solution Approach 2:
The phase change material (paraffin wax) utilizes its solid-liquid phase transition at approximately 47-49°C to store and release large amounts of latent heat. During daylight, it absorbs latent heat while melting; after sunset, it releases this stored latent heat during solidification, maintaining the temperature gradient across the membrane and extending the membrane distillation process duration into the night without additional energy cost.
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
Enhances raw water heating efficiency, maintains membrane distillation efficiency beyond sunset, and prolongs the membrane distillation process duration by regulating temperature differences through the heat pump and phase change material, thereby improving treated water production efficiency.
Implementation Method 1
raw water is heated using the solar absorber with improved heat collection efficiency
Implementation Method 2
utilizing a phase change material to store and release heat when sunlight is scarce
Implementation Method 3
maintains a consistent temperature difference between raw water and coolant, utilizing a phase change material to store and release heat
Implementation Method 4
separation is driven by a phase change that occurs on the surface of a hydrophobic polymer separation membrane, allowing vapor to pass through micropores on the separation membrane surface to condense
Data Source
AI summary
The present disclosure to an apparatus for membrane distillation using a solar absorber and a heat pump, in which in the implementation of a membrane distillation process for producing treated water using a temperature difference between raw water and a coolant, raw water is heated using the solar absorber with improved heat collection efficiency, and through this, the treated water production efficiency of the membrane distillation process is improved.