Solar-Assisted Membrane Distillation Using Air Conditioner Waste Heat
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Solution Overview
Problem
Air conditioning systems generate significant waste thermal energy, which contributes to the 'Urban Temperature Island' phenomenon and increases cooling costs, while also discarding valuable water vapor as waste in evaporators, necessitating a cost-effective method to capture and reuse this energy for water purification.
Innovation Solution
An apparatus integrating a vapor compression air conditioning system with a membrane distillation cell and a photovoltaic solar collector, where waste heat from the air conditioner is reused to heat water, which is then circulated through a membrane distillation system to produce distilled water, leveraging the temperature difference across a membrane for efficient water purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air conditioning systems reject heat to the atmosphere, then cooling function is achieved, but waste thermal energy is lost and urban temperature increases
Solution Approach 1:
The patent converts the harmful waste heat rejected by air conditioner condensers into a beneficial resource by directing it to heat feed water for membrane distillation desalination, thereby eliminating energy waste and enabling fresh water production
Solution Approach 2:
The patent merges the air conditioning system with the membrane distillation desalination system by coupling the condenser outlet to the heat exchanger inlet, creating an integrated system that simultaneously provides cooling and fresh water production
2Use of energy by moving object
If membrane distillation uses only solar heating, then renewable energy is utilized, but heating temperature is insufficient for efficient distillation
Solution Approach 1:
The patent combines solar heating with waste heat recovery from air conditioners in a hybrid thermal system, where solar collectors preheat feed water and waste heat from condensers provides additional heating to achieve temperatures suitable for membrane distillation
3Ease of operation
If air conditioners operate in hot regions, then cooling demand is met, but performance decreases due to high ambient temperature
Solution Approach 1:
The patent converts the high ambient temperature that reduces air conditioner performance into a beneficial heat source, capturing waste heat from condensers to power membrane distillation desalination, thereby turning a performance-limiting factor into a resource
4Quantity of substance
If desalination processes are implemented, then fresh water is produced, but high energy consumption increases costs
Solution Approach 1:
The patent eliminates the need for high-energy desalination processes by using low-grade waste heat from air conditioners to drive membrane distillation, reducing energy consumption while maintaining fresh water production capability
Solution Approach 2:
The patent changes the thermal parameters by using low-temperature waste heat (typically 30-50°C) from air conditioners, which is sufficient for membrane distillation but would be inadequate for conventional thermal desalination methods
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 integrated system efficiently recycles waste thermal energy to drive water distillation, reducing energy consumption and costs, while providing a sustainable method for producing potable water in regions with high cooling demands and limited fresh water resources.
Implementation Method 1
an absorber plate configured to absorb solar radiation
Implementation Method 2
a transparent photovoltaic cell configured to generate electricity
Implementation Method 3
the heated fluid circulates to the hot channel where the heated fluid drives the distillation of water in the MD cell
Implementation Method 4
a membrane distillation (MD) cell including a cold channel, a hot channel, and a membrane
Implementation Method 5
a first heat exchanger including a first fluid input and a second fluid input; a second heat exchanger including a first fluid input and a second fluid input
Data Source
AI summary
An apparatus for water purification includes a membrane distillation (MD) cell; an air conditioner; a photovoltaic solar collector (PVSC) cell including a transparent photovoltaic cell configured to generate electricity, an absorber plate configured to absorb solar radiation, and a flow tube configured to receive the fluid; a first heat exchanger; a second heat exchanger; and a fluid source storing a fluid configured to circulate through the apparatus, wherein the fluid circulating in the apparatus carries heat generated by a condenser of the air conditioner to the PVSC cell where the fluid interacts with the PVSC cell to increase a temperature of the fluid to become a heated fluid; and the heated fluid circulates to the hot channel where the heated fluid drives the distillation of water in the MD cell.