Membrane Contactor Heat Exchange for Scale-Free Solvent Recovery
Solution Overview
Problem
Scale formation on evaporative cooler and heat exchanger surfaces in geothermal and low-grade waste heat driven power systems reduces efficiency due to mineral contamination, and the use of potable water is limited by scarcity and regulation.
Innovation Solution
A heat exchange system incorporating a membrane contactor that transfers heat energy between working fluids and extracts solvent from a second working fluid containing solutes, enhancing efficiency and potentially producing distilled water while minimizing scale formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potable water is used in evaporative coolers and heat exchangers, then scale formation is reduced, but water availability is limited due to scarcity and regulation
Solution Approach 1:
The patent introduces a membrane contactor as an intermediary device between the second working fluid (containing solutes) and the first working fluid. The membrane selectively extracts solvent from the second working fluid while blocking solutes, providing scale-free water for the cooling system without directly consuming potable water. This mediator approach resolves the contradiction by enabling access to purified water through a separation process rather than direct potable water usage.
Solution Approach 2:
The patent changes the physical-chemical parameters of the working fluids by implementing a two-fluid system with a membrane contactor. The first working fluid circulates through heat exchangers and the membrane contactor, while the second working fluid (with solutes) circulates through the evaporator and membrane contactor. This parameter change in fluid composition and circulation paths enables selective solvent extraction and prevents scale formation without relying on potable water availability.
2Temperature
If water evaporates on heat exchanger surfaces, then cooling is achieved, but scale forms on surfaces reducing efficiency
Solution Approach 1:
The patent extracts solutes from the second working fluid using the membrane contactor before the fluid reaches heat exchanger surfaces. By removing the contaminating solutes through selective membrane extraction, the system maintains cooling efficiency through evaporation while preventing scale formation on heat exchanger surfaces. This extraction approach directly addresses the contradiction by separating the beneficial cooling function from the harmful scale formation.
3Reliability
If membrane contactor extracts solvent from second working fluid, then distilled water is produced and scale formation is minimized, but system complexity increases
Solution Approach 1:
The membrane contactor serves multiple functions simultaneously: it extracts solvent from the second working fluid to produce distilled water, prevents scale formation by removing solutes, and enables the system to operate with non-potable water sources. This multi-functionality justifies the added device complexity by delivering multiple benefits from a single component, resolving the contradiction between reliability improvement and system complexity.
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 effectively transfers heat energy and extracts solvent, reducing pressure drop and scale formation, thereby improving the efficiency of the geothermal power system and producing distilled water, which can be used as potable water.
Implementation Method 1
The first heat exchanger and the membrane contactor transfer heat energy from the second working fluid to the first working fluid
Implementation Method 2
the second heat exchanger transfers heat energy from the first working fluid to a third working fluid
Implementation Method 3
The membrane contactor extracts a portion of the solvent from the second working fluid
Implementation Method 4
The water may evaporate into the air as the air passes through the cooler surface. Heat energy from the air may be absorbed by heat of vaporization of the evaporating water
Data Source
AI summary
A heat exchange system may include a first heat exchange circuit and a second heat exchange circuit. The first heat exchange circuit may circulate a first working fluid sequentially through a first heat exchanger, a second heat exchanger and a membrane contactor. The second heat exchange circuit may direct a second working fluid sequentially through the first heat exchanger and the membrane contactor, where the second working fluid includes solute and solvent. The first heat exchanger and the membrane contactor may transfer heat energy from the second working fluid to the first working fluid, and the second heat exchanger may transfer heat energy from the first working fluid to a third working fluid. The membrane contactor may extract a portion of the solvent from the second working fluid.