Bubble Column Condenser Staging for HDH Desalination
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Solution Overview
Problem
Existing desalination systems, such as those using humidification-dehumidification (HDH) processes, face inefficiencies due to the presence of non-condensable gases, which reduce heat and mass transfer rates and increase energy consumption in condensers.
Innovation Solution
The use of bubble column condensers with a configuration that includes a vessel with a liquid layer and a vapor distribution region, where gas bubbles transfer heat and mass to the liquid, enhancing condensation efficiency and reducing energy requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a carrier gas is used in HDH systems, then the humidification-dehumidification process can be implemented, but the presence of non-condensable gas reduces heat and mass transfer rates in the condenser
Solution Approach 1:
The condenser is divided into multiple stages with intermediate cooling sections. Each stage handles a portion of the condensation process, allowing heat and mass transfer to occur in segmented zones. This segmentation reduces the thermal resistance caused by non-condensable gases by creating multiple heat transfer pathways and reducing the thickness of the gas layer that must be traversed.
Solution Approach 2:
The invention introduces a vertical dimension to the condensation process by using a multi-stage columnar structure. Vapor rises through the condenser while cooling occurs at multiple elevation levels. This dimensional approach allows simultaneous heat and mass transfer at different heights, overcoming the limitation of horizontal single-stage condensers where non-condensable gases create uniform thermal resistance across the entire heat transfer surface.
2Adaptability or versatility
If a carrier gas is used in HDH systems, then the humidification-dehumidification process can be implemented, but the presence of non-condensable gas increases thermal resistance to condensation on cold surfaces
Solution Approach 1:
The condensation process is segmented into multiple stages with intermediate cooling sections. Each stage has its own heat transfer surface, reducing the overall thermal resistance by distributing the condensation load across multiple smaller surfaces rather than one large surface where non-condensable gases would create uniform resistance.
Solution Approach 2:
Cool spray water is introduced as an intermediary cooling medium between the vapor stream and the condenser walls. This spray water absorbs heat from the condensing vapor and cools the heat transfer surfaces, effectively reducing thermal resistance by creating a liquid-phase heat transfer pathway that bypasses the thermal barrier created by non-condensable gases.
3Productivity
If traditional condensers are used in HDH systems, then condensation can occur, but large amounts of energy are required to operate
Solution Approach 1:
Cool spray water is introduced preliminarily into the condenser to pre-cool the vapor stream before it reaches the main heat transfer surfaces. This preliminary cooling action reduces the temperature difference required for condensation, thereby reducing the energy consumption of the condenser while maintaining condensation capability.
Solution Approach 2:
The system uses periodic spraying of cool water into the condenser to maintain optimal heat transfer conditions. This periodic cooling action removes heat intermittently, allowing the condenser to operate more efficiently by preventing excessive heat buildup that would require continuous high-energy operation.
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 configuration improves heat and mass transfer rates, reduces energy consumption, and increases the effectiveness of desalination systems by effectively removing water vapor from gas streams, leading to more efficient water purification.
Implementation Method 1
gas bubbles transfer heat and mass to the liquid
Implementation Method 2
gas bubbles transfer heat and mass to the liquid
Implementation Method 3
enhancing condensation efficiency
Data Source
AI summary
Condensing apparatuses and their use in various heat and mass exchange systems are generally described. The condensing apparatuses, such as bubble column condensers, may employ a heat exchanger positioned external to the condensing vessel to remove heat from a bubble column condenser outlet stream to produce a heat exchanger outlet stream. In certain cases, the condensing apparatus may also include a cooling device positioned external to the vessel configured and positioned to remove heat from the heat exchanger outlet stream to produce a cooling device outlet stream. The condensing apparatus may be configured to include various internal features, such as a vapor distribution region and/or a plurality of liquid flow control weirs and/or chambers within the apparatus having an aspect ratio of at least 1.5. A condensing apparatus may be coupled with a humidifier to form part of a desalination system, in certain cases.