Bubble Column HDH Desalination Vacuum Operation
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Solution Overview
Problem
Humidification-dehumidification (HDH) desalination systems face inefficiencies due to high energy consumption and low heat and mass transfer rates, primarily attributed to the presence of non-condensable gases, which reduce the effectiveness of surface condensers and require large amounts of energy for operation.
Innovation Solution
The implementation of a desalination system comprising a vessel with both a humidification region and a dehumidification region, utilizing a bubble column design that incorporates gas bubbles for enhanced heat and mass transfer, and includes features like vapor distribution regions and liquid flow control weirs, reducing the need for separate humidifiers and dehumidifiers, thereby minimizing ducting and piping requirements and increasing thermodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a carrier gas is used in HDH systems, then the humidification and dehumidification processes can be carried out, but the presence of non-condensable gas leads to low heat and mass transfer rates
Solution Approach 1:
The patent changes the physical parameters of the system by operating at reduced pressure (vacuum conditions), which fundamentally alters the behavior of non-condensable gases. At reduced pressure, the partial pressure of non-condensable gases is lowered, reducing their resistance to vapor condensation and improving heat and mass transfer rates despite their presence in the system.
Solution Approach 2:
The system employs periodic operation cycles where the vacuum pump operates intermittently to maintain reduced pressure conditions. This periodic action allows the system to achieve high transfer rates during operation while managing the accumulation and removal of non-condensable gases through the vacuum system.
2Productivity
If non-condensable gas is present in the dehumidifier, then the humidification process can proceed, but thermal resistance to vapor condensation increases
Solution Approach 1:
By changing the operating pressure parameter to reduced pressure conditions, the patent reduces the thermal resistance caused by non-condensable gases. The lower partial pressure of non-condensable gases at vacuum conditions decreases their interference with vapor condensation on cold surfaces, thereby improving condensation effectiveness.
Solution Approach 2:
The vacuum pump continuously extracts and removes non-condensable gases from the system, particularly from the dehumidifier where they cause thermal resistance. This extraction process maintains low concentrations of non-condensable gases in the condensation zone, preserving high vapor condensation effectiveness.
3Productivity
If conventional HDH systems are used, then desalination can be achieved, but relatively large amounts of energy are required
Solution Approach 1:
The patent changes the operating pressure from atmospheric to reduced pressure conditions, which improves the thermodynamic efficiency of the humidification-dehumidification process. The pressure reduction enhances the temperature difference driving force for heat transfer and improves vapor condensation efficiency, thereby reducing the energy required per unit of fresh water produced.
Solution Approach 2:
The system integrates the vacuum pump function with the dehumidifier operation, combining gas removal with the condensation process. This merging of functions allows the vacuum system to serve dual purposes: maintaining reduced pressure for improved transfer rates and removing non-condensable gases that would otherwise increase thermal resistance and energy consumption.
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 enhances thermodynamic efficiency, reduces energy consumption, and increases heat and mass transfer rates, allowing for the production of pure water with a lower footprint and reduced material usage, making the system more cost-effective and easier to deploy in industrial settings.
Implementation Method 1
utilizing a bubble column design that incorporates gas bubbles for enhanced heat and mass transfer
Implementation Method 2
The heated and humidified gas is then brought into contact with cold water in a dehumidifier, thereby producing pure water
Implementation Method 3
contacting a saline solution with a carrier gas in a humidifier, such that the carrier gas becomes heated and humidified
Data Source
AI summary
Embodiments described herein generally relate to humidification-dehumidification desalination systems, including apparatuses that include a vessel comprising a humidification region (e.g., a bubble column humidification region) and a dehumidification region (e.g., a bubble column dehumidification region), mobile humidification-dehumidification (HDH) desalination systems (e.g., systems having a relatively low height and/or a relatively small footprint), and associated systems and methods. Certain embodiments generally relate to methods of operating, controlling, and/or cleaning desalination systems comprising a plurality of desalination units (e.g., HDH desalination units).