Multi-Stage Bubble-Column Condenser for Desalination Energy Recovery

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Solution Overview

Problem

Current seawater desalination technologies are energy- and capital-intensive, with high energy costs due to inefficiencies in heat transfer and energy recovery, particularly due to the presence of incondensable gases which increase thermal resistance and reduce heat-transfer coefficients.

Innovation Solution

A multi-stage bubble-column vapor mixture condenser is used in a humidification-dehumidification system, where a carrier gas is bubbled through a condensing bath in multiple stages, enhancing heat transfer and energy recovery, and reducing energy and equipment costs by maintaining high heat-transfer coefficients and allowing for multi-extraction heat recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If thermal-energy-based multi-stage flash (MSF) distillation or multi-effect distillation (MED) is used, then desalination can be achieved, but energy consumption and capital costs increase significantly

Engineering Contradiction:

Improveenergy consumptionVSAvoiddesalination output

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The condenser is divided into multiple stages with each stage having a condensing bath at progressively lower temperatures. The carrier gas flows through multiple stages, transferring heat progressively from hot to cold baths, enabling multi-stage heat recovery that reduces overall energy consumption while maintaining high desalination output

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the temperature parameter progressively across multiple stages rather than using a single high-temperature process. Each stage operates at a different temperature level, allowing efficient heat transfer at each stage and reducing the total energy input required for the complete desalination process

Inventive Principle:

Principle #35Parameter changes

2Power

If direct-contact condenser is used to reduce thermal resistance, then heat transfer rates increase, but energy efficiency decreases due to loss of energy from humid air

Engineering Contradiction:

Improveheat transfer rateVSAvoidenergy efficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

Instead of discarding the energy contained in the humid air exiting the direct-contact condenser, the system recovers this energy by directing the humid air through multiple condensing stages. Each stage extracts additional heat from the carrier gas, recovering energy that would otherwise be lost and converting it into useful cooling for subsequent stages

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The carrier gas continues to transfer heat through multiple stages in sequence, maintaining continuous useful action. The heat transfer process is extended across multiple stages rather than occurring in a single stage, ensuring that the thermal energy is fully utilized throughout the entire process

Inventive Principle:

Principle #20Continuity of useful action

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 approach significantly reduces the overall cost of water production by achieving higher heat-transfer coefficients and energy recovery, making the process more efficient and cost-effective compared to existing methods.

Implementation Method 1

enhancing heat transfer and energy recovery

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

vapor mixture condensation

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

carrier gas is bubbled through a condensing bath

Methodology Applied

Scientific EffectBubble column mass transfer: Absorption (physical)

Implementation Method 4

multi-extraction heat recovery

Methodology Applied

Scientific EffectHeat recovery: Conduction (thermal)

Implementation Method 5

carrier gas is bubbled through a condensing bath in multiple stages

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS11007455B2Multi-stage bubble-column vapor mixture condensation

Publication Date: 2021.05.18 MASSACHUSETTS INST OF TECH

AI summary

A multi-stage bubble-column vapor mixture condenser comprises at least a first stage and a second stage. Each stage includes a carrier-gas inlet and a carrier-gas outlet, as well as a condenser chamber containing a condensing bath in fluid communication with the carrier-gas inlet and the carrier-gas outlet. The carrier-gas inlet is positioned to bubble carrier gas from the carrier-gas inlet up through the condensing bath, overcoming a hydrostatic head of the condensing bath. The carrier-gas outlet is positioned with an opening for carrier-gas extraction above the condensing bath, wherein the first-stage carrier-gas outlet is in fluid communication with the carrier-gas inlet of the second stage to facilitate flow of the carrier gas through the condensing bath in the condenser chamber of the first stage and then through the condensing bath in the condenser chamber of the second stage.