Methods, apparatus and systems for generating and superheating vapor under sunlight

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Solution Overview

Problem

Conventional solar vapor generators face challenges such as fouling due to contaminants in the liquid, limited vapor temperature to the boiling point of the liquid, and inefficiencies in vapor superheating, which complicates applications like sterilization and industrial processes.

Innovation Solution

A solar vapor generator design that uses an absorber and emitter in thermal communication to radiatively heat and vaporize a liquid, with the emitter physically separated from the liquid to reduce fouling and allow superheating of vapor above the boiling point without solar concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the absorber/emitter is placed in direct contact with the liquid for efficient heat transfer, then heat transfer efficiency is improved, but fouling of the absorber and emitter occurs due to contaminants in the liquid

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidfouling

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary medium (water or vapor) between the absorber/emitter and the liquid. The absorber/emitter heats the intermediary medium through radiation, which then transfers heat to the liquid, eliminating direct contact and preventing fouling while maintaining efficient heat transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct thermal conduction (mechanical contact-based heat transfer) with radiative heat transfer. The absorber/emitter uses electromagnetic radiation to heat the liquid or vapor without physical contact, substituting a non-contact mechanism to avoid fouling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by moving object

If the vapor temperature is limited to the boiling point of the liquid, then energy consumption is reduced, but the vapor cannot be used for applications requiring higher temperatures such as sterilization and industrial processes

Engineering Contradiction:

Improveenergy consumptionVSAvoidvapor temperature

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The patent continues the heating process beyond the phase change point. After the liquid vaporizes, the absorber/emitter continues to radiate heat to the vapor, superheating it above the boiling point. This continuous useful action allows the system to produce high-temperature vapor without requiring additional energy-intensive heating stages.

Inventive Principle:

Principle #20Continuity of useful action

3Temperature

If solar concentration is used to increase vapor temperature above the boiling point, then vapor temperature is improved, but device complexity and the need for specialized optical components increase

Engineering Contradiction:

Improvevapor temperatureVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The absorber/emitter material itself provides the necessary optical properties for both absorption and emission. The material is engineered to absorb solar radiation efficiently and emit thermal radiation at the desired wavelength, eliminating the need for separate optical concentration components and simplifying the overall system.

Inventive Principle:

Principle #25Self-service

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 design effectively reduces fouling, allows for vapor superheating above the boiling point, and enhances efficiency in applications like sterilization and industrial processes by utilizing radiative heating to produce high-temperature vapor without the need for solar concentration.

Implementation Method 1

The absorber absorbs incident sunlight, thus producing heat that is then transferred to the emitter via thermal conduction

Methodology Applied

Scientific EffectAbsorption of electromagnetic radiation: Absorption (EM radiation)

Implementation Method 2

heat that is then transferred to the emitter via thermal conduction

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

The emitter then emits the heat as thermal radiation to radiatively heat and vaporize a liquid

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 4

the liquid absorbs at least some of the thermal radiation close to the surface region of the liquid, and is thus vaporized, resulting in the generation of vapor

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS10976076B2Methods, apparatus and systems for generating and superheating vapor under sunlight

Publication Date: 2021.04.13 MASSACHUSETTS INST OF TECH

AI summary

A solar vapor generator includes an absorber to absorb sunlight and an emitter, in thermal communication with the absorber, to radiatively evaporate a liquid under less than 1 sun illumination and without pressurization. The emitter is physically separated from the liquid, substantially reducing fouling of the emitter. The absorber and the emitter may also be heated to temperatures higher than the boiling point of the liquid and may thus may be used to further superheat the vapor. Solar vapor generation can provide the basis for many sustainable desalination, sanitization, and process heating technologies.