Direct-Absorption Receiver With Reflective Vessel for Lower Thermal Stress

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Solution Overview

Problem

Direct-absorption receivers for solar-thermal applications face issues with thermal stress, fluid degradation, and inefficient heat transfer due to temperature gradients between the absorber surface and the heat transfer fluid, leading to radiation losses and reduced efficiency.

Innovation Solution

A direct-absorption receiver design featuring a transparent containing member and a reflective inner surface, with an inlet for heat transfer fluid and an outlet, forming a vessel under hydrostatic pressure, optionally including flow spreaders and absorber members to manage temperature profiles and minimize radiation losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If concentrated sunlight strikes opaque absorber tubes containing heat transfer fluid, then heat absorption is achieved, but temperature gradients between the absorber surface and fluid cause thermal stress and fluid degradation

Engineering Contradiction:

Improveheat absorption efficiencyVSAvoidthermal stress and fluid degradation

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention extracts the absorber function from the tube wall and relocates it to the heat transfer fluid itself. The fluid contains suspended particles or droplets that directly absorb solar radiation, eliminating the temperature gradient between the absorber surface and bulk fluid. This resolves the contradiction by maintaining high heat absorption while preventing thermal stress and fluid degradation caused by extreme temperature differences.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an intermediary medium (suspended particles or droplets within the heat transfer fluid) that mediates the energy transfer from sunlight to the fluid. These intermediaries absorb radiation and distribute heat throughout the fluid volume, preventing direct contact between concentrated solar energy and the tube walls, thereby reducing thermal stress while maintaining efficient heat absorption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If absorber surface temperatures exceed ambient temperature, then heat transfer to fluid occurs, but radiation losses to ambient increase

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidradiation losses to ambient

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The invention changes the temperature distribution parameter within the system. Instead of creating a localized hot absorber surface, the suspended particles distribute heat throughout the entire fluid volume, creating a more uniform temperature profile. This reduces the temperature difference between the absorber and ambient environment, thereby minimizing radiative heat losses while maintaining effective heat transfer to the bulk fluid.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If temperature gradients exist between absorber and heat transfer fluid, then heat transfer drives the process, but inefficient heat transfer and fluid degradation occur

Engineering Contradiction:

Improveheat transfer driving forceVSAvoidheat transfer efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The invention extracts the heat absorption function from the tube walls and places it directly in the heat transfer fluid through suspended particles. This eliminates the intermediate heat transfer step across the tube wall, allowing sunlight to directly heat the fluid bulk. The result is both sufficient temperature gradient to drive heat transfer and high overall efficiency without fluid degradation.

Inventive Principle:

Principle #2Taking out (Extraction)

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 design achieves high efficiency by minimizing thermal stress, maintaining stable fluid flow, and reducing radiation losses, with temperature profiles optimized to maximize energy absorption and minimize emission, achieving efficiency rates of 93-96% with controlled heat transfer.

Implementation Method 1

a first containing member transparent to sunlight

Methodology Applied

Scientific EffectLight transmission: Refraction

Implementation Method 2

a second containing member comprising an inner surface reflective of sunlight

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

A direct-absorption receiver (DAR) for solar-thermal applications

Methodology Applied

Scientific EffectDirect radiation absorption: Absorption (EM radiation)

Implementation Method 4

form a vessel configured to conduct injected heat transfer fluid from the inlet to the outlet under hydrostatic pressure

Methodology Applied

Scientific EffectHydrostatic pressure: Pressure Gradient

Data Source

PatentUS8640689B1Direct-absorption receiver

Publication Date: 2014.02.04 SEPCOIII ELECTRIC POWER CONSTR CO LTD

AI summary

Embodiments provide a solar thermal receiver comprising: (a) a first containing member transparent to sunlight; (b) a second containing member comprising an inner surface reflective of sunlight; (c) an inlet proximate to the first containing member that is configured to receive injected heat transfer fluid; and (d) an outlet distal from the first containing member, where the first containing member and the second containing member together form a vessel configured to conduct injected heat transfer fluid from the inlet to the outlet under hydrostatic pressure.