HTF Leak Detection in Insulated Solar Thermal Loops Using NDIR

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Solution Overview

Problem

Concentrated Solar Power (CSP) plants face challenges in detecting heat transfer fluid (HTF) leaks at critical points like welds and joints, which are difficult to access and often go unnoticed until significant damage occurs, posing environmental and health risks due to the harmful nature of HTF.

Innovation Solution

A HTF leak detector device using Non-Dispersive Infra-Red (NDIR) gas detection, comprising a guiding conduit with a modulated IR radiation source and receiver, allows early detection of leaks by sensing the transmittance of HTF volatile components through infrared radiation, with optical filters to enhance sensitivity and a pump for gas penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If thermal insulation is used to protect thermal loops against thermal losses, then thermal efficiency is improved, but leak detection becomes difficult because leaks remain hidden inside insulation

Engineering Contradiction:
Improvethermal lossesVSAvoidleak detection
Core Design Contradiction:
Loss of energyVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces an intermediary detection system that senses HTF vapor or gas phase components diffusing through the insulation material. The sensor detects the presence of HTF vapor in the insulation layer, serving as a mediator between the hidden leak source and external detection, allowing leak identification without compromising the thermal insulation barrier.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If early leak detection is implemented, then plant shutdowns are reduced and economic losses are minimized, but device complexity increases due to need for sensitive detection systems

Engineering Contradiction:
Improveplant operation continuityVSAvoiddetection system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical inspection systems with optical or electrochemical sensors that detect HTF vapor through the insulation. This substitution uses field-based detection (optical/electrical) rather than mechanical access, simplifying the overall system while enabling continuous monitoring and early leak detection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If HTF leak is detected at late stage, then immediate repair is necessary to prevent environmental damage, but plant shutdown and revenue loss increase

Engineering Contradiction:
Improveenvironmental damageVSAvoidplant shutdown duration
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent implements preliminary detection by continuously monitoring for HTF vapor presence in the insulation layer before leaks progress to critical stages. This early warning system allows operators to schedule repairs during planned maintenance windows rather than experiencing unplanned shutdowns, preventing both environmental damage and revenue loss.

Inventive Principle:
Principle #10Preliminary 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

Enables early detection of HTF leaks, reducing plant shutdowns and environmental hazards by remotely alerting to leaks at critical points, ensuring timely repair and minimizing damage.

Implementation Method 1

A HTF leak detector device using Non-Dispersive Infra-Red (NDIR) gas detection, comprising a guiding conduit with a modulated IR radiation source and receiver, allows early detection of leaks by sensing the transmittance of HTF volatile components through infrared radiation

Methodology Applied
Scientific EffectNon-Dispersive Infra-Red (NDIR) gas detection: Absorption Spectroscopy

Implementation Method 2

with optical filters to enhance sensitivity

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentEP4703700A1A HTF leak detector device and method for detecting HTF leaks in a solar thermal installation
Publication Date: 2026.03.04 FUNDACION CENER
  • EP4703700A1 patent drawingFigure 1A
  • EP4703700A1 patent drawingFigure 1B
  • EP4703700A1 patent drawingFigure 2~3

AI summary

The present disclosure relates to the field of solar thermal installations and Thermal Transfer Fluid (HTF) leak detectors. Specifically, to an HTF leak detector for an early detection of an HTF leak. This HTF leak detector is installed in a thermally insulated component of a solar thermal installation, which is in communication with a central system to allow monitoring of the occurrence of leaks in various areas, mainly at critical points such as welds, moving parts and fixed joints.