Radiosonde Humidity Sensor Icing Prevention via Periodic Heating

Solution Overview

Problem

Radiosondes face errors in humidity measurements due to icing of sensors, especially in varying temperature and humidity conditions, with existing heating methods either reducing sensor sensitivity or increasing energy consumption.

Innovation Solution

A method for operating a sensor assembly with a humidity sensor, temperature sensor, and heating element, where the humidity sensor is temporarily heated when humidity is above a predetermined limit, specifically using the standard definition of relative humidity over ice to prevent icing without permanent heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the humidity sensor is continuously heated to prevent icing, then icing is prevented, but sensor sensitivity is reduced and measurement accuracy decreases

Engineering Contradiction:

Improveicing preventionVSAvoidhumidity measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The heating element operates periodically rather than continuously. The control unit activates heating only when specific conditions are met (temperature below freezing point and/or high humidity readings), and deactivates it when conditions are favorable. This periodic heating prevents icing while allowing the sensor to return to normal operating temperature for accurate measurements.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The heating strategy is dynamically adjusted based on real-time environmental conditions. The control unit monitors temperature and humidity readings, and adjusts heating activation accordingly - using temperature-based thresholds in freezing conditions and humidity-based thresholds in non-freezing conditions, optimizing both icing prevention and measurement accuracy.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the humidity sensor is continuously heated to prevent icing, then icing is prevented, but energy consumption increases

Engineering Contradiction:

Improveicing preventionVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The heating element operates periodically rather than continuously. The control unit activates heating only when specific conditions are met (temperature below freezing point and/or high humidity readings), and deactivates it when conditions are favorable. This periodic heating prevents icing while allowing the sensor to return to normal operating temperature for accurate measurements.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The heating strategy dynamically changes parameters based on environmental conditions. In freezing temperatures, heating activates at lower humidity thresholds; in non-freezing temperatures, heating activates only at high humidity thresholds. This adaptive parameter adjustment optimizes energy consumption while maintaining reliable icing prevention.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If heating is activated at the WMO humidity limit of 75%, then normal humidity measurements are satisfied, but icing occurs at very low temperatures before reaching this limit

Engineering Contradiction:

Improvehumidity measurement accuracyVSAvoidicing prevention

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The heating activation threshold dynamically changes based on temperature conditions. When the temperature sensor detects freezing temperatures, the control unit lowers the humidity threshold for heating activation below the standard 75% WMO limit. This ensures heating activates early enough to prevent icing in cold conditions while maintaining normal measurement operations in warmer conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The heating strategy is dynamically adjusted based on real-time environmental conditions. The control unit monitors temperature and humidity readings, and adjusts heating activation accordingly - using temperature-based thresholds in freezing conditions and humidity-based thresholds in non-freezing conditions, optimizing both icing prevention and measurement accuracy.

Inventive Principle:

Principle #15Dynamics

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 reliably prevents icing of the humidity sensor at low temperatures, maintaining measurement accuracy while minimizing energy consumption by only heating as needed.

Implementation Method 1

the humidity sensor is at least temporarily heated by the heating element

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11262477B2Method for operating a sensor assembly and sensor assembly suitable therefor

Publication Date: 2022.03.01 E E ELEKTRONIK GES

AI summary

A method is useable for operating a sensor assembly for determining relative humidity in radiosondes. The sensor assembly includes a humidity sensor, a temperature sensor and a heating element. It is determined whether humidity is at or above a predetermined humidity limit selected as the limiting humidity with respect to saturation over ice. The humidity sensor is heated, at least temporarily, wherein in a temperature range below 0° C., the humidity sensor is at least temporarily heated by the heating element based on it having been determined that the humidity is at or above the predetermined humidity limit.