Absorption Refrigerator Tilt Control to Prevent Overheating Stress

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Solution Overview

Problem

Recreational vehicle (RV) refrigerators using gas absorption refrigeration systems are prone to overheating and potential system rupture due to unlevel operation, as the refrigerant flow is disrupted at angles greater than 5 degrees, leading to safety risks from hydrogen release.

Innovation Solution

An electronic control system that monitors the position angle of the RV refrigerator, using a sensor and processor to increment a stress counter based on inclination, limiting operation time at extreme angles to prevent system stress and rupture, and includes a user interface for diagnostic purposes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the refrigerator operates at angles greater than 5 degrees, then the refrigerator can be used in unlevel positions, but the refrigerant flow is disrupted causing overheating and system stress

Engineering Contradiction:

Improveoperation at unlevel positionsVSAvoidsystem stress and rupture risk

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The control system performs preliminary monitoring of the position angle before allowing operation to continue. The sensor detects tilt conditions and the controller preemptively limits operation time when extreme angles are detected, preventing system stress before it occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the position angle via the sensor and provides feedback to the controller, which adjusts the maximum allowable operation time based on the detected tilt angle. This closed-loop feedback ensures the refrigerator operates safely within stress limits while maximizing usable operation time

Inventive Principle:

Principle #23Feedback

2Reliability

If the refrigerator is leveled precisely, then the refrigerant flows properly through the system, but the refrigerator cannot operate in unlevel vehicle positions

Engineering Contradiction:

Improverefrigerant flow and cooling efficiencyVSAvoidoperation in vehicle positions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the maximum operation time parameter based on the detected position angle. When the refrigerator is level, full operation time is permitted. When tilted beyond 5 degrees, the controller dynamically reduces the maximum operation time in proportion to the angle of inclination, allowing flexible operation across varying vehicle positions while maintaining safety

Inventive Principle:

Principle #15Dynamics

3Reliability

If the maximum operation time is limited at extreme angles, then system stress is reduced, but the refrigerator operation is restricted

Engineering Contradiction:

Improvesystem stress preventionVSAvoidoperation time at extreme angles

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The controller changes the operational parameter (maximum operation time) based on the position angle parameter. As the tilt angle increases beyond 5 degrees, the maximum operation time parameter is reduced proportionally. This parameter adjustment resolves the contradiction by allowing operation at extreme angles for shorter durations, preventing system stress while maximizing usable operation time within safety limits

Inventive Principle:

Principle #35Parameter changes

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

Prevents overheating and system rupture by continuously monitoring and controlling the operation of RV refrigerators based on tilt angle, reducing the risk of hydrogen release and ensuring safe operation across varying positions.

Implementation Method 1

a sensor in communication with the controller for measuring the angle of inclination of the refrigerator

Methodology Applied

Scientific EffectAngle sensing:

Implementation Method 2

a heat source for heating a mixture of flowable refrigerant and absorbent

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 3

the flow downward through the absorber is slowed or stopped and refrigerant 'pools' in the lower portions of the absorber

Methodology Applied

Scientific EffectHeat absorption: Absorption (EM radiation)

Implementation Method 4

Gas absorption refrigerators are very sensitive to position angle

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS9228773B2Tilt monitor and stress controller for absorption type refrigerator

Publication Date: 2016.01.05 DOMETIC APPLIANCES

AI summary

An automated control device for monitoring the position angle of an absorption type cooling system or refrigerator that circulates a refrigerant, an absorbent, and a diffusion agent within a conduit system includes a housing, a controller with a processor within the housing, a sensor in communication with the controller for measuring the angle of inclination of the refrigerator, and a stress counter connected to the controller for counting increments of stress induced into the cooling system. The tilt monitoring control method prevents system stress, which in turn prevents personal and property damage due to hydrogen gas leaks, fires and explosions.