Natural Gas Tank Pressure Sensing for Leak Detection in TRUs

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Solution Overview

Problem

Existing transport refrigeration systems face challenges in accurately measuring fuel quantities in individual tanks due to the use of a single pressure sensor that averages the combined pressure of multiple fuel tanks, making it difficult to detect fuel leaks or obstructions efficiently.

Innovation Solution

The system employs a dedicated pressure sensor on each fuel tank, connected to an engine controller, which adjusts the lock-off valves in response to pressure levels, allowing for precise monitoring and detection of fuel leaks or obstructions in both the refrigeration unit's fuel tanks and the vehicle's fuel tanks, using compressed natural gas or liquefied natural gas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single pressure sensor is used to monitor multiple fuel tanks, then the device complexity is reduced, but the measurement precision of fuel quantity in each individual tank deteriorates

Engineering Contradiction:
Improvenumber of pressure sensorsVSAvoidfuel quantity measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the monitoring system into separate segments, with each fuel tank having its own dedicated pressure sensor. This segmentation allows each sensor to independently monitor its specific tank, eliminating the averaging effect that occurs with a single shared sensor and thereby improving measurement precision for each individual tank.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single pressure sensor averages combined pressure of multiple fuel tanks, then the device complexity is reduced, but the reliability of detecting fuel leaks or obstructions deteriorates

Engineering Contradiction:
Improvepressure sensor configurationVSAvoidleak and obstruction detection capability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

By assigning a dedicated pressure sensor to each fuel tank, the system can independently detect pressure changes in each tank. This enables reliable identification of leaks or obstructions in specific tanks, as the controller can compare pressure readings from individual tanks against expected values and trigger alerts for anomalies.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements feedback control by continuously monitoring pressure readings from each tank's sensor and comparing them against predetermined thresholds. When a pressure deviation indicates a potential leak or obstruction, the controller receives feedback and can trigger appropriate responses, improving the reliability of detection.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If dedicated pressure sensors are installed on each fuel tank, then the measurement precision of fuel quantity improves, but the device complexity increases

Engineering Contradiction:
Improveindividual tank pressure measurement accuracyVSAvoidnumber of pressure sensors and control systems
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The controller is designed as a universal multi-functional device that handles monitoring, measurement, and control functions for all fuel tanks through a standardized interface. Each pressure sensor and lock-off valve follows a uniform communication protocol, allowing the single controller to manage multiple tanks efficiently, thereby mitigating the increase in device complexity through standardization and multi-functionality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables accurate monitoring of fuel levels, prevents overfilling, quickly identifies blockages or leaks, and ensures efficient fuel distribution, improving the reliability and efficiency of the refrigeration system by allowing for precise control of fuel flow to each engine.

Implementation Method 1

each of the plurality of first fuel tanks includes a lock off valve and a pressure sensor configured to detect a pressure level within each of the first fuel tanks

Methodology Applied
Scientific EffectPressure detection:

Data Source

PatentEP3669063B1Natural gas tank pressure control for transport refrigeration unit
Publication Date: 2021.10.20 CARRIER CORP
  • EP3669063B1 patent drawingFigure 1
  • EP3669063B1 patent drawingFigure 2
  • EP3669063B1 patent drawingFigure 3

AI summary

A transport refrigeration system (200) comprising: a vehicle (102) having a refrigerated cargo space (119); a refrigeration unit (22) in operative association with the refrigerated cargo space, the refrigeration unit providing conditioned air to the refrigerated cargo space; a first engine (26) configured to power the refrigeration unit; a plurality of first fuel tanks (330) fluidly connected to the first engine, the plurality of first fuel tanks configured to supply fuel to the first engine, wherein each of the plurality of first fuel tanks includes a lock off valve (450) and a pressure sensor (470) configured to detect a pressure level within each of the first fuel tanks; and one or more engine controllers (54) in electronic communication with each pressure sensor and lock off valve, the one or more engine controllers being configured to adjust at least one of the lock off valves in response to a pressure level detected by at least one of the pressure sensors.