Device and method for controlling operation of transport refrigeration unit
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Solution Overview
Problem
Transport refrigeration systems with only two operation modes (low speed and high speed) cannot optimize fuel consumption in real-world applications, leading to inefficient engine operation and high fuel usage, especially when rapid temperature changes are required or when maintaining a setpoint temperature for extended periods.
Innovation Solution
A controller device with a processor and non-transitory computer-readable medium that regulates the compressor of a transport refrigeration unit to operate in a continuously-variable speed mode, allowing for smooth gradient range of speed variations, enabling the compressor to run continuously at varying speeds beyond the traditional discrete low and high speed modes, and allowing the engine to operate at continuously variable speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the compressor operates in discrete low speed and high speed modes only, then the device complexity is reduced, but the fuel consumption cannot be optimized in real-world applications
Solution Approach 1:
The patent applies dynamics by transitioning the compressor from static discrete speed modes to dynamic continuous variable speed operation. The controller continuously adjusts the compressor speed based on real-time temperature differential calculations, enabling the system to adapt optimally to changing thermal conditions rather than being constrained to fixed speed steps.
Solution Approach 2:
The patent implements parameter changes by modifying the compressor speed parameter from discrete values to continuous variable values. The controller calculates the temperature differential between cargo and setpoint and dynamically adjusts the compressor speed proportionally, allowing precise optimization of fuel consumption across the full range of operating conditions.
2Use of energy by moving object
If the engine operates at the lowest possible speed, then fuel consumption is optimized, but the temperature inside the TU takes a very long time to reach the setpoint temperature
Solution Approach 1:
The system dynamically adjusts engine and compressor speed based on the thermal state of the cargo. During pull-down or pull-up situations when the temperature differential is large, the system automatically increases speed to provide rapid cooling or heating. When the setpoint is approached, the system smoothly transitions to lower speeds for efficient maintenance, optimizing both response time and fuel consumption.
Solution Approach 2:
The controller performs preliminary calculation of the temperature differential between current cargo temperature and setpoint temperature. Based on this pre-calculated differential, the system proactively adjusts the compressor and engine speed to the appropriate level before the thermal condition changes, ensuring optimal performance throughout the temperature control process.
3Productivity
If the engine operates at the highest possible speed to bring temperature to setpoint quickly, then the temperature control speed is improved, but fuel consumption becomes very poor
Solution Approach 1:
The system dynamically modulates engine and compressor speed based on the magnitude of the temperature differential. During rapid pull-down or pull-up phases when the differential is large, high speed operation is justified for quick temperature correction. As the setpoint approaches and the differential decreases, the system automatically reduces speed to minimize fuel consumption during the maintenance phase.
Solution Approach 2:
The controller pre-calculates the temperature differential and uses this information to determine the optimal engine speed before operation begins. This preliminary assessment allows the system to apply the minimum necessary power to achieve the required temperature change rate, avoiding unnecessary high-speed operation and associated fuel waste.
4Adaptability or versatility
If the compressor switches between two discrete speed modes frequently, then the temperature control adaptability is improved, but the engine operation hours increase reducing resale value
Solution Approach 1:
The system replaces discrete speed switching with continuous variable speed modulation. Instead of abruptly transitioning between fixed speed modes, the controller smoothly adjusts the compressor and engine speed in proportion to the temperature differential. This continuous adjustment maintains temperature control adaptability while significantly reducing the frequency of operational changes and extending engine life.
Data Source
AI summary
A transport refrigeration unit and a method for controlling the transport refrigeration unit, wherein the transport refrigeration unit has a controller device for operating a compressor of the transport refrigeration unit with a continuously-variable speed, which allows the compressor to run continuously but with a smooth gradient range of speed variations. The controller device allows the transport refrigeration unit to have a start-stop operation stage, continuous run operation stage, and/or a cycle-sentry operation stage.