Adaptive Power Engine Control for Transport Refrigeration Units
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Solution Overview
Problem
Transport refrigeration systems (TRS) face challenges in efficiently managing engine power to prevent engine drooping and stalling, particularly due to emission standards and varying load conditions, which can lead to audible issues and potential engine failure if not addressed promptly.
Innovation Solution
The system employs adaptive power engine control by determining real-time engine speed and compressor power errors, adjusting the electronic throttling valve to optimize refrigerant flow, and calculating a target compressor power to ensure maximum power utilization while preventing engine overload, using a compressor curve map to correlate suction and discharge pressures with engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If emission standards are met by using a smaller engine (25 horsepower or less), then compliance with governmental regulations is achieved, but the engine reaches its power limit quickly and may droop or stall
Solution Approach 1:
The system dynamically adjusts the engine load by controlling the electronic throttling valve in real-time based on engine speed deviations. When the engine approaches its power limit, the controller reduces the compressor load dynamically, preventing engine droop and stalling while maximizing the utilization of available engine power within emission constraints.
Solution Approach 2:
The controller continuously monitors engine speed and compares it to a target speed, using this feedback to calculate power errors and adjust the electronic throttling valve position. This closed-loop feedback system ensures the engine operates reliably within its power limits while maintaining optimal performance and preventing droop conditions.
2Productivity
If the engine operates at maximum power to meet cooling demands, then the TRS can provide sufficient cooling capacity, but the engine may droop or stall due to insufficient fuel supply
Solution Approach 1:
The system dynamically balances cooling demand with engine capacity by continuously adjusting the compressor load. The controller calculates the required cooling capacity and adjusts the electronic throttling valve to maintain the necessary cooling effect while preventing the engine from exceeding its sustainable power output, thus avoiding droop and stalling.
Solution Approach 2:
The system changes the operating parameters of the compressor by adjusting the electronic throttling valve position, which modifies the refrigerant flow and compressor load. This parameter adjustment allows the TRS to maintain adequate cooling capacity while operating the engine within its safe power limits.
3Adaptability or versatility
If the engine speed fluctuates rapidly to respond to changing loads, then the system can adapt to varying cooling demands, but audible engine drooping occurs and user comfort is reduced
Solution Approach 1:
The controller performs preliminary adjustments by detecting engine speed deviations before significant droop occurs. By calculating power errors based on speed deviations and proactively adjusting the electronic throttling valve, the system prevents rapid speed fluctuations and audible drooping, maintaining smooth engine operation while adapting to load changes.
Solution Approach 2:
The system uses dynamic control to smoothly adjust engine load in response to changing cooling demands. The controller calculates appropriate load adjustments based on engine speed feedback and gradually modifies the electronic throttling valve position, avoiding abrupt changes that would cause audible drooping while maintaining adaptability to varying loads.
4Power
If a larger engine (greater than 25 horsepower) is used to avoid power limits, then sufficient power is available, but the system violates emission standards
Solution Approach 1:
The system dynamically controls the engine operating point to maximize power utilization within emission constraints. By continuously adjusting the electronic throttling valve based on real-time engine speed feedback, the system extracts maximum useful work from the smaller engine without violating emission standards, effectively bridging the power gap that would otherwise require a larger engine.
Data Source
AI summary
A method for adaptive power engine control of a transport refrigeration unit (TRU) is provided. The method includes determining a current compressor power of a compressor of the TRU. The method also includes determining an adaptive compressor power error of the compressor. Also, the method includes calculating and setting a target compressor power of the compressor based on the current compressor power and the adaptive compressor power error. Further, the method includes determining a suction pressure control point of the compressor based on the target compressor power and a compressor curve map. Moreover, the method includes operating the compressor with the suction pressure control point of the compressor.