Mobile Refrigeration Generator Speed Control for Light Loads
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Solution Overview
Problem
In transport refrigeration systems, the standalone engine/generator set lacks communication with the refrigeration system, leading to inefficient fuel use due to oversized units operating at constant high speed, even during light load conditions, as there is no unified control system to adjust power delivery based on the refrigeration unit's operating characteristics.
Innovation Solution
A control system that senses current delivery to the refrigeration system, adjusts the generator speed based on current thresholds, and considers ambient temperature to prevent short cycling and transient operations, allowing the engine to operate at lower speeds during light loads while ensuring sufficient power is provided.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine/generator set operates at a single high speed at all times to ensure sufficient power delivery, then power availability is improved, but fuel efficiency deteriorates due to oversized units operating under light load conditions
Solution Approach 1:
The system dynamically adjusts engine speed between high and low speeds based on real-time monitoring of refrigeration system power consumption. The controller senses when the refrigeration system is operating under light load conditions and reduces engine speed accordingly, while maintaining high speed capability when high power is needed. This dynamic adaptation resolves the contradiction by making the engine operate at appropriate speeds rather than fixed high speed.
Solution Approach 2:
The invention changes the operating parameter (engine speed) based on the load conditions of the refrigeration system. By monitoring power consumption and adjusting engine speed between two distinct operating speeds, the system optimizes fuel efficiency while maintaining the ability to provide sufficient power when needed. This parameter adjustment directly addresses the fuel efficiency deterioration caused by continuous high-speed operation.
2Use of energy by moving object
If the engine speed is reduced to lower levels during light load conditions, then fuel efficiency is improved, but power delivery capability deteriorates if high load conditions occur
Solution Approach 1:
The system maintains dynamic adaptability by being able to switch between high and low engine speeds based on actual load conditions. The controller continuously monitors the refrigeration system's power needs and can rapidly transition from low speed (for fuel efficiency during light loads) to high speed (for power delivery during high load conditions). This dynamic capability ensures that reducing speed for fuel efficiency does not permanently compromise power delivery capability.
Solution Approach 2:
The invention implements a feedback control mechanism where the controller senses the power consumption of the refrigeration system and uses this information to determine appropriate engine speed adjustments. The feedback loop ensures that engine speed is reduced only when the refrigeration system indicates light load conditions, and can be increased when high power is required, thus maintaining power delivery capability while improving fuel efficiency during appropriate conditions.
3Power
If the engine/generator set operates at high speed continuously, then power availability is ensured, but the device complexity increases due to lack of communication between standalone engine/generator and refrigeration system
Solution Approach 1:
The invention introduces a controller as an intermediary device that establishes communication between the previously standalone engine/generator set and the refrigeration system. This controller senses power consumption signals from the refrigeration system and translates them into appropriate engine speed commands. By adding this intermediary communication layer, the system achieves coordinated operation and optimized power availability without excessive complexity, as the controller handles the intelligence required for efficient operation.
Data Source
AI summary
A current sensor is installed in a generator set to measure the current being delivered from the generator set to a refrigeration unit. A control is responsive to the current transformer to reduce the speed of the drive engine to a lower speed when the current being delivered to the refrigeration unit is determined to be below a predetermined higher level. Provision is made to override the system when the sensed current is determined to be transient caused or in the event that ambient temperature is determined to be above a predetermined temperature threshold.