Transport Climate Control Trajectory Tracking for Timed Pulldown
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Solution Overview
Problem
Existing transport climate control systems face challenges in managing energy-efficient pulldown and pull-up operations due to uncertainties in completion time and energy savings, leading to unnecessary energy expenditure or delayed use of transport units.
Innovation Solution
Implementing timing-based control of pulldown and pull-up operations by controlling the temperature trajectory over time based on a model of the conditioned space and a given time parameter, using a controller to determine and adjust the operation of the climate control system to ensure timely and efficient temperature adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pulldown/pull-up operation is completed too early, then energy savings are achieved, but the transport unit cannot meet delivery schedules
Solution Approach 1:
The system dynamically adjusts the climate control system operation based on real-time trajectory prediction and actual temperature measurements. The controller continuously updates the pulldown/pull-up trajectory to ensure the target temperature is reached at the required time, adapting to varying thermal loads and environmental conditions while optimizing energy consumption.
Solution Approach 2:
The system uses feedback from temperature sensors to compare actual temperature against the predicted trajectory. When deviations are detected, the controller adjusts the climate control system operation to realign with the trajectory, ensuring timely completion of pulldown/pull-up operations while minimizing energy waste from premature completion or extended operation.
2Loss of energy
If the pulldown/pull-up operation is not completed on time, then energy consumption is reduced, but the transport unit use is delayed
Solution Approach 1:
The system performs preliminary thermal load calculations and predicts the pulldown/pull-up trajectory before initiating the operation. This allows the controller to pre-determine the optimal operation schedule and capacity settings needed to reach the target temperature by the required time, preventing delays and unnecessary energy consumption from trial-and-error adjustments.
Solution Approach 2:
The system changes operational parameters such as compressor capacity, fan speed, and thermostat setpoints dynamically during the pulldown/pull-up operation based on the predicted trajectory and actual temperature measurements. This allows optimization of energy consumption at different stages of the operation while ensuring the target temperature is reached on time.
3Speed
If maximum capacity operation is used, then the target temperature is reached faster, but energy consumption increases
Solution Approach 1:
The system uses periodic modulation of the climate control system capacity rather than continuous maximum operation. The controller cycles the compressor and adjusts fan speeds periodically according to the predicted thermal response, achieving the target temperature faster than steady-state operation would allow while significantly reducing peak energy consumption and thermal stress on the system.
Solution Approach 2:
The system applies partial capacity operation at different stages of the pulldown/pull-up process rather than continuous maximum capacity. High capacity is used initially to overcome thermal mass quickly, then capacity is reduced as the target temperature approaches, optimizing the balance between speed and energy consumption.
Data Source
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Figure 1B
Figure 1C
AI summary
Control systems for time-based pulldown and/or pull-up operation of transport climate control systems include a controller receiving a time for pulldown or pull-up, with the controller modeling the conditioned space and determining a trajectory (604,606) for efficiently completing the pulldown or pull-up according to the received time. The controller further operates the transport climate control system according to the determined trajectory. The controller can receive information from the conditioned space and adjust operations in order to bring the pulldown or pull-up closer to the determined trajectory. The model can be a dynamic model of the specific conditioned space in which the pulldown or pull-up is being performed. The controller can further determine when a pulldown or pull-up will be completed (610) and provide notifications based on whether the pulldown or pull-up can be completed by a particular time. The model can be updated based on system dynamics observed during pulldown or pull-up.