Cold Storage Thermal Battery Control for Peak Energy Cost Reduction
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Solution Overview
Problem
Cold storage facilities face inefficiencies in refrigeration management due to varying heat intrusion rates and energy costs, leading to high operational costs and energy wastage, as traditional cooling systems are often toggled on and off intermittently, consuming more energy during peak demand hours.
Innovation Solution
Implementing a system that models cold storage facilities as thermal batteries, allowing them to be pre-cooled to a lower temperature during off-peak hours and then warmed by ambient temperatures during peak hours, thereby reducing energy consumption and shifting energy use to non-peak periods, using a control system with temperature sensors and an energy cost model to optimize refrigeration schedules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling systems are toggled on and off intermittently to maintain temperature, then temperature control is achieved, but energy consumption increases during peak demand hours
Solution Approach 1:
The system pre-cools the cold storage facility below the setpoint temperature during off-peak hours when energy costs are lower and heat intrusion is reduced. This preliminary cooling action stores thermal energy in the facility's thermal mass, allowing the refrigeration system to be reduced or shut off during peak demand periods while maintaining temperature within acceptable ranges.
2Stability of the object's composition
If refrigeration system runs continuously to maintain setpoint temperature, then temperature stability is improved, but operational costs increase
Solution Approach 1:
The system dynamically changes the target temperature parameter based on external conditions. During off-peak hours, the setpoint is lowered below the normal operating temperature to charge the thermal battery. During peak hours, the setpoint is relaxed to allow the facility to warm passively, reducing energy consumption while maintaining temperature stability within acceptable bounds.
Solution Approach 2:
The refrigeration system transitions from static continuous operation to dynamic variable operation. The system adjusts its running schedule based on heat intrusion forecasts, energy cost signals, and thermal model predictions, creating a dynamic control strategy that optimizes both temperature stability and operational costs.
3Temperature
If cooling is performed during peak demand hours to maintain temperature, then temperature requirements are met, but energy costs and environmental impact increase
Solution Approach 1:
The system performs preliminary cooling during off-peak hours to build up thermal energy storage in the facility structure and contents. This advance preparation reduces or eliminates the need for cooling during peak demand periods, thereby meeting temperature requirements while avoiding energy wastage associated with peak-hour operation.
Solution Approach 2:
The system converts the normally harmful effect of heat intrusion during off-peak hours into a beneficial charging opportunity. By allowing controlled heat gain during low-cost periods and using it to pre-charge the thermal battery, the system transforms what would be unwanted warming into a strategic advantage for reducing peak demand energy consumption.
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 approach reduces operational costs by minimizing peak energy consumption, extends the lifespan of refrigeration systems, and helps balance energy demand, thereby lowering overall energy wastage and environmental impact.
Implementation Method 1
Heat removal from a cold storage facility generally requires the consumption of power (e.g., electricity to drive refrigeration compressors)
Implementation Method 2
models of cold storage facilities, such as refrigerated warehouses, can be generated and used to determine the cooling strategies for more efficiently selecting times when and temperatures to which the cold storage facilities are cooled. Cold storage facilities can be modeled as thermal batteries that are capable of absorbing and storing thermal energy that can then be released over time
Implementation Method 3
Heat intrusion within a cold storage facility can come from many different sources, such as the environment (e.g., ambient air temperature, solar radiation)
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a method for time shifting when a cold storage facility is cooled that includes determining a thermal model of a cold storage facility, obtaining an energy cost model that describes a schedule of variable energy costs over a predetermined period of time in the future, determining an operational schedule for at least a portion of a refrigeration system based on the thermal model, the energy cost model, and a maximum allowed temperature, and powering on the portion the refrigeration system based on the operational schedule, cooling, by the powered portion of the refrigeration system to a temperature below the maximum allowed temperature, reducing power usage of the powered portion of the refrigeration system based on the operational schedule, and permitting the facility to be warmed by ambient temperatures toward the maximum allowed temperature.