Electric Trailer Refrigeration with Multi-Source Power Switching
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Solution Overview
Problem
Current trailer refrigeration systems rely on fossil fuels, are inefficient when the tractor is not connected, and struggle to maintain temperature during long periods of inactivity, leading to potential cargo spoilage and excessive fuel consumption.
Innovation Solution
An energy-efficient electric trailer refrigeration unit system powered by multiple sources, including a battery pack, photovoltaic cells, and an auxiliary power source, with intelligent power management and variable speed motors to optimize energy use and maintain temperature without fossil fuels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a diesel engine generator is used to power the refrigeration unit, then the trailer can be refrigerated during transport, but the system consumes excessive fuel and produces exhaust emissions
Solution Approach 1:
The refrigeration power system is segmented into multiple independent power sources: a diesel generator for transport mode, a battery pack for parked mode, and photovoltaic panels for supplemental charging. This segmentation allows the system to operate without the diesel generator during parking, eliminating fuel consumption and exhaust emissions while maintaining refrigeration capability.
Solution Approach 2:
The refrigeration unit is designed with multi-functionality to accept power from multiple sources (diesel generator, battery pack, or photovoltaic panels) depending on the operational mode. This universal power acceptance capability allows the system to eliminate fossil fuel consumption during parking while maintaining continuous refrigeration functionality.
2Loss of energy
If the diesel generator is turned off during parking, then fuel consumption is reduced, but the trailer temperature rises above desired levels
Solution Approach 1:
The mechanical diesel generator system is replaced with an electrical power system consisting of a battery pack and photovoltaic panels during parking operations. This substitution eliminates the need for fossil fuel combustion while providing sufficient electrical power to maintain the refrigeration unit's operation and keep the trailer at desired temperatures.
Solution Approach 2:
The battery pack is pre-charged using photovoltaic panels during daylight hours before parking begins. This preliminary charging action ensures that sufficient electrical energy is stored in the battery to power the refrigeration unit throughout the entire parking duration, preventing temperature rise without requiring diesel fuel.
3Productivity
If the trailer is parked for long periods without the tractor connected, then transport efficiency is improved, but the refrigeration system cannot maintain temperature without external power
Solution Approach 1:
The trailer is equipped with self-service power capabilities through an integrated battery pack and photovoltaic panel system that can independently power the refrigeration unit during parking without requiring connection to the tractor or external power sources. This self-service capability allows the trailer to maintain refrigeration autonomously during extended parking periods, improving turnaround efficiency while ensuring temperature maintenance.
Solution Approach 2:
The power system dynamically adapts to different operational states: during transport, the diesel generator powers the refrigeration unit; during parking, the battery pack takes over; and during daylight parking, photovoltaic panels supplement charging. This dynamic power source selection enables the system to maintain temperature reliably during extended parking while maximizing productivity.
4Device complexity
If a single motor is used for the refrigeration unit, then the system is simpler, but it cannot optimize power distribution between compressor and air moving device
Solution Approach 1:
The single motor system is segmented into two independent motors: a compressor motor and an air moving device motor. This segmentation allows each motor to be independently controlled and optimized for its specific function, enabling precise power distribution that maximizes overall system efficiency while maintaining manageable complexity through modular design.
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
The system effectively maintains trailer temperature for extended periods without fossil fuels, reducing energy consumption and emissions, and allows for efficient operation when the tractor is not connected, ensuring cargo safety and improving refrigeration efficiency.
Implementation Method 1
A battery pack may receive a charging power from an auxiliary power source such as an electrical generator, fuel cell, shore power or an outlet, or a photovoltaic cell
Implementation Method 2
A battery pack may receive a charging power from an auxiliary power source such as an electrical generator, fuel cell, shore power or an outlet, or a photovoltaic cell
Implementation Method 3
A battery pack may receive a charging power from an auxiliary power source such as an electrical generator, fuel cell, shore power or an outlet, or a photovoltaic cell
Implementation Method 4
The compressor motor and an air moving device motor can be operated at a power level that is required
Implementation Method 5
The compressor motor and an air moving device motor can be operated at a power level that is required
Data Source
AI summary
A trailer refrigeration system incorporates a trailer refrigeration unit that is powered by multiple sources including a generator coupled to the truck, photovoltaic cells and a battery pack. The trailer refrigeration unit may be a conventional refrigerator having a compressor, an evaporator and a compressible refrigerant. The refrigeration unit may be powered by one or more electric motors, such as an axial flux or transverse flux motor that has high efficiency, high torque at low revolutions per minute (RPM). The refrigeration unit is powered at least in part by the generator when the truck is running below a threshold power level and may be powered by the battery pack and/or photovoltaic cells when the truck engine is not running or running above a threshold power level. A power management system including the battery management system is used to control the flow of power to the refrigeration unit and to and from the battery pack.