Alternator-Driven Refrigeration With DC-DC Boost for Idle Cooling
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Solution Overview
Problem
Existing refrigeration systems in commercial cargo vehicles face limitations in cooling capacity when operating at low alternator voltage, particularly at engine idle, leading to insufficient cooling capacity to maintain desired setpoint temperatures under varying ambient and vehicle conditions.
Innovation Solution
The integration of DC-to-DC power converters, specifically solid state switched mode power supplies, between the alternator and the compressor, boosts the electric potential from 12 VDC to 48 VDC, enabling the use of higher-capacity compressors and fans, thereby increasing the refrigeration system's power capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a compressor is driven directly by the alternator at engine idle, then the refrigeration system can operate without shore power, but the cooling capacity is insufficient to maintain desired temperatures under varying conditions
Solution Approach 1:
A DC-to-DC power converter is introduced as an intermediary between the alternator and the compressor motor. The converter boosts the alternator's low-voltage output (at engine idle) to the higher voltage required by the compressor motor, enabling the compressor to operate at full capacity even when the alternator is running at low speed. This resolves the contradiction by allowing operational independence while maintaining sufficient cooling capacity.
Solution Approach 2:
The system changes the electrical parameters (voltage and current) between the alternator and compressor through the DC-to-DC converter. By dynamically adjusting voltage and current based on alternator output and compressor demand, the system maintains adequate cooling capacity across varying engine speeds and alternator outputs, resolving the power insufficiency at idle conditions.
2Power
If higher-capacity compressors are used to increase cooling capacity, then desired temperatures can be maintained under varying conditions, but the electric current draw from the alternator increases
Solution Approach 1:
The DC-to-DC converter dynamically adjusts electrical parameters by boosting voltage and reducing current draw from the alternator while delivering the higher power required by the compressor. This allows high-capacity compressors to operate without proportionally increasing the alternator's current burden, as the converter efficiently transforms the electrical characteristics to match both the compressor's power needs and the alternator's output capabilities.
3Loss of energy
If the alternator voltage is low at engine idle, then the vehicle can operate with the engine running at efficient speeds, but the refrigeration system cannot maintain desired setpoint temperatures
Solution Approach 1:
The DC-to-DC power converter serves as a mediator that decouples the alternator's low-voltage output at idle from the compressor's voltage requirements. This allows the engine to operate at efficient idle speeds while the converter ensures the compressor receives adequate voltage and power to maintain cargo space temperatures, resolving the contradiction between engine efficiency and refrigeration performance.
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 solution enhances the refrigeration system's ability to maintain desired temperatures across a broader range of conditions by increasing the compressor's power capacity, reducing electric current draw from the alternator, and improving operational efficiency, ensuring effective cooling even at low alternator output.
Implementation Method 1
The integration of DC-to-DC power converters, specifically solid state switched mode power supplies, between the alternator and the compressor, boosts the electric potential from 12 VDC to 48 VDC
Implementation Method 2
A compressor is mounted on the chassis and body assembly, located in the refrigerant path, and configured to pump refrigerant located in the refrigerant path so that the refrigerant flows through the refrigerant path
Implementation Method 3
A condenser is mounted in the chassis and body assembly and is located in the first refrigerant path... so that the condenser transfers heat to the first air from refrigerant in the refrigerant path
Implementation Method 4
An evaporator is mounted on the chassis and body assembly and located in the refrigerant path... so that the evaporator transfers heat from the second air to the refrigerant in the refrigerant path that moves through the evaporator
Implementation Method 5
A first fan is disposed on the chassis and body assembly with respect to the condenser to move first air in a first air flow across the condenser... A second fan is disposed on the chassis and body system with respect to the evaporator to move second air in a second air flow across the evaporator
Data Source
AI summary
A refrigerated cargo vehicle has a refrigerated enclosure and a refrigeration system that delivers a refrigerated air flow to the enclosure. The refrigeration system includes a compressor that has a voltage rating higher than the electric potential output of an alternator driven by an engine of the refrigerated cargo vehicle. A DC-to-DC power converter is disposed electrically between the alternator and the compressor so that the power converter receives electric current from the alternator at a first electric potential and outputs a second electric current to the compressor at a second electric potential higher than the first electric potential.