Economized Scroll Compressor Control for Trailer Refrigeration Power Limits
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Solution Overview
Problem
Electrically powered truck trailer refrigeration units face challenges in efficiency due to electrical losses, leading to increased engine, generator, compressor, and fan sizing, which affects cost, fuel efficiency, emissions, and design space limitations, especially when requiring varying refrigeration capacities for different products.
Innovation Solution
The system incorporates an economized scroll compressor with an economizer circuit and a bypass circuit, along with a controller to selectively operate in economized, non-economized, or bypass modes based on refrigeration demand and available power, optimizing power usage and reducing the need for increased component sizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If component sizing is increased to compensate for electrical losses, then refrigeration capacity is improved, but engine horsepower and generator power requirements increase
Solution Approach 1:
The system changes the operating parameters of the compressor by implementing variable speed control, allowing the compressor to operate at optimal efficiency across different refrigeration loads. This prevents the need to oversize components to handle peak demands, thereby reducing the required engine horsepower and generator power while maintaining adequate refrigeration capacity.
Solution Approach 2:
The invention introduces dynamic operation capabilities through variable speed compressor control and electronic expansion valves that can adjust their operation in real-time based on actual refrigeration needs. This dynamic adjustment allows the system to match power consumption with actual refrigeration demand, eliminating the need for oversized static components.
2Productivity
If component sizing is increased to compensate for electrical losses, then refrigeration capacity is improved, but system cost increases
Solution Approach 1:
By changing the operational parameters through variable speed control and electronic regulation, the system achieves high refrigeration capacity without requiring physically larger components. This parameter-based optimization allows the use of smaller, less expensive components that are controlled more precisely, thereby reducing overall system cost while maintaining or improving refrigeration capacity.
3Productivity
If component sizing is increased to compensate for electrical losses, then refrigeration capacity is improved, but design space requirements increase
Solution Approach 1:
The system uses parameter changes including variable speed operation and electronic control to achieve high refrigeration capacity from smaller components. This allows the refrigeration unit to fit within standard trailer designs and confined spaces without requiring increased design envelope, as the enhanced capacity comes from improved component efficiency rather than increased size.
4Productivity
If component sizing is increased to compensate for electrical losses, then refrigeration capacity is improved, but fuel efficiency decreases
Solution Approach 1:
The variable speed compressor and electronic control systems allow the refrigeration unit to dynamically adjust its power consumption to match actual refrigeration needs. This dynamic operation prevents the engine and generator from constantly operating at high power levels, thereby improving fuel efficiency while maintaining adequate refrigeration capacity throughout the transport cycle.
Solution Approach 2:
By changing operational parameters such as compressor speed and valve positioning, the system optimizes the ratio of refrigeration capacity to power consumption. This parameter optimization ensures that the refrigeration unit delivers required cooling performance while minimizing the power demand on the engine-generator system, thereby improving overall fuel efficiency.
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 engine horsepower and generator power requirements, improves fuel efficiency, and increases design space by optimizing refrigeration system performance, allowing for efficient operation across a range of refrigeration demands while minimizing emissions.
Implementation Method 1
The economizer circuit is operatively associated with the economized scroll compressor and in refrigerant flow communication with the intermediate compression stage injection port of the economized scroll compressor
Implementation Method 2
The economized scroll compressor has a discharge port, a suction port, an intermediate pressure stage injection port, and an electric drive motor
Implementation Method 3
The condenser heat exchanger unit has a refrigerant inlet coupled in refrigerant flow communication with the discharge port of the compressor, a refrigerant outlet
Implementation Method 4
The evaporator heat exchanger unit has a refrigerant outlet coupled in refrigerant flow communication with the suction port of the compressor, a refrigerant inlet coupled in refrigerant flow communication with the refrigerant outlet of the condenser heat exchanger
Implementation Method 5
an evaporator expansion device, and an evaporator heat exchange unit connected via appropriate refrigerant lines in a closed refrigerant circuit
Data Source
AI summary
The refrigeration unit of an electrically powered trailer refrigeration system includes an economized scroll compressor and an economizer circuit selectively operable to inject refrigeration vapor into an intermediate stage of the scroll compressor. An engine driven generator produces AC current to power the scroll compressor and other electric components of the system. During operation of the refrigeration system at high capacity demand, a controller will operate the refrigeration system in an economized mode if sufficient electric power is available from the generator and in the non-economized mode if insufficient power is available to sustain operation of the refrigeration system in the economized mode.