Transport Refrigeration Voltage Control for Faster Heat and Defrost
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Solution Overview
Problem
Conventional all-electric transport refrigeration systems operate the prime mover at only two speeds, leading to inefficient use of the heater during heating and defrost modes, as the heater can only operate at two voltages, resulting in longer periods of reduced cooling capacity.
Innovation Solution
A method and system where a controller dynamically adjusts the speed of the prime mover based on the voltage of the electric generation device, increasing the speed when the voltage is below a selected threshold to ensure the heater operates at its maximum heating voltage, thereby shortening heating and defrost modes and improving overall efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the prime mover operates at only two speeds, then the system structure is simple, but the heater operates inefficiently and cannot reach maximum heat output quickly
Solution Approach 1:
The patent applies dynamics by transitioning from fixed two-speed prime mover operation to continuous variable speed control. The controller dynamically adjusts the prime mover speed based on real-time voltage measurements from the electric generation device, enabling the heater to receive optimal power and reach maximum heat output quickly while maintaining simple system structure.
Solution Approach 2:
The patent changes the operational parameters of the prime mover from discrete two-speed settings to continuous variable speed control. By monitoring voltage output and adjusting speed accordingly, the system optimizes the heater's performance parameter (heat output) without adding complex hardware, resolving the contradiction between simplicity and efficiency.
2Device complexity
If the heater operates at two voltages only, then the control system is simple, but the duration of heating and defrost modes is prolonged
Solution Approach 1:
The patent implements feedback control by continuously monitoring the voltage output from the electric generation device and using this information to adjust the prime mover speed. This closed-loop feedback enables the heater to operate at optimal voltage levels, reaching maximum heat output faster and reducing heating and defrost mode duration while keeping the control system relatively simple.
Solution Approach 2:
The system transitions from static two-voltage heater operation to dynamic voltage control. The controller continuously adjusts the prime mover speed based on voltage feedback, enabling the heater to dynamically reach its maximum operating voltage and heat output, thereby reducing the time required for heating and defrost operations.
3Productivity
If the prime mover speed is increased to reach maximum voltage quickly, then heating efficiency improves, but fuel consumption increases
Solution Approach 1:
The patent applies partial action by increasing the prime mover speed only to the extent necessary to reach the selected voltage threshold, not continuously at maximum speed. The controller monitors voltage and adjusts speed proportionally, achieving maximum heating efficiency when needed while avoiding excessive fuel consumption during normal operation.
Solution Approach 2:
The system dynamically changes the prime mover speed parameter based on voltage requirements. Rather than maintaining high speed continuously, the controller adjusts speed to match the heating demand and voltage threshold, optimizing the balance between heating speed and fuel consumption by varying the operational parameter as needed.
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 enhances the efficiency of the heating and defrost processes by allowing the heater to reach its maximum heat output more quickly, reducing the duration of these modes and maintaining optimal cooling performance.
Implementation Method 1
a prime mover 26 for driving an electric generation device 24
Implementation Method 2
an electric resistance heater 48 which may be associated with the refrigerant heat absorption heat exchanger
Data Source
Figure 1
Figure 2
AI summary
A method of operating a transport refrigeration system comprises: controlling, using a controller (30), a plurality of components of the refrigeration system and monitoring, using the controller, a plurality of operating parameters of the refrigeration system. The controlling comprises operating at least one of a prime mover (26), heater (48), and electric generation device (24). The operating parameters comprise at least one of a speed of the prime mover and a voltage of the electric generation device. The method comprises detecting, using the controller, when at least one of a heating mode and a defrost mode is required; activating, using the controller, the heater when at least one of the heating mode and the defrost mode is required; comparing, using the controller, the voltage of the electric generation device to a selected voltage; and controlling, using the controller, the speed of the prime mover in response to the voltage of the electric generation device.