Condenser Fan Power Control Using Back-EMF Airflow Detection
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Solution Overview
Problem
Existing transport refrigeration units (TRUs) face challenges in reducing power consumption, particularly with condenser fans that continue to operate when airflow is sufficient, leading to unnecessary energy usage.
Innovation Solution
Implementing a control system that disconnects power to the condenser fan when airflow exceeds a predetermined lower limit volume flow rate, using back emf voltage detection and GPS data to determine airflow requirements, thereby optimizing fan operation based on actual airflow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the condenser fan operates continuously to ensure sufficient airflow over the condenser, then the cooling performance is maintained, but the power consumption increases unnecessarily
Solution Approach 1:
The condenser fan operation is made dynamic rather than static. The controller continuously monitors airflow conditions and adjusts fan operation accordingly - operating the fan only when airflow is insufficient and stopping it when airflow is adequate. This dynamic control resolves the contradiction by adapting fan operation to actual cooling needs rather than maintaining continuous operation.
Solution Approach 2:
The system implements feedback control by detecting airflow conditions (through various sensors measuring parameters like RPM, temperature differential, or pressure differential) and using this information to control fan operation. The controller receives feedback about actual airflow over the condenser and adjusts fan status to maintain adequate cooling while minimizing power consumption.
2Use of energy by moving object
If the condenser fan is stopped to reduce power consumption, then energy efficiency improves, but the airflow over the condenser may become insufficient
Solution Approach 1:
The feedback mechanism ensures cooling reliability is maintained while enabling power savings. The controller continuously monitors airflow parameters and only stops the fan when it detects that airflow is sufficient to meet cooling demands. This feedback loop guarantees that the fan will restart if cooling requirements increase, thus maintaining reliability while achieving energy efficiency.
Solution Approach 2:
The system uses environmental conditions (ambient airflow, vehicle motion, wind) to supplement or replace fan-provided airflow. When sufficient natural airflow is detected, the system relies on this self-service airflow source, eliminating the need for fan operation and reducing power consumption while maintaining adequate cooling.
3Use of energy by moving object
If a control system is implemented to optimize fan operation based on airflow detection, then power consumption is reduced, but the device complexity increases
Solution Approach 1:
The controller serves multiple functions: it monitors airflow parameters, determines fan operation status, controls fan power, and integrates with the existing TRU control system. By making the controller multi-functional rather than adding a separate dedicated control device, the patent reduces overall system complexity while achieving intelligent fan control and power savings.
Solution Approach 2:
The fan control functionality is merged with the existing TRU controller rather than being implemented as a separate standalone system. This consolidation combines multiple control functions into a single device, reducing the number of components and simplifying the overall control architecture while maintaining the ability to optimize fan operation based on airflow conditions.
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
Reduces power consumption by ensuring the condenser fan operates only when necessary, thus enhancing energy efficiency in TRUs.
Implementation Method 1
detecting a fan voltage produced by back emf of the condenser fan
Data Source
AI summary
A method for controlling power to a condenser fan of a transport refrigeration unit (TRU) includes disconnecting power to the condenser fan; detecting a fan voltage produced by back emf of the condenser fan; obtaining an input volume flow rate corresponding to airflow over a condenser in response to the fan voltage; comparing the input volume flow rate to a lower limit volume flow rate; disconnecting power to the condenser fan when the input volume flow rate is greater than the lower limit volume flow rate.