Transport Refrigeration Capacity Control to Prevent Engine Stall
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional transport refrigeration systems face challenges in maintaining cooling performance while preventing engine stalls and overloads, especially under high ambient temperatures and high altitude conditions, due to the lack of real-time control over engine operating conditions.
Innovation Solution
A method is implemented to match the capacity output of the transport refrigeration unit with the available shaft power of the diesel engine by monitoring and adjusting the operating fuel rack position and engine speed, selectively limiting refrigerant mass flow, and using a suction modulation valve to control the compressor's capacity output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refrigeration unit operates at high cooling capacity demand, then the cooling performance is improved, but the engine shaft power demand exceeds available power causing engine stall or overload
Solution Approach 1:
The system implements closed-loop feedback control by continuously monitoring engine RPM and fuel rack position, then adjusting compressor capacity accordingly. The controller receives real-time engine operating data and modulates the compressor to maintain engine RPM within a predetermined range, preventing both stall and overload conditions while optimizing cooling capacity.
Solution Approach 2:
The system dynamically adjusts compressor capacity based on real-time engine operating conditions. By continuously varying the compressor capacity in response to changing engine load and RPM, the system adapts to different operating scenarios (high ambient temperature, high altitude, transient operations) to prevent engine stall while maintaining adequate cooling performance.
2Reliability
If conventional open loop control with safety margins is used, then engine overload is attempted to be prevented, but refrigeration performance is lost during transient operations and aggravated service conditions
Solution Approach 1:
The system replaces open-loop control with closed-loop feedback control that actively monitors engine RPM and fuel rack position. This feedback mechanism allows the system to respond to actual engine conditions in real-time, adjusting compressor capacity to prevent overload while maintaining optimal refrigeration performance during transient operations and aggravated service conditions.
Solution Approach 2:
The control system automatically adjusts compressor capacity based on real-time engine operating parameters without requiring external intervention. The system self-regulates by monitoring its own engine conditions and making appropriate capacity adjustments, eliminating the need for conservative fixed safety margins that would compromise refrigeration performance.
3Reliability
If larger engines are used to prevent engine stall under high cooling demand, then engine stall prevention is improved, but fuel economy deteriorates and device complexity increases
Solution Approach 1:
Instead of using a larger engine that would consume more fuel, the system dynamically adjusts compressor capacity to match available engine power. This dynamic capacity modulation allows a smaller, more fuel-efficient engine to prevent stall under high cooling demand by reducing compressor load when engine RPM approaches the stall threshold.
Solution Approach 2:
The system changes the operating parameters of the compressor (capacity, speed) in response to engine conditions. By modulating compressor capacity based on real-time engine RPM and fuel rack position, the system enables a smaller engine to operate efficiently across a wider range of conditions without stalling, thereby improving fuel economy.
Data Source
AI summary
The performance of a transport refrigeration system (12) having a transport refrigeration unit powered by a diesel engine is optimized by matching a capacity output of the transport refrigeration unit to an available shaft power of the diesel engine. The power consumption of the transport refrigeration may be controlled by selectively limiting refrigerant mass flow through the refrigerant circuit of the transport refrigeration unit in response to an operating engine load and an operating speed of the diesel engine.