Multi-Compartment Refrigeration Control Under Limited Cooling Capacity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multiple compartment transport refrigeration systems face challenges in achieving precise temperature control, particularly in secondary compartments, and in apportioning cooling capacity effectively during startup and high load conditions, while also limiting electrical power consumption.
Innovation Solution
The system employs a common compressor and condenser with primary and secondary evaporators, using electronic suction modulation valves (ESMVs) for precise temperature control and a prioritization algorithm to manage cooling capacity between compartments, limiting refrigerant flow to non-priority compartments when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single compressor and two evaporators are used in a dual compartment system, then device complexity is reduced, but temperature control precision in the secondary compartment deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from static on/off control to dynamic continuous modulation of refrigerant flow. The secondary evaporator's refrigerant flow is continuously adjusted based on real-time temperature feedback, enabling precise temperature control despite using a single compressor system.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the secondary compartment temperature and using this information to modulate the refrigerant flow to the secondary evaporator. This closed-loop control system maintains temperature precision without requiring separate compressors for each compartment.
2Quantity of substance
If refrigerant flow to secondary compartment is cycled on and off, then cooling capacity is reduced, but temperature regulation precision deteriorates
Solution Approach 1:
The patent eliminates periodic on/off cycling and replaces it with continuous periodic modulation. The refrigerant flow is continuously adjusted in small increments rather than being cycled between fully on and fully off states, preventing temperature fluctuations and achieving precise regulation.
Solution Approach 2:
The system transitions from static binary control (on/off) to dynamic continuous control. The refrigerant flow to the secondary evaporator is continuously modulated based on temperature deviations, enabling precise temperature maintenance without the temperature swings caused by cycling.
3Reliability
If cooling capacity is increased to maintain all compartments at setpoint temperature, then electrical power consumption increases, but this may exceed circuit breaker limits
Solution Approach 1:
The patent applies partial action by providing just enough cooling capacity to maintain the primary compartment at its setpoint temperature, rather than allocating excessive cooling capacity to all compartments. The secondary compartment receives only the portion of cooling capacity needed after the primary compartment's requirements are satisfied, preventing electrical overload while maintaining reliability.
Solution Approach 2:
The patent segments the cooling capacity allocation into primary and secondary priorities. The single compressor's output is first dedicated to maintaining the primary compartment at its setpoint, with any remaining capacity then allocated to the secondary compartment. This segmentation ensures critical temperature maintenance while limiting total power consumption within circuit breaker limits.
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 allows for precise temperature regulation in both compartments, maintaining setpoint temperatures even under insufficient cooling capacity, and effectively manages electrical load to prevent overheating, ensuring the integrity of perishable goods during transport.
Implementation Method 1
a compressor to supply high pressure refrigerant vapor to a condenser
Implementation Method 2
the condenser to condense the high pressure vapor to a high pressure liquid
Implementation Method 3
a primary compartment evaporator to accept heat from the air in a primary compartment and to transfer the heat to a refrigerant circulated within the primary compartment evaporator
Data Source
AI summary
A refrigerated transport system includes a prioritizing algorithm to limit the maximum amount of refrigerant flow available to at least one limited cooling compartment by holding a delta T (difference between the supply air temperature and return air temperature) instead of a setpoint temperature in the at least one limited cooling compartment when the available cooling capacity is insufficient to hold a substantially constant temperature in all compartments. A method for creating multiple refrigerated compartment spaces having precision temperature control includes the steps of: prioritizing the compartments by identifying at least one priority compartment to be held at a setpoint temperature; and limiting refrigerant flow to all but the priority compartment when there is insufficient cooling capacity to maintain all compartments at their respective setpoint temperatures.