Multi-Barrel Refrigeration Control for Variable Cooling Loads
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Solution Overview
Problem
Conventional frozen product dispensers face inefficiencies due to large variations in cooling load demands, leading to poor temperature control and excessive energy usage, as fixed speed compressors struggle to match refrigerant flow with dynamically changing cooling requirements.
Innovation Solution
The implementation of a refrigeration system with multiple evaporators and compressors, along with variably controllable expansion valves and a control system, allows for efficient matching of cooling capacity to changing demands by shutting down unnecessary components, reducing the turndown ratio and minimizing compressor cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed speed compressor is used, then the device complexity is reduced, but the ability to match refrigerant flow with dynamically changing cooling load requirements deteriorates
Solution Approach 1:
The patent divides the single compressor system into multiple compressors (first and second compressors), each capable of independent operation. This segmentation allows the system to better match cooling load requirements by activating only the necessary number of compressors, thereby improving adaptability while maintaining relatively simple device complexity.
Solution Approach 2:
The patent implements variable speed capability in the compressors, allowing them to dynamically adjust their refrigerant flow rate according to changing cooling load demands. This dynamic adjustment resolves the contradiction by enabling fixed-speed simplicity to be combined with variable-speed adaptability through electronic control.
2Productivity
If expansion valves are variably controlled to match cooling load requirements, then the cooling capability matches the load, but the refrigeration system balance deteriorates causing poor evaporator temperature control
Solution Approach 1:
The patent incorporates feedback control mechanisms where sensors monitor evaporator temperature and compressor performance, and the control system adjusts expansion valve positions and compressor operation accordingly. This feedback loop maintains refrigeration system balance while achieving accurate cooling load matching and stable evaporator temperature control.
Solution Approach 2:
The patent changes multiple system parameters simultaneously (compressor speed, expansion valve opening, refrigerant flow distribution) rather than adjusting only expansion valve positions. This coordinated parameter adjustment maintains system balance while achieving accurate cooling load matching and stable temperature control.
3Ease of operation
If the compressor is not matched with the cooling load, then the system operates during periods of low product demand, but the compressor cycles on/off excessively increasing energy consumption
Solution Approach 1:
The patent implements variable speed control in compressors, allowing them to operate continuously at reduced speeds during low cooling load periods rather than cycling on/off. This dynamic speed adjustment eliminates excessive cycling while maintaining continuous operation, thereby reducing energy consumption and improving ease of operation.
Solution Approach 2:
The patent ensures continuous compressor operation by using multiple compressors that can modulate their capacity to match cooling loads. This continuous operation eliminates the start-stop cycling losses and maintains system readiness, reducing energy consumption while improving operational continuity.
4Adaptability or versatility
If multiple compressors are used, then the turndown ratio is reduced and cooling capacity matches load better, but the device complexity increases
Solution Approach 1:
The patent divides the cooling capacity into discrete segments provided by multiple compressors that can be independently activated. This segmentation achieves a reduced turndown ratio by allowing selective operation of compressors while keeping device complexity manageable through modular architecture and automated control.
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 operational efficiency, reduces energy consumption, and provides better control over evaporator temperatures, enabling the system to handle large variations in cooling load demands with improved turndown ratios and reduced energy usage.
Implementation Method 1
each evaporator being heat transfer coupled to a respective one of the barrels
Implementation Method 2
chilling the plurality of barrels to freeze liquid product therein
Implementation Method 3
a plurality of variably controllable expansion valves, each fluid coupled at an inlet to an inlet to an associated evaporator
Implementation Method 4
at least two compressors having inlets fluid coupled to outlets from each evaporator
Implementation Method 5
at least one condenser in fluid circuit between outlets from the at least two compressors and inlets to the expansion valves
Data Source
AI summary
A frozen product dispenser is characterized by at least two product freeze barrels for receiving product therein and for freezing the product for dispensing, and a refrigeration system for chilling the at least two barrels. The refrigeration system has at least two evaporators for and heat transfer coupled to each barrel, separate and controllable expansion valves each having an outlet coupled to an inlet to an inlet to an associated one of the evaporators, at least two compressors having outlets coupled to inlets to the expansion valves and inlets coupled to outlets from the evaporators, and at least one condenser in fluid circuit between outlets from the compressors and inlets to the expansion valves. The refrigeration system is controllable to selectively operate one or more of the compressors and one or more of the expansion valves in accordance with the cooling requirements of the barrels to provide an improved turndown ratio for improvements in efficiency of operation of the refrigeration system in response to changing cooling load requirements of the product barrels.