Slush Generation Using Variable Coolant Flow for Ice-Ratio Control
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Solution Overview
Problem
Existing slush generation machines for medical and beverage applications are expensive, unreliable, and energy-inefficient due to the use of large geared motors and vapor compression refrigeration systems, which also result in high product wastage and complexity.
Innovation Solution
A recirculating system that varies the coolant flow rate to control the fraction of frozen liquid in the slush, using a separate 'stand alone' chiller unit and a heat exchanger with adjustable heat transfer rates to maintain the desired ice/liquid ratio, allowing for efficient and cost-effective slush generation with a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scraped surface freezer systems are used to generate slush, then ice crystals can be formed on the refrigerated surface, but the systems become very expensive due to large geared motors and are unreliable due to rotating seal failures
Solution Approach 1:
The patent extracts the ice generation function from the complex scraped surface freezer system. Instead of using a refrigerated surface with scrapers, the invention uses a recirculating system where ice forms in a conduit and is broken up by flow dynamics, eliminating the need for motors, gears, and rotating seals while maintaining reliable slush generation
Solution Approach 2:
The patent replaces the mechanical scraping system with a fluid dynamic system. Ice crystals are formed and broken up through controlled recirculation and flow conditions in the conduit, substituting mechanical action with hydrodynamic forces to achieve the same slush generation function without complex mechanical components
2Power
If vapor compression refrigeration systems are used to directly cool freezer surfaces, then sufficient cooling power can be achieved, but energy input becomes very high due to low coefficients of performance
Solution Approach 1:
The patent introduces an intermediary glycol cooling system between the vapor compression refrigeration unit and the slush generation conduit. The glycol circulates through a heat exchanger, transferring cooling energy efficiently to the recirculating liquid, allowing sufficient cooling power while improving overall system energy efficiency compared to direct freezing
Solution Approach 2:
The patent segments the cooling function into separate components: a vapor compression refrigeration unit that cools glycol, and a recirculating system that delivers cooling to the liquid. This segmentation allows each component to operate optimally, with the refrigeration unit providing efficient bulk cooling and the recirculating system providing precise local cooling control
3Productivity
If scraped surface ice generators with large holding volumes are used, then slush can be generated, but product wastage increases when the system is cleaned
Solution Approach 1:
The patent uses a dynamic recirculating system with a relatively small conduit volume where liquid continuously circulates through the cooling section. This dynamic approach maintains slush generation capability while minimizing the total volume of product in the system, thereby reducing wastage during cleaning operations compared to large static holding volumes
4Productivity
If long conduits are used in recirculating systems to achieve higher freeze rates, then throughput can be increased, but the apparatus becomes less compact and more complicated
Solution Approach 1:
The patent employs a concentric heat exchanger design where the cooling conduit is nested within or alongside the recirculating liquid conduit. This nested arrangement maximizes heat transfer surface area and cooling efficiency within a compact volume, achieving high freeze rates without requiring long, space-consuming conduit lengths
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
The system achieves reliable and efficient slush generation with reduced energy consumption and lower costs by controlling the ice/liquid ratio independently of throughput, maintaining the desired texture and consistency of the slush beverage, and allowing for the use of a more compact and less complex apparatus.
Implementation Method 1
a heat exchanger with adjustable heat transfer rates to maintain the desired ice/liquid ratio
Implementation Method 2
control the fraction of frozen liquid in the slush... achieve the desired ice/liquid ratio in the slush
Data Source
AI summary
Apparatus for generating, at a target ice/liquid ratio with a corresponding target temperature, a slush comprising frozen and non-frozen liquid comprises a flow path (1,3) for recirculation of liquid (1 10) therethrough, the flow path comprising a heat exchanger (6) having a coolant inlet (106) and a coolant outlet (107), the heat exchanger (6) being configured for flow therethrough of coolant (109) at a temperature below the target temperature, the apparatus being configured to vary the rate of coolant flow through the heat exchanger (6) between a first rate and a second, lower rate.