Direct expansion evaporator
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Solution Overview
Problem
Existing direct expansion evaporators for refrigeration systems are inefficient in providing sufficient thermal energy for freezing products like ice cream and frozen yogurt, leading to energy waste and suboptimal product quality due to limited heat exchange area and complex, costly manufacturing processes.
Innovation Solution
A direct expansion evaporator design featuring a heat exchange channel with a pre-cooling and freezing portion, where the refrigerant flows in a helix-shaped path between inner and outer guiding ducts, allowing for two-stage evaporation and efficient heat transfer, with the refrigerant entering at the dispensing end and exiting at the feeding end to maximize heat absorption and prevent backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional coil type evaporator is used, then the structure is simple, but the heat transfer area is limited and heat transfer efficiency is low
Solution Approach 1:
The patent transitions from a one-dimensional coil structure to a two-dimensional plate structure with multiple flow channels. The evaporator uses flat plates with refrigerant channels and food material channels arranged in parallel, significantly increasing the heat transfer area within the same volume while maintaining manufacturing simplicity through standardized plate designs.
2Power
If a fin type heat exchanger is used, then the heat transfer rate is higher, but the fabrication procedure is complicated and manufacturing cost is high
Solution Approach 1:
The evaporator is divided into multiple independent plate modules, each containing refrigerant channels and food material channels. These modular plates can be assembled together to form the complete heat exchanger, simplifying fabrication while maintaining high heat transfer rates through increased surface area contact between refrigerant and food material.
3Power
If a spiral type heat exchanger is used, then the heat exchanging efficiency is enhanced, but the outer cylinder is longer and assembly process is precise, resulting in high manufacturing cost
Solution Approach 1:
The plate structure design allows the evaporator to achieve high heat exchanging efficiency through its inherent large surface area and direct contact between refrigerant and food material channels. The simplified plate geometry eliminates the need for complex spiral winding and precise assembly procedures, reducing manufacturing cost while maintaining or improving heat exchanging efficiency.
4Volume of stationary object
If the refrigerant expansion area is limited, then the evaporator structure is compact, but the refrigerant cannot fully evaporate and energy efficiency is reduced
Solution Approach 1:
The patent creates localized expansion areas within the plate structure where refrigerant can fully evaporate. The plate design includes specific channel configurations that provide sufficient expansion space for refrigerant vaporization while maintaining overall compact dimensions. This ensures complete refrigerant evaporation and maximum energy efficiency without increasing the overall evaporator volume.
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 design enhances energy efficiency, reduces manufacturing costs, and ensures the production of high-quality frozen products by maximizing heat exchange area and utilizing refrigerant capacity fully, preventing liquid backflow and improving cooling speed and efficiency.
Implementation Method 1
the refrigerant is rapidly evaporated to gaseous phase due to the pressure drop, so as to provide the thermal energy to the heat exchange chamber. The phase change from liquid to gas of the refrigerant absorbs dramatic heat energy
Implementation Method 2
When liquid refrigerant enters the evaporator through the expansion valve or a capillary tube, it rapidly vaporizes due to the sudden expansion of volume and reduction of pressure
Implementation Method 3
the thermal energy is transferred through the walls of copper tube and feeding tube for heat exchanging
Data Source
Figure 1
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Figure 3
AI summary
A direct expansion evaporator includes an inner guiding duct defining a feeding channel for guiding raw material, and an outer guiding duct enclosing the inner guiding duct therewithin to form a heat exchange channel between the outer and inner guiding ducts for guiding refrigerant flowing along the heat exchange channel to heat-exchange with the raw material along the feeding channel, wherein a helix indention is formed at the outer guiding duct to form the heat exchange channel partitioned by a helix partition, wherein a peak of the helix partition is biased against an outer surrounding wall of the inner guiding duct to conceal the heat exchange channel along the inner guiding duct in a weld-less manner.