Refrigeration system and a method for controlling such a refrigeration system
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Solution Overview
Problem
Refrigeration systems face inefficiencies due to bulky and costly heat exchangers, high refrigerant volume requirements, and challenges in maintaining zero superheat to prevent liquid refrigerant from entering the compressor, which can lead to flash boiling and damage.
Innovation Solution
A brazed plate heat exchanger with alternating plate patterns and chevron angles, incorporating a balance valve to control suction gas heat exchange, ensuring minimal superheat and efficient fluid distribution, thereby reducing pressure drop and enhancing heat transfer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a flooded evaporator configuration is used to achieve zero superheat, then refrigeration efficiency is improved, but the heat exchanger becomes bulky and heavy with high material cost
Solution Approach 1:
The patent employs thin plate structures instead of bulky shell-and-tube heat exchangers. The brazed plate heat exchanger uses multiple thin plates with corrugated patterns that provide large heat transfer surfaces with minimal material, achieving zero superheat without the weight and bulk of traditional flooded evaporators.
2Loss of energy
If a flooded evaporator configuration is used to achieve zero superheat, then refrigeration efficiency is improved, but the refrigerant volume required becomes large
Solution Approach 1:
The brazed plate heat exchanger design provides efficient heat transfer with minimal refrigerant hold-up volume. The thin plate construction with optimized flow channels allows complete refrigerant vaporization without requiring the large refrigerant volumes needed by traditional flooded shell-and-tube evaporators.
3Manufacturing precision
If a shell and tube heat exchanger is used for flooded evaporation, then zero superheat can be achieved, but the heat exchanger is bulky and costly to manufacture
Solution Approach 1:
The brazed plate heat exchanger replaces expensive shell-and-tube construction with thin stamped or formed plates that are brazed together. This approach achieves zero superheat control with significantly reduced material costs and manufacturing complexity while maintaining compact dimensions.
4Quantity of substance
If a compact brazed plate heat exchanger is used, then material cost is reduced and refrigerant volume is minimized, but maintaining zero superheat becomes challenging
Solution Approach 1:
The patent incorporates dynamic control elements including expansion valves and suction gas heat exchangers that actively adjust refrigerant flow and heat exchange to maintain zero superheat. The system dynamically balances the compact heat exchanger's operation to ensure complete vaporization despite the reduced refrigerant volume and compact dimensions.
5Quantity of substance
If heat exchanger size is reduced to minimize refrigerant volume, then legislation compliance is improved, but heat exchange efficiency may be compromised
Solution Approach 1:
The brazed plate heat exchanger achieves high heat transfer coefficients with minimal surface area through optimized plate geometries and flow channel designs. This allows the system to comply with refrigerant volume legislation while maintaining excellent heat exchange efficiency through the thin plate construction that maximizes heat transfer per unit 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
The solution achieves close to zero superheat of refrigerant entering the compressor, improving system efficiency, reducing material costs, and minimizing refrigerant volume, while allowing for co-current heat exchange without compromising performance.
Implementation Method 1
a compressor for compressing a gaseous refrigerant, such that the temperature and pressure thereof increases
Implementation Method 2
a condenser, in which the gaseous refrigerant from the compressor exchanges heat with a high temperature heat carrier, said heat exchange resulting in the refrigerant condensing
Implementation Method 3
said heat exchange resulting in the refrigerant condensing
Implementation Method 4
an expansion valve reducing the pressure of liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant
Implementation Method 5
an evaporator, in which the low boiling point refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes
Implementation Method 6
such that the refrigerant vaporizes
Implementation Method 7
a suction gas heat exchanger exchanging heat between high temperature liquid refrigerant from the condenser and low temperature gaseous refrigerant from the evaporator
Data Source
AI summary
A refrigeration system includes a compressor for compressing a gaseous refrigerant, such that the temperature and pressure thereof increases; a four-way valve controlling whether the refrigeration system is in a heating mode or a cooling mode; a condenser, in which the gaseous refrigerant from the compressor exchanges heat with a high temperature heat carrier, said heat exchange resulting in the refrigerant condensing; an expansion valve reducing the pressure of liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant; an evaporator, in which the low boiling point refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes; and a suction gas heat exchanger exchanging heat between high temperature liquid refrigerant from the condenser and low temperature gaseous refrigerant from the evaporator. A balance valve is arranged for controlling the amount of heat exchange between the high temperature liquid refrigerant and the low temperature gaseous refrigerant in the suction gas heat exchanger by directing a flow of high temperature liquid refrigerant directly from the condenser to the expansion valve. Disclosed is also a method for controlling such a system.