Refrigeration systems and methods using water-cooled condenser and additional water cooling
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Solution Overview
Problem
Conventional refrigeration systems with water-cooled condensers face inefficiencies and temperature responsiveness issues due to calcium carbonate deposits, which diminish heat transfer performance over time, necessitating further improvements in energy efficiency and pull-down times.
Innovation Solution
Incorporating a liquid line heat exchanger upstream of the condenser to transfer heat energy from the refrigerant to water before it reaches the condenser, combined with a water-cooled condenser and additional cooling stages, to enhance energy efficiency and temperature responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If water is used to cool the condenser, then heat transfer efficiency is improved, but calcium carbonate deposits build up and diminish heat transfer performance over time
Solution Approach 1:
A liquid line heat exchanger is introduced as an intermediary component between the condenser and the expansion device. This heat exchanger uses cold liquid refrigerant to cool the water before it reaches the condenser, preventing calcium carbonate precipitation while maintaining effective heat transfer. The intermediary component solves the contradiction by addressing the root cause (temperature-induced deposition) without sacrificing the beneficial water cooling effect.
2Loss of time
If additional cooling stages are added, then pull-down time is reduced, but device complexity increases
Solution Approach 1:
The liquid line heat exchanger serves multiple functions simultaneously: it acts as a heat exchanger to provide additional cooling, a water cooling pre-treatment device to prevent deposits, and a system component that utilizes existing cold refrigerant. By making one component multi-functional, the system achieves faster pull-down times without proportionally increasing complexity.
Solution Approach 2:
The system performs preliminary cooling of the water in the liquid line heat exchanger before the water reaches the condenser. This preliminary action removes heat from the water early in the cycle, preventing calcium carbonate deposition and maintaining optimal heat transfer conditions throughout operation, thereby reducing pull-down time without adding complex control systems.
3Loss of energy
If water temperature is reduced to prevent calcium carbonate buildup, then heat transfer efficiency is improved, but cooling capacity is reduced
Solution Approach 1:
The cooling process is segmented into two distinct stages: first, the liquid line heat exchanger provides localized cooling of water to prevent calcium carbonate deposition; second, the condenser performs the primary heat rejection function. This segmentation allows each component to operate at optimal temperatures for its specific function, maintaining both heat transfer efficiency and cooling capacity.
Solution Approach 2:
Water temperature is reduced locally in the liquid line heat exchanger where calcium carbonate deposition is a concern, rather than cooling the entire water supply. This localized quality change prevents deposits and maintains high heat transfer efficiency at the condenser without unnecessarily reducing the overall cooling capacity of the system.
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 configuration improves energy efficiency and reduces pull-down time to desired temperatures by up to 60-110 minutes compared to conventional designs, maintaining cooling capacity and preventing calcium carbonate buildup.
Implementation Method 1
Incorporating a liquid line heat exchanger upstream of the condenser to transfer heat energy from the refrigerant to water before it reaches the condenser
Implementation Method 2
transfer heat energy from the refrigerant to water before it reaches the condenser
Implementation Method 3
water-cooled condenser and additional water cooling... the first condenser is water cooled by having heat energy transferred from the first refrigerant into the water
Implementation Method 4
water-cooled condenser... heat energy transferred from the first refrigerant into the water
Data Source
AI summary
A refrigerator of the present invention includes a refrigeration system having a water-cooled condenser and a liquid line heat exchanger for additional cooling with the water, at a position upstream in the direction of flow of water from the cooling that occurs at the condenser. The use of water cooling at these two portions of the refrigeration system improves the energy efficiency of the refrigerator, while also significantly improving temperature responsiveness (e.g., reducing an amount of time necessary to “pull down” the temperature of a cooled space in the refrigerator to a desired set point temperature). The refrigerator may include one or a plurality of refrigeration stages, in various embodiments, and an additional sub-cooling heat exchanger may be provided in the refrigeration system downstream from the liquid line heat exchanger when the refrigerator includes multiple cascaded circuits.