Refrigeration Circuit Pumpdown Storage for Micro-Channel Condensers
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Solution Overview
Problem
Refrigeration circuits face challenges during system pumpdown when micro-channel heat exchanger coils replace round tube and fin coils, resulting in reduced storage volume for compressed system charge, leading to insufficient space for storing the compressed refrigerant.
Innovation Solution
A refrigeration circuit design with a sealed refrigerant charge holding area, angled from the condenser to the receiver, and appropriately sized to accommodate the reduced storage volume, featuring micro-channel heat exchanger coils, and a receiver that ensures continuous system charge availability during pumpdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If micro-channel heat exchanger coils are substituted for round tube and fin coils, then heat transfer coefficient is improved, but storage volume for compressed system charge is reduced
Solution Approach 1:
The storage system is segmented into two distinct components: the condenser with micro-channel coils and a separate sealed refrigerant charge holding area. This segmentation allows the condenser to focus on heat transfer efficiency while the holding area provides the necessary storage volume, resolving the contradiction between improved heat transfer and reduced storage space.
Solution Approach 2:
The sealed refrigerant charge holding area is positioned in a vertical dimension below the condenser, utilizing gravitational flow. This dimensional arrangement allows the storage volume to be added without increasing the horizontal footprint of the condenser, thereby maintaining heat transfer efficiency while providing adequate storage capacity.
2Volume of stationary object
If the sealed refrigerant charge holding area is made larger to compensate for reduced storage volume, then storage capacity is improved, but device complexity and cost increase
Solution Approach 1:
The sealed refrigerant charge holding area serves multiple functions: it acts as an expansion device, provides storage volume for compressed charge during pumpdown, and utilizes gravity as a natural driving force. This multi-functionality reduces the need for additional components and controls, thereby limiting the increase in device complexity despite increased storage capacity.
Solution Approach 2:
The system utilizes gravity as a self-service mechanism to drive refrigerant flow from the condenser through the holding area and to the evaporator. This eliminates the need for additional pumps or complex control systems, allowing increased storage capacity without proportionally increasing device complexity.
3Volume of stationary object
If a larger receiver is used to accommodate compressed system charge, then storage volume is improved, but cost and regulatory compliance burden increase
Solution Approach 1:
The storage function is segmented from the receiver and placed in the sealed refrigerant charge holding area. This allows the receiver to remain a standard-sized component that does not require special regulatory compliance, while the holding area provides the necessary storage volume for compressed charge during pumpdown operations.
Solution Approach 2:
The sealed refrigerant charge holding area acts as an intermediary component between the condenser and receiver. It provides the necessary storage volume for compressed charge while allowing the receiver to maintain its standard design, thereby avoiding the cost and compliance issues associated with larger receivers.
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 design effectively compensates for the reduced storage volume, allowing for the storage of compressed system charge during system pumpdown, maintaining operational efficiency without the need for a larger receiver, thus reducing costs and regulatory compliance issues.
Implementation Method 1
the sealed refrigerant charge holding area is angled on a downward slope from the condenser to the receiver
Data Source
Figure 1
AI summary
A refrigeration circuit having a system charge and a system charge storage area. The system charge area has a condenser having a set of micro-channel heat exchanger coils. The condenser is appropriately sized to receive a first volume of the system charge. There is a compressor for compressing the system charge from an expanded state to a compressed state. There is a sealed refrigerant charge holding area fluidly connected to the condenser and the compressor. The sealed refrigerant charge holding area is appropriately sized for storing a second volume of the system charge during a system pumpdown. A receiver is fluidly connected to the sealed refrigerant charge holding area. The receiver is appropriately sized to receive a third volume of the system charge during a system pumpdown.