Condenser Circuit Isolation for HVAC Refrigerant Pressure Control
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Solution Overview
Problem
Existing HVAC systems face challenges in controlling refrigerant pressure, leading to icing issues during low ambient temperatures, with existing solutions being costly, complex, and reducing system capacity.
Innovation Solution
A method and system that utilize a condenser with a header arrangement capable of distributing refrigerant to multiple circuits and selectively isolating them based on pressure, using valves to manage refrigerant flow and maintain adequate pressure without additional piping or expensive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable speed condenser fan or multiple independent condenser fans are used to control refrigerant pressure, then icing is prevented, but system cost and control complexity increase
Solution Approach 1:
The condenser is divided into multiple independent circuits with individual isolation valves. By selectively closing valves to isolate specific circuits, the system can control refrigerant flow paths and maintain proper pressure without requiring complex variable speed controls or multiple independent fan systems.
Solution Approach 2:
The system dynamically adjusts refrigerant flow by opening or closing isolation valves based on operating conditions. This dynamic valve control allows the system to adapt to changing ambient temperatures and load conditions, preventing icing while maintaining simplicity in the control mechanism.
2Reliability
If parallel refrigerant condensers are used to control system pressure, then head pressure increases preventing icing, but system cost and installation complexity increase
Solution Approach 1:
Instead of installing parallel condenser units, the invention segments a single condenser into multiple circuits with independent valve control. This segmentation allows the system to create artificial pressure control zones within one condenser, eliminating the need for additional condenser coils and complex piping while maintaining head pressure control capability.
Solution Approach 2:
A single condenser unit performs multiple functions: it provides the primary heat rejection surface and simultaneously enables pressure control through internal circuit isolation. This multi-functionality eliminates the need for separate parallel condenser systems while achieving the same pressure control objective.
3Reliability
If refrigerant flooding of condenser coil is used to increase head pressure, then icing is prevented, but system capacity decreases
Solution Approach 1:
The system applies partial flooding by isolating only specific circuits within the condenser rather than flooding the entire coil. This partial action maintains sufficient head pressure to prevent icing while preserving adequate condensing surface area and refrigerant availability to maintain system capacity.
Solution Approach 2:
Different regions of the condenser are treated differently through selective circuit isolation. Some circuits are flooded to increase local pressure, while other circuits remain active to maintain system capacity. This local differentiation allows simultaneous achievement of pressure control and capacity maintenance.
4Reliability
If a pressure-response valve with downstream receiver vessel is used to control condenser pressure, then head pressure is maintained, but system cost and space requirements increase
Solution Approach 1:
The invention extracts the pressure control function from complex external components (pressure-response valves and receiver vessels) and implements it directly within the condenser structure through internal circuit isolation. This extraction eliminates the need for additional specialized components and complex piping arrangements.
Solution Approach 2:
The pressure control function is merged with the condenser structure itself by incorporating isolation valves within the condenser circuits. This integration combines the heat rejection function and pressure control function into a single component system, eliminating the need for separate pressure control devices and their associated piping.
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 approach effectively controls refrigerant pressure, preventing icing at lower ambient temperatures without increasing costs or complexity, and maintains system capacity by isolating less efficient circuits and redirecting refrigerant to maintain higher pressures.
Implementation Method 1
the amount of heat being removed from the refrigerant in the condenser increases
Implementation Method 2
the refrigerant proceeds to a compressor, then a condenser
Implementation Method 3
the refrigerant absorbs heat from a heat transfer fluid to be cooled
Implementation Method 4
As the refrigerant travels through the evaporator, it absorbs heat from a heat transfer fluid to be cooled and changes from a liquid to a vapor phase
Implementation Method 5
the refrigerant proceeds to a compressor
Data Source
AI summary
A method and system for controlling refrigerant pressure in an HVAC system. The method includes providing a compressor, a condenser and an evaporator connected in a closed refrigerant loop. The condenser has a header arrangement capable of distributing refrigerant to a plurality of refrigerant circuits within the condenser. The header arrangement also is capable of selectively isolating at least one of the circuits from refrigerant flow. Refrigerant pressure is sensed at a predetermined location in the refrigeration system. At least one of the circuits is isolated when the refrigerant pressure is less than or equal to a predetermined pressure.