Heat Pump Refrigerant Charge Control by Isolating Idle Heat Exchangers
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Solution Overview
Problem
Heat pumps that both heat and cool spaces and heat water face challenges with inappropriate refrigerant charge levels, leading to inefficiencies and the need for complex and expensive management systems, especially when switching between modes of operation.
Innovation Solution
The implementation of a system that delivers hot refrigerant gas to idle heat exchangers to drive out liquid refrigerant and isolate them, using a digital controller and refrigerant management valves to adjust refrigerant charge and operate the heat pump efficiently across various modes, including the use of a refrigerant recovery valve to remove idle refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a heat pump operates in multiple modes (heating space, cooling space, heating water), then the versatility and adaptability of the system is improved, but the refrigerant charge becomes inappropriate for different modes leading to inefficiency
Solution Approach 1:
The system dynamically adjusts refrigerant charge distribution by isolating inactive heat exchangers through valve control. The refrigerant management valve changes system configuration based on operating mode, making the refrigerant charge dynamic rather than static, thereby maintaining appropriate charge levels across different operational states.
Solution Approach 2:
The refrigerant system is segmented into active and inactive portions through the use of isolation valves. By dividing the heat exchanger network into separate controllable segments, the system can isolate portions of the refrigerant circuit that are not currently needed, preventing refrigerant accumulation in inactive areas and maintaining proper charge in active areas.
2Reliability
If complex refrigerant charge management hardware is added to manage refrigerant levels, then the refrigerant charge management reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The refrigerant management valve serves multiple functions: it acts as a reversing valve for heat pump mode switching, a refrigerant isolation valve for charge management, and a flow distribution valve. By making this single component multi-functional, the system achieves reliable refrigerant charge management without adding dedicated complex hardware solely for charge management.
Solution Approach 2:
The patent combines the refrigerant charge management function with the existing heat pump reversing valve and expansion device functions. By merging these control functions into existing components rather than adding separate dedicated systems, the overall device complexity is minimized while achieving reliable refrigerant management.
3Reliability
If the heat pump avoids certain modes of operation to maintain proper refrigerant charge, then the refrigerant charge level is maintained, but the adaptability and versatility of the system deteriorates
Solution Approach 1:
The system dynamically reconfigures the refrigerant circuit using isolation valves to adapt to different operating modes. This dynamic reconfiguration allows the heat pump to operate in all desired modes (heating space, cooling space, heating water simultaneously) while maintaining proper refrigerant charge distribution, eliminating the need to avoid any operational modes.
4Quantity of substance
If liquid refrigerant accumulates in an inactive heat exchanger, then the refrigerant charge is redistributed, but the available charge for the active system becomes inappropriately low
Solution Approach 1:
The system extracts or removes refrigerant from inactive heat exchangers by isolating them with closure valves before they can accumulate liquid refrigerant. This extraction of refrigerant from inactive portions ensures that the full refrigerant charge remains available in the active system, preventing charge deficiency in the operational areas.
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 allows for more efficient operation of heat pumps with less complexity and cost, enabling them to handle multiple modes of operation while maintaining reliability and longevity, and can withstand extreme environmental conditions.
Implementation Method 1
delivering hot refrigerant gas to a particular idle heat exchanger of the heat pump that is not needed at that time for transferring heat, driving liquid refrigerant out of the particular idle heat exchanger
Implementation Method 2
an outdoor heat exchanger that transfers heat between the refrigerant and outdoor air or a heat source/sink, an indoor heat exchanger that transfers heat between the refrigerant and indoor air
Data Source
AI summary
Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, and methods of managing refrigerant charge. Various embodiments remove idle refrigerant from a heat exchanger that is not needed for transferring heat by opening a refrigerant recovery valve and delivering the idle refrigerant from the heat exchanger to an inlet port on the compressor. The heat exchanger can be isolated by closing an electronic expansion valve, actuating a refrigerant management valve, or both. Refrigerant charge can be controlled by controlling how much refrigerant is drawn from the heat exchanger, by letting some refrigerant back into the heat exchanger, or both. Heat pumps can be operated in different modes of operation, and various components can be interconnected with refrigerant conduit. Some embodiments deliver refrigerant gas to the heat exchanger and drive liquid refrigerant out prior to isolating the heat exchanger.