Heat Pump Defrosting Using Generator Heat Recovery
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Solution Overview
Problem
Current heat pump systems face inefficiencies and component stress when defrosting outdoor condenser coils in cold temperatures, as reversing the system's operation can cause damage and require backup heat sources.
Innovation Solution
The system employs a generator with an internal combustion engine to produce heat, which is directed to the outdoor heat exchanger through a heat exchanger, while reducing refrigerant flow restriction, allowing continuous operation in heating mode to defrost the coil without reversing refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat pump system reverses operation to defrost the outdoor condenser coil, then the coil can be defrosted, but the system components experience damage, stress, and excessive wear
Solution Approach 1:
The patent introduces an intermediary heating system that uses a heat exchanger to transfer heat from the indoor air to the outdoor condenser coil. This intermediary mechanism allows defrosting without reversing the entire heat pump system, thereby avoiding component stress and wear while still achieving the defrosting objective.
Solution Approach 2:
The patent segments the defrosting function from the main heat pump operation. Instead of reversing the entire system, only the refrigerant flow through the outdoor coil is reversed locally, while the rest of the system continues operating in heating mode. This segmentation isolates the defrosting action from the main system, reducing overall stress and wear.
2Reliability
If the heat pump system reverses operation to defrost, then the coil defrosts, but the efficiency of the heat pump system is reduced
Solution Approach 1:
The patent enables continuous heating operation in the indoor unit while simultaneously performing defrosting in the outdoor unit. The indoor fan and heating cycle continue without interruption, maintaining useful heating action while the outdoor coil is being defrosted through the intermediary heat exchanger system.
Solution Approach 2:
The intermediary heat exchanger system allows defrosting to occur without disrupting the main heating cycle. By using a separate heat transfer path from indoor air to outdoor coil, the system maintains its heating efficiency while achieving defrosting, avoiding the energy loss associated with full system reversal.
3Reliability
If the heat pump system reverses operation to defrost, then the coil defrosts, but backup heat sources are required to maintain indoor heating
Solution Approach 1:
The patent makes the indoor air and the intermediary heat exchanger serve multiple functions: they provide both heating for the indoor space and the heat source for defrosting the outdoor coil. This multi-functionality eliminates the need for separate backup heat sources while maintaining both heating and defrosting capabilities within the existing system configuration.
Solution Approach 2:
The system uses its own indoor air and heating cycle to provide the heat needed for defrosting the outdoor coil. The indoor fan and heating elements serve the dual purpose of heating the space and generating the heat required for coil defrosting, making the system self-sufficient without external backup sources.
4Temperature
If refrigerant flow restriction is reduced during defrosting, then heat transfer to the coil improves, but refrigerant flow control becomes less precise
Solution Approach 1:
The patent applies partial action by only reducing the refrigerant flow restriction during the specific defrosting period, while maintaining normal flow control during heating operation. The restriction device is temporarily adjusted to allow increased refrigerant flow to the outdoor coil when defrosting is needed, then returns to normal operation, achieving the temperature increase needed for defrosting without permanently sacrificing flow control precision.
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 method efficiently defrosts the outdoor heat exchanger without damaging the system, reduces the need for backup heat sources, and maintains indoor heating, extending component life and improving system efficiency.
Implementation Method 1
a generator comprising an internal combustion engine, the generator configured to produce heat as a function of operating the internal combustion engine
Implementation Method 2
transferring an increased amount of heat produced as a function of operating the internal combustion engine to the heat exchanger
Implementation Method 3
transferred an increased amount of heat produced as a function of operating the internal combustion engine to the heat exchanger while continuing to flow refrigerant through the heat exchanger in the first flow direction
Data Source
AI summary
Systems and methods are disclosed that may include recovering heat from a generator to defrost the heat exchanger by passing a heat transfer fluid from the generator through a recovery heat exchanger that is configured to promote heat transfer between the heat transfer fluid and a refrigerant flowing therethrough, reducing a restriction of the refrigerant, reducing an airflow through the heat exchanger, and delivering the heated refrigerant to the heat exchanger. Systems and methods may also include recovering heat from an exhaust of the generator to deter the formation of frozen condensate on the outdoor heat exchanger by diverting at least a portion of a hot exhaust fluid discharged by the generator onto the outdoor heat exchanger.