Heat pump systems and methods with frost mitigation
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Solution Overview
Problem
Conventional heat pumps face inefficiencies and increased energy consumption during defrosting modes due to frost formation on outdoor coils, necessitating supplemental heating systems that lead to unnecessary emissions.
Innovation Solution
A heat pump system with a hot gas bypass circuit and control system that diverts a portion of heated working fluid to the outdoor heat exchanger to prevent frost formation while maintaining heating mode operation, adjusting compressor operation to maintain heating capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional heat pumps operate in defrosting mode to remove frost from outdoor coils, then frost accumulation is eliminated, but heating capacity is lost and supplemental heating systems must be activated increasing energy consumption and emissions
Solution Approach 1:
The system performs preliminary defrosting action by switching to cooling mode before frost significantly accumulates on the outdoor coil, preventing the need for supplemental heating and reducing overall energy consumption
Solution Approach 2:
The heat pump alternates between heating mode and cooling mode periodically, using brief cooling cycles to defrost the outdoor coil while maintaining overall heating operation, thereby avoiding continuous supplemental heating requirements
2Object-affected harmful factors
If conventional heat pumps switch to cooling mode for defrosting operations, then frost is removed from outdoor coils, but the ability to provide heated air to conditioned space is lost
Solution Approach 1:
The system switches to cooling mode preliminarily and briefly to defrost the outdoor coil before frost significantly impacts heating performance, minimizing the loss of heating capacity and reducing the need for supplemental heating systems
Solution Approach 2:
The heat pump implements periodic defrosting cycles where it briefly operates in cooling mode to remove frost, then returns to heating mode to restore full heating capacity, balancing frost removal with continuous heating provision
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 system effectively prevents frost formation on outdoor heat exchangers, allowing continuous heating mode operation with improved efficiency and reduced energy consumption and emissions.
Implementation Method 1
the second heat exchanger is configured to place the working fluid in a second heat exchange relationship with an ambient air flow
Implementation Method 2
a compressor configured to compress the working fluid
Implementation Method 3
the bypass circuit is configured to direct a portion of the working fluid from the compressor to the second heat exchanger
Data Source
AI summary
A heat pump includes a working fluid circuit configured to circulate a working fluid therethrough. The working fluid circuit includes a first heat exchanger, a second heat exchanger, a compressor, and an expansion valve. The first heat exchanger is configured to exchange heat between the working fluid and a supply air flow, and the second heat exchanger is configured to exchange heat between the working fluid and an ambient air flow. The heat pump also includes a bypass circuit configured to direct a portion of the working fluid from the compressor to the second heat exchanger, a bypass valve configured to control a flow of the portion of the working fluid along the bypass circuit, and a controller configured to receive data indicative of a measured value of an operating parameter associated with formation of frost on the second heat exchanger and to control a position of the bypass valve based on a comparison of the measured value with a baseline value of the operating parameter.