Heat Pump Water Tank Switching for Defrost Without Heating Freeze
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Solution Overview
Problem
Existing space heating and water supply systems with heat pumps face efficiency issues due to frost formation at the heat-source-side heat exchange means, leading to potential freezing of the heating medium at the usage-side heat exchange means, especially when the amount of circulating heating medium is insufficient, which can result in prolonged defrosting times and suspended space heating.
Innovation Solution
The system incorporates a circuit switching means and heat pump control means to switch between space heating and water supply modes during defrosting, utilizing the heat from the water supply circuit to complete defrosting quickly, even with minimal heating medium in the space heating circuit, and includes temperature detection and electrical heating to maintain water tank temperature, ensuring efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating medium circulates during the reversed cycle defrosting operation, then the risk of freezing at the usage-side heat exchange means is reduced, but the total amount of circulating heating medium must be sufficiently large, which conflicts with energy efficiency requirements for high-sealed rooms
Solution Approach 1:
The patent introduces a water tank as an intermediary thermal storage device between the heat pump and the space heating system. During defrosting operation, the water tank supplies thermal energy to prevent freezing without requiring a large volume of heating medium to circulate through the entire space heating circuit. This mediator allows the system to maintain reliability with minimal heating medium circulation.
Solution Approach 2:
The system performs preliminary heating of water in the water tank during normal operation modes. When defrosting is required, this pre-heated water is immediately utilized to prevent freezing at the usage-side heat exchange means, eliminating the need to maintain a large circulating volume of heating medium solely for defrosting protection.
2Reliability
If the heat pump unit performs reversed cycle defrosting operation, then frost on the heat-source-side heat exchange means is removed, but the space heating function is suspended during the defrosting process
Solution Approach 1:
The patent merges the defrosting function with the water heating function by directing the refrigerant cycle to simultaneously serve both purposes. During defrosting operation, the heat pump extracts heat from the water tank (which has excess thermal capacity) to melt frost on the outdoor heat exchanger, while the water tank continues to supply hot water for domestic use. This combination allows defrosting to occur without suspending space heating.
Solution Approach 2:
The system changes the operational parameters of the heat pump by switching between different refrigerant flow paths and heat exchange configurations. During defrosting, the refrigerant circulation is reversed and the water tank temperature setpoint is temporarily adjusted to enable heat extraction for defrosting while maintaining adequate temperatures for space heating continuity.
3Loss of energy
If the amount of heating medium in the space heating circuit is reduced for energy efficiency, then energy consumption decreases, but the ability to maintain defrosting operation without freezing risk is compromised
Solution Approach 1:
The water tank serves as a thermal buffer and intermediary energy source during defrosting operations. It provides the necessary thermal energy to prevent freezing at the usage-side heat exchange means without requiring a large volume of heating medium to circulate, thus maintaining reliability with minimal heating medium circulation consistent with energy efficiency goals for high-sealed buildings.
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 rapid defrosting without suspending space heating, maintaining water supply efficiency, and reducing the minimum heating medium requirement in the space heating circuit, thus enhancing overall system performance and energy efficiency.
Implementation Method 1
a heat pump unit having a compressor configured to compress a refrigerant, a first heat exchange means configured such that the refrigerant exchanges with ambient air therein, and a second heat exchange means configured such that the refrigerant exchanges heat with the heating medium
Implementation Method 2
the first heat exchange means working as an evaporator and the second heat exchange means working as a condenser
Implementation Method 3
the first heat exchange means working as an evaporator and the second heat exchange means working as a condenser
Implementation Method 4
a compressor configured to compress a refrigerant
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
An apparatus (100) configured to be connected to a space heating unit (200) and a water supply unit (300) with a water tank (310) so as to form a space heating circuit (250) and a water supply circuit (350) in which a heating medium is supplied to the space heating unit (200) and the water supply unit (300), respectively. The apparatus comprises a heat pump unit (20), an operation mode means (92) configured to set an operation mode of the apparatus to a space heating mode or a water supply mode by controlling a circuit switching means (40), and a heat source control means (94) configured to set an operation mode of the heat pump unit (20) to a heating mode or a defrosting mode. During the operation in the defrosting mode of the heat pump unit (20) and during the operation of the space heating mode of the apparatus (100), the operation mode means (92) is configured to switch the operation mode of the apparatus (100) from the space heating mode to the water supply mode.