Anti-freezing control method and system for failure of four-way valve of heat pump water heater
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Solution Overview
Problem
Existing heat pump water heaters lack effective methods to determine if a four-way valve is failed, leading to potential freezing of low-temperature water and ice blockages, which can misjudge the valve's failure and affect user usage.
Innovation Solution
A method and system that monitor the water temperature in the tank, assess the cooling rate, and use preset temperature differences and time periods to determine if the four-way valve is failed, controlling the heat pump and auxiliary heating systems to prevent freezing and misjudgment, including stopping the heat pump, starting auxiliary heating, and counting valve failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the four-way valve is failed, then refrigeration is performed and low-temperature water in the water tank may freeze, but there is no effective method to judge the valve failure in existing systems
Solution Approach 1:
The system uses its own operational parameters (compressor status, water temperature, running time) to self-diagnose four-way valve failure without requiring external detection devices. The control board analyzes existing sensor data and operational patterns to identify valve failure conditions.
Solution Approach 2:
The system continuously monitors water temperature, compressor operation status, and running time, and uses this feedback to determine whether the four-way valve has failed. When failure conditions are detected, the system provides feedback by activating an alarm and switching to auxiliary heating mode.
2Adaptability or versatility
If temperature difference between heat exchanger and environment is used to judge valve failure, then the method is feasible in most instances, but it fails in low temperature conditions and low-temperature water conditions
Solution Approach 1:
The system changes the detection parameters from simple temperature difference to a multi-parameter analysis including compressor running time, water temperature, and temperature change rate. This allows accurate detection across various operating conditions including low temperature environments.
Solution Approach 2:
The system dynamically adjusts detection criteria based on operational context, considering the compressor running time and temperature change rates. This dynamic approach enables reliable detection whether the system is in heating mode, cooling mode, or idle state.
3Object-affected harmful factors
If the four-way valve is failed and refrigeration is performed, then low-temperature water may freeze causing ice blockage, but existing systems cannot accurately detect this condition
Solution Approach 1:
The system performs preliminary detection of valve failure conditions by monitoring water temperature, compressor running time, and temperature change rates before freezing actually occurs. When failure conditions are detected, the system preemptively switches to auxiliary heating mode to prevent ice blockage.
Solution Approach 2:
The control board acts as an intermediary that analyzes multiple parameters (temperature, running time, rate of change) to precisely determine valve failure conditions. This intermediary analysis enables accurate detection and appropriate response to prevent freezing and ice blockage.
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
Precisely judges the failure of the four-way valve, preventing ice blockages and ensuring accurate detection, thereby maintaining normal hot water usage and protecting the heat pump system from breakdown.
Implementation Method 1
a heat pump system to stop and starting an electric auxiliary heating system if it is judged that a current water temperature T of water in a lower part of a water tank is lower than a preset minimum temperature Tmin for the water tank
Implementation Method 2
controlling a heat pump system to stop and starting an electric auxiliary heating system
Data Source
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AI summary
The present disclosure relates to a method and a system for preventing freezing when a four-way valve in a heat pump water heater is failed, which includes following acts: In act S1, it is judged that whether current water temperature T is lower than a preset minimum temperature Tmin for the water tank, if yes, perform act S2; if no, perform act S1 again. In act S2, it is judged that whether a cooling rate Td of the current water temperature T is greater than or equal to a preset rate ΔT; or, it is judged that whether the current water temperature T satisfies T<Tmin-a and whether T<Tmin-a stands for a first time period t1, in which a is a limit value of a temperature difference; if at least one yes, perform act S3, otherwise, return to act S1. In act S3, a heat pump system is controlled to stop and an electric auxiliary heating system is started. By judging whether a cooling rate Td of the current water temperature T is greater than or equal to a preset rate ΔT; or by judging whether the current water temperature T satisfies T<Tmin-a and whether T<Tmin-a stands for a first time period t1, it may be judged precisely that whether the four-way valve is failed, which avoids a misjudgment.