Heat Pump Defrosting Control Using Fan Power and Air Speed Monitoring
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Solution Overview
Problem
Existing methods for initiating defrosting processes in heat exchangers of heat pumps in vehicles are prone to unnecessary activation due to external parameters influencing air flow, leading to inefficiencies and energy waste.
Innovation Solution
A method that monitors fan power consumption and speed, adjusting threshold values based on parameters such as relative air speed, driving conditions, and ambient factors to accurately determine the need for defrosting, thereby minimizing unnecessary processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suction pressure monitoring is used to initiate defrosting, then defrosting can be detected, but unnecessary defrosting processes are initiated during motor vehicle start-up due to temporary pressure drops
Solution Approach 1:
The patent changes the monitoring parameter from suction pressure to fan power consumption. This parameter change resolves the contradiction because fan power consumption directly reflects air flow conditions through the heat exchanger and is not affected by temporary pressure drops during vehicle start-up, thereby eliminating false defrosting initiations while maintaining reliable detection
Solution Approach 2:
The patent implements continuous monitoring of fan power consumption with comparison against threshold values, creating a feedback mechanism that accurately reflects real-time air flow conditions. This feedback system prevents unnecessary defrosting by only triggering when actual icing conditions are detected, thus resolving the contradiction between reliable detection and energy efficiency
2Device complexity
If fixed threshold values are used for defrosting initiation, then the control system is simple, but external parameters such as air speed influence cause false positives
Solution Approach 1:
The patent makes the threshold value dynamic by adjusting it based on detected air speed conditions. When high air speed is detected, the threshold is adjusted to account for the increased air flow that can mask icing effects. This dynamic adjustment maintains control system simplicity while significantly improving reliability by preventing false positives under varying external conditions
Solution Approach 2:
The patent changes the threshold parameter based on air speed conditions. By modifying the threshold value according to detected air speed, the system maintains simplicity while adapting to external parameters, thus resolving the contradiction between simple control and accurate detection
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
Ensures efficient and timely defrosting by reducing false initiations, optimizing energy use, and maintaining heat pump efficiency.
Implementation Method 1
a fan is assigned to the heat exchanger... wherein a power consumption and/or a speed of the fan is monitored
Implementation Method 2
During the defrosting cycle, the ice melts and a flow through the heat exchanger can take place again
Implementation Method 3
If the outside air falls below the dew point thereof, frost forms on the surface of the ambient heat exchanger
Data Source
AI summary
A method for initiating a defrosting process of a heat exchanger of a heat pump of a motor vehicle, wherein a fan is assigned to the heat exchanger, wherein the power consumption and/or the speed of the fan is monitored, a defrosting process is initiated when the power consumption and/or the speed exceeds and/or falls below a threshold value, and the threshold value is determined as a function of a parameter, wherein the parameter is an indicator of a current relative air speed of the ambient air in relation to the motor vehicle.