Heat Pump Dryer Dryness Detection Using Compressor Watt Trends
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Solution Overview
Problem
Current clothes dryers using mechanical refrigeration cycles struggle to accurately determine when clothes are completely dry, leading to inefficient energy use and potential over-drying, as existing systems rely on capacitance readings that lose signal before clothes are fully dry.
Innovation Solution
A method and apparatus that monitor working fluid temperature, pressure, and compressor power over time, using sensors and a controller to determine when a predetermined decision condition is reached, allowing for precise control of the mechanical refrigeration cycle and automatic shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance reading between dry rods is used to determine dryness, then the drying process can be monitored, but the signal is lost before clothes are completely dry leading to inaccurate determination
Solution Approach 1:
The patent replaces the electrical capacitance measurement system with a mechanical refrigeration cycle parameter monitoring system. By monitoring working fluid temperature, pressure, and compressor power consumption, the system determines dryness indirectly through thermodynamic parameters that remain measurable throughout the entire drying process, avoiding the signal loss issue of direct capacitance measurement.
Solution Approach 2:
The patent introduces working fluid parameters (temperature, pressure, power) as intermediary indicators to assess dryness. These parameters serve as mediators between the actual moisture content and the measurement system, providing continuous information about the drying state without requiring direct contact with the clothes that would cause signal loss.
2Measurement precision
If drying cycle is extended to ensure complete dryness, then measurement accuracy improves, but energy consumption increases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors working fluid parameters and adjusts the drying cycle accordingly. By analyzing trends in temperature, pressure, and power consumption, the system can determine when clothes are completely dry and shut down the compressor, preventing unnecessary energy consumption while maintaining accurate dryness determination.
Solution Approach 2:
The patent employs dynamic analysis of refrigeration cycle parameters, using rolling averages and rate-of-change calculations to detect the point of complete dryness. This dynamic approach allows the system to respond in real-time to changing moisture conditions, extending the cycle only as long as necessary to achieve complete dryness without wasting additional energy.
3Reliability
If compressor runs longer to ensure complete drying, then drying thoroughness improves, but energy waste increases
Solution Approach 1:
The patent performs preliminary analysis of working fluid parameter trends during the drying cycle to predict when complete dryness will be achieved. By monitoring the rate of change in temperature, pressure, and power consumption, the system can anticipate the endpoint of the drying process and shut down the compressor at the optimal moment, ensuring complete drying while minimizing energy waste from excessive running time.
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 enables accurate determination of dryness, reducing energy consumption by ensuring the dryer shuts down only when clothes are completely dry, improving efficiency and preventing over-drying.
Implementation Method 1
The at least one parameter includes at least one of temperature of the working fluid, pressure of the working fluid, and power consumption of the compressor
Implementation Method 2
The at least one parameter includes at least one of temperature of the working fluid, pressure of the working fluid, and power consumption of the compressor
Implementation Method 3
The at least one parameter includes at least one of temperature of the working fluid, pressure of the working fluid, and power consumption of the compressor
Implementation Method 4
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser, a compressor, and an expansion device, cooperatively interconnected and containing the working fluid
Implementation Method 5
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator
Implementation Method 6
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser
Implementation Method 7
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser, a compressor
Data Source
AI summary
An apparatus includes a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser, a compressor, and an expansion device, cooperatively interconnected and containing the working fluid. The apparatus also includes a drum to receive clothes to be dried, a duct and fan arrangement configured to pass air over the condenser and through the drum, a sensor located to sense at least one parameter, and a controller coupled to the sensor and/or the compressor. The parameter(s) includes at least one of temperature of the working fluid, pressure of the working fluid, and power consumption of the compressor. The controller is operative to monitor, as a function of time, the parameter(s), determine whether the parameter(s) reaches a predetermined decision condition; and, if the parameter(s) reaches the predetermined decision condition, power down the mechanical refrigeration cycle at least by causing the compressor to shut off.