Heat Pump Compressor Preheating to Reduce Dryer Start-Up Time
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Solution Overview
Problem
Household appliances with heat pumps, such as clothes dryers, experience a prolonged initial heating phase before achieving high dehumidifying capacity, leading to extended drying times due to the time required for refrigerant stabilization in the cooling circuit.
Innovation Solution
Incorporating a dedicated heater to rapidly warm the compressor, reducing the time needed for refrigerant solubilization and stabilization in the cooling circuit, thereby shortening the initial start phase and reducing drying time by up to 50%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat pump is gradually heated up from ambient temperature, then the refrigerant stabilizes in the cooling circuit, but the heating-up time stretches from 20 to 50 minutes
Solution Approach 1:
The patent applies preliminary action by heating the compressor before the heat pump system operates. The heating device pre-warms the compressor to a predetermined temperature, so that when the heat pump starts, the refrigerant can immediately dissolve in the oil without causing instability. This preliminary heating action eliminates the need for gradual warming and reduces the heating-up time from 20-50 minutes to a much shorter duration.
2Productivity
If the compressor is heated to a higher temperature, then the solubilisation of refrigerant into oil is significantly reduced, but additional heating components are required
Solution Approach 1:
The patent applies multi-functionality by designing the heating device to serve multiple purposes: it heats the compressor housing, warms the refrigerant oil, and prepares the entire compression system for immediate operation. This single heating component performs what would otherwise require multiple separate heating elements, thereby improving dehumidifying efficiency while minimizing the increase in device complexity.
3Loss of time
If the initial start phase is shortened, then the drying time is reduced by up to 1 to 3.5 min/kg, but the refrigerant must be quickly stabilized
Solution Approach 1:
The patent applies preliminary action by pre-heating the compressor and refrigerant oil before the heat pump system operates. This ensures that when the refrigerant is introduced into the cooling circuit, it immediately dissolves in the warmed oil without causing instability or requiring a gradual warming period. This preliminary preparation allows the system to achieve full dehumidifying capacity instantly, reducing drying time by 1 to 3.5 minutes per kilogram of laundry while maintaining reliable refrigerant stabilization.
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 significantly enhances dehumidifying efficiency, allowing for a substantial reduction in drying time by achieving a stable refrigerant condition in the cooling circuit faster, with potential reductions of up to 1 to 3.5 minutes per kilogram of laundry.
Implementation Method 1
the heater is adapted to heat the compressor
Implementation Method 2
a first heat exchanger which is coupled to the process air supply and is designed to dehumidify the process air
Data Source
Figure 1
AI summary
A household appliance (1) comprises a heater (19) and a heat pump (11) including a compressor (12), wherein the heater (19) is adapted to heat the compressor (12). A method for operating a compressor (12) of a household appliance (1) comprising a heat pump (11) including a compressor (12), wherein the compressor (12) is heated by a heater (19). The invention is particularly useful for clothes drying appliances.