Household appliance comprising a heat pump, and method of operating such household appliance
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Solution Overview
Problem
Heat pumps face operational issues due to liquid refrigerant reaching the compressor system, leading to slugging, noise, and potential damage under adverse conditions like low ambient temperatures, where the accumulator is filled with liquid and lacks sufficient superheating, impairing compressor operation.
Innovation Solution
A household appliance with a sensor system monitoring superheating temperature and a heating device controlling the engagement based on this temperature to maintain sufficient superheating, ensuring only gaseous refrigerant reaches the compressor by heating the accumulator when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the accumulator volume is increased to prevent liquid refrigerant from reaching the compressor, then the reliability of the compressor system is improved, but the device complexity and refrigerant quantity required increase
Solution Approach 1:
The patent changes the temperature parameter of the refrigerant by introducing a heating device that heats the refrigerant in the accumulator to a temperature above the saturation temperature, creating superheated refrigerant. This parameter change ensures that only gaseous refrigerant reaches the compressor, preventing slugging and improving reliability without requiring excessive accumulator volume or refrigerant quantity
Solution Approach 2:
The patent introduces a heating device as an intermediary component between the accumulator and the compressor. This heating device acts as a mediator that transforms the refrigerant state by adding heat, ensuring that the refrigerant entering the compressor is superheated and gaseous, thereby protecting the compressor from liquid damage without requiring a larger accumulator
2Reliability
If the superheating temperature is increased to ensure only gaseous refrigerant reaches the compressor, then the reliability is improved, but the energy consumption increases
Solution Approach 1:
The patent implements a feedback control system where a sensor detects the temperature of the refrigerant in the accumulator, and the control device adjusts the heating device operation based on this temperature feedback. The heating device is controlled to maintain the refrigerant temperature above the saturation temperature, ensuring superheating without excessive energy consumption by operating only when and where needed
Solution Approach 2:
The patent applies heating locally only in the accumulator where the refrigerant needs superheating, rather than heating the entire refrigerant circuit. The heating device is positioned specifically in the accumulator to provide localized heating to the refrigerant, ensuring that only the necessary portion of the system consumes energy for superheating
3Reliability
If a heating device is added to control superheating temperature, then the reliability of compressor operation is improved, but the device complexity increases
Solution Approach 1:
The heating device is designed to serve multiple functions: it heats the refrigerant in the accumulator to ensure superheating, prevents liquid refrigerant from reaching the compressor, and can potentially serve as a defrosting device or emergency heating source. This multi-functionality justifies the added component by providing multiple benefits from a single addition
Solution Approach 2:
The system incorporates sensors and control devices that automatically monitor and regulate the heating device operation based on refrigerant temperature conditions. The system serves itself by detecting when heating is needed and automatically activating the heating device, reducing the need for complex external control systems and manual intervention
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 solution effectively prevents liquid refrigerant from being compressed, reducing noise and mechanical strain, ensuring smooth operation and reducing the need for excessive accumulator volume, thus conserving refrigerant and avoiding damage.
Implementation Method 1
a sensor system for determining a superheating temperature of the refrigerant as a difference between an outlet temperature of the refrigerant at an outlet of the heat sink and an inlet temperature of the refrigerant at an inlet of the heat sink
Implementation Method 2
the heating device is arranged for providing heating to the accumulator
Implementation Method 3
ensuring only gaseous refrigerant reaches the compressor by heating the accumulator when necessary
Implementation Method 4
a heat source for providing heating by condensing the refrigerant
Implementation Method 5
a heat sink for providing cooling by evaporating the refrigerant
Implementation Method 6
a compressor located downstream of the accumulator for driving and compressing the refrigerant
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a household appliance 1 comprising a heat pump having a closed refrigerant circuit 2 for guiding a flow of a refrigerant, and integrated into the refrigerant circuit 2 a heat source 3 for providing heating by condensing the refrigerant, an expansion device 4 for expanding the flow and located downstream of the heat source 3, a heat sink 5 for providing cooling by evaporating the refrigerant, and located downstream of the expansion device 4, and a compressor system 6, 7 for driving and compressing the flow and located downstream of the heat sink 5 and upstream of the heat source 3, the household appliance 1 also comprising a control device 8 for controlling operation of the household appliance 1 and a heating device 9 for providing heating to the heat pump. The household appliance 1 further comprises a sensor system 10, 11 for determining a superheating temperature of the refrigerant as it exits the heat sink 5, and the control device 8 is connected to the sensor system 10, 11 and the heating device 9, and configured for operating the heating device 9 in dependence of the superheating temperature. The invention also relates to a method of operating such household appliance 1.