Refrigerator Compressor Start Delay for Low-Pressure Startup
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Solution Overview
Problem
Existing cooling devices face inefficiencies and reliability issues, particularly during startup under critical conditions such as high ambient temperatures and low power supply, due to premature refrigerant recondensation and increased pressure on the compressor.
Innovation Solution
Incorporating a control unit with a delay mechanism that opens a valve between the compressor outlet and inlet, allowing a time delay before the compressor starts, which reduces pressure and prevents recondensation, thereby facilitating easier startup and improving efficiency by adjusting the delay based on voltage and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is switched on immediately after the valve opens, then the startup response time is short, but the compressor experiences high pressure and recondensation leading to unreliable operation under critical conditions
Solution Approach 1:
The valve is opened before the compressor starts running, allowing refrigerant to flow from the compressor side to the evaporator side in advance. This preliminary action reduces the pressure on the compressor discharge side before startup, preventing recondensation and ensuring reliable operation under critical conditions such as high ambient temperatures and low power supply.
2Reliability
If a valve is opened before compressor startup to reduce pressure, then startup reliability improves, but the system complexity increases
Solution Approach 1:
The valve serves multiple functions: it controls refrigerant flow during normal operation and also acts as a pressure reduction mechanism before compressor startup. By making the valve multi-functional, the patent avoids adding separate components, thus improving startup reliability without significantly increasing system complexity.
3Reliability
If the compressor motor is dimensioned for high starting torque to overcome high pressure, then startup under critical conditions is ensured, but energy consumption increases
Solution Approach 1:
By opening the valve before compressor startup, the refrigerant pressure on the discharge side is reduced in advance. This eliminates the need for high starting torque, allowing the use of a smaller, more energy-efficient motor while still ensuring reliable startup under critical conditions.
4Ease of operation
If refrigerant flows into the evaporator before compressor startup, then pressure is reduced for easier startup, but cooling efficiency may be temporarily reduced
Solution Approach 1:
The valve is opened temporarily before startup to allow refrigerant flow and pressure reduction, then closed or adjusted once the compressor starts. This periodic action ensures easy startup while minimizing the impact on cooling efficiency, as the valve operation is limited to the startup phase rather than continuous operation.
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 enhances the refrigeration device's efficiency, reduces energy consumption, and allows for a smaller, more energy-efficient electric motor, ensuring reliable operation even under adverse conditions.
Implementation Method 1
the control unit has a delay unit which causes the compressor to only start after the valve has opened with a time delay
Implementation Method 2
The valve prevents the warm refrigerant from flowing into the evaporator and heating it up
Implementation Method 3
the evaporator is supplied with liquefied coolant which evaporates during the subsequent expansion in the evaporator. After evaporating and absorbing heat
Implementation Method 4
During a subsequent expansion, the coolant cools down due to the Joule-Thomson effect and/or the phase transition from liquid to gas
Implementation Method 5
The compressor is designed in particular as a compressor by which a gaseous refrigerant is compressed. During the compression, the gaseous coolant can be converted into the liquid aggregate state
Data Source
Figure 1~2
AI summary
The invention relates to a refrigeration device (1), in particular a refrigerator, comprising a compressor (2) with a compressor inlet (11) and a compressor outlet (12), an evaporator (3) with an evaporator inlet (13) and an evaporator outlet (14), at least one valve (4), connection lines (5) and a control unit (6), wherein the compressor (2) and the evaporator (3) are combined by the connecting lines (5) in a fluid-conducting manner to form a coolant circuit (7) and the valve (4) is arranged in the coolant circuit (7) between the compressor outlet (12) and the evaporator inlet (13), and wherein the compressor (2) and the valve (4) are actuated by the control unit (6), wherein the control unit (6) has a delay unit (8) which causes the compressor (2) to be switched on with a time delay only after the valve (4) is opened; and also to a corresponding method for operating a refrigeration device (1). The invention is distinguished in that reliable operation of the refrigeration device (1) is ensured even during the start-up phase of the compressor (2), wherein a high degree of efficiency and high energy utilization are achieved.