Compression cooling system and method for operating a compression cooling system
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Solution Overview
Problem
Compression refrigeration systems face challenges in maintaining operating limits, particularly for compressors, leading to performance losses and potential system shutdowns when pressure limits are exceeded.
Innovation Solution
A control method that detects high and low pressures, compressor speed, and defines permissible speed range classes to adjust actuators such as the throttle element and compressor, using change factors to maintain operating within safe limits, preventing excessive control interventions and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor speed is increased to improve cooling performance, then the cooling capacity increases, but the risk of exceeding pressure limits and causing system shutdown increases
Solution Approach 1:
The control unit continuously monitors the high pressure and low pressure of the refrigerant, as well as the compressor speed. Based on this feedback, it dynamically adjusts the compressor speed and throttle element position to maintain safe operating limits while maximizing cooling performance. The control unit compares actual pressure values against predetermined limit values and modifies operational parameters accordingly.
Solution Approach 2:
The system employs dynamic speed range classes that define different permissible counteracting actions based on the current compressor speed. The control unit can adjust compressor speed and throttle element position in real-time, transitioning between different operational modes (normal operation, approaching limits, exceeding limits) to optimize performance while preventing system shutdown.
2Reliability
If control interventions are increased to maintain pressure limits, then system reliability improves, but performance losses increase due to unnecessary shutdowns
Solution Approach 1:
The control unit applies partial control interventions by adjusting the compressor speed and throttle element position proportionally to the degree to which pressure limits are approached or exceeded. Rather than immediate full shutdown, the system applies graduated control actions that are sufficient to maintain safety while minimizing performance impact. The control unit determines appropriate change factors based on the distance to limit values.
Solution Approach 2:
The system changes operational parameters (compressor speed, throttle element position) dynamically based on the current operating state. The control unit calculates permissible counteracting actions and applies parameter changes that maintain pressure within safe limits while preserving maximum cooling performance. Different speed range classes enable different parameter adjustment strategies.
3Reliability
If the throttle element is adjusted to maintain low pressure limits, then component protection is ensured, but the system response time and control precision are reduced
Solution Approach 1:
The control unit takes preliminary action by continuously monitoring pressure values and predicting potential limit violations. When approaching pressure limits, the control unit preemptively adjusts the throttle element position and compressor speed to prevent exceeding limits, rather than reacting after limits are violated. This reduces the need for frequent shutdowns and restarts.
Solution Approach 2:
The control unit uses continuous feedback from pressure sensors to adjust the throttle element position in real-time. Based on the detected high pressure and low pressure values, the control unit modifies throttle opening to maintain low pressure within safe limits while minimizing control interventions that would cause shutdowns.
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 ensures the compression refrigeration system operates within safe limits, minimizing performance losses and preventing unnecessary shutdowns by selecting appropriate counteracting actions based on current speed range and pressure distances.
Implementation Method 1
a vapor compression system in which a gaseous refrigerant is compressed from a low pressure to a high pressure by a compressor
Implementation Method 2
The refrigerant is forced through the condenser, where it transfers heat to a heating medium located in a heat sink system
Implementation Method 3
the refrigerant is expanded from high pressure to low pressure depending on a set value
Implementation Method 4
The low-pressure refrigerant evaporates in the evaporator by absorbing source heat
Implementation Method 5
Internal heat is transferred in an optional internal heat exchanger, such as a recuperator, between the high-pressure refrigerant flowing from the condenser to the expansion valve and the low-pressure refrigerant flowing from the evaporator to the compressor
Data Source
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AI summary
The present invention relates to a method for controlling a compression refrigeration system (200) and an associated compression refrigeration system (200).The procedure comprises determining, for the current compressor speed, a maximum permissible high pressure (HPmax), a minimum permissible high pressure (HPmin), a maximum permissible low pressure (LPmax), and a minimum permissible low pressure (LPmin); determining the distances of the current high pressure to the minimum and maximum permissible high pressure, as well as the distances of the current low pressure to the maximum and minimum permissible low pressure; determining the current speed range class to obtain the permissible counteracting actions; determining, for each permissible counteracting action, a change factor of the actuator belonging to the counteracting action as a function of at least one of the determined distances; and controlling the compression refrigeration system (200) based on the determined change factors of the actuators.