Refrigeration Compressor Speed Control for Damage-Free Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Refrigeration machines with speed-controlled compressors face the risk of damage from operating at excessively high or low speeds, which existing methods fail to adequately prevent, leading to potential mechanical failure and inefficiencies.
Innovation Solution
A method that determines the required compressor speed based on desired thermal output and sets it within a permissible range defined by evaporation and condensation temperatures, using a mathematical model and closed control loop to continuously adjust and avoid harmful resonance vibrations, with optional tolerance periods to prevent unnecessary shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor speed is increased to meet higher thermal output requirements, then the cooling or heating capacity is improved, but the risk of mechanical damage to the compressor increases
Solution Approach 1:
The patent implements dynamic speed adjustment by continuously monitoring operating conditions (evaporation temperature, condensation temperature, thermal output requirements) and adjusting the compressor speed in real-time to remain within the permissible range. This dynamic control allows the system to adapt to changing thermal demands while preventing mechanical damage through automated speed limitation.
Solution Approach 2:
The system employs feedback control by comparing the required compressor speed (calculated from thermal output) against the permissible speed range (determined from current operating conditions). When the required speed exceeds the permissible range, the system provides feedback to limit the speed to the maximum permissible value, ensuring reliable operation while meeting thermal requirements as closely as possible.
2Reliability
If the compressor speed is decreased to reduce mechanical stress, then the compressor reliability is improved, but the thermal output capability deteriorates
Solution Approach 1:
The patent changes the operating parameters (evaporation temperature, condensation temperature) to expand the permissible speed range when possible. By adjusting these parameters within acceptable limits, the system can maintain higher compressor speeds without causing mechanical damage, thus preserving thermal output capability while ensuring reliability.
Solution Approach 2:
The system accepts partial reduction in thermal output capability when the required speed exceeds the permissible range. Rather than completely sacrificing thermal performance, the system operates at the maximum permissible speed, providing partial thermal output while prioritizing compressor protection. This partial action approach balances reliability and productivity.
3Reliability
If fixed speed limits are applied to the compressor, then the protection against mechanical damage is simplified, but the adaptability to different operating conditions deteriorates
Solution Approach 1:
The patent implements dynamic speed limits that automatically adjust based on current operating conditions (evaporation temperature, condensation temperature, thermal output). Rather than using fixed speed limits, the permissible speed range is recalculated continuously to match the actual operating point, providing both protection and adaptability.
Solution Approach 2:
The system changes the speed limit parameters dynamically by calculating the permissible speed range from current operating parameters. When operating conditions change (e.g., different evaporation or condensation temperatures), the permissible speed range is recalculated to reflect the new conditions, allowing the compressor to operate at optimal speeds for each specific operating point while maintaining protection.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The method involves determining thermal performance of refrigerating machine (1) and required speed of compressor (3). An allowable rotational speed range of the compressor is determined for each operating point of refrigeration machine. A speed of the compressor is regulated to lower and upper speed limit, when required speed of compressor is below or above the permissible speed range respectively. An independent claim is included for a refrigerating machine.