Chiller suction flow limiting with input power or motor current control
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Solution Overview
Problem
In refrigeration systems, the presence of liquid droplets in the refrigerant flow to the compressor can decrease efficiency and damage mechanical components, particularly due to increased gas velocity caused by lower differential pressure across the compressor, which existing technologies fail to effectively manage.
Innovation Solution
Implementing a chiller suction flow limiting system that uses a controller to predict energy levels based on evaporator and condenser pressures, modifying input power or motor current to prevent liquid droplet flow into the compressor, thereby maintaining efficient operation and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the differential pressure across the compressor is reduced, then the gas velocity increases and liquid droplet flow to the compressor increases, but the compressor efficiency decreases and mechanical components are damaged
Solution Approach 1:
The controller predicts the energy level associated with liquid droplet flow before it occurs and proactively modifies the input power or current to prevent the condition. By using pressure sensors to detect evaporator and condenser pressures and comparing predicted energy levels to operating energy levels, the system takes preliminary action to limit power input before liquid droplet carryover can damage the compressor or reduce efficiency.
2Productivity
If the input power to the compressor is increased to maintain cooling capacity, then the compressor can handle higher loads, but liquid droplet flow into the compressor increases causing damage
Solution Approach 1:
The system continuously monitors evaporator and condenser pressures using pressure sensors and uses this feedback to predict the energy level associated with liquid droplet flow. The controller compares the predicted energy level to the operating energy level and dynamically adjusts the input power or current to the compressor accordingly. This closed-loop feedback mechanism ensures the compressor operates within safe limits while maintaining optimal cooling capacity.
Data Source
AI summary
A chiller includes an evaporator, a compressor including a prime mover, a first pressure sensor that detects a first pressure in the evaporator, a second pressure sensor that detects a second pressure in a condenser, and a controller. The controller determines a predicted energy level of the compressor based on the first pressure and the second pressure, the predicted energy level associated with liquid droplet flow into the compressor, compares the predicted energy level to an operating energy level, and modifies the at least one of the input power and the input current to the prime mover based on the comparison satisfying a modification condition.