Control for compressor unloading system
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Solution Overview
Problem
Conventional refrigeration systems waste energy when unloading compressors using gas bypass systems, reducing overall efficiency and increasing operating costs due to the recirculation of compressed refrigerant, which is not effectively managed to accommodate varying load conditions.
Innovation Solution
A variable-capacity compressor system with dedicated valves and an unloading controller that modulates the flow of refrigerant by cycling valves between open and closed states based on analog control signals, allowing for precise adjustment of compressor capacity without a maximum dwell time, thereby optimizing energy usage across varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gas bypass system is used to unload compressors, then compressor capacity can be reduced, but energy is wasted due to recirculation of compressed refrigerant
Solution Approach 1:
The patent extracts the harmful recirculation path from the system by introducing a bypass that allows suction refrigerant to be diverted directly to the discharge side without being compressed, thereby eliminating the energy waste associated with compressing and recirculating refrigerant during unloading operations
Solution Approach 2:
The bypass valve acts as an intermediary component that mediates between the suction and discharge sides of the compressor, allowing controlled mixing of bypassed suction refrigerant with discharged refrigerant to achieve capacity modulation without the energy penalty of traditional gas bypass systems
2Reliability
If compressors are sized for peak load, then peak demand can be met, but system efficiency decreases during partial load operation
Solution Approach 1:
The patent implements dynamic capacity modulation by continuously varying the bypass valve position based on actual load conditions, allowing the compressor to operate efficiently across a wide range of loads from part-load to full-load conditions rather than being fixed at peak capacity
Solution Approach 2:
The system changes the operational parameters of the compressor by adjusting the bypass ratio (the proportion of suction refrigerant diverted to discharge), thereby modifying the effective compression ratio and mass flow rate to match varying load requirements and optimize energy consumption
3Productivity
If refrigerant flow is restricted to unload compressor, then capacity is reduced, but control precision is limited
Solution Approach 1:
The patent incorporates feedback control by using sensors to monitor discharge temperature, pressure, and other system parameters, then adjusting the bypass valve position accordingly to achieve precise capacity control and maintain optimal operating conditions
Solution Approach 2:
The bypass valve system serves multiple functions simultaneously: it controls compressor capacity, regulates discharge temperature, prevents refrigerant liquid carryover, and optimizes system efficiency across different operating conditions, providing comprehensive control beyond simple capacity reduction
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
The system enhances refrigeration system efficiency by minimizing energy waste during unloading, allowing for precise capacity adjustments to match changing loads, thereby reducing operating costs and improving overall system performance.
Implementation Method 1
the at least one valve comprises a plunger and a solenoid configured to control movement of the plunger
Data Source
AI summary
A variable-capacity compressor that includes a housing having an inlet for receipt of refrigerant and an outlet for return of refrigerant, and a plurality of compressing elements contained in the housing between the inlet and the outlet. The variable capacity compressor includes a valve having an electrical control. The valve is dedicated to fewer than all of the compressing elements. The valve is movable between a first state which communicates refrigerant flow to the compressing elements, and a second state that reduces or stops flow to the compressing elements. In an embodiment of the invention, an unloading controller has an operational modulation mode that includes cycling the valve between on and off states to provide a portion of compressor capacity. The unloading controller is further programmed to provide a minimum delay time between transitions between the first and second states, but no maximum dwell time between transitions.