Variable Volume Index Valve for Screw Compressor Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Screw compressors in air conditioning and refrigeration applications face inefficiencies due to fixed volume index, leading to over-compression or backflow when operating conditions vary, as they are optimized for specific suction and discharge pressures which rarely remain constant.
Innovation Solution
A compressor with a volume index valve featuring a piston within a hollow chamber that automatically moves between closed and open positions to control bypass flow from an intermediate portion to the discharge outlet, adjusting based on operating pressures and temperatures to maintain optimal pressure equality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed volume index is used in the compressor, then the compressor is optimized for specific suction and discharge conditions, but the compressor efficiency deteriorates when operating conditions vary
Solution Approach 1:
The patent applies the dynamics principle by making the volume index adjustable through a control valve that can change the bypass flow rate. The control valve dynamically adjusts the volume index based on operating conditions, transforming the fixed geometric design into a variable system that adapts to different suction and discharge pressures, thereby resolving the contradiction between optimization for specific conditions and adaptability to varying conditions
Solution Approach 2:
The patent implements parameter changes by varying the volume index parameter through the control valve mechanism. By changing the bypass flow rate, the system adjusts the effective volume index to match different operating conditions, allowing the compressor to maintain high efficiency across a range of suction and discharge pressures rather than being fixed at a single optimized point
2Reliability
If the pressure inside the compressor exceeds the discharge pressure, then over compression occurs, but system loss increases
Solution Approach 1:
The patent applies feedback control by using a control valve that responds to pressure differential signals between the compression chamber and discharge line. The control valve adjusts the bypass flow rate based on feedback from the pressure condition, opening to reduce volume index when over-compression is detected (pressure inside exceeds discharge pressure) and closing when backflow occurs (pressure inside is too low), thereby maintaining pressure equality and minimizing energy loss
3Reliability
If the pressure inside the compressor is too low, then back flow occurs, but system loss increases
Solution Approach 1:
The control valve uses feedback control to detect when the pressure inside the compressor is too low relative to the discharge pressure, which would cause backflow. In response to this feedback signal, the control valve closes to increase the volume index, preventing backflow and eliminating the associated energy loss, thereby maintaining optimal pressure conditions
4Adaptability or versatility
If a control valve is added to adjust volume index, then adaptability improves, but device complexity increases
Solution Approach 1:
The control valve is designed to operate automatically based on the pressure differential between the compression chamber and discharge line, without requiring external control systems or complex mechanisms. The valve self-regulates the bypass flow rate in response to pressure conditions, providing adaptive volume index control while minimizing device complexity by eliminating the need for sensors, controllers, or actuation systems
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 dynamically adjusts the volume index to match varying operating conditions, preventing over-compression and backflow, thereby enhancing compressor efficiency across non-uniform operating conditions.
Implementation Method 1
when the pressure of the first chamber is lower than the pressure of the second chamber, differential pressure is applied to the piston and the intermediate port is moved to a low-pressure side
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A compressor is provided including a housing having a suction inlet and a discharge outlet. A compression mechanism within the housing is configured to receive a vapor at the suction inlet and to provide a compressor vapor to the discharge outlet. A volume index valve is arranged near the discharge outlet. The volume index valve includes a piston positioned within a hollow chamber and configured to move between a closed position and an open position to provide a bypass flow path from an intermediate portion of the compression mechanism to the discharge outlet. The piston is configured to move within the chamber automatically in response to the operating pressure of the vapor within the compressor.