Screw comptressor with intermediate discharge port
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Solution Overview
Problem
Screw compressors in vapor compression systems often overpressurize working fluids during part-load operations, leading to inefficiencies.
Innovation Solution
The introduction of an intermediate discharge port between the compression chamber and the outlet port, which includes a sealing member and a biasing mechanism, allows for controlled fluid flow based on pressure differential, preventing overpressurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the screw compressor operates at part-load conditions, then energy consumption is reduced, but overpressurization of the working fluid occurs leading to inefficiency
Solution Approach 1:
The discharge path is segmented into two stages: a first discharge port that opens first to allow fluid discharge at intermediate pressure, and a second discharge port that opens later at higher pressure. This segmentation allows the compressor to discharge fluid in stages, preventing overpressurization while maintaining part-load energy efficiency.
Solution Approach 2:
The discharge ports are made dynamically controllable through biasing mechanisms (springs) that control the opening pressure of each port. The first discharge port has a lower biasing force and opens at lower pressure, while the second discharge port has a higher biasing force and opens at higher pressure. This dynamic control allows adaptation to varying load conditions, enabling efficient part-load operation without overpressurization.
2Device complexity
If a single discharge port is used, then the device complexity is low, but the compressor cannot efficiently discharge fluid at part-load operations
Solution Approach 1:
The single discharge port is segmented into two separate discharge ports with different opening pressures. The first discharge port handles part-load conditions by opening at lower pressure, while the second discharge port handles full-load conditions by opening at higher pressure. This segmentation improves fluid discharge efficiency across different operating conditions without significantly increasing overall system complexity.
Solution Approach 2:
The discharge ports are designed with different pressure parameters - the first discharge port operates at a lower pressure threshold while the second discharge port operates at a higher pressure threshold. This parameter differentiation allows the system to adapt to varying operating conditions, improving productivity without requiring complex control systems.
3Productivity
If the intermediate discharge port is always open, then fluid can be discharged at part-load operations, but fluid flow cannot be controlled based on pressure differential
Solution Approach 1:
The intermediate discharge port is made dynamically controllable through a biasing mechanism (spring) that maintains it in a closed state until a specific pressure differential is achieved. When the pressure differential between the compression chamber and discharge port exceeds the biasing force, the port automatically opens to allow fluid discharge. This dynamic control enables both part-load discharge capability and pressure-based flow control.
Solution Approach 2:
The discharge port system is designed to automatically respond to pressure conditions without external control. The biasing mechanism (spring) provides the closing force, and when the pressure differential exceeds this force, the port opens automatically. This self-service mechanism eliminates the need for complex external control systems while maintaining both productivity and ease of operation.
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 increases the efficiency of the screw compressor by up to 12% by reducing overpressurization and allowing for efficient fluid discharge at part-load operations.
Implementation Method 1
an intermediate discharge port including a sealing member and a biasing mechanism, fluid flow being prevented between the compression chamber and the intermediate discharge port when in a flow-blocked state
Implementation Method 2
A fluid flow state (e.g., flow-permitted, flow-blocked) of the intermediate discharge port of the screw compressor is controlled based on a pressure differential
Data Source
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AI summary
There is provided a screw compressor (100), comprising: a compressor housing defining a working chamber, the housing including a plurality of bores; a first rotor (105) having helical threads (125), the first rotor being housed in a first of the plurality of bores; a second rotor (110) having helical threads (130) intermeshing with the helical threads of the first rotor, the second rotor being housed in a second of the plurality of bores; an inlet suction port (135) that receives a fluid to be compressed; an outlet discharge port (140) that receives a compressed fluid; a compression chamber formed by the intermeshing of the helical threads of the first rotor and the helical threads of the second rotor between the inlet suction port and the outlet discharge port; and an intermediate discharge port (175) fluidly connectable to the compression chamber and disposed between the inlet suction port and the outlet discharge port to allow a working fluid to leave the compression chamber prior to reaching the outlet discharge port, the intermediate discharge port being disposed at a top portion of the compressor housing so that a biasing mechanism (180) included in the intermediate discharge port is fluid-forced vertically upward or downward to selectively transition the intermediate discharge port between a flow-blocked state and a flow-permitted state, the intermediate discharge port including a sealing member (185) having a sealing surface and forms a sealing engagement with a surface within the intermediate discharge port when biased by the biasing mechanism to be in the flow-blocked state so that fluid flow is prevented between the compression chamber and the intermediate discharge port when in the flow-blocked state, and fluid flow being enabled from the compression chamber through the intermediate discharge port when biased by the biasing mechanism to be in the flow-permitted state in which the sealing surface is disengaged from sealing engagement with the surface within the intermediate discharge port.