Screw Compressor Rotor Cooling Grooves for Thermal Deformation Control
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Solution Overview
Problem
Existing screw compressors face inefficiencies due to thermal deformation of screw rotors, which enlarges gaps and leads to internal leaks, necessitating improved cooling methods without increasing coolant temperature or flow rate, and existing cooling technologies complicate the structure.
Innovation Solution
A screw compressor design with a groove structure in the cooling flow path of the screw rotor and a stationary nozzle arrangement enhances heat transfer coefficients by increasing the relative speed of the coolant, effectively cooling the discharge-side shaft section without altering coolant temperature or flow rate, using a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of coolant is lowered to improve cooling capability, then the cooling capability is improved, but the size of cooler increases and cost increases
Solution Approach 1:
The invention applies local quality by providing groove structures at specific locations on the cooling flow path wall surface (between discharge-side end face and discharge-side bearing mounting position) rather than uniformly modifying the entire cooling system. This localized modification enhances heat transfer coefficient in the critical thermal deformation zone without requiring system-wide changes or larger coolers.
Solution Approach 2:
The invention changes the physical parameter of the cooling flow path by introducing groove structures that modify the flow characteristics and increase relative speed of coolant. This parameter change enhances cooling capability through improved heat transfer coefficient rather than by lowering coolant temperature or increasing cooler size.
2Temperature
If the flow rate of coolant is increased to improve cooling capability, then the cooling capability is improved, but the size of pump increases and overall motive power increases
Solution Approach 1:
The groove structures are localized to the critical heating zone on the discharge-side shaft section, allowing enhanced cooling where thermal deformation occurs most without requiring increased overall coolant flow rate. This prevents the need for larger pumps and reduced motive power.
Solution Approach 2:
The invention changes the flow velocity parameter locally through groove-induced turbulence and increased relative speed, enhancing heat transfer without increasing the overall coolant flow rate. This avoids the need for larger pumps and additional motive power consumption.
3Temperature
If inwardly directed fins are provided in the cooling channel to increase heat exchange surface area, then the cooling capability is improved, but the structure becomes complicated
Solution Approach 1:
Instead of adding complex fin structures throughout the cooling channel, the invention applies simple groove structures locally on the wall surface in the critical thermal zone. This achieves enhanced cooling capability without complicating the overall cooling channel structure.
Solution Approach 2:
The invention replaces the mechanical addition of fins (which would increase structural complexity) with groove structures that achieve similar heat transfer enhancement through flow modification rather than surface area expansion. This substitutes a simpler geometric modification for a more complex mechanical addition.
4Manufacturing precision
If cooling capability is improved to reduce thermal deformation, then the discharge-side end face gap is maintained, but the structure becomes complicated
Solution Approach 1:
The groove structures are applied locally to the discharge-side shaft section where thermal deformation most affects the end face gap. This targeted approach maintains the critical gap dimension without requiring complex system-wide modifications to the cooling system.
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 enhanced cooling capability reduces thermal deformation, minimizes internal leaks, and improves compressor efficiency by maintaining the discharge-side end face gap, thus enhancing overall performance.
Implementation Method 1
A groove structure is provided at at least a part of a region on a wall surface of the cooling flow path... The groove structure includes grooves or a groove that has a lengthwise component in a circumferential direction of the screw rotor and that are spaced apart in the axial direction... enhance the heat transfer coefficient on the wall surface of the cooling flow path
Implementation Method 2
A nozzle that is a stationary member for supplying a coolant is arranged inside the cooling flow path with a gap between the nozzle and the wall surface... increase the relative speed of the coolant, effectively cooling the discharge-side shaft section
Data Source
AI summary
A male rotor of a screw compressor has a cooling flow path extending in an axial direction inside a discharge-side shaft section. A groove structure is provided at at least a part of a region on a wall surface of the cooling flow path between the position of a discharge-side end face of the male rotor and a mounting position of a discharge-side bearing. The groove structure includes grooves or a groove that has a lengthwise component in a circumferential direction of the screw rotor and that are spaced apart in the axial direction. A nozzle which is a stationary member is arranged inside the cooling flow path with a gap between the nozzle and the wall surface of the cooling flow path. The nozzle is arranged in such a manner as to overlap at least a part of the groove structure in the axial direction.