Crescent-Shaped Slide Valve for Screw Compressor Pressure Loss Reduction
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Solution Overview
Problem
Existing screw compressors face challenges in increasing the opening area of the slide valve without enlarging the casing size, which leads to increased pressure loss and potential deformation of the casing due to increased thickness of the screw rotor.
Innovation Solution
A screw compressor design featuring a crescent-shaped valve body with a smaller outer arc-like curved surface radius and central angle, combined with a guide portion positioned inside the radial direction, allows for increased opening area without increasing the casing size, and reduces pressure loss by minimizing the thickness of the valve body and guide portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the slide valve is enlarged to increase the opening area, then the flow rate of working fluid is restricted and pressure loss is reduced, but the diameter of the slide valve is increased, the thickness of the slide valve along a radial line of the screw rotor is increased, and consequently the size of the casing of the screw compressor is increased
Solution Approach 1:
The valve body is designed with an asymmetric crescent shape where the outer arc-like curved surface has a smaller radius of curvature than the inner arc-like curved surface. This asymmetric geometry allows the valve body to achieve a compact profile that reduces radial thickness while maintaining a large opening area, thereby reducing pressure loss without increasing casing size.
Solution Approach 2:
The invention transitions from conventional circular or symmetric valve designs to a crescent-shaped valve body with specific curvature relationships. By optimizing the geometry in multiple dimensions (different radii of curvature for inner and outer surfaces, and controlling the central angle), the design achieves reduced radial thickness while maintaining functional opening area, effectively solving the contradiction between pressure loss reduction and casing size.
2Loss of energy
If the opening area of the opening of the cylindrical wall is increased, then the flow rate of working fluid is restricted and pressure loss is reduced, but the thickness of the valve body along a line connecting the center of the outer arc-like curved surface and the center of the inner arc-like curved surface is increased
Solution Approach 1:
The valve body employs asymmetric curvature where the outer arc-like surface has a smaller radius of curvature than the inner arc-like surface. This asymmetric design allows the valve to achieve optimal thickness distribution, providing sufficient opening area for low pressure loss while keeping the overall radial thickness compact.
Solution Approach 2:
The invention optimizes specific geometric parameters of the valve body including the radius of curvature of the outer arc-like surface, the radius of curvature of the inner arc-like surface, and the central angle. By carefully selecting and coordinating these parameters, the design achieves reduced valve body thickness while maintaining large opening area, thereby resolving the contradiction between pressure loss reduction and valve thickness.
3Ease of operation
If the guide portion is positioned outside in the radial direction with respect to the outer arc-like curved surface of the valve body, then the valve body can rotate along the outer arc-like curved surface, but interference of the inner arc-like curved surface with the outer peripheral surface of the screw rotor occurs
Solution Approach 1:
The guide portion serves as an intermediary element that mediates between the valve body and the housing. By positioning the guide portion inside the radial direction and displacing its center from the center of curvature of the outer arc-like surface, the design enables controlled movement while preventing harmful interference between the valve body and screw rotor, thus resolving the contradiction between operational ease and interference prevention.
Data Source
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AI summary
In a screw compressor including a slide valve (52), a valve body (53) of the slide valve (52) has a crescent shape in a cross section; the radius of curvature (R2) of an outer arc-like curved surface (P2) is smaller than the radius of curvature (R1) of an inner arc-like curved surface (P1), which is substantially the same as the radius of curvature of an inner peripheral surface of a cylindrical wall (25); the central angle (θ) of the outer arc-like curved surface (P2) is smaller than or equal to 180°; and the thickness of the valve body (53) in a radial direction of a screw rotor is small.