Abstract
A novel screen valve with rectilinear ports is presented for use in advanced high-efficiency compressors, expanders, heat pumps, or engines. The novel design aims to minimize the pumping losses generated as the working gas flows through the valve by maximizing the effective opening cross-sectional area. In this work, various screen valve configurations have been investigated through a series of experimental tests conducted on a heavily modified research engine for high-speed, high-pressure valve testing. The valves were designed and tested to operate efficiently at both low and high engine speeds ranging between 1500 and 3000 rpm. The valve dynamics were optimized to meet two high-level criteria for performance—namely (1) high speed metrics quantified by its percentage of “maximum dynamic pressure” and (2) low speed metrics quantified by the valve “minimum closure angle.” The valves were tested to meet the objective of avoiding any friction-locking issues associated with the valve retainer design. Multiple tests were carried out in pursuit of attaining an improved design. The work concluded that by including a carrier frame (rather than a retainer frame) and upstands on the valve seat, the valve performance was improved significantly. The best design yielded results of 50.4% of maximum dynamic pressure and 25.1° as the minimum closure angle.
Highlights
The valve dynamics were optimized to meet two highlevel criteria for performance—namely (1) high speed metrics quantified by its percentage of “maximum dynamic pressure” and (2) low speed metrics quantified by the valve “minimum closure angle.”
Sliding valves offer strong potential to improve the performance of internal combustion engines and heat pump applications by overcoming some of the inherent shortcomings associated with poppet
The results identified that the valve should not open unless the pressure is equalized across the valve, as this would avoid the sudden pressure blow-down events which yield significant losses
Summary
Sliding valves offer strong potential to improve the performance of internal combustion engines and heat pump applications by overcoming some of the inherent shortcomings associated with poppet. These include pumping losses, parasitic losses (associated with moving the valve), and accurate valve opening timing control. Each directly reduces the overall system efficiency. Over the decades, there have been numerous patents[1,2,3,4,5] which have included designs for “slide type” valve technologies. To date, in compressor, expander, heat pump, or engine applications, these solutions have yet to be realized as the principal means to regulate fluid flow into and out of the working chamber
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