The development of a screen valve for reciprocating heat pump/engine applications

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.