Compressors are intolerant to liquids. In reciprocating compressors with inherently large volumetric displacement rates, all modes of liquid ingestion pose a serious problem and can even result in catastrophic failures. This paper describes a simple method of estimating the cylinder pressure and “rod load” (force on the crosshead pin, in compressor terminology) in a double-acting reciprocating compressor. The results indicated that even with moderate volume of liquid present inside the cylinder, the pressure could reach values as high as four to five times its normal value with a correspondingly higher rod load.

No abstract

Vinyl acetate (a polar compound) has become a key ingredient in many industrialand consumer products. However, very little is known about its thermodynamic properties. This article presents a simple modijication of Wu and Stiel's (1 985) method (original/) developed for predicting thermodynamic properties of polar compounds up to P, = 10) for extending its range of applicability to very high pressures of the order of P, = 80. The predictions show good agreement with the experimental data for specific volume in the case of vinyl acetate, and specific volume, enthalpy and entropy for mixtures of ethylene and vinyl acetate for compositions up to 50 wt. % of vinyl acetate. Further validation for other polar systems would determine if this method is applicable to polar compounds in general.

CFD use is spreading fast to all industrial and non-industrial sectors. The progress in the science of Computational fluid Dynamics is not keeping pace with its own technological progress, particularly with reference to applications. Mathematical modeling of fluid flows in most cases is an art which depends on intuition. To gain more credibility in the complex computations of flows in modern machinery, it is not just sufficient to debate about validation, but is becoming increasingly necessary to at least start debating about establishing standards for development, distribution and use of CFD codes. Otherwise, not only the nickname of Colorful Fluid Dynamics might become more permanent, but the rate of growth of the technology of Computational Fluid Dynamics and the development of it’s underlying science might be hampered. This paper discusses the problems in application of CFD for industrial flows and suggests possible solutions and the need for unified action by the CFD community including the concept of ‘Global Benchmarking’.

Inlet manifolds in HVAC systems are required to deliver specified amounts of refrigerant and oil to multiple compressors. However, multiphase flow through such manifolds is quite sensitive to upstream geometry and flow conditions. This paper reports a CFD investigation done to understand the sensitivity of oil flow (the minor component) in such manifolds with a T junction and 3 outlet pipes to the design of the inlet feed pipe geometry. The main objective was to understand the effect of upstream bends and settling length on the nature of flow through the outlets, particularly with reference to the delivery of the required amount of oil and refrigerant to each compressor. The results indicated that the refrigerant flow was not sensitive to upstream effects, while the oil flow was quite sensitive to distortions introduced in to the upstream flow field by lack of sufficient settling length and bends. It further showed that the sensitivity increased with oil droplet size.