Constant heat outflow rates for air/surge vessel modelling during pressure transients. (May 2019)

• Record Type: Journal Article
• Authors: Akpan, P.U.; Mgbemene, C.A.; Ume, J.I.; Jones, S.; Yeung, H.
• Is Part Of: International journal of pressure vessels and piping. Volume 172(2019)
• Page Start: 295
• Page End: 303
• Publication Date: 2019-05
• Subjects: Air/surge vessels -- Pressure transient analysis -- Water pipelines protection -- Heat transfer rates -- Polytropic model; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2019.04.002
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: Air/surge vessels protect water pipelines during pressure transients. A Rational Heat Transfer (RHT) model and Polytropic ( P V n = C ) model exists for predicting the thermodynamic behaviour of the enclosed air in the vessel during pressure transients. The RHT model is not used today for design of air vessels because of the difficulty involved in the substitution of the correct form of the heat outflow rate. This work investigated through modelling and simulation, the constant heat outflow rates suitable for predicting the thermodynamic behaviour of the entrapped air. Initial laboratory data and experimental results obtained from literature were used. The results show that when constant heat outflow rate values of 0.7124 W and 0.98 W are assumed, the thermodynamic behaviour of the enclosed air closely matches those obtained from the Polytropic model at index values of 1.0 and 1.4 respectively. These rates are independent of the vessel size, and initial pressure transient event type. Highlights: Dynamic behaviour of air column in surge vessels was studied during pressure transients. Suitable constant heat outflow rates were proposed for different scenarios. These heat transfer rates were independent of the size of the air vessel modelled. These heat transfer rates were also independent of the initial pressure transient event type. The results predicted were validated against experimental data in literature.