CFD Analysis of a Cryogenic Pressure Vessel Hydrogen Leak

This paper reports the numerical simulation of the sudden hydrogen release from a cryogenic pressure vessel due to a broken tube where hydrogen vents into the vacuum jacket. Real gas effects are considered and the specific “vessel within vessel” geometry of cryogenic vessels. For practical reasons, this study focuses on hydrogen release from 34.5 MPa, with initial temperatures of 62 K and 300 K. The high pressure vessel internal volume is 151 L. Pressure versus time graphs indicate that the vacuum jacket resist the pressure build up until reaching the rupture disc setting to finally release into the atmosphere, and a comparative of this result with the ASME Code burst pressure calculation is presented.

Numerical Analysis of Heat Loss From a Parabolic Trough Absorber Tube With Active Vacuum System

In current designs of parabolic trough collectors for concentrating solar power plants, the absorber tube is manufactured in segments that are individually insulated with glass vacuum jackets. During the lifetime of a power plant, some segments lose vacuum and thereafter suffer from significant convective heat loss. An alternative to this design is to use a vacuum pump to actively maintain low pressure in a long section of absorber with a continuous vacuum jacket. A detailed thermal model of such a configuration is needed to inform design efforts for such a receiver. This paper describes a combined conduction, convection, and radiation heat transfer model for a receiver that includes the effects of nonuniform solar flux on the absorber tube and vacuum jacket as well as detailed analysis of conduction through the rarefied gas in the annular gap inside the vacuum jacket. The model is implemented in commercial CFD software coupled to a Monte Carlo ray-tracing code. The results of simulations performed for a two-dimensional cross-section of a receiver are reported for various conditions. The parameters for the model are chosen to match the current generation of parabolic trough receivers, and the simulation results correspond well with experimental measurements.

Numerical Analysis of Heat Loss From a Parabolic Trough Absorber Tube With Active Vacuum System

In current designs of parabolic trough collectors for concentrating solar power plants, the absorber tube is manufactured in segments that are individually insulated with glass vacuum jackets. During the lifetime of a power plant, some segments lose vacuum and thereafter suffer from significant convective heat loss. An alternative to this design is to use a vacuum pump to actively maintain low pressure in a long section of absorber with a continuous vacuum jacket. A detailed thermal model of such a configuration is needed to inform design efforts for such a receiver. This paper describes a combined conduction, convection, and radiation heat transfer model for a receiver that includes the effects of nonuniform solar flux on the absorber tube and vacuum jacket as well as detailed analysis of conduction through the rarefied gas in the annular gap inside the vacuum jacket. The model is implemented in commercial CFD software coupled to a Monte Carlo ray-tracing code. The results of simulations performed for a two-dimensional cross-section of a receiver are reported for various conditions. The parameters for the model are chosen to match the current generation of parabolic trough receivers and the simulation results correspond well with experimental measurements.

Some Problems of the Laboratory Modelling of Non-Isothermal Adsorption in a Fixed Bed of Adsorbent

The course of non-isothermal adsorption of carbon dioxide from nitrogen stream in laboratory glass adsorbers with a polyurethane insulation, without insulation, with a vacuum silvered jacket and with a vacuum jacket with radiation curtain of aluminium sheet was investigated from the point of view of the possibility to employ a one-dimensional model to describe the adsorption course. The assumptions of the one-dimensional model are fulfilled, from the adsorbers investigated, by the adsorber with vacuum silvered jacket and the adsorber with vacuum jacket with radiation curtain.