NH3/CO2 cascade refrigeration system is recognized one of the most promising technologies in low-temperature application. In this paper, a with subcooling circuit driven by recovery expansion work has been proposed. The aim study to investigate proposed compared conventional system. Mathematical models based on energy conservation and exergy balance are established. selection different refriger...

Abstract Twin-screw expanders are widely used for small to medium-sized organic Rankine cycle (ORC) power generation. In order improve the performance of twin-screw in ORC, this study aims inlet efficiency and reduce pressure loss by changing geometry shell. The CFD transient simulation is pressure, gas flow conditions other parameters working chamber that not easily obtained through experiment...

This paper investigates the results of a Second Law analysis applied to a mobile air conditioning system (MACs) integrated with an internal heat exchanger (IHX) by considering R152a, R1234yf and R1234ze as low global warming potential (GWP) refrigerants and establishing R134a as baseline. System simulation is performed considering the maximum value of entropy generated in the IHX. The maximum e...

Developments for air cycle systems with respect to special requirements concerning the use of compression and expansion machines for transport refrigeration are discussed in this paper. Historic aspects are mentioned briefly and the present situation in Germany is sketched in the example of an air cycle air-conditioning system for the new generation of the German high speed train ICE 2.2. In or...

Conical shock waves are generated as sharp conical solid projectiles fly supersonically in the air. We study such conical shock waves in steady supersonic flow using isentropic Euler system. The stability of such attached conical shock waves for non-symmetrical conical projectile and non-uniform incoming supersonic flow are established. Meanwhile, the existence of the solution to the Euler syst...

Pumped Thermal Energy Storage (PTES) is an increasingly attractive area of research due to its multidimensional advantages over other grid scale electricity storage technologies. This paper built a model and numerically studied the performance Argon based Brayton type PTES system. The was used optimise total work output round-trip efficiency aspect ratio thermal tanks operation packed bed segme...

In this manuscript, a general formulation of 3-dimensional compressible fluids based on the port-Hamiltonian framework is presented, both for isentropic and non-isentropic assumptions, describing energy flux between mechanical, chemical, thermal domains, with an explicit characterization first second law thermodynamics. For fluids, conversion kinetic into heat by viscous friction considered as ...

We investigate inertial mode oscillations of slowly and uniformly rotating, isentropic, Newtonian stars. Inertial mode oscillations are induced by the Coriolis force due to the star’s rotation, and their characteristic frequencies are comparable with the rotation frequency Ω of the star. So called r-mode oscillations form a sub-class of the inertial modes. In this paper, we use the term “r-mode...

We announce recent results obtained through a combination of asymptotic ODE estimates and numerical Evans function calculations, which together yield stability of isentropic Navier–Stokes shocks for a γ-law gas with 1 ≤ γ ≤ [1, 2.5]. Other γ may be treated similarly.

This study, which developed a laboratory prototype of a hermetic C02 compressor, was motivated by three primary factors. First, the C02 cycle is important because of global concern about ozone depletion and global wanning. Second, the leak tightness, efficiency, size and weight of hermetic motor-driven compressors make them preferable to open-type compressors for conventional residentiallcommer...