Abstract Reducing the diameter of copper tube is beneficial to reduce the amount of metal material used in heat exchanger. The change of the diameter of the copper tube can not only reduce the volume of the heat exchanger, but also the filling amount of the refrigerant can be reduced. In this paper, the R22 fin-tube evaporator with 7mm tube diameter is improved. The diameter of the tube is reduced to 5mm, and the environment protection refrigerant R290 is used. Diameter reduction may cause the pressure drop increases, and the new branch number is 5 by calculating. Using the simulation software EVAP-COND to simulate the heat transfer performance and compare the refrigerant flow, pressure drop, copper usage with the evaporator before improved. Result show that the heat transfer effect of R290 evaporator is better than that of R22 system, and the heat transfer effect of system is the best. Under the premise of no increasing pressure drop, the heat transfer of the R290 fin-tube evaporator with a small tube diameter increased by 34.62%, refrigerant flow rate, pressure drop, copper and aluminum consumption decreased by 28.7%, 43.1%, 28.6%, 30%.
We study phase transition of self-avoiding fluid surface model on dynamically triangulated lattices using the Monte Carlo simulation technique. We report the continuous transition between the branched polymer and inflated phases at ${\it Δ}p \!=\!0$, where ${\it Δ}p (=\!p_{\rm in}\!-\!p_{\rm out})$ is the pressure difference between the inner and outer sides of the surface. This transition is characterized by almost discontinuous change of the enclosed volume versus the variations of the bending rigidity $κ$ and the pressure difference ${\it Δ}p$. No surface fluctuation transition accompanies this transition up to the surface with the number of vertices $N\!=\!2562$.
Frederic Lechenault, Benjamin Thiria, Mokhtar Adda-Bedia
We investigate the mechanics of thin sheets decorated by non-interacting creases. The system considered here consists in parallel folds connected by elastic panels. We show that the mechanical response of the creased structure is twofold, depending both on the bending deformation of the panels and the hinge-like intrinsic response of the crease. We show that a characteristic length scale, defined by the ratio of bending to hinge energies, governs whether the structure's response consists in angle opening or panel bending when a small load is applied. The existence of this length scale is a building block for future works on origami mechanics
Suriyanarayanan Vaikuntanathan, Phillip L Geissler
The physics of air-water interfaces plays a central role in modern theories of the hydrophobic effect. Implementing these theories, however, has been hampered by the difficulty of addressing fluctuations in the shape of such soft interfaces. We show that this challenge is a fundamental consequence of mapping long wavelength density variations onto discrete degrees of freedom. Drawing from studies of surface roughness in lattice models, we account for the resulting nonlinearities simply but accurately. Simulations show that this approach captures complex solvation behaviors quantitatively.
"Micro-alloying", referring to the addition of small concentration of a foreign metal to a given metallic glass, was used extensively in recent years to attempt to improve the mechanical properties of the latter. The results are haphazard and nonsystematic. In this paper we provide a microscopic theory of the effect of micro-alloying, exposing the delicate consequences of this procedure and the large parameter space which needs to be controlled. In particular we consider two very similar models which exhibit opposite trends for the change of the shear modulus, and explain the origins of the difference as displayed in the different microscopic structure and properties.