The Direction of Time

An explanation of the direction of time from the past into the future has not yet been possible. With this publication an explanation is given. In general a connection between time and entropy is assumed. Like time, entropy should have only one direction, it should increase. For this purpose the development of space is described with the classical methods of thermodynamics. Furthermore, a closed and thermally insulated container with different temperature ranges is considered: Even if there is no transport of mass or energy across the system boundaries, there is a temperature equalization. This is interpreted as entropy growth. Furthermore, the concentration equalization in a closed and heat-insulated container with areas of different concentrations is investigated in a similar way. After these three investigations the explanation for the direction of time can be given. Furthermore, an explanation for the heat flow from "hot" to "cold" as well as for the diffusion flow during concentration equalization is given.

Temperature modes of the contactor contacts during the test for the limiting breaking capacity

The processes of electric arc quenching of an electromagnetic contactor during testing for ultimate breaking capacity are considered. The conditions for facilitating the successful arc quenching when turning off the limiting currents are shown: by reducing the phase shift between current and voltage, by reducing the amplitude of the restriking and recovery voltages. The processes of anode heating during arcing (heat saturation mode), after the change of polarity and transition of the current through zero, processes on the cathode in the temperature equalization mode are considered. The mathematical models of cathode thermal processes adressed the heat fluxes of the ionic component and evaporation. The mathematical models of anode thermal processes in the temperature equalization mode took into account the heat fluxes of the ionic component, thermionic emission, and evaporation. The calculations were carried out for the averaged values of thermophysical coefficients for copper, since the arc base moves from the contacts to the contact holders, which are made of copper or its alloys. The calculation results showed that the used mathematical models of thermal processes are appropriate both for the cathode and for the anode. This was confirmed by the results of previously performed and published experimental and theoretical studies of thermal processes at the switching contacts of electrical devices.

Stratification and equalization cycles in shallow maturation ponds with different operational configurations and at different periods of the year

This study aimed at evaluating the occurrence of stratification/equalization cycles in two full-scale shallow maturation ponds in Brazil, with different operational configurations and different periods of the year, through monitoring of temperature and other constituents in the vertical profile of the ponds. The study comprised two operational phases: one phase in which both ponds had no baffles and operated in parallel (one pond had sludge accumulated on the bottom while the other did not); and another phase in which the ponds operated in series, the first pond without baffles and with accumulated sludge on the bottom while the second pond had two longitudinal baffles, a shallower depth and no accumulated sludge. Overall, there were systematic daily periodic events of thermal stratification followed by temperature equalization and vertical mixing in both ponds and operating phases. Vertical temperature gradients were predominantly in the 0–7 °C m−1 range. Statistical tests showed a significant positive correlation between the thermal gradient in the pond and air temperature, but not between the thermal gradient and wind speed. Data suggested that ponds remained 56% of the time under thermal stratification and 44% in vertical mixing. The data also highlighted the importance of sludge in the thermal balance of ponds.

Analysis of thermal stratified storage tank

The basic aim of the task is to compile a temperature stratification system in an accumulation tank. The range of the thesis concerns the shape and dimensions of a stratification system for an accumulation tank. Thermal stratification is a process that comprises the maintaining of temperature stratification at different levels of an accumulation tank which reduce to a minimum the process of temperature equalization. It results from the fact that the thermal stratification in a tank significantly increases the installation efficiency and improves the process of energy storing. It is connected with a thermodynamic element quality, that is the higher the temperature, the higher the energy, and, thus, the thermos-dynamic element quality. In this phenomenon, thanks to the same amount of accumulated thermal energy and average temperature, as in a fully mixed tank, the user has a higher temperature in the upper part of the tank at his disposal. It has significant importance in the case when there is a low-temperature heating medium that transfers heat to the accumulation tank. Such a situation occurs when heat is absorbed from synthetic freons used in cooling and air-conditioning systems.

Oxidative decomposition of methanol in a vibroacoustic fluidized bed of Ag-coated cenosphere core-shell catalyst

The paper presents results of a study of oxidative decomposition of methanol in a fluidized bed of silver catalyst. The process of methanol oxidation was carried out on Ag-coated cenospheres core-shell catalyst. The catalyst was obtained by precipitation of silver from methanolic solution of silver nitrate on cenospheres. Cenospheres are lightweight, inert, hollow spheres, which can be easily introduced into a fluidized bed. Application of the catalyst in a form of fluidized bed should ensure good temperature equalization which is very important at low temperatures due to the possibility of generation of formaldehyde. It turned out that local hot points occur in that kind of a catalyst (in the form of a fluidized bed but with very low density), thus use of additional acoustic wave is necessary to ensure good control over the temperature of the process. The products of the process of methanol oxidation were monitored on-line by Fourier transform infrared spectroscopy (FTIR). The catalyst has proven to be highly active in the oxidative decomposition of methanol. Full of methanol conversion in reaction of complete oxidation was achieved at 350°C.

Evolutionary scenario for W UMa-type stars

An alternative to TRO model of a W UMa-type star is presented in which the binary is past mass exchange with mass ratio reversal. The secondary is hydrogen depleted and both components are in thermal equilibrium. Evolution in contact is driven by orbital angular momentum loss and mass transfer from the secondary to primary component, similarly as it is observed in Algols. Temperature equalization of both components results from an assumed energy transfer by a large scale flow encircling the whole system in the common envelope.