Search

The article presents the results of experimental investigations of the relative pressure losses in finned air coolers with different pitch of the finning.

The characteristics of XeF and XeCl lasers stabilized by an external low-power ionizer were considered. Two laser operating regimes were investigated, one with a buildup of negative ions and the other with a discharge stabilized by an external low-power ionizer. The temporal, spectral, and energy characteristics of these lasers were investigated. The minimum ion concentration in the negative-ion buildup regime was found to be [F−]=1011cm−3 and [Cl−]=1012cm−3, while the use of a discharge stabilized by a low-density electron beam made it possible to reduce the current density of the electron beam to ~0.1mA/cm2 in the case of the XeCl laser. A value of 10 J/liter was achieved for the maximum specific output energy of the XeCl laser.

Results are presented from an experimental study of heat exchange and pressure loss in plate-finned air coolers with different spacings of the fins.

The results of an experimental study of frosting in finned air coolers with a different fin spacing are presented.

From the diagrams of isothermal transformation of austenite one can determine which region of isothermal transformation characterizes the hardenability of the steel and determine the numerical value of the hardenability (the value of the critical diameter, the depth of the quenched layer in the end quenched samples of pipes, the thickness of the quenched layer in steel articles of different diameters).

This paper presents a method for measuring the thermal conductivity of frost accumulated on the fins of air conditioners and estimating the subsequent losses in thermal efficiency to the conditioner. The method is intended for use in optimizing the configuration of the fin design and working conditions of the conditioner for minimum frost accumulation and maximum defrost capacity.

A study was made of the influence of the strength of an electro-optic negative feedback, delay of the feedback signal, resonator configuration, pump energy, and the resonator Q-switching law on the stability and shape of microsecond pulses emitted by a ruby laser. It was found experimentally that the most stable microsecond pulses with a smooth top were formed by a laser with a semiconcentric resonator and the largest number of transverse oscillation modes. In this resonator the delay of the feedback signal and the mode beats, which would have resulted in a jagged pulse top, had little influence. A suitable selection of the pump parameters, feedback, and resonator Q-switching law made it possible to obtain different shapes of radiation pulses with durations from 100 nsec to several microseconds.

An experimental investigation was made of the resolution of a neodymium-activated glass fiber laser image amplifier and of the dependence of the signal/noise ratio at the amplifier output on the signal power at the input. The resolution in the active regime (in the presence of pumping) was not inferior to that in the passive regime (without pumping) and the signal/noise ratio (and, consequently, the contrast of the amplified image) improved, compared with the passive regime.