T. Kruczek

Frictional, diathermal flow of steam in a pipeline

Nonadiabatic one-dimensional flow of steam in elementary modules of pipe networks, i.e. straight pipes and fittings, has been considered. A simple method of determining the amount of condensed water, distributions of pressure and temperature along these modules has been developed. The problem of critical flow regime has been discussed and a general formula of checking for the presence of sonic velocities at arbitrary cross section of the pipeline has been given. When embedded into a supervising procedure, the described routines can be used to build a mathematical model of a steam pipe network of arbitrary topology. Numerical examples are included. A set of equations describing all the steam properties used in the calculations is given in the Appendix.

Experimental analysis of heat conditions of the laser braze welding process of copper foil absorber tube for solar collector elements

In the case of laser braze welding, the heating technology and temperature distribution in the joint have a significant impact on the joint quality of solar collector elements, especially for joints of copper foil as thin as 0.2mm and with very low heat capacity with copper tube with a diameter of 8.0mm and a thickness of 0.5mm, thus being an element of much larger heat capacity. Electrolytic copper has a high thermal conductivity in the range of 400W/mK, which further impedes the heating

Study of titanium sheets HPDL welding phenomenon

Butt joints of titanium alloy Ti6Al4V (AMS 4928Q) thin sheets 1.0 and 1.5 mm thick were continuous-wave High Power Diode Laser (HPDL) laser welded. During course of experiments HPDL ROFIN SINAR DL 020 laser of maximum output power 2.3 kW and a rectangular laser beam spot of 1.8x6.8 mm at focusing distance 82 mm, and 1.8x3.8 mm at 30 mm was used. To provide precise positioning of the laser beam to weld joint and welding track, CNC positioning system was used. The heat input of surfacing was controlled by proper combination of the following parameters: laser beam spot size, beam spot position, laser power and welding speed. Bead on plate welds were produced, to avoid the influence of the sheet edges preparation, the joint fit-up, the welding gap and the laser beam alignment with the welding gap on the welding process. Special clamping device to provide total gas protection of weld root side was used and also special shape trailing shield was used to protect face area of the weld. The commercial grade argon and helium were used as shielding gases. Metallographic examinations and static and dynamic images of the weld pool have proved that the laser welding parameters have very strong influence on the shape of the weld pool, penetration depth, shape of the fusion zone and weld width.Butt joints of titanium alloy Ti6Al4V (AMS 4928Q) thin sheets 1.0 and 1.5 mm thick were continuous-wave High Power Diode Laser (HPDL) laser welded. During course of experiments HPDL ROFIN SINAR DL 020 laser of maximum output power 2.3 kW and a rectangular laser beam spot of 1.8x6.8 mm at focusing distance 82 mm, and 1.8x3.8 mm at 30 mm was used. To provide precise positioning of the laser beam to weld joint and welding track, CNC positioning system was used. The heat input of surfacing was controlled by proper combination of the following parameters: laser beam spot size, beam spot position, laser power and welding speed. Bead on plate welds were produced, to avoid the influence of the sheet edges preparation, the joint fit-up, the welding gap and the laser beam alignment with the welding gap on the welding process. Special clamping device to provide total gas protection of weld root side was used and also special shape trailing shield was used to protect face area of the weld. The commercial grade argon ...

Use of Matlab package for external local calibration of IR camera with microbolometric FPA detector

This work presents the method of improving the accuracy of temperature measurement results obtained by means of long-wave infrared camera equipped with focal plane array detector. The typical accuracy of infrared cameras specified by their manufacturers amounts to ±2 K or ±2 % of the measured value of temperature. Very often a better accuracy of the measurements is required, e.g. during the measurements of human body temperature. To improve the measurement accuracy an external correction of obtained results on the basis of comparison measurement of black body temperature and next with use of MATLAB package has been proposed. Nomenclature a - coefficient, constant, 1/K b - coefficient, constant 2 1 c c , - first and second radiant constant, respectively, W·m 2 or m·K C - calibration coefficient