European Journal of Technology and Design

52-55

Authors: Abbas Salimi Fard, Farshad Farahbod

Experimental work is held to investigate how nanoparticle affects the hydrodynamic properties of the fluid. Nano zinc oxide particles with different diameters using different time duration with ultrasonic method are produced. Thermal conductivity enhancement, changes in viscosity, heat capacity, shear rate and density of nanofluid are compared with those in water base fluid.

61-65

Authors: Anastasiya B. Khorun

On-line monitoring systems allow assessing the condition of generator stator windings, bearings and the air gap are now widely employed by hydrogenerator plant operators. However, there is no on-line monitor that explicitly determines the condition of the rotor field windings. Although salient pole field windings tend to be very reliable, in each major outage plant personnel spend a considerable amount of time doing the ‘pole drop’ test, to assure themselves that there are no shorted turns on the field poles. In addition, the pole drop test may not be effective in detecting shorted turns in the standstill condition. Investigations have occurred to determine if rotor shorted turns can be detected at lower cost during normal generator operation by measuring the magnetic flux from each pole as it passes a probe that is placed in the air gap. The article presents the results of tests on several hydrogenerators which show that there is some promise in the method.

72-78

Authors: Olga V. Liyasova

The new method of short-circuit of coils protection in synchronous generator’s rotor winding is based on the circuit of Pot'e. The mathematical model is developed and researched, allows to determine the number of damaged coils in real time.

86-94

Authors: N.B. Sigimon, Jose K Jacob, A. Surendran

Thermal designing of an aftercooler typically includes the determination of heat transfer area ,number of tubes, tube length and tube diameter ,tube layout, number of shell and tube passes ,tube pitch, number of baffles, its type and size. CFD model of the after cooler had been developed and it is validated. Unexpected heat is generated at the after cooler of a 2HA4TERS, horizontally balanced opposed air compressor. This causes overheating and burning of the after cooler. This paper aims to determine the effect of variation in oil discharge in to the cylinder of the compressor by analyzing the CFD model of the after cooler. LMTD, Heat flow Q, Weight flow W, Clearance between the tubes C1,Baffle space B, Flow area a, Mass velocity G, Average temperature of the cold fluid ta, Average temperature of the hot fluid Ta, Reynolds number for heat transfer Re, Heat transfer coefficient in general h, for inside fluid hi, and for out side fluid ho, Value of hi when referred to the tube outside diameter hio, Clean overall coefficient of heat transfer Uc, Design overall heat transfer coefficient Ud and dirt factor Rd are determined by using Kerns method.