Miomir Raos

Testing of Level of Vibration and Parameters of Bearings in Industrial Fan

Climate chambers are a complex system of electromechanical components used for conditioning of air for providing comfort and projected parameters of temperature, humidity, velocity and air cleanliness in the area. In this paper is presented examination of the fan unit company Flaktwoods GJLB-5-071, 17.95 kW, n=1450 rpm, with a multi-functional device Vibrotest 60, the Danish manufacturer Bruel & Kjaer, for diagnostic of parameters of vibration and condition of bearing. The measured parameters are related to: - levels of vibrations (including measurement points on the motor and on the fan) in the directions of coordinate axes, according to ISO 10816-1. - parameters of condition of bearing through the index of bearing condition BCU (Bearing Conditions Unit) and BCS (Bearing Spectrum Conditions) - analysis of the characteristic frequency of vibration in the spectrum, presented by FFT (Fast Fourier Transformation).

Estimating the Effects of Environmental Conditions on Active Solar Wall Air Heating System Efficiency

AbstractThis study analyzed the effect of the environmental conditions on the thermal efficiency of an active solar wall with forced convection. The analyzed system is comprised of a double glass glazing and a massive wall with an opening and central channel in it. In order to increase the efficiency, we provided a fan at the bottom vent of the wall. The active solar wall is more advanced compared to the simple Trombe solar wall with a relatively low thermal resistance, which we took as a reference in our experimental analysis. This paper presents a one-dimensional steady-state mathematical model for simplified analysis of the efficiency of active solar wall air heating systems. We analyzed the obtained results in order to predict the effects of environmental parameter variations, such as solar radiation, ambient temperature, and wind velocity, on thermal efficiency.

Vibration Analysis of Insufficiently Repaired Well Pump - A Case Study

Vibration analysis of the repaired well pump is to determine whether vibrations occur due to an insufficient pump repair or due to some new malfunction that happened after the repair. This paper presents vibration analysis of well pump as well as the applied corrections in order to lower the vibration levels. Vibration measurement of well pump is conducted on measurement points defined by standard ISO 10816-1.

Vibration Analysis of the Boiler Supply Air Fan—A Case Study

The air supply fan is an important element for boiler operation, responsible for providing the necessary air flow with respect to the combustion process demands. Vibration measurements of the boiler fan were conducted on measurement points defined by standard ISO 10816-1. Vibration measurements were done with Bruel&Kjaer Vibrotest 60, vibration analyzer and offline data acquisition device. The measured parameters are related to: levels of vibrations, parameters of condition of bearing BCU (Bearing Conditions Unit) and BCS (Bearing Spectrum Conditions), analysis of the characteristic frequency of vibrations is presented on FFT Spectrum diagrams. Based on the analysis the main conclusion is: measured vibrations are high and fan is in the field of unstable work.

Simulation of fire spread between residential buildings regarding safe separation distance

Original scientific paper Determination of optimal safe distance between buildings is a task of many safety and economic analyses. Generally, it is known that increasing separation distance increases fire protection of an adjacent building, but decreases the cost effectiveness of urban solutions. For this reason, CFD Large Eddy Simulation method of Fire Dynamics Simulator software package has been used in this paper to determine optimal separation distance required for preventing fire spread between two residential buildings facing each other. The minimum conditions necessary for ignition of the window curtains in the fire-exposed building located at different building distances (3,5 m, 4,0 m and 4,5 m) were analysed. The obtained results show that the fire does not spread at the distance of 4,5 m, and that the incident heat flux at the curtain surface is higher than the critical heat flux value of 12,6 kW/m adopted in many building codes.

Simulation of hybrid electrical vehicle for two different driving modes

Original scientific paper This paper shows an example of computer simulation of hybrid vehicle in two different driving modes. This example shows multiple areas of operation of a simulated hybrid electric vehicle. The hybrid electric vehicle is of combined type, similar to Toyota Prius cars. This hybrid electric vehicle has two types of driving power: the electric motor and the internal combustion (IC) engine, to increase the level of efficiency of driving assembly and to reduce air pollution. A hybrid electric vehicle combines the advantages of electric motor drive (no pollution and high available power at low speeds) and the advantages of IC engine (high dynamic performances and little pollution at high speeds). In the simulation of a hybrid electric vehicle SimPowerSystemsTM and SimDrivelineTM (MATLAB) were used.