Papers by Keyword: Temperature Profile

Abstract: The solar parabolic trough collector technology is one of the most reliable technologies in the field of solar thermal. This is due to the fact that temperatures as high as 300-400°C can be achieved using this technology. This technology is used for hot water production, process steam requirement, power generation and many more. In the present work a thermal study on a parabolic trough collector is performed to observe the range of steam temperatures to be useful for small scale industry applications. The paper presents the steam temperatures, temperature profiles for the solar collector components and the solar radiation variation over the day. On the basis of several experiments it was found that in the parabolic trough collector the maximum pressure of 221 bar and the maximum steam temperature of around 374°C is achieved. From the experimental data obtained, the variation in temperatures with solar radiation on clear and intermittent cloud cover is discussed. From the results it can be concluded that this system may be used successfully for production of hot water and steam for use in many different industries such as dairy, textile, paper, timber, bricks, chemicals, plastics etc. Hot water and steam from solar system can be used in small scale industries for rose water making, cooking, drying, sterilization, food processing etc. In this paper a design for rose water making process through parabolic trough collector has been proposed. Keywords: Solar concentrator, parabolic trough, cylindrical parabolic collector, steam, temperature profile, industry applications.

Abstract: The influence of applying an external distributed pressure along the upper surface of the molten metal (Aluminum ) during the solidification process on the temperature reduction profile was studied including the time of solidification of the cast and the phase change moving boundary location for two mould wall thicknesses (10mm and 15mm). A 3D model was built up by Solidworks and simulated by ANSYS FLUENT; each mould wall thickness was discussed for two press cases (1bar and 3bar) sequentially, comparing with no press cases. The discussion includes the ambient temperature effect, which is taken (300K then 310K), the overall cases that studied was 7 cases. The study shows a remarkable effect of press on the temperature reduction profile especially when mix with the mould thickness effect as well as the ambient temperature which has a great order in guiding the results. The results showed that the heat reduction increases by increasing the mould thickness as well as the applied pressure. Moreover, this effect will reduce the solidification time and the moving of the boundary of phase change become faster in appearance.

Abstract: Nowadays, increase in numbers of automotive results in a large amount of used engine oil, which is a waste and has a tremendous effect on the environment. Used engine oil, however, has a relatively high calorific value so that it is interesting to be used this waste as a renewable fuel for heat generation. The present experimental study on used engine oil combustion in a vertical tube burner, therefore, had been conducted. The two-stage combustion was divided by the air supply to the burner into two levels and the air flow rate of both levels can be adjusted. The fuel in the first stage was heated and vaporized by the incompletes combustion. The exhaust gases and residual fuel vapor from the first stage were then flow to the second combustion stage and the complete combustion was achieved. The combustion temperatures along the length of the burner in both of the single and the two stage combustion had been measured and compared. Amount of exhaust gases at the exit of the burner was also monitored. The results revealed that the temperature profile along the length of the burner in the combustion zone of the two-stage burner was higher than those in the single-stage type as a result of a better mixing of air and fuel. In addition, it also found that an increase in a distance of air supply location between two stages resulted in an increase of the emission.

Abstract: This paper discusses the modeling of gas-tungsten arc welding (GTAW) process being adopted for maraging steel plates used in aerospace applications. Primary objective of this work is to predict the temperature profile of heat affected zone in a maraging steel weld. Finite element modeling was done utilizing a gaussian heat flux distribution on a weldment. Model also incorporated a moving heat source along with provision for heat sinks in the form of copper backup plates. For validating the model, welding experiments were conducted on 2 mm and 8 mm thick 250 grade maraging steel plates. Thermal profiles were acquired at different locations of heat affected zone using thermocouples and compared with the predictions from the model.

Abstract: Observing the latest manufacturing processes, the following tendencies can be noted: the gain of the energetic efficiency and shortening of the processing time with parallel preservation of the dimensions tolerance, shape tolerance and outer layer quality of the processed workpiece. Also the possibilities of gaining efficiency by rising criteria for process parameters are limited. It is mainly observed in the processing of hard machinable materials like titanium alloys or sintered carbides. Problems related to poor machinability were revealed during the final manufacturing processes using abrasive grinding [1,2]. In this work the results which have been presented are related to the influence by selected electrical parameters of the Abrasive Electrodischarge Grinding (AEDG) on the surface layer temperature of machined samples, in comparison to conventional grinding. Also the change in temperature during the AEDG has been depicted. The basis of this work is similar to the investigations of the deep grinding of surfaces of the titanium alloy Ti6Al4V using CBN and a diamond grinding wheel. For the comparative evaluation of the conventional grinding and AEDG, measurements of the specific grinding energy, energy of the spark discharge and internal stresses in the surface layer have been used.

Abstract: Process time reduction and energy/cost savings are usually in the focus of production process improvements. New technologies provide possibilities to achieve significant enhancements for relevant operation figures.Curing cycle times for CFRP manufacturing depend on several requirements: Type of resin, requested glass transition temperature, used equipment and energy source as well as sample size, weight, fibre volume ratio, fibre orientation etc. Conventional methods are mostly based on heat conduction while microwaves offer a selective and volumetric heating of the samples. Process time reduction and energy saving are the positive effects of the microwave curing technology.This paper will give an overview of the current status of this process technology not only focussing on technical aspects but also covering the process and economic effects.This work has been performed under the German BMBF project 02PJ2131, FLAME under the program Energy Efficient Light Weight Construction.

Abstract: Thermal modeling is a method used to formulate a temperature profile for a generator. The most common types of thermal model used by researchers are transient and steady-state model. There is insufficient of information regarding prolong usage of a generator in a confined space. The purpose of this paper is to formulate an empirical temperature model for the winding coils for the duration of 24 hours and to investigate whether a peak temperature exists. From the results, it can be concluded that there is a peak temperature detected for the winding coils in a non-controlled room temperature that occurs after 9 hours of experiment. The effect of room temperature on the winding coils temperature for no load condition is only 6.6%.

Abstract: The largest been realized installations of heat pumps in the Czech Republic, where the primary collector of low-potential heat is formed deep wells, is heating complex building of new Auditorium and CIT in campus of VSB Technical University of Ostrava. This building represents two independent functional units (Auditorium with side halls and Information Technology Centre - CIT) with a total floor area of 9234 m². The original project planned compound heating using district heating as a primary source of heat. Heating the object itself is a combination of floor heating systems and hot-air heaters. During project preparation has changed the project heating and a modern, technically unique and highly cost-effective solution has been designed with heat pump (type rock-water). Currently building heats 10 heat pumps with a total output of 700 kW through 110 wells with a depth of 130 m each. To assess the proportions of individual internal and external sources to the overall heat balance, the verification of systems designed for long-term monitoring of the behaviour of the rock massive around the energy used wells and energy storage options have been proposed and gradually implemented two research measuring polygons. They are located in the area of energy utilized wells. Each of the monitoring wells is instrumented with sensors at a certain depth. This article discusses the implementation of research polygons on experience with the excavation of wells using temperature sensors, a data acquisition system and finally outlines the possibilities of evaluating the measurement data.

Abstract: The spirally water wall are distributed on the plane and divided into seven sections. The mean heat flux of each section is determined using furnace thermal calculation in sections. The value of the pressure and temperature concerning the working medium at inlet and outlet of each tube are established by calculating enthalpy increasing. The vaporizing processes of the working medium in the spiral tube under the three working conditions: 70%BMCR, 65%BMCR and 60%BMCR are analyzed. The state of the working medium and the possibility of the heat transfer deterioration are estimated. More reliable references are provided for the appearance of the heat transfer deterioration.

Abstract: The modified Siemens process is the primary technology of polycrystalline production at present. The Siemens reactor, which is the main equipment in the modified Siemens process, consists of a chamber where several high purity silicon slim rods are heated by an electric current flowing through them. The temperature on the rod centre must be under melting temperature of silicon (1687K) in order to avoid its breaking-down because of an uneven temperature profile of the silicon rod. Therefore the temperature profile of the silicon rod heated by direct current (DC) has been investigated by molding. The current density profile of silicon rod has also been studied to investigate the interaction of current density and temperature. The results show that the temperature is not homogeneous in the rod and the temperature in the center of the polysilicon rod is 1750K which is much higher than the melting temperature (1687K) when the temperature is 1423K on the surface of polysilicon and the radius of rod is 5cm. Therefore, the maximum growth radius of the polysilicon rod in Siemens reactor should be less than 5cm when the joule heating generated by DC. The current density increases from the center to the surface of the polysilicon rod.