Combined electromagnetic and thermal design platform for totally enclosed induction machines

The aim of the thesis is to design a suitable thermal model that can be used as a tool for constructing the TEFC squirrel cage induction machine in addition to the electromagnetic model. A lumped-parameter thermal model is developed. The related problems and aspects of implementation are discussed in details. Losses are calculated analytically and the loss values are used in the thermal model. The sensitivity analysis is introduced to determine the most critical parameters of the model.

The energy efficiency of chilled beam systems in an office building at different climates

Besides the sustaining of healthy and comfortable indoor climate, the air conditioning system should also achieve for energy efficiency. The target indoor climate can be ob-tained with different systems; this study focuses on comparing the energy efficiency of different air conditioning room unit systems in different climates. The calculations are made with dynamic energy simulation software IDA ICE by comparing the indoor cli-mate and energy consumption of an office building with different systems in different climates. The aim of the study is to compare the energy efficiency of chilled beam systems to other common systems: variable air volume, fan coil and radiant ceiling systems. Besides the annual energy consumption also the sustainability of target indoor climate is compared between the simulations. Another aim is to provide conclusions to be used in the product development of the chilled beam systems’ energy efficiency. The adaptable chilled beam system and the radiant ceiling system prove to be energy efficient independent of the climate. The challenge of reliable comparison is that other systems are not able to reach the target indoor climate as well as the others. The complex calculation environment of the simulation software, made assumptions and excluding of the financial aspects complicate comparing the big picture. The results show that the development of the chilled beam systems should concentrate on energy efficient night heating, flexible demand based ventilation and capacity control and possibilities on integrating the best practices with other systems. 

Kestomagneettitahtikonekäyttöjen erot

Permanent magnet drives with nominal power over 10 kW were not a cost-sufficient system 25 years ago due to high material expenses. The improvements in motor drives, the rise in competition and the tightening of standards and regulations have caused that the PM-drives are more and more common in the over 10 kW nominal power range. The goal of this thesis is to research the performance in relation to nominal power of a PM-drive technique that is vastly increasing its popularity in fan related devices. The studied motor technique brushless direct current drive (BLDC) consists of a voltage source inverter, permanent motor and six-step-control. The reference drive is a brushless alternating current drive (BLAC) which consists of a VSI, PM and a hysteresis control. As a conclusion there are no major obstacles that would impede the BLDC-drive technique from expanding to larger power stages. The following factors must be taken into consideration when designing a BLDC-drive: motor’s current change rate, inverter switching frequency, motor’s nominal electric frequency, phase inductance and the current handling capability of the inverter. The fluctuating material costs create instability to the end prices of PM-motors that can in the worst case lead to diminished interest towards BLDC- and PM-drives in general.

Teollisuuspuhaltimien runkorakenteiden ja siipipyörien suunnittelu

Tämä diplomityö tehtiin Voikkaalla Dust Control Systems Oy:lle. Työ on osa teollisuuspuhaltimien tuotekehitystä yrityksen olemassaolevan puhallinratkaisujen, sekä suunnitteluprosessin kautta. Työn tavoitteena oli tutkia puhaltimen toiminnasta aiheutuvan värähtelyn vaikutusta puhaltimen rakenteisiin nykyisillä puhallinmalleilla, sekä tutkia eri rakenneratkaisujen käyttöä yrityksen normaalista tuotelinjasta suuremmilla puhaltimilla. Työ toteutettiin kahden toteutuneen puhallinprojektin yhteydessä, joiden rakenteellisia ominaisuuksia pyrittiin arvioimaan normaalin suunnitteluprosessin ohella puhallinkomponenttien mitoituksen suhteen. Molemmat projektit olivat yrityksen mittakaavassa huomattavan suuria sekä suunnittelultaan haastavia, joten ne sopivat diplomityön toteutukseen hyvin. Suunnittelussa käytettiin FE-mallinnukseen Femap ja COMSOL-ohjelmistoja, sekä värähtelyn simulointiin yliopistolla kehitettyä RoBeDyn – laskentaohjelmaa. Työn aikana todettiin, että tarkempi FE-mallinnus yrityksen valmiista 3D-malleista on varsin hankala toteuttaa ja vaatisi mallien suunnittelun erityisesti lujuuslaskentaa varten. Laskennassa päädyttiin käyttämään yksinkertaistettuja malleja, joiden avulla saatiin johdonmukaisia arvioita puhaltimien toiminnasta eri materiaalivahvuuksilla. Käytännössä tuloksien oikeellisuutta päästään arvioimaan kesällä 2015 puhaltimien valmistuttua.

Comparison of Model-Based Flow Rate Estimation Methods in Frequency-Converter-Driven Pumps and Fans

Fluid handling systems such as pump and fan systems are found to have a significant potential for energy efficiency improvements. To deliver the energy saving potential, there is a need for easily implementable methods to monitor the system output. This is because information is needed to identify inefficient operation of the fluid handling system and to control the output of the pumping system according to process needs. Model-based pump or fan monitoring methods implemented in variable speed drives have proven to be able to give information on the system output without additional metering; however, the current model-based methods may not be usable or sufficiently accurate in the whole operation range of the fluid handling device. To apply model-based system monitoring in a wider selection of systems and to improve the accuracy of the monitoring, this paper proposes a new method for pump and fan output monitoring with variable-speed drives. The method uses a combination of already known operating point estimation methods. Laboratory measurements are used to verify the benefits and applicability of the improved estimation method, and the new method is compared with five previously introduced model-based estimation methods. According to the laboratory measurements, the new estimation method is the most accurate and reliable of the model-based estimation methods.

Rigid body dynamics and Kalman filtering

X-ray computed log tomography has always been applied for qualitative reconstructions. In most cases, a series of consecutive slices of the timber are scanned to estimate the 3D image reconstruction of the entire log. However, the unexpected movement of the timber under study influences the quality of image reconstruction since the position and orientation of some scanned slices can be incorrectly estimated. In addition, the reconstruction time remains a significant challenge for practical applications. The present study investigates the possibility to employ modern physics engines for the problem of estimating the position of a moving rigid body and its scanned slices which are subject to X-ray computed tomography. The current work includes implementations of the extended Kalman filter and an algebraic reconstruction method for fan-bean computer tomography. In addition, modern techniques such as NVidia PhysX and CUDA are used in current study. As the result, it is numerically shown that it is possible to apply the extended Kalman filter together with a real-time physics engine, known as PhysX, in order to determine the position of a moving object. It is shown that the position of the rigid body can be determined based only on reconstructions of its slices. However, the simulation of the body movement sometimes is subject to an error during Kalman filter employment as PhysX is not always able to continue simulating the movement properly because of incorrect state estimation.

Reducing auxiliary power of a fluid bed boiler island

The aim of this thesis is to find and analyze different methods which reduce fluid bed boilers’ auxiliary power consumption. The objective is to examine the effects and feasibility of these methods. The literature part explains how fluid bed boilers work and what are the main sources of auxiliary power consumption. Designs and operation of these equipment are presented. The literature part also discusses the basics of auxiliary power consumption reduction and introduces four low pressure drop constructions. The experimental part inspects six different methods. Effects of these methods on the auxiliary power consumption are calculated and their impacts on the operation of the boiler are modeled. Calculations show that reasonable changes can reduce fluid bed boiler’s auxiliary power consumption by 2,1-10,2 %. Biggest reductions come from lower air coefficients, smaller bed a-level pressures and lower primary/secondary air –ratios. Models showed no problems with the smaller bed a-level pressures. With the lower air coefficients and smaller primary/secondary air –ratios the models showed a significant increase in the carbon monoxide levels.

Motor Types Comparison Determining Efficiency in Pumping Systems

Pumping, fan and compressor systems consume most of the motor electricity power in both the industrial and services sectors. A variable speed drive brings relevant improvements in a fluid system leading to energy saving that further on can be translated into Mtons reduction of CO 2 emissions. Standards and regulations are being adopted for fluid handling systems to limit the less efficiency pumps out of the European market on the coming years and a greater potential in energy savings is dictated by the Energy Efficiency Index (EEI) requirements for the whole pumping system and integrated pumps. Electric motors also have an International Efficiency (IE) classification in order to introduce higher efficiency motors into the market. In this thesis, the applicability of mid-size common electric motor types to industrial pumping system took place comparing the motor efficiency characteristics with each other and by analyzing the effect of motor dimensioning on the pumping system and its impact in the energy consumption.

Natural freeze crystallization : purification of aqueous Na2SO4 solutions with cold air

The aim of this thesis was to examine efficiency of freeze crystallization and eutectic freeze crystallization in purification of wastewater by imitating natural freezing. In addition, a mathematic model based on heat transfer to determine ice thickness and ice growth rate was examined. Also, the amount of sodium sulfate crystallized at the eutectic point was under investigation. In literature part, advantages and applications of the freeze crystallization are discussed, and possibility to apply it in Northern hemisphere winter weather conditions is under study. Furthermore, main sources of sodium sulfate from Finnish industries are described. The experiments were carried out in modified chest freezer, where a fan was placed in order to obtain laminar air flow inside. Picolog PT-104 data logger was used to monitor temperature changes in the salt-water solution, and constant temperature was maintained in the crystallizer with Lauda RP 850 thermostat. The impurity of formed ice layer was determined by weighing ice samples after experiment and again after 24 hours drying to full dryness in oven. Volume of salt-water solution was also measured after experiment. The highest purity of formed ice layer was obtained with small temperature difference and with long freezing time. On the other hand, the amount of crystallized sodium sulfate was its greatest with long freezing time and higher temperature difference. The results obtained by the mathematic model and empirical results did not differ significantly in most of the experiments. However, the difference increased when salt-water mixture reached its eutectic point, leading to simultaneous ice and salt crystallization. Eutectic point was reached only with the highest salt concentration with one exception. In these cases, calculated values were in many cases greater than the experimental ones. In winter weather conditions freeze crystallization is cost-effective wastewater treatment method and rather simple. Nonetheless, the efficiency and separation rate are strongly depended on ambient temperature and its changes

Prerequisites for commercialization of tube granulator for fly ash

A large amount of fly ash is produced in power plants and a big fraction of it ends up as waste to landfills. Disposal of fly ash to landfills is expensive for power plants due to for example waste taxation. However fly ash can utilized in different applications. Possibility of utilizing fly ash can be increased by granulation which also removes the dustiness problems of ash. This Thesis deals with the prerequisites for commercialization of a new granulation technique, tube granulation. Tube granulation technique utilizes water, calcium oxide in fly ash plus carbon dioxide and heat from flue gas. This Thesis determines the necessary auxiliary equipment for tube granulation, approaches for process dimensioning and implementation of the granulation process into a continuous power plant process. In addition, the economic benefits of tube granulation are examined from the user’s perspective. A continuous tube granulation process requires the following auxiliary systems to function: ash system, water feed system and flue gas system. Implementation of tube granulation system into a power plant process depends on the specific power plant but a general principle is that fly ash should be obtained to the granulator as fresh as possible and flue gas should be taken from the pressure side of a flue gas fan. Dimensioning of the process can be examined for example in terms of degree of filling and residence time in the granulator or in terms of granule drying. Determining the optimal dimensioning parameters requires pilot tests with the granulator.

Variable-speed-drive-based detection methods for problems in fluid handling systems

Fluid handling systems account for a significant share of the global consumption of electrical energy. They also suffer from problems, which reduce their energy efficiency and increase life-cycle costs. Detecting or predicting these problems in time can make fluid handling systems more environmentally and economically sustainable to operate. In this Master’s Thesis, significant problems in fluid systems were studied and possibilities to develop variable-speed-drive-based detection methods for them was discussed. A literature review was conducted to find significant problems occurring in fluid handling systems containing pumps, fans and compressors. To find case examples for evaluating the feasibility of variable-speed-drive-based methods, queries were sent to industrial companies. As a result of this, the possibility to detect heat exchanger fouling with a variable-speed drive was analysed with data from three industrial cases. It was found that a mass flow rate estimate, which can be generated with a variable speed drive, can be used together with temperature measurements to monitor a heat exchanger’s thermal performance. Secondly, it was found that the fouling-related increase in the pressure drop of a heat exchanger can be monitored with a variable speed drive. Lastly, for systems where the flow device is speed controlled with by a pressure measurement, it was concluded that increasing rotational speed can be interpreted as progressing fouling in the heat exchanger.