Solar production of electricity

V této bakalářské práci jsou uvedeny základní způsoby přeměny slunečního záření na energii elektrickou. Stručně se zabývá vznikem slunečního záření a jeho následným dopadem na zemský povrch. Dále je zde historie fotovoltaiky a princip funkce fotovoltaických článků. V dalších kapitolách se pak zabývá druhy článků, konstrukcí fotovoltaickcýh panelů a možnostmi zvýšení jejich výkonu. V následujících kapitolách jsou pak probrány základní tepelné cykly využívané při nepřímě přeměně slunečního záření na energii elektrickou, jejich použití v různých aplikacích a nakonec jsou zde uvedeny možnosti využití získané elektrické energie z přímé i nepřímé přeměny.In this bachelor’s thesis are mentioned basic methods how to convert solar radiation into electric energy. Shortly introducing the origin of solar radiation and its subsequent lightening of the Earth surface. Then is here the history of photovoltaic and principle of function of photovoltaic cells. In next chapters are mentioned a variety of cells, construction of photovoltaic panels and methods, how to increase their productivity. In the following chapters are mentioned basic thermal cycles used for indirect conversion of solar radiation into electric energy, their usage in various applications. At last, here are mentioned ways of using the gained electric energy both from direct and indirect conversion.

Steam boiler for biomass and sand 92,5t/h

Tato diplomová práce se zabývá návrhem parního kotle spalujícího dřevní štěpku. Dřevní štěpka patří mezi biomasu a kotel by tak měl být šetrný k životnímu prostředí. Základem práce je výpočet velikosti a množství teplosměrných ploch tak, aby kotel produkoval páru o zadaných parametech teploty, tlaku a množství.This master’s thesis is dealing with design of steam boiler for wood chips. Wood chips are considered as biomass and so the steam boiler is considerate to enviroment. Main purpose of this work is calculation of size and number of water/steam heating surfaces so the boiler can produce steam with required parametres of temperature, pressure and amount.

OPERATING SPECIFICATIONS OF CATALYTIC CLEANING OF GAS FROM BIOMASS GASIFICATION

The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e., tar) in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate) from Horní Lánov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5%, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/mn3. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning

Optimalization of afterburner channel in biomass boiler using CFD analysis

This contribution presents the results of parametrical studies focused on the mixing process in a small rectangular duct within a biomass boiler. The first study investigates the influence of a local narrowing located in the central part of the duct. This narrowing works as an orifice with very simple rectangular geometry. Four different free cross sections of the orifice were considered in the center of the duct, namely 100 %, 70 %, 50 %, 30 % of free cross section area in the duct. The second study is focused on the investigation of the influence of secondary air distribution pipe diameter on the mixing process in a flue gas duct without a narrowing

Particulate Matter Produced by Micro-Scale Biomass Combustion in an Oxygen-Lean Atmosphere

This article extends earlier research by the authors that was devoted to the experimental evaluation of ultra-fine particles produced by the laboratory combustion of beechwood samples. These particles can have severe influence on human health. The current paper presents a parametrical study carried out to assess the influence of the composition of the atmosphere and the temperature on the production of ultra-fine particles during the micro-scale combustion process. The paper presents a laboratory procedure that incorporate the thermogravimetric analysis (TGA) and detailed monitoring of the size distribution of the produced fine particles. The study utilises the laboratory scale identification of the formation and growth of the fine particles during the temperature increase of beech wood samples. It also compares the particle emissions produced by beech heartwood and beech bark. The size of the emitted particles is very strongly influenced by the concentration of light volatiles released from the heated wood sample. From the experimental study, decreasing oxygen content in the atmosphere generally results in higher particulate matter (PM) production

The Effective and Ecological Burning of Biomass

Tato práce pojednává o tvorbě numerického modelu komory spalující biomasu na roštu. V rešeršní části práce jsou popsány základní vlastnosti biomasy s ohledem pro její spalování a samotný proces spalování biomasy, pro který je potřeba znát dynamiku chemických reakcí spalovacího procesu a celkový průběh spalování paliva na roštu. Popsána je také produkce škodlivých emisí, které spalováním biomasy mohou vznikat, a důraz je kladen hlavně na produkci oxidů dusíku. V další části je popsáno samotné zařízení a použitý základní matematický model, ve kterém jsou využity mechanismy přenosu tepla, proudění tekutin a transportu chemických látek. Základní matematický model je následně rozšířen na úplný matematický model určením počátečních a okrajových podmínek. Následně jsou uvedeny a okomentovány výsledky počítačové simulace vytvořeného modelu, které se týkají především produkce emisí oxidů dusíku a dehtů, a nakonec jsou tyto výsledky použity pro návrh úpravy geometrie zkoumané spalovací komory.This work deals with the creation of a numerical model of a biomass combusting chamber on a grate. The research part of this work describes the basic properties of biomass important for its combustion and the biomass combustion process itself. For this process which it is necessary to know the dynamics of the chemical reactions and the overall mechanism of a grate combustion of fuels. It also describes the production of harmful emissions that can be generated by combustion of biomass and the emphasis is mainly on the production of nitrogen oxides. In the next part is described the combustion device itself and the basic mathematical model which incorporates the mechanisms of heat transfer, flow of fluids and transport of chemical species. The basic mathematical model is then extended to a complete mathematical model by determining the initial and boundary conditions. Subsequently, the results of the computer simulation of the mathematical model are presented and commented. The main focus are the emissions of nitrogen oxides and hydrocarbons. These results are used to design an improvement of the geometry of the combustion chamber.

SIZE ANALYSIS OF SOLID PARTICLES AT THE EXPERIMENTAL DEVICE FOR MULTI-STAGE BIOMASS COMBUSTION

This paper presents the results of an analysis of ash content particles produced in biomass combustion at an experimental device. The main parts of the device are: the water heater, the gasifying chamber, the air preheater, and the fuel feeder. This device can be modified for combustion in an oxygen-enriched atmosphere. Sawdust and wood chips were used as fuel, and were laid loosely into the device. Ash specimens were extracted from various parts of the device. For the measurements themselves, we used the Analysette 22 MicroTec Plus universal laser diffraction device manufactured by the Fritch Company, in the size range from 0.08 μm to 2000 μm. The device utilizes laser diffraction for particle size analysis

Seasonal COP of an Air-to-Water Heat Pump when Using Predictive Control Preferring Power Production from Renewable Sources in the Czech Republic

The paper presents a parametric study evaluating the effects of various predictive controls on the operating parameters of heat pumps. The heat pump represents a significant power appliance in the residential sector. Its connection to the heat accumulator creates a system with considerable potential to control electricity consumption according to the needs of the electricity grid. The air-water heat pump is considered in this study. A predictive control is used for priority operation of the heat pump at periods of peak power production from renewable sources. The following were tested as the parameters of predictive control: outdoor air temperature, photovoltaic power production and wind power production. The combination of photovoltaic and wind power production was also tested. A parametric analysis considering different sizes for the thermal accumulator and the heating capacity of the heat pump were proposed. The benefits of predictive control are evaluated based on historical records of meteorological data from 2015 to 2018 in the city of Brno, Czech Republic. The data on the historical development of the real electrical energy production from renewable sources in the Czech Republic are used for regulation control in a monitored period. The main comparison parameter is the heat pump seasonal coefficient of performance (SCOP). From the carried out study results, an increase in SCOP by 14% was identified for priority operation of heat pump (HP ) at periods with highest outdoor air temperature. Priority operation of HP at periods with peak photovoltaic (PV) production increased SCOP by 10.25%. A decrease in SCOP only occurred in case with priority operation of HP at peak production of wind power plants. Increasing the size of the accumulator contributes to an increase in SCOP in all assessed modifications of predictive control

Provozní podmínky katalytického čištění plynu ze zplyňování biomasy

The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e,. tar) in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate) from Horní Lánov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5 per cent, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/m3n. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.Příspěvek se zabývá teoretickým popisem čištění energoplynu, vznikajícího při zplyňování biomasy a odpadů, pomocí katalytických metod a také ověřením teoretických předpokladů pomocí experimentů. Hlavním překážkou při využívání tzv. energoplynu vznikajícího při fluidním zplyňování organické hmoty je obsah celé řady výševroucích uhlovodíků, označovaných souhrnným názvem dehet. Odstranění dehtu z plynu je klíčovou otázkou pro jeho využití v dalších technologiích pro kogenerační výrobu elektrické energie a tepla. Jednou z možných metod sekundárního odstranění dehtu z energoplynu je katalytický rozklad dehtu s využitím přírodního nebo uměle vytvořeného katalyzátoru. V tomto konkrétním případě byl využíván katalyzátor přírodní, konkrétně dolomite uhličitan hořečnato-vápenatý) z locality Horní Lánov, který vykazuje dobré mechanické a katalytické vlastnosti pro tyto účely. Výhodou přírodních katalyzátorů oproti těm uměle vyrobeným je jejich snadná dostupnost, nízká cena a větší odolnost proti tzv. otravě katalyzátoru. Přírodní vápenaté katalyzátory jsou navíc schopny zachytávat take nežádoucí sloučeniny síry a chloru. V předloženém článku je uveden teoretický popis a analýza katalytického rozkladu dehtu na spalitelné složky plynu, vliv kalcinace dolomite na jeho účinnost a teoretické předpoklady jsou ověřeny pomocí laboratorního ověření účinnosti navržené metody. Ověření bylo provedeno na poloprovozní zplyňovací jednotce o výkonu 150 kW s laboratorním katalytickým filtrem. Dosažená účinnost odstranění dehtu byla až 99,5%, dosažené koncentrace dehtu splňovaly limity pro využití plynu ve spalovacích motorech, obsah dehtu se pohyboval okolo 35 mg/m3n. Výsledky měření na laboratorním zařízení byly použity pro návrh poloprovozní technologie katalytického čištění plynu