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Tepelná čerpadla ve vzduchotechnice / Heat pumps used in airconditioningGéryk, Ondřej January 2012 (has links)
This thesis deals with issues of heat pumps for air conditioning purposes. Mainly addresses itself with physical principles of heat pumps and with division of heat pumps according to natural resources, from which they draw heat energy. The next part of this thesis dedicates itself to experimental measurement of air conditioning unit, which in winter time operates on the principle of heat pump. The last part of this thesis is focused on design of two options of employment of heat pumps as sources of heat and coldness for a central air handling unit, which regulates incoming air for a dining room in a retirement home in Brno.
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Energetické hodnocení systémů VRF / Energy evaluation of systems VRFGašpár, Juraj January 2013 (has links)
This master thesis deals with VRF systems, which are used for extensive commercial and office buildings, or for buildings where there are multiple zones with different required parameters. The aim of the thesis is to explain the functions of the system and their evaluation and inclusion into energy classes according to the new legislation. The practical part deals with an application of the VRF system and its variants in the building of bank branch. The comparison of initials costs and resultant costs to operate the system. The experiment focuses on comparison of the measured values of VRF system and their comparison with data from the manufacturer.
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Klimatizace učeben a kanceláří / Air-conditioning of lecture rooms and officesBečvář, Jaroslav January 2008 (has links)
The diploma thesis is consisting of two parts. Forepart is a theoretic survey. It construes basic office of the air conditioning and deal with used air conditioner arrangements. More deeply it deals with air conditioner systems with refrigerant and the air conditioning for electronic equipments. Project of split system for air conditioning lecture rooms and schoolrooms, and units for air conditioning rooms with cluster and server is processed in the second part. Project is derives from calculation thermal stress of air conditioned space. There is calculated price of air conditioner system and made comparison offers of several accessible suppliers. Elaboration drawing documentation of project is part of the diploma thesis.
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Návrh tepelného čerpadla voda-voda / Water to water heat pump designJašek, František January 2012 (has links)
First part of my diploma thesis contains theoretical description of compressor based heat pumps, refrigeration cycle, main components of refrigeration cycle and auxiliary equipment. Second part contains the heat pump WATER-WATER desing. It will be used for heat recovery from cogeneration units in heating plants.
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ORC oběh pro využití tepla KJ / ORC cycle for waste heat utilizingVítek, Stanislav January 2013 (has links)
The aim of this diploma work is the study and the modeling of an Organic Rankine Cycle (ORC). Organic Rankine Cycle is used for heat recovery from low-potential heat sources. Their working fluid is a refrigerant or a hydrocarbon whose properties are adapted to the conditions in which the heat recovery is performed. The other chapters include the technical resolution of exhaust-heat exchanger of cogeneration unit for application ORC and partially economic study use in Czech Republic.
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Experimentelle und theoretische Untersuchung der thermophysi-kalischen Eigenschaften von Kohlenstoffdioxid, Ethan und Ethen im Gemisch mit niedrigviskosen PolyolesternGöpfert, Tobias 31 March 2021 (has links)
In einer Vielzahl von Kältemaschinen und Wärmepumpen werden ölgeschmierte Verdich-ter eingesetzt. Aufgrund ihrer Konstruktion kommt es zu einer Durchmischung des Arbeitsfluides mit dem eingesetzten Schmierstoff. Die thermodynamischen und Transporteigenschaften der so entstehenden Gemische können sich von denen der jeweiligen Reinstoffe deutlich unterscheiden. Für eine optimale Auslegung des Prozesses und der Komponenten ist daher die Kenntnis der Gemischeigenschaften notwendig. Für die Modellierung der Stoffdatenberechnungsalgorithmen ergeben sich jedoch Probleme, da eine Vielzahl von Eigenschaften des reinen Öles und des Gemisches nicht oder nur unzureichend genau vermessen werden können.
Durch den Ersatz von Kältemitteln mit hohem Treibhauspotential kann ein Beitrag zum Klimaschutz geleistet werden. Insbesondere das Kältemittel R23 sowie die Gemische R508A und R508B sind solche Kältemittel.Im Rahmen dieser Arbeit wird experimentell dargestellt, dass sich diese Fluide durch Gemische von Kohlenstoffdioxid und Ethan oder Ethen ersetzen lassen. Hierzu werden die Gefriertemperaturen der Gemische sowie der mögliche Ersatz von R23 dargestellt.
Im Rahmen dieser Arbeit wurden experimentell die thermophysikalischen Eigenschaften Dampfdruck, Mischungslücke, Flüssigkeitsdichte, dynamische Viskosität, spezifische iso-bare Wärmekapazität und Grenzflächenspannung von niedrigviskosen Polyolestern im Gemisch mit Kohlenstoffdioxid, Ethan und Ethen untersucht. Diese Schmierstoffe sind typi-sche Vertreter für die Anwendung in kältetechnischen Kaskadenanlagen mit dem Arbeitsfluid R23. Basierend auf den experimentellen Daten wird in dieser Arbeit dargestellt, wie sich mittels mathematischer und thermodynamischer Zusammenhänge Zustands- und Be-rechnungsgleichungen für die genannten thermophysikalischen Eigenschaften ableiten lassen.
Zur Anpassung der Form und Koeffizienten der Zustandsgleichung werden neben den ther-modynamischen Eigenschaften auch die Grenzflächenspannung und die dynamische Vis-kosität mittels des Ansatzes der Viskosität-Residualentropie-Korrelation verwendet. An-hand der Methode des hängenden Tropfens können die Grenzflächenspannungen experimentell abgeleitet werden. Die dabei wesentliche Tropfenkontur kann im Weiteren über die Grenzflächenspannung auch zur Anpassung der Zustandsgleichung und somit auch zur Ableitung anderer thermophysikalischer Eigenschaften genutzt werden.:Inhaltsverzeichnis
Kurzfassung
Nomenklatur
Abbildungsverzeichnis
Tabellenverzeichnis
Anhangsverzeichnis
1. Einleitung
2. Ziele der Arbeit
3. Tieftemperaturkältemittel für Anwendungen bis –100 °C
3.1 Thermophysikalische Eigenschaften von R23, R508A und R508B
3.2 Technische Anwendungen von R23 und R508A
3.3 Kohlenstoffdioxidgemische für Tieftemperaturanwendungen und potentielle R23-Ersatzstoffe
3.4 Kältemaschinenöle für Kälteanwendungen bis -100 °C
3.5 Untersuchte Fluide und Gemische mit Polyolestern
4. Berechnungsansätze zur Bestimmung der thermophysikalischen Eigenschaften der Stoffgemische
4.1 Berechnung von Fest-Flüssig-Gleichgewichten mittels der Schrödergleichung und deren Erweiterung
4.2 Ableitung von Phasengleichgewichten und thermodynamischen Zustandsgrößen aus der freien Helmholtz-Energie Fundamentalgleichung
4.3 Berechnung der Viskosität von Öl-Kältemittel-Gemischen mittels der Viskosität-Residualentropie-Korrelation
4.4 Berechnung der Oberflächenspannung der Öle und der Grenzflächenspannung der Gemische
4.5 Bestimmung der Koeffizienten und Terme der Zustandsgleichung mittels Messdaten und Strukturanpassung
5. Messapparaturen und Messdurchführungen zur Bestimmung der thermophysikalischen Eigenschaften der Gemische
5.1 Vorbereitung der untersuchten Fluide
5.2 Vermessung der Fest-Flüssig-Gleichgewichte von Kohlenstoffdioxid-Ethan und Kohlenstoffdioxid-Ethen Gemischen
5.2.1 Messapparatur zur Bestimmung von Fest-Flüssig-Gleichgewichte
5.2.2 Bestimmung der Fest-Flüssig-Gleichgewichte mittels der Rosini-Methode
5.3 Messapparatur und Auswertung der VLE- und LLE-Messungen von Öl-Kältemittel Gemischen
5.3.1 Messapparatur zur Bestimmung von VLE und LLE
5.3.2 Dampfraumkorrektur für isochore Messungen
5.3.3 Bestimmung der Form der LLE durch Vermessung der Mischungslückenteilvolumina
5.4 Vermessung der Dichte und dynamischen Viskosität der Öl-Kältemittel-Gemische
5.5 Messapparatur zur Bestimmung der spezifischen isobaren Wärmekapazität
5.5.1 Ermittlung der spezifischen Wärmekapazitäten mittels Kalorimetrie
5.5.2 Messapparatur zur Bestimmung der spezifischen isobaren Wärmekapazität
5.6 Optische Vermessung der Oberflächenspannung mittels der Methode des hängenden Tropfens
5.6.1 Ermittlung der Grenzflächenspannung von Fluiden in Gasatmosphären
5.6.2 Messapparatur zur Bestimmung der Oberflächenspannung
5.6.3 Auswertungsprozedur der Oberflächenspannungsmessung und Ableitung der Laplace- und Kapillarkonstanten
6. Messergebnisse der thermophysikalischen Stoffeigenschaften und Koeffizientenbestimmung
6.1 SLE von Kohlenstoffdioxid-Ethan und Kohlenstoffdioxid-Ethen-Gemischen
6.2 Mischungslücken der untersuchten Gemische
6.3 Dampf-Flüssigkeits-Gleichgewichte der Öl-Kältemittelgemische
6.4 Flüssigkeitsdichten der untersuchten Gemische
6.5 Dynamische und kinematische Viskosität der Stoffgemische
6.6 Spezifische isobare Wärmekapazitäten der Öle und Gemische
6.7 Grenzflächenspannung der Öl-Kältemittelgemische
7. Anlagentest zum Ersatz von R23 durch Kohlenstoffdioxid-Ethen-Gemische
7.1 Versuchsstand einer zweistufigen Kältekaskade
7.2 Vorbereitung, Durchführung und Ergebnisse der experimentellen Untersuchungen an einer zweistufigen Kaskadenkälteanlage
7.3 Verbesserungsvorschläge für den Einsatz von Kohlenstoffdioxid-Ethen-Gemischen als Ersatz für R23 in Kaskadenkältemaschinen
8. Kurzdiskussion der Ergebnisse
9. Zusammenfassung
10. Literaturverzeichnis
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Design and Construction of a Small Ammonia Heat PumpA Monfared, Behzad January 2010 (has links)
In view of the fact that most of the synthetic refrigerants, in case of leakage or release, are harmful to the environment by contributing in global warming or depleting stratospheric ozone layer, many research works have been done recently to find alternative refrigerants posing no or negligible threat to the environment. Among alternative refrigerants, ammonia, a natural refrigerant with zero Global Warming Potential (GWP) and Ozone Depletion Potential (ODP), can be a sensible choice.Although ammonia has been used for many years in large industrial systems, its application in small units is rare. In this project a small heat pump with about 7 kW heating capacity at -5 °C and +40 °C evaporation and condensation temperatures is designed and built to work with ammonia as refrigerant. The heat pump is expected to produce enough heat to keep a single-family house warm in Sweden and to provide tap hot water for the house. After successful completion of this project, it is planned to install the heat pump in a house to test it throughout a heating season to study its performance in real working conditions.Since ammonia is flammable and toxic in high concentrations, the refrigerant charge is tried to be kept low in the heat pump to reduce the risk of fire or poisoning in case of unwanted release of refrigerant to the surroundings. The compact design of the heat pump helps reducing the refrigerant charge. Besides, considering the limited space normally reserved for installation of a heat pump in a house, the compact design of the heat pump is necessary.
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Evaluation of CO2 Ice rink heat recovery system performanceThanasoulas, Sotirios January 2018 (has links)
Ice rinks are the largest energy consumers in terms of public buildings due to their simultaneous need of cooling, heating, ventilation, and lighting for different parts of the building which means that these facilities also have a lot of potential for energy saving. Due to the size of the cooling unit in an ice rink the refrigerant charge can become quite high, which potentially has a big impact on the environment. CO2 refrigeration units could cover all these challenges that are linked to ice rink operation. CO2 as a refrigerant has a very low impact on the environment and at the same time it could provide enough energy to cover the heating demands of an ice rink. CO2-based systems should operate in trans-critical mode which affects the performance of the refrigeration system, but by using the released heat that otherwise would be rejected to the ambience the total energy consumption becomes lower. The process of heat recovery is therefore vital for an efficient system. The refrigeration unit can produce enough energy to cover all the heating demands of an ice rink, but only when the heat recovery is controlled properly. The energy recovery method is very important, but it should also be tailored in order to cover all demands. This is because all the subsystems, i.e. demands, have different temperature and load requirements. The energy could be recovered in one or two stages from the refrigeration system. However, hardware is not enough in order to achieve proper operation, the system should also operate in the best conditions (discharge pressure and subcooling) in order to be efficient. The more proper operation, the less energy consumption. This energy recovery method could also be used as subcooling in climates where the ambient temperature is very high, making CO2 a very efficient solution. Regular refrigerants are still often used in warm countries despite their high environmental impact. A refrigeration system using natural refrigerants and more specific CO2 does not have constraints, however. The only limitation is the wrong operation. / Isrinkar är de största energikonsumenterna när det gäller offentliga byggnader på grund av deras ständiga behov av nedkylning, uppvärmning, ventilation och belysning. Detta innebär också att anläggningarna har en stor potential att effektivisera sin energibesparing. Isrinkar konsumerar stora mängder kylmedel på grund av deras storlekar, vilket potentiellt har en stor negativ inverkan på miljön. CO2 kylenheter skulle kunna klara av alla dessa utmaningar som är kopplade till isrinkens drift. Att använda CO2 som en kylarvätska har en ytterst liten inverkan på miljön och kan dessutom bidra med tillräckligt mycket energi för att täcka uppvärmningsbehovet för en isrink. CO2 baserade system bör köras i ett transkritiskt läge vilket påverkar kylsystemets prestanda, men genom att återanvända den utsläppta värmen som annars skulle gå förlorad till omgivningen så blir den totala energiförbrukningen lägre. Värmeåtervinningsprocessen är därför avgörande för ett effektivt energisystem. Kylaggregatet kan producera tillräckligt med energi för att täcka alla värmebehov för en isrink, men endast när värmeåtervinningen behärskas ordentligt. Energiåtervinningsmetoden är också väldigt viktig, men den bör skräddarsys för att täcka alla krav. Detta beror på att alla delsystem, dvs krav, har olika temperatur- och belastningskrav. Energin kan återvinnas i ett eller två stadier från kylsystemet. Tyvärr så räcker dock inte hårdvaran till för att uppnå en önskad drift, men systemet bör även fungera under de bästa förutsättningarna (utloppstryck och underkylning) för att vara effektiv. Ju bättre drift, desto mindre är energiförbrukningen. Denna energiåtervinningsmetod kan också användas som underkylning i varma klimat vilket gör CO2 till en mycket effektiv lösning. Vanliga typer av kylmedel används fortfarande ofta i varma länder trots att deras negativa miljöpåverkan. Ett kylsystem med ett naturligt kylmedel som till exempel koldioxid har emellertid inga begränsningar. Den enda begränsningen är den felaktiga hanteringen av driften.
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Biurų pastatų naudojant skirtingus šilumnešius vėsinimas / Cooling of office buildings using different coolantsKanapienytė, Rasa 15 June 2011 (has links)
Baigiamajame magistro darbe nagrinėjama problema – dideli energijos poreikiai vėsinimui biurų pastatuose, dėl vis didėjančių mikroklimato kokybės reikalavimų, didesnių šilumos pritekėjimų į patalpas ir šilumos išsiskyrimų dėl naudojamos įrangos. Problemos sprendimui darbe suprojektuotos keturios oro kondicionavimo sistemos su skirtingais šilumnešiais: oru, vandeniu ir freonu. Atsižvelgiant į šilumnešio tipą suprojektuotos ventiliatorinių konvektorių, aktyviųjų šalčio sijų, freoninė ir orinė vėsinimo sistemos. Oro kondicionavimo sistemos analizuojamos remiantis realaus tipinio administracinio pastato pavyzdžiu. Lyginamoms sistemoms buvo atlikti hidrauliniai ir aerodinaminiai skaičiavimai, įvertintos sistemų pradinės investicijos, apskaičiuotos energijos sąnaudos ir eksploatacijos išlaidos. Ekonominio skaičiavimo metu buvo įvertintas sistemų atsipirkimo laikas ir atlikta elektros kainų jautrumo analizė. Šio tyrimo rezultatai parodo, kokia sistema iš visų darbe nagrinėtųjų sistemų yra tinkamiausia biurų pastatams, pagal efektyvų elektros energijos naudojimą ir pradines investicijas. / The final master's work deals with the problem of high energy needs for cooling in office buildings, due to the growing of higher quality requirements for microclimate, higher heat gains in premises and equipment heat emissions used in. To solve the problem four different types of cooling systems with different coolants: air, water and refrigerant are designed at work. Depending on the type of coolant were designed fan coil units, active chilled beams, variable refrigerant volume system and air cooling systems. Air conditioning systems are analyzed on the basis of an example of the real typical office building. The hydraulic and aerodynamic calculations were made, initial investments, energy expenditures and operating costs were estimated for the compared systems. The pay-back time of the systems was assessed and the sensitivity analysis of electricity prices was carried out by economic calculations. The results of this investigation show, which system of all analysed systems at work is the most appropriate for office buildings, according to the efficient use of electricity and the initial investments.
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[en] EVALUATION OF THE GAS LOAD INFLUENCE ON AN AUTOMOTIVE AIR CONDITIONING SYSTEM / [pt] AVALIAÇÃO DA INFLUÊNCIA DA CARGA DE GÁS EM UM SISTEMA DE CONDICIONAMENTO DE AR AUTOMOTIVORAFAEL PRUDENCIO SACSA DIAZ 07 July 2003 (has links)
[pt] A tecnologia automotiva moderna alcança progressos
consideráveis tanto no aspecto mecânico como funcional, com
esses avanços tecnológicos, o maior progresso foi feito na
estrutura dos automóveis e dos sistemas de ar condicionado.
O presente trabalho é desenvolvido considerando a
importância da utilização de gás refrigerante, já que se
tornou um assunto ambiental de grande importância pelo
fato de ter um papel na destruição da camada de ozônio.
Foi construída uma bancada experimental que consta de duas
câmaras isoladas para a colocação do equipamento,
instrumentos, dispositivos de medição e geração de
carga térmica, em seguida foi montado um condicionador de
ar automotivo composto por componentes originais do sistema
de condicionamento de ar de um automóvel para simular
funcionamentos, com a finalidade de avaliar os parâmetros
de funcionamento afetados quando são utilizadas diferentes
cargas de gás refrigerante.
Foram realizados testes controlando a temperatura e umidade
constantes no habitáculo automotivo (câmara 1), para
variações de temperatura na câmara (2), da vazão mássica no
sistema e variações de torque e velocidade, no sistema
motor - compressor, com diferentes quantidades de gás
refrigerante originando situações de insuficiência de
carga, carga adequada e sobre carga.
Para o controle da carga térmica dentro das câmaras foram
utilizados controladores de potência e um software
aplicativo. Os parâmetros de operação do equipamento foram
obtidos e arquivados mediante um sistema automático de
aquisição de dados.
Os resultados experimentais mostraram o comportamento real
do ciclo de refrigeração, a queda de pressão nas linhas de
descarga e de sucção, assim como no condensador e no
evaporador. Apresenta-se o sub-resfriamento do refrigerante
na saída do condensador bem como o superaquecimento na
sucção. Verifica-se uma tendência politrópica, no lugar do
processo isentrópico do ciclo ideal. Esta divergência
do ciclo faz com que a temperatura de descarga do
compressor (T2) seja elevada.
A carga de gás refrigerante exerce influência no desempenho
de um sistema de condicionamento de ar e os resultados do
presente trabalho concordaram bem com as expectativas
teóricas do problema considerado. / [en] The modern automotive technology reaches considerable
progress s in the mechanical aspect as in the functional,
with these technological advances, the biggest progress was
made in the structure of the automobiles and in the air
conditioning systems. Considering the importance of the use
of refrigerant, the present work is developed, because the
refrigerant gas became a great importance ambient subject
for its paper in the ozone layer destruction.
An experimental bench was constructed; it consists of two
isolated chambers, where equipment, instruments, devices of
measurement and thermal load generation were installed.
After that, an automotive air conditioner was mounted, made
up of original components from an automobile air
conditioning system to simulate operation, with the purpose
to evaluate the operation parameters affected when using
different refrigerant loads.
Tests with constant temperature and humidity in the
simulated automotive chamber (1) for variations of chamber
(2) temperature, of mass outflow in the system
and variations of torque and speed in the motor-compressor
system were performed with different refrigerating amounts
creating situations of insufficient load, adequate
load and over load.
For the chambers thermal load controlling, power
controlling and appropriate software were used. The
equipment operational parameters had been gotten and filed
by means of an automatic data acquisition system. The
experimental results had shown the real behavior of the
refrigeration cycle, the pressure drop in the discharge and
suction lines, as well as in the condenser and the
evaporator. Also the refrigerant sub-cooling in the exit of
the condenser, the gas overheating in the suction, the
polytrophic trend instead of the ideal cycle isentropic
process was observed. This divergence from the ideal cycle
makes the discharge compressor temperature (T2) was higher.
The refrigerant gas charge influences the performance of an
air conditioning system and the present work results agreed
well with the theoretical expectations for the considered
problem.
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