The characteristics of thermofluid flow cycle for natural refrigerants R-600a and R-290 applying to an air-conditioning system are studied in this project. In system performance analysis, The exergy analysis incorperated with heat transfer and fluid mechanics are also adopted to analyze the exergy transfer and destroy of each component and the whole system. The simulation parameters in this research include room temperatures, outdoor temperatures, and the types of refrigerants. If all the conditions remain constant except room temperature, the numerical results show that the coefficient of performance (COP) and the energy efficiency ratio (EER) will increase when the room temperature increases, or the outdoor temperature decreases. If all simulation conditions are the same, COP and EER with R-600a is better than those with R-290. By using exergy analysis, the numerical results show that the flow exergies through compressor and expansion valve will decrease due to the friction of the fluid flow. However, the flow exergies through condenser and evaporator will decrease due to finite-temperature heat transfer and energy carried away by exterior air. The destruction of the flow exergy due to the irreversibility of the frictional fluid flow is relative small to heat transfer. By using the exergy analysis, we can clearly understand the exergy change within each component of an air-conditioning system. This treatment is very useful in the design of air-conditioning systems and its optimum analysis.

Presently, auto manufacturers do not have do not have efficient or accurate methods to determine the amount of refrigerant (R-134a) in an air conditioning system of an automobile. In the research presented, vibration analysis is examined as a possible method to determine this R-134a amount. Initial laboratory tests were completed and experimental modal analysis methods were investigated. This approach is based on the hypothesis that the natural frequency of the accumulator bottle is a function of the mass of refrigerant in the system. Applying this theory to a working automotive air conditioning bench test rig involved using the roving hammer method—forcing the structure with an impact hammer at many different points and measuring the resulting acceleration at one point on the structure. The measurements focused on finding the natural frequency at the accumulator bottle of the air condition system with running and non-running compressor scenarios. The experimental frequency response function (FRF) results indicate distinct trends in the change of measured cylindrical natural frequencies as a function of refrigerant level. Using the proposed modal analysis method, the R-134a measurement accuracy is estimated at ±3 oz of refrigerant in the running laboratory system and an accuracy of ±1 oz in the non-running laboratory system. / Master of Science

Being located in subtropical area, the weather in Taiwan is hot and humid which imposing huge cooling load on buildings. Conventionally, central air-conditioning plants were designed using refrigerant compressors to make chilled water, and then pumped through the zone pumps to meet the cooling load, providing air-conditioning by Fan Coil Unit (FCU) or Air-Handling Units (AHU) by ductwork. To meet the varying cooling demand, two important systems were developed for energy savings, namely, the Variable Water Volume (VWV) system, and the Variable Air Volume (VAV) system, which has been widely adapted in Taiwan area. The working principle is mainly devoted to adjusting the volume of the chilled water and/or air volume delivered through inverter-driven pimps and fans to achieve energy saving. On the other hand, recently in Japan, an important energy-saving air-conditioning system has been developed which directly varying the refrigerant flow rate to meet the varying cooling demand by inverter-driven compressors, named VRV system. Comparative to the conventional air-conditioning system, the heat exchange mechanism of the VRV system has been effectively enhanced by direct exchange of the refrigerant and the cool air, which is in effect a combination of the VWV and VAV system. It provided huge energy saving potential for the application on buildings with moderate cooling loads, such as 100 USRT or so. It is the goal of this research project, to evaluate the performance of the VRV system in Taiwan¡¦s hot and humid climate, by performing full-scale experimental investigation so that energy savings effect can be validated quantitatively. Since VRV system is fairly new in Taiwan, the validation of the system performance under local weather condition is of particular importance. It is anticipated that through the changing of the operation conditions, such as different outdoor conditions, various partial load conditions, and different scheduling of the VRV system, the power consumption of the VRV vs. conventional system can be compared precisely and quantitatively. These experimental data will, in turn, provides valuable reference to the establishment of the building energy consumption index in Taiwan, which outwits the direct adoption of the foreign data such as from Japan, in achieving a much reliable database.

<p>Air conditioning, space heating, and refrigeration account for approximately 40% of the electricity usage in the U.S. residential and commercial building sector. To improve energy utilization and reduce energy consumption in space conditioning applications, advanced heat pumping technologies are needed. The chemical looping heat pump (CLHP) is a promising thermodynamic cycle that has shown the potential to achieve a cooling coefficient of performance (COP_c) increase of over 20% relative to conventional vapor compression (VC) systems.</p> <p><br></p> <p>The overarching goal of this study is to evaluate the chemical looping heat pump concept for residential applications, including thermodynamic potential, as well as technical and economic feasibility before developing and deploying a pilot scale system. The evaluation process includes advanced thermodynamic modeling for better assessments of working fluids and systems, techno-economic analysis for initial cost assessment of the scaled-up system, and small-scale experiments for proof-of-concept.</p> <p><br></p> <p>A working fluid screening process was developed to identify suitable working substance pairs for CLHP systems. The key metrics for evaluating the working fluids are associated with the possibility of phase change after a chemical reaction, reversible cell potential and power consumption, and cooling capacity of the system. Such metrics were applied to several fluids to assess their suitability. It was found that isopropanol/acetone working substances showed the highest cooling capability for a given power consumption. Even though this approach was applied to particular organic fluids (e.g., alcohols and ketones), this analysis can be generalized to other single-component fluids, multi-component fluids, and several chemical designs.</p> <p><br></p> <p>A modeling framework to estimate operating cost, capital cost, and levelized cost of energy was developed to enable a direct early-stage comparison of a CLHP with conventional VC systems. The models were helpful in understanding the influence of key factors such as efficiency, unit utilization (annual cooling and heating delivered, kWh_t/yr), and price of electricity ($/kWh_e) with the goal of determining target markets for initial CLHP products. The LCOE of CLHP could be less than that of VC in the case of high utilization (≥  20,000 kWh_t) with high performance improvements (COP_CLHP/COP_VC = 1.3) even though the capital cost of the CLHP is nearly 1.5-2 times higher than VC.</p> <p><br></p> <p>The key process of a CLHP cycle, which is electrochemically driven phase transformation, was experimentally demonstrated based on the advanced test rig and electrochemical cell. A polymer electrolyte membrane flow cell with a self-fabricated membrane electrode assembly and flow channels was employed to drive the reaction. The breakdown voltage analysis indicates that ohmic and mass transfer overpotentials account for more than 90% irreversibilities of the reactions. In addition, the results showed the possibility of phase transition of 20-30% at current density of ~0.003 A/cm² and the cell voltage of 0.025 V. The extent of a chemical reaction can be further improved by increasing the current and reducing the flow rate.</p> <p><br></p> <p>A semi-empirical cycle model was leveraged to predict realistic system performance. The model includes an electrochemical cell model with other component models in a CLHP cycle. The Second law efficiency was 50% of the Carnot limit with a cooling capacity of 2.24 mW (cooling density of 1.6 W/m²) at sink temperature of 40 °C  and source temperature of 23 °C. The cause for the precipitous drop in COP_c with increasing current density was overpotential, which requires further research on the optimization of membrane and catalytic materials as well as a geometry of flow channels to minimize the losses. Higher efficiency can theoretically be achieved at an elevated fluid temperature as long as an electrochemical cell can achieve a greater degree of conversion.</p> <p><br></p> <p>There are several challenges that should be reconciled in a future operational device and cycle at scale. Additional research on both material- and system-level performance is indispensable to meet practical size requirements. Nevertheless, this study is intriguing in terms of the possibility of developing a high efficiency device with the ability to use more environmentally friendly working fluids. Broadly, this CLHP research can contribute to accelerating the development of the newly emerging field, which is thermal systems coupled with electrochemical processes, that can maximize system efficiency using low-GWP fluids.</p>

Beim Betrieb von Raumlufttechnischen Anlagen ist eine Vielzahl von Vorschriften zu beachten. ...

This report shows the study performed at Taipei National University of Technology in Taipei to evaluate the performance of a solar air conditioning system. The performance is evaluated under Taiwan climate conditions. The research is performed under summer weather conditions. No influence is done on these conditions. A solar air conditioning system currently available on the market is used. No changes are made to the system. The work to be done is divided into different phases in order to guide the process. First, a literature research is done to find similar research done on this topic and to gain a basic understanding of the topic. Then several measurement plans are made to investigate different parts of the system.. Measurements are done. It is tried to developing a computer model in order to be able to simulate the system performance. The overall objective was to gain knowledge about a solar assisted air-conditioning system and develop a model to simulate the system. Initially a list of research questions was made in order to quantify ‘gaining knowledge’ about the system. The plan was to answer them by using measurement data and creating a model to perform simulations. There are measurements done in this report, however due to too many ‘unknowns’* it is difficult to draw conclusions from them. A lot of research questions are still open and they are also not included in this report. It is also not succeeded to make a working model of a solar assisted air conditioner. It is succeeded in making a model to predict the performance of the evaporator. This model is currently within 11% accurate.

The subject of the master's thesis is elaboration of the complete project design documentation of a administrative building, ready for implementation in the construction phase. The object is divided into four above-ground floors and one underground floor. It is divided into three blocks A, B, K and into three independent functional units. The prevailing part of building is administrative part, which is located in blocks A and B. In the basement there is a compound garage. Part of the building comprises of a service, a café, located and operated on the first floor above ground in block K. The individual blocks have separate entries and are without any mutal limitation to their independent operations. The building has a carrier system designed as a monolithic, reinforced concrete skeleton with two reinforced cores, placed on reinforced concrete feet. Ceramic fittings are slated for filling . The roof structure designed as a single-shell flat roof area, eventually vegetative. The facade is designed as ventilated with cement-bonded particle boards. Within the specialization is the solution of technical equipment, forced ventilation by means of air-conditioning system.

Der zunehmende Ausstoß von Treibhausgasen gilt als wahrscheinlichste Ursache für die beschleunigte Erwärmung des weltweiten Klimas in den vergangenen Dekaden [1]. Zur Begrenzung des Temperaturanstiegs auf maximal 2°C im Vergleich zum vorindustriellen Niveau wurden weltweit Ziele zur Reduktion der Kohlenstoffdioxidemissionen definiert. Maßnahmen zur Effizienzsteigerung im Klimatisierungssystem von Personenkraftwagen können hierzu einen doppelten Beitrag leisten. Zum einen wird der Gesamtenergiebedarf der Fahrzeuge reduziert. Zum anderen kann die Realreichweite elektrifizierter Fahrzeuge erhöht und damit die Marktdurchdringung der Elektromobilität gefördert werden. Ein entscheidendes Hindernis bei der Umsetzung von Effizienzmaßnahmen im Klimatisierungssystem ist das Fehlen einer vereinheitlichten Methodik zur Bewertung der Emissionseinflüsse [3] sowie der finanziellen Auswirkungen für Endkunden und die Automobilindustrie in den weltweiten Vertriebsmärkten. Im Rahmen der vorliegenden Arbeit wird eine solche Bewertungsmethodik entwickelt und das Emissionsvermeidungspotential von aktuell diskutierten Maßnahmen abgeleitet. Die Methodik kombiniert ein thermisches Kabinenmodell und ein vereinfachtes Modell des Klimatisierungssystems mit statistischen Daten zum lokalen Klima, dem lokalen, tageszeitabhängigen Mobilitätsverhalten und Daten der lokalen Energiemärkte (Preise und Emissionsintensitäten). Die Methodik betrachtet dabei jeweils fünf Karosserietypen und sechs Antriebssystemtypen für 61 Orte weltweit. Zur Bewertung von Kundenakzeptanz und Umsetzungsquoten der Maßnahmen wird als statistische Größe der relative Umsetzungsfaktor entwickelt. Er setzt sowohl die Emissionsbilanz als auch die Kostenbilanz für Kunden ins Verhältnis zur Schwankung der Werte in den einzelnen Vertriebsmärkten. Daraus werden eine Empfehlung zum Angebotsszenario und eine Abschätzung von Ausstattungsquoten abgeleitet. Auf Grundlage dieser Ergebnisse kann das weltweite Emissionsvermeidungspotential von einzelnen Maßnahmen oder Maßnahmenpaketen abgeschätzt werden. Eine Untersuchung von 20 aktuell diskutierten Maßnahmen zeigt, dass sich das aus dem 450-Szenario der IEA abgeleitete Reduktionsziel von jährlich 27 MtCO2 nicht ohne zusätzliche Kosten für Endkunden oder Automobilhersteller erreichen lässt. Die Emissionsvermeidungskosten sind mit 154 EUR/tCO2 jedoch deutlich geringer als für viele aktuell bereits umgesetzte Maßnahmen. Durch geschickte Anreizsysteme seitens der politischen Entscheidungsträger scheint daher eine Realisierung von großen Teilen des Potentials möglich.

Abstract: The aim of the study was to evaluate the indoor air quality (IAQ) of a semi-airtight (the building only utilises mechanical means to ventilate the occupied spaces however an airtight seal is not established as a result of infiltration due to building design) office building that is situated in central Johannesburg that exclusively uses a heating, ventilation and air-conditioning (HVAC) system for ventilation. This implies a system that only utilises mechanical ventilation to heat, cool, humidify and clean the air for comfort, safety and health of employees. This includes the control of odour levels, and also the maintenance of carbon dioxide (CO2) below stipulated levels. Methods: The building is divided into two sections; west and east. Each section has its own ventilation supply. A randomisation process was used to ascertain which offices needed to be sampled, in which section as well as on which floor. For this study, five offices per section were measured. Thus, ten offices per floor were measured and measurements were taken on every second floor. All measurements were done in accordance with the specific requirements of the manufacturer of any specific instrument used and measurements were taken over an eight hour period (full work shift). Results were compared to the available standard, as well as compared to the ambient concentrations. Results: None of the monitored contaminants’ concentration were above the provided standards (ASHRAE or ACGIH). Where standards were unavailable, the HVAC system maintained an indoor contaminant concentration that is substantially lower when compared to the outdoor air concentrations. Conclusion: The buildings’ HVAC system maintains indoor air quality at a healthy level it is unlikely that any one of these contaminants may lead to SBS amongst the employees. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

Submitted by William Justo Figueiro (williamjf) on 2015-06-26T22:57:56Z No. of bitstreams: 1 43.pdf: 3316113 bytes, checksum: 59a696189af2b9803f0adedd6828d93e (MD5) / Made available in DSpace on 2015-06-26T22:57:56Z (GMT). No. of bitstreams: 1 43.pdf: 3316113 bytes, checksum: 59a696189af2b9803f0adedd6828d93e (MD5) Previous issue date: 2012 / Banco Santander / Banespa / O trabalho apresenta um estudo do sistema de climatização do aeroporto da cidade de Porto Alegre, visando determinar e mensurar as oportunidades de redução dos seus custos operacionais utilizando o tanque de termoacumulação já existente, recurso que por razões diversas encontra-se atualmente inoperante. Para possibilitar uma avaliação global do comportamento do sistema em estudo, tanto a edificação do terminal de passageiros quanto os equipamentos integrantes da sua planta de climatização foram modelados e simulados através do programa EnergyPlus, com uso de arquivo climático específico para a cidade de Porto Alegre. As simulações ratificaram as previsões de que o sistema de climatização do aeroporto de Porto Alegre trabalha atualmente com custos de operação superiores àqueles que poderiam ser obtidos caso o sistema de termoacumulação estivesse em operação. A economia integrada ao longo de um ano pela redução de custos com as faturas de energia do aeroporto atingiu R$ 312.206,00. Ficou evidente que a redução da demanda e consumo de energia em horário de ponta são as parcelas com maior representatividade na diminuição dos custos operacionais do sistema de climatização do aeroporto, respondendo, respectivamente, por 77% e 18% sobre todas as economias obtidas nas faturas de energia após o uso da termoacumulação. Constatouse que além da redução nos valores pagos pela utilização de energia elétrica em horário de ponta, a participação da termoacumulação possibilita também redução no consumo energético dos equipamentos da planta de climatização, motivada por estratégias de operação mais eficientes. Desta forma, considerando apenas os meses de verão, as simulações apontaram uma redução média de 11% no consumo referente aos equipamentos da planta de climatização. Se para o mesmo período forem também contabilizadas as economias devido redução de demanda e consumo em horário de ponta dos equipamentos de climatização, a redução total sobre a fatura de energia do aeroporto a partir do uso da termoacumulação situase em 30%. Outra importante questão relacionada ao uso da termoacumulação diz respeito à ampliação da capacidade frigorífica que a mesma proporciona ao sistema de climatização, efeito de elevada relevância para fazer frente ao aumento na movimentação de passageiros da aviação civil dos últimos anos. Nesse sentido, as simulações apontaram um incremento de cerca de 25% na capacidade de refrigeração da planta atual, após participação do tanque de termoacumulação. Tal efeito representa notória contribuição ao aumento da longevidade das instalações existentes, limitando ou eliminando a necessidade de maiores intervenções para aumento de capacidade de refrigeração da planta até o momento em que o terminal de passageiros venha a sofrer ampliações mais significativas. / The study presents the heating, ventilation and air conditioning system (HVAC) used in Porto Alegre city airport, aiming cost reductions opportunities due to its cool storage tank operation, a feature that for various reasons is currently out use. To enable a comprehensive assessment of the system’s behavior, both the passenger terminal building and HVAC equipment were modeled and simulated using the EnergyPlus software, along with the weather file that contains Porto Alegre’s meteorological data. The simulations have reaffirmed the predictions that Porto Alegre’s airport HVAC system is currently working with operating costs above those that could be obtained if the cool storage system were in operation. The integrated economy over a year by reducing costs to the electricity bills from the airport reached R$ 312.206,00. It became notorious that the reduction of demand and energy consumption during the peak hours are the most representative from all economies, accounting respectively for 77% and 18% of the total energy bills savings after cool storage tank operation. It was found that, besides the reduction in the amounts paid for electricity at peak hours, the participation of cool storage also enables reduction in energy consumption for HVAC plant equipments, driven by more efficient operating strategies. Thus, considering only the summer months, the simulations showed an average reduction of 11% in HVAC plant equipment consumption. As for the same period, if it is also accounted for the savings due to electric demand and consumption reduction during peak hours, the total energy bill reduction for the airport after applying the cool storage tank stands at 30%. Another important issue related to the use of cool storage is the HVAC cooling capacity increase, very relevant if considering the terminal passenger handling increase along last years. In that sense, the simulations showed a 25% increase in cooling capacity for the current system after the cool storage has joined the HVAC plant. This effect is a noticeable contribution to the existing installations longevity, as it limits or eliminates the need for further increase in the airport cooling capacity, not until the time when the passenger terminal may suffer significant enlargements.