Дисертації з теми "Transcritical CO2"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-16 дисертацій для дослідження на тему "Transcritical CO2".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Yang, Chen. "Thermodynamic Cycles using Carbon Dioxide as Working Fluid : CO2 transcritical power cycle study." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50261.
Повний текст джерелаQC 20111205
Mureddu, Alessandro. "Thermodynamic analysis of an ORC plant and a transcritical CO2 plant for low temperature waste heat recovery." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Знайти повний текст джерелаBouteiller, Paul. "Etude expérimentale de cycles de pompe à chaleur utilisant des mélanges à base de CO2." Thesis, Paris, CNAM, 2017. http://www.theses.fr/2017CNAM1089/document.
Повний текст джерелаThe aim of this work is to experiment CO2 based mixtures as working fluids for heat pump applications in buildings, in order to enhance their performances compared to pure CO2 dual services heat pumps. Since adding other chemicals to CO2 moves the critical point and generally equilibrium lines, it is expected that lower operating pressures as well as higher global efficiencies can be reached. A simple stage pure CO2 cycle is used as reference, with fixed external conditions. Two scenarios are considered: water is heated from 10 °C to 65 °C for Domestic Hot Water (DHW) scenario and from 30 °C to 35 °C for Central Heating (CH) scenario. In both cases, water at the evaporator inlet is set at 7 °C to account for such outdoor temperature conditions. In order to understand the dynamic behaviour of thermodynamic cycles with mixtures, it is essential to measure the fluid circulating composition. To this end, we have developed a non intrusive method. Online optical flow cells allow the recording of infrared spectra by means of a Fourier Transform Infra Red spectrometer. A careful calibration is performed by measuring a statistically significant number of spectra for samples of known composition. Then, a statistical model is constructed to relate spectra to compositions. After calibration, compositions are obtained by recording the spectrum in few seconds, thus allowing for a dynamic analysis. Mixtures of CO2 & propane and CO2 & R-1234yf have been tested and showed great potential on enhancing performances of the heat pump for central heating applications
Bouzrara, Ali. "Etude expérimentale des éjecteurs : Application à la récupération de l'énergie de détente des machines frigorifiques au CO2." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI065/document.
Повний текст джерелаNatural refrigerants used in refrigeration and air conditioning have low GWP and are therefore a real alternative to HFCs. However, their generalization comes up against limits due to their toxic (NH3), flammable (hydrocarbons, NH3) or their unfavorable thermodynamic characteristics (CO2). Their increased use requires the implementation of specific components (intermediate heat exchangers, ejector) which without performance would be lower than those obtained with HFCs (COPCO2 = 55% of COPHFC-134a for temperatures source of 0 °C and 40 °C). The use of an ejector as an expansion device is a solution considered to reduce irreversibility. Two-phase ejector has been an interesting alternative for conventional expansion devices for several decades. The main advantage of the ejector is to recover some of the kinetic energy of the process of expansion from high pressure to low pressure to increase the suction pressure of the compressor. This results in a reduction of the work consumed by the latter and, consequently, an increase in the coefficient of performance of the system. Nevertheless, a good design of a two-phase ejector requires a detailed analysis in terms of numerical simulations and experimental work. Thus, the objective of this work is to make an experimental contribution to the study of transcritical CO2refrigeration machines equipped with two-phase ejector. Significant efforts have been invested in the design of a two-phase ejector with various geometries to evaluate the main characteristics namely the entrainment ratio and the compression ratio. The tests carried out made it possible to highlight the influence of the various geometrical parameters on the performances of the machine (different diameters of the throat of the primary nozzle, different mixers diameters and lengths, distance between the exit of the primary nozzle and the inlet of the mixer, the divergence angle of the primary nozzles ...) as well as the thermodynamic parameters (evaporation temperature, temperature at the inlet of the primary nozzle)
Goodman, Christopher L. "Modeling, validation and design of integrated carbon dioxide heat pumps and water heaters." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22560.
Повний текст джерелаSANTINI, FABRIZIO. "Impianti di refrigerazione a CO2 transcritici Caratterizzazione sperimentale ed analisi teoriche per l’ottimizzazione energetica." Doctoral thesis, Università degli Studi dell'Aquila, 2020. http://hdl.handle.net/11697/148279.
Повний текст джерелаSamakai, Elsie. "TRANSCRIPTIONAL CONTROL OF Ca2+ SIGNALING IN T CELLS." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/466164.
Повний текст джерелаPh.D.
Antigen presentation to T cells results in their activation through T Cell Receptor (TCR) stimulation, resulting in sustained elevation of cytosolic Ca2+ concentration critical for T cell activation. Sustained Ca2+ signals are important for the activation of Nuclear Factor of Activated T cells (NFAT), which is a key regulator of T cell activation through its transcriptional control of genes in multiple process including cytokine production, proliferation and differentiation(Rao, Luo, & Hogan, 1997). Recently it was shown that Stromal Interaction Molecule 1 (STIM1) inhibits plasma membrane Ca2+/ATPase 4 (PMCA4) function during T cell activation resulting in sustained elevation of Ca2+ signals(Ritchie, Samakai, & Soboloff, 2012). This interaction requires upregulation of both STIM1 and PMCA4. In this thesis, I hypothesize that changes in Ca2+ signals arising from transcriptional changes of STIM1 and PMCA are important for the efficient activation of T cells. In the first part of this thesis, I assess the transcriptional regulation of STIM1 and PMCA4. My in vitro studies show that expression of both proteins is regulated by the EGR family members, EGR1 and EGR4. Additionally, transcriptional regulation of PMCA inhibition by EGR1 and EGR4 is required for efficient activation of T cells. Interestingly, whereas significant roles for EGR1, EGR2 and EGR3 in T cell development and function have been established, a role for EGR4 has not, hitherto been elucidated. In the second half of this thesis, using qPCR, I reveal that EGR4 expression is stimulated by TCR engagement in primary double positive, CD4 and CD8 positive murine T cells. Further, EGR4-null mice exhibit shifts in early thymic development, although this does not affect the relative number of double or single positive T cells in the thymus. Interestingly, EGR4-null primary T cells exhibit normal Ca2+ entry, but fail to exhibit activation-induced inhibition of Ca2+ clearance. Although not all subsets of EGR1 and EGR4 null primary T cells exhibited decreased STIM1 expression, significant defects in proliferation, migration and/or cytokine production were observed upon stimulation in all populations, albeit to different extents. These findings reveal a two-faceted role in which EGRs regulate T cell development and function through both Ca2+-dependent and independent methods. I believe that these findings have important implications towards the general understanding of transcriptional control of Ca2+ signaling, as well as having a possible impact in the quest to advance therapies targeting immunological disorders.
Temple University--Theses
Rocha, Tomás Pinto de Freitas Teixeira da. "Modelling of a transcritical CO2 ejector with variable geometry." Master's thesis, 2021. https://hdl.handle.net/10216/135891.
Повний текст джерелаRocha, Tomás Pinto de Freitas Teixeira da. "Modelling of a transcritical CO2 ejector with variable geometry." Dissertação, 2021. https://hdl.handle.net/10216/135891.
Повний текст джерелаAvila, Rony Andre Sian, and 羅翔安. "Modeling and Simulation of Transcritical CO2 for Heat Pump and Dryer Applications." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/t85ag4.
Повний текст джерела國立交通大學
機械工程系所
107
In this thesis, a constrains-free transcritical CO2 heat pump model for medium and large system applications and a transient heat pump for clothes drying applications are developed. On each model, the detailed geometric characteristics of the major component are taken into account and, unlike existing models existing in literature applicable for CO2 system, the developed models do not impose constraints upon simulation, such as fixed operating pressures and constant temperatures. Yet, pressure optimization is also addressed and heat rejection pressure is modulated through a recent sophisticated generalized dimensionless log-linear correlation of the Poisson type. The models are tested against experimental data for a wide range of operating conditions and the results accurately reflected an actual system with a maximum error of 9.6% and 3.9% for the coefficient of performance and heating capacity, respectively. Moreover, the simulation results of both models are discussed and substantiated in the context of experimental results reported in literature. Yet, the generalized correlation employed for pressure optimization is also tested, validated and discussed thorough comparison to experimental data and other correlations available from literature. The correlation can accurately predict heat rejection pressure with an average error of 1.31% and a standard deviation of 4.26 bar, with a valid range of applicability for ambient temperatures from -18 to 50 °C, and within -7 to 15 °C and 10 to 50 °C for the evaporator and gas cooler outlet, respectively. Once the transcritical heat pump model, pressure optimization method and heat pump dryer models are validated, a fully transient heat pump dryer model is developed and simulated using CO2 and then R-134a, for comparison purposes. A standard performance test is carried out and employed later as the reference case when investigating the influence of relevant parameters affecting the overall performance of the system for both refrigerants. Subsequently, comprehensive parametric studies are conducted to identify relevant parameters influencing system performance. In this regard, simulations for both systems (CO2 and R-134a) are conducted for comparison purposes. Additionally, guidelines and control strategies to optimize system performance and highlight the advantages of transcritical CO2 systems are provided.
Janecke, Alex Karl. "A Comparison of Fault Detection Methods For a Transcritical Refrigeration System." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9717.
Повний текст джерелаMoreira, João Carlos Mendes. "Desenvolvimento de central transcritica CO2 com compressão paralela." Master's thesis, 2018. https://hdl.handle.net/10216/113599.
Повний текст джерелаMoreira, João Carlos Mendes. "Desenvolvimento de central transcritica CO2 com compressão paralela." Dissertação, 2018. https://hdl.handle.net/10216/113599.
Повний текст джерелаMoreira, João Carlos Mendes. "Desenvolvimento de central transcritica CO2 com compressão paralela." Dissertação, 2002. https://repositorio-aberto.up.pt/handle/10216/113599.
Повний текст джерелаMarques, Jose Soeiro. "Desenvolvimento de um modelo de dimensionamento de ejetores transcriticos com fluido de trabalho CO2." Master's thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/111220.
Повний текст джерелаMarques, Jose Soeiro. "Desenvolvimento de um modelo de dimensionamento de ejetores transcriticos com fluido de trabalho CO2." Dissertação, 2018. https://repositorio-aberto.up.pt/handle/10216/111220.
Повний текст джерела