Modeling and Testing of an R-23/R-134a Mixed Refrigerant System for Low Temperature Refrigeration

Low temperature refrigeration storage equipment in the biotechnology industry typically uses cascade refrigeration to achieve evaporating temperatures of -80 °C (-112 °F) or below. Current systems utilize multiple compressors leading to high energy consumption. Equipment operating costs contribute significantly to the total operating costs of biotechnology companies and therefore motivate the development of more efficient alternatives for low temperature refrigeration. This paper describes a single compressor R-23/R-134a mixed refrigerant cycle that has been designed to extract a load of 0.256 kW (873.5 Btu/hr) from a conditioned space at -80 °C (-112 °F). The designed system compresses a mixture of the gaseous refrigerants to a high pressure and then condenses the R-134a in a water-cooled separator while the R-23 remains in vapor phase. The stream of liquid R-134a is expanded to the suction pressure and is used to condense the R-23 that remains in vapor phase, operating much like an inter-stage heat exchanger in a cascade cycle. The condensed stream of R-23 then expands to the suction pressure and enters a low-temperature evaporator, where it absorbs energy from the load. A model of the cycle is developed based upon first and second law principles of thermodynamics and used to refine the design of a mixed refrigerant test apparatus. Theoretical analysis of the prototype system predicts that it will reach an evaporating temperature of -78.6 °C (-109.5 °F) when it operates with a mixture of 33.4% R-23 and 66.6% R-134a by mass. In experiments conducted using the same condensing temperature and mixture composition the mixed refrigerant apparatus reached an evaporating temperature of -75.0 °C (-103 °F), corresponding closely to the predicted temperature of -78.6 °C (-109.5 °F). To reach the desired evaporating temperature of -80 °C (-112 °F) the refrigerant mixture must be altered to increase the amount of R-23

Modeling And Testing Of R23/R134a Mixed Refrigerant System With Water Cooled Separator For Low Temperature Refrigeration

Low temperature (LT, -35 °C to -50 °C) and ultra low temperature (ULT, -50 °C to -100 °C) refrigeration is required in the life sciences industry for the production and storage of biological systems. The minimum practical storage temperature of a simple, single-stage refrigeration system is -30 °C, and this is incapable of meeting the requirements of biotechnology applications. Current LT and ULT refrigeration systems utilize cascade systems, which are combinations of single-stage refrigeration systems operating at successively lower temperatures. Because they use multiple compressors, cascade systems have higher capital and operating costs than simple single-stage vapor compression refrigeration systems. Equipment operating costs of LT and ULT refrigeration contribute significantly to the operating costs of biotechnology companies and therefore motivate the development of lower cost, higher performance refrigeration systems. One approach to achieving greater efficiency is the development of single compressor systems that utilize a refrigerant mixture and a condensing separator. After compression, the refrigerants are separated and follow refrigeration cycles similar in working temperature and pressure to cascade systems to achieve the desired temperature and heat load capacity. The refrigerant mixture streams are combined at the suction side of the compressor and compressed again to complete the cycle. This concept has the benefit of using a single compressor to reach low temperatures rather than the multiple compressors used in cascade systems. This work addresses the modeling, analysis and testing of a single compressor mixed refrigerant system (MRS) for low temperature applications. A model will be developed using first and second law principles of thermodynamics to calculate the refrigeration capacity, power consumption, coefficient of performance (COP), and second law efficiency. The model results will be validated through comparison with experimental results for a prototype system under steady-state conditions. Also, the model results will be explored to determine the impact of mixture composition on the system performance. Performance and benefits of the MRS will be compared to a similar cascade refrigeration system operating under similar conditions. The experimental performance of the prototype MRS will be used to make recommendations to advance the development of more efficient low temperature storage refrigeration systems

'Mr. Keats'

Full exploration of the implications of the surgical episode involving 'Mr Keats, one of the Surgeons belonging to Guy's Hospital' in March-April 1816.PostprintPeer reviewe

The divine agent in Intertestamental Judaism : the origins of the concept in the Hebrew tradition and its application in the figures of the the "Son of Man" in the Similitudes of Enoch and the "Logos" in the writings of Philo of Alexandria

Bibliography: pages 157-161.Many New Testament scholars have recently come to understand aspects of Christology in terms of the rabbinic legal concept of agency. Whereas Rengstorf attempted to understand apostleship in terms of the rabbinic agency concept (1964, first published 1933), works such as those of Borgen (1983, first published 1968), and Buehner (1977) attempt to explain the Johannine Jesus in such terms, following on Eduard "Zum religionsgeschichtlichen Hintergrund der "Sendungsformel" Gal .4:4f; Roem.8:3f; John 3:16f; I John 4:9", published in the Zeitschrift fuer die neutestamentliche Wissenschaft in 1966. The aim of this dissertation is to locate the roots of the concept of Divine Agency at the heart of the Hebrew tradition, rather than in later rabbinic abstractions, and to examine the development of the tradition from ancient times to the period contemporary with Jesus of Nazareth. Two figures, in works reflecting some of the diversity of Intertestamental Judaism and dating from the first decade of the Christian Church, have been selected for assessment as Divine Agents. These are the "Son of Man" in the Similitudes of Enoch and the "Logos" in the writings of Philo of Alexandria. While the rabbinic and other legal abstractions are not a valid ideal model for understanding Divine Agency, they are nevertheless useful in that they articulate concepts more concisely than is the case elsewhere. A brief treatment of the legal material is therefore included. This is followed by a survey of the development of the Hebrew religious tradition, with particular attention to the concept of the Divine Council assembled round the Throne of God. It is in the context of this tradition that messianic and other ideal figures emerged, and therefore in this context that the origins of the Divine Agency Concept are sought. The Agency idea is found to be well-attested in the Hebrew tradition, particularly during the post-Exilic period

Paul, Antioch, and Jerusalem: a study in relationships and authority in earliest Christianity

Paul's life and work, including his relationship with the Jerusalem church, were dynamic, rather than having been predetermined in his conversion. The Antiochene church was crucial to Paul's development, to a degree not previously appreciated. Little is known of the years following Paul's conversion, other than it was unsettled, and included travels and sojourns in Arabia, Damascus, Jerusalem, and Tarsus. The encounter with the Jerusalem church did not result in a stable relationship or social integration. It was at Antioch that Paul was first fully incorporated into a Christian community, from which he derived his dyadic identity, and later his apostolic commission. His relationship with the Jerusalem church consisted in corporate participation in the коιυυυία between the churches of Jerusalem and Antioch. In this context, Paul joined Barnabas in defending the Antiochene gospel of uncircumcision, and not his own theology or apostleship, at the Jerusalem conference. The Antioch incident resulted in Paul's separation from the Antiochene church, and exclusion from its коιυυυία with the Jerusalem church. His independent ministry followed, during which he developed his conception of apostleship independent of human authority, in which his self-identity is bound up with the gospel, in response to his isolation, and loss of dyadic identity and apostolic commission. Paul sought to end his isolation through reconciliation with the Antiochene church, and, through its коιυυυία, with the Jerusalem church. This was the object of the collection, but the crisis in Corinth delayed completion, requiring Paul to convey his offering separately. His implicit claim to коιυυυία accordingly became overt, and the collection became the basis, rather than a correlative obligation, of the relationship. This jeopardized the acceptability of Paul's overtures, and, while his reception is uncertain, the journey occasioned his arrest, and ended his missionary career

From Information to Sense-Making: Fetching and Querying Semantic Repositories

Information, its gathering, sharing, and storage, is growing at a very rapid rate. Information turned into knowledge leads to sense- making. Ontologies, and their representations in RDF, are increasingly being used to turn information into knowledge. This paper describes how to leverage the power of ontologies and semantic repositories to turn today’s glut of information into sense-making. This would enable better applications to be built making users’ lives easier and more effective

Reason, scepticism and politics: theory and practice in the enlightenment's politics

This thesis is concerned to discuss two related questions in political theory. First, the relationship of 'theory' and 'practice', concentrating specifically on the relationship between 'philosophy' and 'polities'; and, secondly, how the political theory of the Eighteenth Century Enlightenment is helpful in revealing an answer to the first problem. In order to encompass this dual task, the thesis is divided into three parts. Part One, 'Philosophy in its Place', delineates two trends in modern political thought that most explicitly bracket off the theoretical and the practical. It goes on to discuss the thesis of Alisdair Maclntyre in AFTER VIRTUE, that it was the Enlightenment that was, in fact, the intellectual origin of these two trends. Chapter Two of Part One, continues this discussion by considering recent adaptations of the central claims (such as that offered by Bernard Williams), and challenges to them from thinkers who emphasise the methodological importance of the history of thought (such as Maclntyre himself, and Richard Rorty). It concludes with an analysis of an issue central to the discussions of all three thinkers: incommensurability. Part Two, 'Theory and Practice in the Enlightenment’s Politics ', consists of three chapters which together offer an interpretation of the Enlightenment's reflections on the relation between theory and practice and, specifically, of the two thinkers most important for this question, Hume and Kant. The analysis also discusses rival interpretations and concentrates specifically on refuting Maclntyre's arguments in AFTER VIRTUE on the nature, character and implications of Enlightenment thought. Part Three, 'Bringing Philosophy Back In', ties these various threads together by first discussing the methodological questions set out in Part One in more detail, and then by showing how the Enlightenment's thought on this topic is still of the utmost importance for modern political theorists and why this should be so

Addressing the American Approach to Emerging Technologies: Utilizing the AI Arms Race to Highlight the Need to Develop Public-Private Partnerships in C4ISR and 5G

he world of emerging technologies has changed countries\u27 access and placement to these digital enablement tools of the future, with blockchain, decentralization, and a myriad of other compounding technologies accelerating the pace of development and growth combining the physical and the digital world. Historically, America\u27s Silicon Valley has led the world\u27s development of new technologies, particularly during the latter part of the digital revolution. In contrast, China focused on enhancing its manufacturing capabilities, becoming a world leader by capitalizing on the ever-connected world and leveraging its economic prowess. These roles became reversed in the early-2000s,1 when China first surpassed the United States in the output of artificial intelligence (AI)-specific scientific papers, demonstrating its commitment to becoming the world\u27s AI superpower. To solidify its emphasis on changing perceptions as a consumable goods manufacturer to a global leader in emerging technologies, the People\u27s Republic of China (PRC) unveiled its Made in China 2025 plan in May 2015.2 Made in China 2025 aims to invest in domestic innovations across 10 industries to reduce reliance on foreign technology and enable Chinese companies to compete globally. In this respect, the PRC\u27s plan to place emphasis on enhancing home-grown AI technologies serves as a cautiously aspirational tale of how critical public private partnerships are in terms of strategic competition. These partnerships are critical to drive innovation in AI and other fields as part of America\u27s shift to regain the competitive advantage