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Thesis (Ph.D.) University of Adelaide, Dept of Mining, Metallurgical and Chemical Engineering, 1959. / Typewritten.

Thesis (Ph. D.)--University of Michigan, 1936. / Cover title. "By Jesse Coates ... and W.L. Badger." "This paper was presented at the twenty-eighth meeting of the American Institute of Chemical Engineers, Columbus, Ohio, November 13-15, 1935, and is reprinted from the Transactions, volume 32, no. 1." "Literature cited": p. 12.

Thesis (M.S.)--University of Michigan, 1958. / Project completed 1957. Degree awarded Feb. 1958.

Climbing film evaporators are in widespread use in the South African sugar industry, with the vast majority of the local sugar mills currently utilising these evaporators as first effect vessels in multiple effect evaporator sets. However, it is generally considered that the performance of these evaporators has not been maximised, and that improvements could be achieved by proper optimisation of the operating parameters. Unfortunately, very little comprehensive design information has been published in the literature. owing to the complexity of the heat transfer and hydrodynamic interactions in the evaporator tube. Attempts at performance improvement have been hampered by the lack of any theory to explain fully the effects of the operating parameters and physical properties of the feed liquor on the performance of the evaporator. In this study. a mathematical model of the climbing film evaporator system was developed in order to assess the effects of changing operating conditions on evaporator performance, based on as solid a theoretical foundation as cunendy possible. The model was tested against experimental data from a pilot plant climbing film evaporator and this experimental data was used to enhance the accuracy of the model by means of process identification. Because of the complexity of the model and the extensive computational time required for its solution, a simplified evaporator model was also developed, based on Iinearisation of the system of ordinary differential equations describing the climbing film evaporator system. This simplified model was used to predict trends in evaporator behaviour under various operating conditions. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.

PhD, Faculty of Engineering and the Built Environment, University of the Witwatersrand / In this study the heat transfer and frictional pressure drop performance characteristics of plate heat exchangers (PHE’s) used as refrigerant liquid overfeed evaporators were investigated. PHE’s have been gaining new applications in the refrigeration industry, especially as evaporators, during the last few decades, but the available information in the open literature for operation in this mode is rather limited. This study aims to extend the knowledge of PHE evaporator performance and to develop a model for use in evaluating heat transfer and pressure drop over as wide a range of operating conditions as possible. A laboratory experimental facility was constructed and the thermal-hydraulic characteristics of three middle-size industrial PHE’s were measured. The exchangers all had 24 plates of the same size but with different chevron angle combinations of 28°/28°, 28°/60°, and 60°/60°. Two sets of tests were carried out with the three units: single-phase performance tests with water, and evaporator performance tests with R134a and R507A, for which the exchangers operated as refrigerant liquid over-feed evaporators. The tests with water served to provide accurate water-side heat transfer information for the evaporator performance analysis which is the primary purpose of this study. In the evaporator performance tests, refrigerant flow boiling heat transfer and two-phase pressure drop data were obtained under steady conditions, over a range of heat flux from 1.9 to 6.9 kW/m2, refrigerant mass flux from 5.6 to 31.4 kg/(m2s), outlet vapour quality from 0.2 to 0/95, and saturation temperatures from 5.9 to 13.0 °C. Additional field data of thermal performance were collected on an ammonia and a R12 PHE water chiller, operating as thermo-siphon evaporators at their design working conditions. All experimental data were reduced and analyzed to obtain the refrigerant-side heat transfer coefficients and frictional pressure drops in the PHE evaporators. The heat transfer results showed a strong dependence on heat flux and a weak dependence on mass flux, vapour fraction and the chevron angle. Along with the ii observations from the ammonia and R12 evaporators, it is concluded that the dominating heat transfer mechanism in this type of evaporator is nucleate boiling rather than forced convection. In contrast to the heat transfer characteristics, the refrigerant two-phase frictional pressure drop was found to be strongly influenced by mass flow rate, vapour fraction and also the chevron angle. An almost linear increase of the frictional pressure drop with the homogeneous two-phase kinetic energy per unit volume was observed for both refrigerants. Based on the experimental data, correlations were developed for predicting the refrigerant boiling heat transfer coefficient and two-phase frictional pressure drop in PHE liquid over-feed evaporators. Two correlations were developed for boiling heat transfer, one of these reflecting the h-q relationship in pool boiling, the other with all constants and exponents determined by regression analysis. The mean absolute errors are respectively 7.3% and 6.8% for these correlations. For two-phase frictional pressure drop, data were correlated using two established methods, namely the homogeneous and the Lockhart-Martinelli methods, with means absolute errors of 6.7% and 4.2%, respectively. The homogeneous model showed a slightly higher discrepancy with the experimental data but is likely to be more physically sound for PHE evaporators, and is much simpler to apply. Validation of these correlations with other data has been difficult due to the shortage of published information. For other refrigerants operating at comparable conditions, these correlations should serve as a guide, while more accurate design or evaluation may need to be based on further testing. The performance analysis carried out in this study was based on systematic experimental investigations and field tests on industrial PHE units. Correlations were developed covering a rather extensive range of flow parameters, plate geometry and various refrigerants. Such correlations have not been reported previously for PHE liquid over-feed evaporators. The results simplify the performance analysis of PHE evaporators and provide a reliable thermalhydraulic model of PHE liquid over-feed evaporators, which can be used for system modeling of water-chilling machines employing this type of evaporator.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 107-109). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 107-109). Also available on the Internet.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-22Bitstream added on 2014-06-13T19:30:01Z : No. of bitstreams: 1 suguimoto_fk_me_ilha.pdf: 2910417 bytes, checksum: 0c31904819edbccc5cd91079714d3574 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho apresenta-se um modelo numérico para a simulação do escoamento e da transferência de calor, nos regimes permanente e transiente, ao longo de um evaporador do tipo roll-bond instalado no interior do gabinete de um refrigerador doméstico. Evaporadores roll- bond são amplamente utilizados na maioria dos refrigeradores domésticos no Brasil. A análise desse tipo de evaporador é de fundamental importância para a indústria de refrigeradores domésticos, uma vez que melhora o entendimento das trocas de calor envolvidas e, portanto, pode contribuir com a melhoria do desempenho do sistema. Divide-se o estudo em duas etapas: a modelagem do evaporador e a modelagem do gabinete. A análise do evaporador envolve o escoamento do fluido refrigerante no interior dos canais formados por duas chapas de alumínio justapostas, que formam a placa evaporadora. Tais canais são separados por filetes que atuam como uma aleta única, originando significativa transferência de calor por condução na placa evaporadora. As duas chapas de alumínio justapostas são consideradas como uma única placa plana vertical, com transferência de calor por condução nas direções horizontal e vertical. No lado externo a transferência de calor ocorre por convecção natural e por radiação entre a placa evaporadora e o gabinete do refrigerador. No interior dos canais do evaporador o escoamento é considerado unidimensional e dividido em uma região monofásica de vapor superaquecido e uma região bifásica líquido-vapor. Na região bifásica o escoamento é considerado homogêneo, ou seja, são consideradas condições de equilíbrio térmico e hidrodinâmico entre as fases. A influência da curvatura dos canais sobre o escoamento é desconsiderada e a queda de pressão no interior dos canais é considerada. A simulação do escoamento... / This works presents a numerical model to simulate the unsteady refrigerant fluid flow and heat transfer along a roll-bond evaporator installed inside the cabinet of a household refrigerator. Roll-bond evaporators are widely used in most household refrigerators in Brazil. The analysis of this type of evaporator is fundamental to the industry of household refrigerators. It improves understanding of the refrigerant flow and heat transfer and, therefore, could contribute to the improvement of system performance and energy savings. The model is divided into two stages, one for the evaporator and the other for the cabinet. The analysis of the evaporator involves the refrigerant flow inside the channel formed by powder-coated aluminum. This channel is separated by fillets that act as a single fin, causing significant heat transfer by conduction in the evaporator plate. The powder-coated aluminum channel is considered as a single vertical flat plate, where conduction heat transfer takes place along horizontal and vertical directions. Heat transfer by free convection and radiation between the evaporator plate and the air inside the cabinet is taken into account. The refrigerant flow inside the channel is divided in two regions: a two-phase flow, of liquid-vapor, and another of single-phase flow, of superheated vapor. The refrigerant flow is assumed to be one-dimensional and a homogeneous flow model is employed for the two-phase flow. The influence of the curvature of the channels on the flow is disregarded, although the pressure drop inside the channels is taking into account. The fundamental equations governing the flow through evaporator are derived from the mass conservation, momentum and energy conservation laws. The heat conduction equation is also solved to obtain the temperature distribution along the evaporator plate. A Finite Volume approach... (Complete abstract click electronic access below)

Orientador: André Luiz Seixlack / Banca: José Luiz Gasche / Banca: Ricardo Augusto Mazza / Resumo: Neste trabalho apresenta-se um modelo numérico para a simulação do escoamento e da transferência de calor, nos regimes permanente e transiente, ao longo de um evaporador do tipo roll-bond instalado no interior do gabinete de um refrigerador doméstico. Evaporadores roll- bond são amplamente utilizados na maioria dos refrigeradores domésticos no Brasil. A análise desse tipo de evaporador é de fundamental importância para a indústria de refrigeradores domésticos, uma vez que melhora o entendimento das trocas de calor envolvidas e, portanto, pode contribuir com a melhoria do desempenho do sistema. Divide-se o estudo em duas etapas: a modelagem do evaporador e a modelagem do gabinete. A análise do evaporador envolve o escoamento do fluido refrigerante no interior dos canais formados por duas chapas de alumínio justapostas, que formam a placa evaporadora. Tais canais são separados por filetes que atuam como uma aleta única, originando significativa transferência de calor por condução na placa evaporadora. As duas chapas de alumínio justapostas são consideradas como uma única placa plana vertical, com transferência de calor por condução nas direções horizontal e vertical. No lado externo a transferência de calor ocorre por convecção natural e por radiação entre a placa evaporadora e o gabinete do refrigerador. No interior dos canais do evaporador o escoamento é considerado unidimensional e dividido em uma região monofásica de vapor superaquecido e uma região bifásica líquido-vapor. Na região bifásica o escoamento é considerado homogêneo, ou seja, são consideradas condições de equilíbrio térmico e hidrodinâmico entre as fases. A influência da curvatura dos canais sobre o escoamento é desconsiderada e a queda de pressão no interior dos canais é considerada. A simulação do escoamento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This works presents a numerical model to simulate the unsteady refrigerant fluid flow and heat transfer along a roll-bond evaporator installed inside the cabinet of a household refrigerator. Roll-bond evaporators are widely used in most household refrigerators in Brazil. The analysis of this type of evaporator is fundamental to the industry of household refrigerators. It improves understanding of the refrigerant flow and heat transfer and, therefore, could contribute to the improvement of system performance and energy savings. The model is divided into two stages, one for the evaporator and the other for the cabinet. The analysis of the evaporator involves the refrigerant flow inside the channel formed by powder-coated aluminum. This channel is separated by fillets that act as a single fin, causing significant heat transfer by conduction in the evaporator plate. The powder-coated aluminum channel is considered as a single vertical flat plate, where conduction heat transfer takes place along horizontal and vertical directions. Heat transfer by free convection and radiation between the evaporator plate and the air inside the cabinet is taken into account. The refrigerant flow inside the channel is divided in two regions: a two-phase flow, of liquid-vapor, and another of single-phase flow, of superheated vapor. The refrigerant flow is assumed to be one-dimensional and a homogeneous flow model is employed for the two-phase flow. The influence of the curvature of the channels on the flow is disregarded, although the pressure drop inside the channels is taking into account. The fundamental equations governing the flow through evaporator are derived from the mass conservation, momentum and energy conservation laws. The heat conduction equation is also solved to obtain the temperature distribution along the evaporator plate. A Finite Volume approach... (Complete abstract click electronic access below) / Mestre