<p>Computer-Aided Concurrent Engineering Design (CACED) is an emerging field which stems from the realization that a holistic design approach, simultaneously considering all requirements, will result in systems that can be fielded quickly, and at the lowest practical lifetime cost. The philosophy inherent to CACED is that in a multi-faceted design arena, requirements such as cost, performance, reliability, produceability, size and supportability will conflict. Traditionally, designs are established then "audited" for compliance with various requirements. Subsequent "corrections" might then create new problems, but they certainly would slow the process and probably result in a less than optimum solution from the overall, long-term view.</p> <p> To concurrently (or simultaneously) consider numerous interdependent design issues, in order to optimize within constraints, requires an application-specific model and considerable computing power. The thrust of CACED is to develop appropriate models that allow designers to quickly establish and judge alternatives, simultaneously evaluating the compromises between often conflicting requirements.</p> <p>Computer hardware is readily available to perform design evaluation tasks--the challenge lies in establishing appropriate equations and a framework in which they are to be effectively used. This report explains CACED structure, illustrates a practical application to refrigeration system design, and suggests areas of further study.</p> / Master of Science

This dissertation presents experimental data correlations for the spatially - averaged convective heat transfer coefficient for thin walled closed containers during and after gas injection. The different modes of heat transfer were identified, and correlations were made for each. Correlations are presented for the injection period, post-top injection, post-bottom injection, post- tangential, post-radial injection, and post-ejection heat transfer for various tank geometries. Of special significance are the very high heat transfer rates that were shown to be present in some cases immediately after injection. Heat transfer rates were shown to be, for a short period, up to almost two orders of magnitude higher than the natural convection predictions would indicate.

Modifications to the quasistatic Carnot cycle are developed in order to formulate improved theoretical bounds on the thermal efficiency of certain refrigeration cycles that produce finite cooling power. The modified refrigeration cycle is based on the idealized endoreversible finite time cycle. Two of the four cycle branches are reversible adiabats, and the other two are the high and low temperature branches along which finite heat fluxes couple the refrigeration cycle with external heat reservoirs. This finite time model has been used to obtain the following results: First, the performance of a finite time Carnot refrigeration cycle (FTCRC) is examined. In the special case of equal heat transfer coefficients along heat transfer branches, it is found that by optimizing the FTCRC to maximize thermal efficiency and then evaluating the efficiency at peak cooling power, a new bound on the thermal efficiency of certain refrigeration cycles is given by $\epsilon\sb{m} = (\tilde\tau\sp2\sb{m}\ (T\sb{H}/T\sb{L}) - 1)\sp{-1},$ where $T\sb{H}$ and $T\sb{L}$ are the absolute high and low temperatures of the heat reservoirs, respectively, and $\tilde\tau\sb{m}=\sqrt{2}$ + 1 $\simeq$ 2.41 is the dimensionless cycle period at maximum cooling power. Second, a finite time refrigeration cycle (FTRC) is optimized to obtain four distinct optimal cycling modes that maximize efficiency and cooling power, and minimize power consumption and irreversible entropy production. It is found that to first order in cycling frequency and in the special symmetric case, the maximum efficiency and minimum irreversible entropy production modes are equally efficient. Additionally, simple analytic expressions are obtained for efficiencies at maximum cooling power within each optimal mode. Under certain limiting conditions the bounding efficiency at maximum cooling power shown above is obtained. Third, the problem of imperfect heat switches linking the working fluid of an FTRC to external heat reservoirs is studied. The maximum efficiency cycling mode is obtained by numerically optimizing the FTRC. Two distinct optimum cycling conditions exist: (1) operation at the global maximum in efficiency, and (2) operation at the frequency of maximum cooling power. The efficiency evaluated at maximum cooling power, and the global maximum efficiency may provide improved bench-mark bounds on thermal efficiencies of certain real irreversible refrigeration cycles.

A computer model of a fin and tube air-to-air heat exchanger is presented. The model incorporates a computational scheme to account for latent effects due to small amounts of moisture in one or both fluid streams. A testing program is described which was performed in order to mathematically characterize the heat transfer and pressure drop relationships of the tube with turbulator used in the heat exchanger. These relationships are included in the computer model. A comparison of the computer model to heat exchanger test data indicates that the computer model may be relied upon to provide design and analysis information. Finally, a parametric study is performed using the computer model in order to explore the characteristics of the heat exchanger and to demonstrate its usefulness to the heat exchanger designer. It is concluded that, in addition to presenting an analysis tool for heat exchanger design, there are several important secondary results. These include: verification of the modelling techniques, the analytical description of the tube with turbulator and, identification of a problem area in the header design.

Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 191-196). Also available in electronic format on the Internet.

This experim ental project aims to describe the influencing factors in the vacuum boiling o f w ater in w ater vapour refrigeration system s Testing was conducted using a 2 kW three-stage steam je t ejector system, w ith barom etric condensers, as the com pression device. Three direct-contact evaporators were used to investigate the boiling phenom ena. T hese were : a through-flow evaporator w here heal and mass transfer rates were established for boiling m echanism s at various positions within the evaporator; a vertical cylinder where small quantities o f w ater were subjected to rapid decom pression and the effects m easured, and a sim ple channel for photographic studies o f the process. Boiling in direct-contact water vapour systems is described herein The vacuum boiling proo ss was found to be controlled by a com bination o f the w ater surface tem perature and the hydrostatic pressure gradient, these being governed by the w ater vapour flow geometry between the w ater surface and ejector suction and convective heat transfer below the boiling region. The contributions o f the various boiling regim es to the total heat transfer are discussed. Heat and mass transfer coefficients and their applicability to evaporator design are presented

近年來微型製冷系統有許多應用。例如，電子器件的冷却是研製更快速、更小型和更可靠的芯片的重要課題, 隨著電子芯片功耗的增加，散熱量不断增長，傳統的被動式散熱方法已經過時，新的主動式散熱方法成爲必須。又例如微型個人冷卻系統可用於救火等各種惡劣環境。与其它製冷方法相比，蒸氣壓縮製冷技術是最有潜力的方法。 / 本文闡述了两种微型蒸氣壓縮製冷系統的研製工作：一是電子冷却系统，一是個人热舒适系统。研究主要包括以下幾個方面： / 1) 微型蒸氣壓縮製冷系統的熱力學分析。對系統在不同工作條件下（包括壓縮機效率、環境溫度等）的性能進行了分析。对換熱器的設計也作了详述。 / 2) 微型蒸氣壓縮製冷系統的熵分析。通過分析發現，壓縮機和系統漏熱造成的熵是產生系統不可逆性的主要因素,因此高效的壓縮機和降低系統漏熱是提高微型蒸氣壓縮製冷系統性能的關鍵所在。 / 3) 實驗系统的詳細介紹。一共做了两套微型蒸氣壓縮製冷系統，一为電子冷卻系統和一为個人冷卻系統。爲了縮小微型蒸氣壓縮製冷系統的尺寸，系統的元件必須小型化。系統的壓縮機是在市場上直接购買的，但是換熱器包括冷板蒸發器、管翅式蒸發器和微通道冷凝器都是特別設計和製造的。實驗裝置建成可以方便的改變工作條件，諸如壓縮機轉速、製冷劑充灌量、毛細管長度、換熱器面積等。 / 4) 對電子冷卻系統和個人冷卻系統分別進行了實驗。對於電子散熱系統來，當發熱管的功率為200瓦時，冷板溫度可以控制在大約60攝氏度。系統的熱力學完善度在0.23到0.31，而壓縮機的效率介乎40%至65%。對個人冷卻系統來，系統製冷量可達321瓦，其性能係數達到4.59。系統的熱力學完善度為0.21 ~ 0.27。 兩种系統的熱力學完善度都與當前家用製冷系统的熱力學完善度相似。相信不久的将来会有不少应用。 / Micro refrigeration systems are being increasingly used nowadays. One example is electronic cooling. With the rapid advancement of chips, traditional passive heat dissipation techniques are becoming obsolete and hence, new active cooling techniques become necessary. The other example is the personal thermal comfort system demanded by people working in the hazardous environment, such as fire fighting. Among various cooling methods, Vapor Compression Refrigeration (VCR) is the most promising method. According literatures, however, few miniature refrigeration systems are available. / This thesis presents two Miniature Vapor Compression Refrigeration (MVCR) systems, one for electronics cooling and the other for personal thermal comfort. In particularly, following aspects are focused: / 1) Thermodynamic analysis. The thermodynamic models of the systems are developed and the performances are studied under various working conditions including compressor efficiencies, ambient temperature and so on. / 2) Entropy analysis. It is found that entropy of the compressor and the heat leakage play crucial roles. High efficient compressor and the heat leakage minimization are very important. / 3) Prototype building. Two prototypes are built: one for electronics cooling and the other for personal thermal comfort. The miniature compressors are purchased from market. The heat exchangers, including the cold pate, tube-fin evaporator and micro channel condenser, are custom designed and made. / 4) Experiment testing. The two prototypes are tested under various working conditions such as compressor speed, refrigerant charge and capillary tube length. For the electronics cooling system, the cold plate temperature could be maintained at about 60 ºC under the 200 W heater power input. The second-law efficiency of the system varies from 0.23 to 0.31; and the compressor efficiency is between 40% ~ 65%. For the personal thermal comfort system, its capacity could reach 321 W with 100 g refrigerant charge, 1200 mm capillary tube length, and the compressor speed of 4503 rpm. The COP is 4.59 and the second-law efficiency is between 0.21 ~ 0.27. The performances of the two systems are comparable to that of the current domestic refrigeration systems. Therefore, it is expected that they will find some practical applications in the near future. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wu, Zhihui. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 99-110). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.I / Acknowledgement --- p.IV / List of Tables --- p.VIII / List of Figures --- p.IX / Nomenclature --- p.XII / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Backgound --- p.1 / Chapter 1.2 --- Thesis Outline --- p.5 / Chapter Chapter 2 --- Literature Review --- p.6 / Chapter 2.1 --- History of Refrigeration --- p.6 / Chapter 2.2 --- Availabe Refrigeration Methods --- p.7 / Chapter 2.2.1 --- Heat pipe and vapor chamber --- p.9 / Chapter 2.2.2 --- Thermoelectric cooler --- p.10 / Chapter 2.2.3 --- Stirling refrigerator --- p.10 / Chapter 2.2.4 --- Pulse tube refrigerator --- p.11 / Chapter 2.2.5 --- Absorption refrigerator --- p.12 / Chapter 2.3 --- Vapor Compression Refrigeration System --- p.14 / Chapter 2.3.1 --- Development of the miniature refrigeration system --- p.15 / Chapter 2.3.2 --- Development of the miniature compressors --- p.20 / Chapter 2.3.3 --- Development of the micro heat exchangers --- p.24 / Chapter 2.3.4 --- Applications --- p.28 / Chapter Chapter 3 --- System Analsysis and Components Design --- p.29 / Chapter 3.1 --- A Brief Review of a Typical VCR System --- p.29 / Chapter 3.1.1 --- Refrigerant comparison --- p.33 / Chapter 3.1.2 --- Effect of the compressor efficiency --- p.34 / Chapter 3.1.3 --- Effect of the ambient temperature --- p.35 / Chapter 3.1.4 --- Effect of the evaporator temperature --- p.36 / Chapter 3.2 --- Analysis on Entropy Generation of a MVCR System --- p.37 / Chapter 3.2.1 --- Derivation of coefficient of performance --- p.38 / Chapter 3.2.2 --- Entropy generation calculation for a MVCR system --- p.39 / Chapter 3.3 --- System Design --- p.46 / Chapter 3.3.1 --- System Configuration --- p.46 / Chapter 3.3.2 --- Heat Exchanger Design --- p.47 / Chapter 3.3.2.1 --- Condenser design --- p.48 / Chapter 3.3.2.2 --- Cold plate design --- p.50 / Chapter 3.3.2.3 --- Tube-fin evaporator design --- p.51 / Chapter Chapter 4 --- The MVCR System for Electronics Cooling --- p.55 / Chapter 4.1 --- Experimental Setup --- p.55 / Chapter 4.1.1 --- Components --- p.55 / Chapter 4.1.2 --- Instrumentation --- p.61 / Chapter 4.1.3 --- Testing plans --- p.63 / Chapter 4.1.4 --- Data reduction --- p.64 / Chapter 4.1.5 --- Uncertainty analysis --- p.67 / Chapter 4.2 --- Results and Discussion --- p.68 / Chapter 4.2.1 --- Effect of the compressor speed --- p.68 / Chapter 4.2.2 --- Effect of the refrigerant charge --- p.70 / Chapter 4.2.3 --- Effect of the capillary tube length --- p.71 / Chapter 4.2.4 --- Cold plate temperature comparison --- p.72 / Chapter 4.2.5 --- Location of the Cartridge heater --- p.76 / Chapter 4.2.6 --- System efficiency --- p.78 / Chapter 4.2.7 --- Thermal resistance --- p.81 / Chapter 4.3 --- Summary --- p.83 / Chapter Chapter 5 --- The MVCR System for Personal Cooling --- p.85 / Chapter 5.1 --- Experimental Setup --- p.85 / Chapter 5.2 --- Results and Discussions --- p.87 / Chapter 5.2.1 --- Effect of the compressor speed --- p.87 / Chapter 5.2.2 --- Effect of the refrigerant charge --- p.88 / Chapter 5.2.3 --- Effect of the capillary tube length --- p.89 / Chapter 5.2.4 --- Effect of the evaporator area --- p.90 / Chapter 5.2.5 --- Effect of the evaporator fan speed --- p.91 / Chapter 5.2.6 --- System efficiency --- p.92 / Chapter 5.3 --- Summary --- p.94 / Chapter Chapter 6 --- Conclusions and Future Work --- p.96 / Chapter 6.1 --- Conclusions --- p.96 / Chapter 6.2 --- Future Work --- p.98 / Bibliography --- p.99

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1. A Diffusion-Absorption-Refrigeration (DAR) system for air conditioning (DAAC) is developed. It is directly driven by heat, uses a bubble pump to replace the mechanical pump, uses three-component working fluid, and operates under the same system pressure level. Hence, it is quiet, long lasting and environmental friendly. To investigate the practicality of using the DAAC system for air conditioning, the thermodynamic model is derived first, and then an experimental prototype is built for validation. From the experimental results under various operating conditions, it is found that the bubble pump is the key component that dominates the system performance, so it should be designed carefully with respect to the designed cooling capacity and operating condition. Meanwhile, the system also shows good performance under the ambient temperature disturbance. / 2. A novel absorption air conditioning system based on solar energy and energy storage is proposed. This system uses Lithium-Bromide water solution as refrigerant and is powered by solar energy. Moreover, a new energy storage technique is also proposed to transform and store the solar energy in the form of chemical potential difference of the working fluid. Thus, the system flexibility and energy usage efficiency are improved. To validate the system design, the thermodynamic models for the air conditioning system are developed. Then by computer simulation, the system characteristics and performance are achieved under the proposed operation strategy. It is found that the proposed air conditioning system is energy efficient with high energy storage density and shows great potential in the future. / 3. A complex absorption air conditioning system is proposed by using an advanced energy storage technology called Variable Mass Energy Transformation and Storage (VMETS). This system is based on both compression and absorption refrigeration, uses water-LiBr or ammonia-water as working fluid, and can shift the off-peak electric energy for effective air conditioning. The key of the technology is to regulate the chemical potential by controlling the refrigerant mass fraction in the working fluid with respect to time. By using a solution storage tank and a refrigerant storage tank, the energy transformation and storage can be carried out at the desirable time to provide the low cost air conditioning efficiently. Based on the derived system models, the system characteristics and performance under two system strategies, full-storage and partial-storage strategies, are investigated in details. By computer simulation, it is found that the VMETS technology has high energy conversion efficiency. / 4. A novel thermoelectric air conditioning system is developed. Different from the conventional air conditioning systems, this system is based on the thermoelectric effect and semiconductor technology. It consists of thermoelectric (TE) modules, a power supply, a water circulation system and a computer control system. The thermoelectric system has three functions: heating, cooling, and power generation. To improve the efficiency, it uses the so-called symbiotic generation to optimize the energy usage. In order to investigate the system performance, a theoretical model is developed. By computer simulation, it is found that the system can achieve acceptable performance for cooling and heating under a typical condition. A small experimental model is also built, and the testing result confirms the simulation results. / 5. An intelligent thermal comfort controller is developed to improve the comfort level for air conditioning system. This controller adopts Predicted Mean Vote (PMV) as the control objective rather than the conventional temperature control, and takes six variables into consideration. Meanwhile, a kind of direct neural network (NN) control algorithm is designed by combining a proposed energy saving strategy. By computer simulation, it is found that this controller can achieve high comfort level and energy saving for the conventional Heating, Ventilation and Air-Conditioning (HVAC) systems. Moreover, a compact thermal comfort controller is also developed for the DAAC system. / 6. A cost-effective Fault Detection and Diagnosis (FDD) method is proposed for HVAC system to maintain the energy saving and thermal comfort. It combines the model-based method and the neural network classifier, so it is called Model-Based Fault Detection and Diagnosis method (MBFDD). To validate the performance, the MBFDD is applied to a HVAC system by simulation. Based on the derived system models, the output variables sensitive to the faults can be selected. After pre-processing the acquired data under normal and faulty conditions, the MBFDD based on neural network classifier can be trained first, and then used for on-line monitoring and FDD. The simulation results show that this method is efficient for the HVAC system, and is able to enhance the comfort level and energy saving as well as the system health and safety. / Air conditioning system plays an important role in modern living. Every year millions of air conditioning systems are made and sold. Consequently, even small technological improvement may add up to significant energy saving. Currently, most of the air conditioning systems are based on the compression refrigeration technology, which uses electricity as power and chlorofluorocarbon (CFCs) as refrigerant. Facing the ever-increasing energy and environmental crisis in the world, developing energy-efficient and environmental-friendly air conditioning system is of great importance. / This thesis presents the research on developing air conditioning systems by employing several kinds of technologies: (1) absorption refrigeration technology; (2) bubble pump technology; (3) energy storage technology; (4) renewable energy technology; (5) thermoelectric refrigeration technology; (6) thermal comfort control technology; and (7) fault detection and diagnosis technology. Based on these technologies, this thesis addresses the following topics: / Liang Jian. / "June 2006." / Adviser: Ruxu Du. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6700. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 175-194). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.