The aim of this Diploma thesis is calculating the parameters of the heat balance diagram as well as creating balance sheet for winter and summer operation. In one of the first parts, the reader is acquainted with two P&I diagrams containing main accessories, which are also used in the heat scheme, KKS marking system is used to name the acces-sories. The main part of the thesis consists of a detailed calculation of the heat transfer surface of the condenser with design of the tube bundle including the main dimensions of the condenser. Last but not least, the calculations of the hydraulic losses of condenser are included in the thesis.

This diploma thesis deals with a pressure suppression system containment during the loss of coolant accidents. It is focused on the containment systems of the nuclear power plants with VVER-440/V-213 reactors. There is described the process of loss of coolant accident. There was designed input model which consists of the zones representing the areas which are connected with junctions and heat structures. Were then selected input parameters for the model calculations. And finally, there have been several calculations for the selected parameters.

The South African electricity mix is highly dependent on subcritical coal-fired power stations. The average thermal efficiency of these power plants is low. Traditional methods to increase the thermal efficiency of the cycle have been widely studied and implemented. However, utilising the waste heat at the condenser, which accounts for the biggest heat loss in the cycle, presents a large potential to increase the thermal efficiency of the cycle. Several methods can be implemented for the recovery and utilisation of low-grade waste heat. This theoretical study focuses on replacing the traditional condenser in a fossil fuel power station with a boiling condenser (BC), which operates in a similar manner to the core of a boiling water reactor at a nuclear power plant (Sharifpur, 2007). The system was theoretically tested at the Komati Power Station, South Africa's oldest power station. The power station presented an average low-grade waste heat source. The BC cycle was theoretically tested with several working fluids and numerous different configurations. Several of the theoretical configurations indicated increased thermal efficiency of the cycle. The BC cycle configurations were also tested in two theoretical scenarios. Thirty configurations and 103 working fluids were tested in these configurations. The configuration that indicated the highest increase in thermal efficiency was the BC cycle with regeneration (three regenerative heat exchangers) from the BC turbine. A 2.4% increase in thermal efficiency was obtained for the mentioned theoretical implementation of this configuration. The working fluid tested in this configuration was ethanol. This configuration also indicated a 7.6 MW generating capacity. The increased thermal efficiency of the power station presents benefits not only in increasing the available capacity on South Africa's strained grid, but also environmental benefits. The mentioned reduction of 7.6 MW in heat released into the atmosphere also indicated a direct environmental benefit. The increase in thermal efficiency could also reduce CO2 emissions released annually in tons per MW by 5.74%. The high-level economic analysis conducted, based on the theoretically implemented BC cycle with the highest increase in thermal efficiency, resulted in a possible saving of R46 million per annum. This translated to a saving of R19.2 million per annum for each percentage increase in thermal efficiency brought about by the BC cycle. The theoretical implementation of the BC, with regeneration (three regenerative heat exchangers) from the BC turbine and ethanol as a working fluid, not only indicated an increase in thermal efficiency, but also significant economic and environmental benefits. / Dissertation (MEng)--University of Pretoria, 2016. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

The following thesis looks into modeling a chilled water system equipped with variable speed drives on different piece of equipment and optimization of system setpoints to achieve energy savings. The research was done by collecting data from a case-study and developing a system of component models that could be linked to simulate the overall system operation.

In Sweden the industries releases about 50 TWh / year of low temperature waste heat[1], often in the form of humid air flows. Today, conventional flue gas condensation is only exploiting a minor part of the energy from these flows. It is a well-established and profit­able way of improving the efficiency of district heating plants and other boilers for wet fuels. How­ever, the condensation is only applicable when the dew point of the flue gas is above the temperature demand for the heating net. The paper industry gives a good illustration of the limitations for conventional condensation: several MW of wet air streams with dew points of 60-65 ̊ C are released but cannot be recovered since the tempe­ra­ture demand is 70-80 ̊ C for the heating net. Different technologies for more advanced waste heat recovery are developing and this report is evaluating a demonstration plant for “hygro­scopic condenser”, which uses a hygroscopic solution that allows condensation above the dew point. The hygro­scopic solution is potassium formate, which enables condensation to start about 20 ̊ C above the dew point and is sufficiently non-toxic and non-corrosive. The objective of this work is to evaluate both the equipment and the process during some initial tests at the paper mill at Holmen, Braviken. The aim is also to suggest improvements of the process, the components and the additional equipment for future continuous operation.  The equipment consists of two main parts:  a hygroscopic absorption stage and a regene­ration stage. The major part of the humid air is led into an absorption column where vapor is absorbed by the formate solution and rises its temperature. This recovered waste heat is transferred to the heating net by a plate heat exchanger. The regeneration unit is used to maintain the hygroscopic concentrations by evaporation of vapor from the formate solution (amount of absorbed vapor = amount of evaporated vapor). The regene­rator is driven by process steam from the existing 3.5 bar net. The evaporated vapor is led to a conventional condenser where the regeneration energy can be recovered and the condensate is bled off.  The recovered heat from the process (hygroscopic absorber + regeneration condenser) is used in the heating net at Holmen, Braviken (VVG-net).    The initial tests have been made during 15 hours of initial operation, when the equipment has delivered about 3 MWh in total. The tests show a good temperature performance since the dew point of the humid air has been lowered from about 60oC to 47oC. The reco­vered heat was used for heating from 65oC to about 80oC. During the initial tests the capacity has not yet reached the design values. As an example the delivered heat was measured to 280 kW where­of 46kW from absorbed vapor, 129 kW from the sensible heat in the incoming humid air and 105 kW from the regeneration. The bottle-neck parts of the equipment have been localized and will be overseen during the summer of 2011 and the process is planned to be in use during the autumn with an output capacity of 500kW. The coefficient of performance (COP) is calculated to just below 2 during normal operation but was about 2.7 in the test runs due to the high portion of sensible heat. [1]Förekomst av industriellt spillvärme vid låga temperaturer,  Ingrid Nyström, Per-Åke Franck, Industriell Energianalys AB, 2002-04-15

Air cooled heat exchangers are used in many technology applications. Compactness, functionality and prize is decision maker for many future customers. Current development of compact heat exchangers is evident. Mostly used technology - expanded copper tube on aluminium fin is fluently changed by all aluminium heat exchangers with sophisticated heat exchange surface. Heating, Ventilating and Air-Conditioning with Refrigeration industry (HVAC-R) uses more and more extrude aluminium profiles as the main structure for all size heat exchangers. Similarly to Automotive industry HVAC-R uses minichannels as the basis of their products. It is not a new technology, it is technology proved through many years use in car industry. It is also true that current well known minichannel technology is not the last step. New designs and production lines are currently developed as well. All these new technologies have one unsolved thing together – how will be the new technologies easily computed through models. Current correlations which were used till now are obsolete, because of system miniaturization mainly. It is not easy to adapt old macro channel correlations on minichannel or microchannels where is not possible to diminish capillarity effects, different flow structures, etc. All these difficulties causes in model changes, software changes or iterative procedures upgrades. It is also evident that a lot of experimental exercises have to be done to examine heat exchanger behaviour ad characteristics. Because of precise computation of minichannel heat exchangers need or its geometry optimization is dissertation theme aimed to compare computation methodologies. PhD thesis is also aimed to check functionality of proposed computation system used simple similarity model. All proposed methods are compared to experimentally measured data and as the outcome of thesis are these data used to develop new computation basis.

The thermal performance of two thermosyphons with different geometries was experimentally investigated in this study. The first thermosyphon utilized a 310 mm long vertical evaporator and a 385 mm long condenser section that was inclined at 5 degrees from the vertical. The second was an elbow configuration with a 140 mm long vertical evaporator and a 190 mm long condenser oriented 8 degrees from the horizontal. Both thermosyphons were made of internally grooved copper tubing with an outer diameter of 15.87 mm, wall thickness of 0.5 mm and a nominal groove height of 0.3 mm. Tests were performed over a range of input heat fluxes where the condenser was cooled by flowing water around the condenser with inlet temperature of 10°C, 20°C, and 35°C. The effects of incrementally increasing and decreasing heat flux was investigated for the elbow thermosyphon. Temperature measurements along the thermosyphon were taken when incrementally changing the heat flux from 0.5 to 11 W/m2 for the first thermosyphon and 0.3 to 6 W/m2 for the second thermosyphon. Internal flow regimes were characterized using temperature transient profiles and compared to existing flow regime maps for closed thermosyphons suggested by Smith et al. (2018: Part a and Part b) and Terdoon et al. (1997). The temperature transients along the evaporator for the first thermosyphon settled to a more uniform profile as heat flux was increased. For the second thermosyphon the temperature profiles suggested a change to a more dynamic flow in the evaporator at heat flux of approximately 6 W/m2. The elbow thermosyphon showed evidence of a significant hysteresis in the evaporator performance at moderate heat fluxes between 2 and 8 W/cm2. Comparisons were made between the two thermosyphons to study the effects of inclination angle and the feasibility of angle corrections to the Nusselt film condensation model from Guichet and Jouhara (2020). A modification to the Rohsenow condensation model from Guichet and Jouhara (2020) was recommended for the first thermosyphon showing good representation of the condenser performance. The evaporator performance results were compared to existing models from the literature. / Thesis / Master of Applied Science (MASc)

プラズマ診断は，プラズマプロセス中の荷電粒子の役割を理解する上で重要である．しかしながら，一般的なプラズマ診断は低圧の場合に限られているため，大気圧プラズマの特性を把握するためには新たな診断技術の開発が必要である．本論文では，ゲルディエンコンデンサーを用いた大気圧プラズマ診断を提案し，実用上十分な性能を有すことを実証した内容について報告している．さらに測定に影響を及ぼす要因についても調査した. / Plasma diagnostics plays an important part in understanding the role of charged particles during plasma processes. However, since common plasma diagnostic techniques are limited to low-pressure case, there is a need for the development of a new diagnostic method specifically for atmospheric pressure plasma characterization. In this dissertation, a diagnostic technique based on the Gerdien condenser theory is developed for laboratory-produced atmospheric pressure plasma. The Gerdien condenser, which is a classical instrument employed in atmospheric science, is capable in measuring the ion mobility and density from an obtained current-voltage characteristic. The factors that can affect the measurements are also investigated. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

Nonwetting surfaces including superhydrophobic (SHS) and liquid infused surfaces (SLIPS) exhibit diverse exceptional characteristics promoting numerous application opportunities. Engineered textured surfaces demonstrate multiple features including drag reduction, fouling reduction, corrosion resistance, anti-fogging, anti-icing, and condensation enhancement. Integrating these properties, nonwetting surfaces have shown significant potential in improving the efficiency of energy applications. The first part of the thesis work aims at developing a fundamental mathematical understanding of the wetting process on the solid surface followed by presenting fabrication methodologies specifically focused on metallic substrates. The second part of this thesis presents an exhaustive survey on recent advancements and researches about features of nonwetting surfaces that could be implemented in major industrial applications. To establish how realistically these features could enhance the real-life applications, the third part of this work investigates the dynamic performance and economic benefits of using textured surfaces fabricated using an electrodeposition process for condenser tubes in thermoelectric power plants. The textured surfaces are expected to provide enhanced performance by deterring fouling and promoting dropwise condensation of the steam on the shell side. Using a thermal resistance network of a shell and tube condenser, detailed parametric studies are carried out to investigate the effect of various design parameters on the annual condenser performance measured in terms of its electric energy output of a representative 550 MW coal-fired power plant. A cost modeling tool and a new Levelized cost of condenser (LCOC) metric have been developed to evaluate the economic and performance benefits of enhanced condenser designs. The LCOC is defined as the ratio of the lifetime cost of the condenser (and associated costs such as coating, operation and maintenance) to the total electric energy produced by the thermoelectric power plant. The physical model is coupled with a numerical optimization method to identify the optimal design and operating parameters of the textured tubes that minimizes LCOC. Altogether, the study presents the first effort to construct and analyze enhanced condenser design with textured tube surfaces on annual thermoelectric power plant performance and compares it against the baseline condenser design with plain tubes. / Master of Science / Liquid repellant surfaces have attracted lots of attention due to their numerous promising characteristics including promoting condensation, drag reduction, prohibiting fouling/deposition, corrosion, and fog/dew harvesting. These attributes have the potential to inspire a variety of applications for these surfaces in power plants, automotive and aviation industries, oils/organic solvents clean-up, fuel cells, solar panels, membrane distillation, stone/concrete protection, surgical fabrics, and biological applications, to name a few. Some of these applications have reached their potential for real-life implementation and more are still at the research phase needing more experimental and fundamental studies to get them ready. The first part of this study presents the fundamentals of the wetting process. Next, fabrication methods for metallic surfaces have been explored to identify the most scalable and cost-effective approaches which could be administered in large scale industrial applications. A comprehensive review of recent publications on features of nonwetting surfaces has been carried out and presented in the second part of this thesis. To establish how realistically these features could enhance the real-life applications of a thermo-economic a performance model is developed for a powerplant condenser in the third section. Through a simple and cost-effective electrodeposition process, the common condenser tubes are modified to achieve textured tubes with superhydrophobic properties. The influence of using textured tubes on the plant's performance and its economic benefits are investigated to predict the potential promises of nonwetting surfaces.

Industrial and mining sectors are amongst the largest single energy consumers in South Africa, making them a primary focus for implementing energy saving initiatives. Refrigeration systems on mines are responsible for consuming up to25 % of the electrical energy consumption on a typical South African deep level mine. Ample opportunities to reduce the energy consumption of these systems exists, as many of the current systems rely on old technology and function under partial or inadequate control management. In compiling this thesis, various energy saving strategies on deep level mines were investigated. In specific, the effects of controlling and improving the cooling auxiliaries. Scenarios were investigated and simulated, where after an optimum solution was implemented. Implementations, such as the ones covered in this dissertation, form part of the IDM (Integrated Demand Management) energy efficiency incentive introduced by Eskom, where funding is made available based on actual power saving; ensuring that the projects will be financially viable to the clients. Reduced electrical energy consumption realised from the abovementioned projects were measured, captured and compared to the consumption before project implementation to determine the achieved savings. Savings of up to 30 % of the plant installed capacity were realised, providing average savings of up to 2.3 MW per day. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013