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The risk of metallic armour melting constitutes a major concern for ITER and DEMO. Combined computational and experimental effort has led to a successful understanding of melt dynamics in present-day tokamaks, but there remain unexplored melting regimes of relevance to future reactors. Analysis of recent poor-versus -efficient thermionic emitter sample exposures in ASDEX-Upgrade and ITER-like actively cooled tungsten leading edge exposures in WEST is presented. The coupled thermal response and melt dynamics is modelled with the new MEMENTO code employing the MEMOS-U physics model which has no adjustable parameters. In the weak Lorentz force regime accessed in the exposures, very close agreement between modelling and experiments is achieved not only for the deformation profiles, but also for the additional, unique to these experiments, constraints; simultaneous thermal response of two different materials in ASDEX-Upgrade and in-situ detection of melt build-up in WEST., QC 20230201

This paper presents the design of an open-ended waveguide (OEWG) array element operating between 34 GHz and 36 GHz. The OEWG is coupled to a quarter-wave patch antenna on a PCB, which connects to a millimeter-wave IC via a grounded co-planar waveguide. The radiating element is co-designed with an integrated liquid cooling solution to remove heat from the amplifier and phase-shifting IC. Furthermore, a 4x4-element is presented to demonstrate the OEWG design, feed and cooling operation. Although PCB manufacturing deviations were observed in the demonstrator, the realized elements are expected to operate over the entire desired frequency range.

This paper presents the design of an open-ended waveguide (OEWG) array element operating between 34 GHz and 36 GHz. The OEWG is coupled to a quarter-wave patch antenna on a PCB, which connects to a millimeter-wave IC via a grounded co-planar waveguide. The radiating element is co-designed with an integrated liquid cooling solution to remove heat from the amplifier and phase-shifting IC. Furthermore, a 4x4-element is presented to demonstrate the OEWG design, feed and cooling operation. Although PCB manufacturing deviations were observed in the demonstrator, the realized elements are expected to operate over the entire desired frequency range.

The demand for lightweight construction is constantly increasing. One approach to meet this challenge is the development of hybrid components made of dissimilar materials. The use of the hybrid construction method for bulk components has a high potential for weight reduction and increased functionality. However, forming workpieces consisting of dissimilar materials requires specific temperature profiles for achieving sufficient formability. This paper deals with the development of a specific heating and cooling strategy to generate an inhomogeneous temperature distribution in hybrid workpieces. Firstly, the heating process boundaries with regard to temperature parameters required for a successful forming are experimentally defined. Secondly, a design based on the obtained cooling strategy is developed. Next a modelling embedded within an electro-thermal framework provides the basis for a numerical determination of admissible cooling rates to fulfil the temperature constraint. Here, the authors illustrate an algorithmic approach for the optimisation of cooling parameters towards an effective minimum, required for applicable forming processes of tailored forming.

To answer the need for renewable fuels, Zero Emission Fuels is designing a microplant to create methanol from carbon dioxide and water from the ambient air using only renewable energy from solar panels. For this microplant, gaseous carbon dioxide must be compressed from 1 to 50 [bar] with the low mass flow of 336.7 [g/h]. This thesis examines the compression system which uses rolling piston compressors. This thesis also examines a solution to compress the carbon dioxide optimally. Because of the low mass flows, the compressors are very small and have relatively high friction and leakage losses. Meanwhile, due to the high pressure ratio of the system, the temperature increase due to compression also poses a problem for the lubrication of the system. Therefore, this thesis looks for solutions for these problems while trying to gain a better understanding of what exactly is happening inside the compressors. For the temperature regulation, different options for active cooling were assessed with a dimensionless analysis. Eventually, the concept of cooling through the compressor housing was chosen. Afterwards, a computational model was made to calculate the inner workings of the compressors and assess whether the concept of active cooling would still work. Then the computational model was verified by doing experimentation. After that, the results from the model and the experimentation were compared. The model was able to predict the mass flow and the outside heat transfer coefficient accurately. However, the model was still off from the experimental values by quite a margin. After assessing all the data, the system seemed to perform better as a 2-stage system then as a 3-stage system. However, due to the inaccuracies of the model and experimentation, a definite recommendation on the number of stages of the system cannot be formed., Mechanical Engineering | Energy and Process Technology

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out.

A photovoltaic (PV) module’s electrical efficiency depends on the operating temperature of the cell. Electrical efficiency reduces with increasing PV module temperature which is one of the drawbacks of this technology. This is due to the negative temperature coefficient of a PV module which decreases its voltage significantly while the current increases slightly. This study combines both active and passive cooling mechanisms to improve the electrical output of a PV module. A heat sink made up of aluminum fins and an ultrasonic humidifier were used to cool the panel. The ultrasonic humidifier was used to generate a humid environment at the rear side of the PV module. The cooling process in the study was able to reduce the temperature of the panel averagely by 14.61 ℃. This reduction led to a 6.8% improvement in the electrical efficiency of the module. The average power of 12.23 W was recorded for the cooled panel against 10.87 W for the referenced module. In terms of water consumption, a total of 1.5 L was approximately consumed during the whole experimental process due to evaporation. In effect, the proposed cooling approach was demonstrated as effective. © 2021 by the author. Licensee MDPI, Basel, Switzerland.

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out., Peer Reviewed, Postprint (author's final draft)

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out.

This work aimed at introducing and exploring the potential of a thermal management technique, named as near-immersion active cooling (NIAC), to mitigate heat accumulation in Wire + Arc Additive Manufacturing (WAAM). According to this technique concept, the preform is deposited inside a work tank that is filled with water, whose level rises while the metal layers are deposited. For validation of the NIAC technique, Al5Mg single-pass multi-layer linear walls were deposited by the CMT® process under different thermal management approaches. During depositions, the temperature history of the preforms was measured. Porosity was assessed as a means of analyzing the potential negative effect of the water cooling in the NIAC technique. The preform geometry and mechanical properties were also assessed. The results showed that the NIAC technique was efficient to mitigate heat accumulation in WAAM of aluminum. The temperature of the preforms was kept low independently of its height. There was no measurable increase in porosity with the water cooling. In addition, the wall width was virtually constant, and the anisotropy of mechanical properties tends to be reduced, characterizing a preform quality improvement. Thus, the NIAC technique offers an efficient and low-cost thermal management approach to mitigate heat accumulation in WAAM and, consequently, also to cope with the deleterious issues related to such emerging alternative of additive manufacturing., Funders: Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES); Brazilian National Council for Scientific and Technological Development (CNPq)[302863/2016-8 and 315092/2018-1]

This study proposes a new approach that can be used to generate the optimal surface state information and associated uncertainties from the estimates provided by the six land surface models used by the Global Land Data Assimilation System (GLDAS). The Förstner and best quadratic unbiased variance component estimators are used simultaneously with the least-squares method to calculate optimal values and the associated uncertainties. To demonstrate the concept, the research focused on three GLDAS hydrological products, namely soil moisture (SM), snow water equivalent (SWE), and canopy water (CAN) over the Canadian Prairies. When the Förstner estimator is applied, the estimated SM and SWE differ from their corresponding mean values by 26 mm and 9 mm respectively. Almost similar result was found with the best quadratic estimator. The estimated maximum uncertainties of each component including SM, SWE and CAN vary from year to year (e.g. 35 mm in 2006, 12 mm in 2007 and 2009 and 0.1 mm in 2001, respectively). The uncertainties of the total water storage (TWS) are almost similar to that of SM, which contributes more importantly to TWS in the area considered. The results obtained by the two proposed estimators were compared to the waterGAP hydrological models (WGHM), and to the Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage anomalies. The optimal SWE anomalies generated from GLDAS using the proposed approach show a maximum correlation of r = 0.97 with the WGHM SWE anomalies. The optimal TWS anomalies have a correlation of r = 0.91 with WGHM, and r = 0.71 with GRACE. However, the correlation jumps to r = 0.81 when GRACE TWS is corrected for groundwater signals (with a mean RMSE of 8.5 mm). The RMSE and mean absolute error between our proposed methods and WGHM and GRACE are better than those obtained with each individual LSM or their average value. No significant mean bias error is observed in each case. Finally, the analysis of the time-lag charact, Funders:Natural Sciences and Engineering Research Council of Canada (NSERC) [Grant Number: RGPIN-2018-06101)]; the Mitacs Globalink Research Award Organisation in Canada [Application Ref. IT14672]Erratum to “A new approach for generating optimal GLDAS hydrological products and uncertainties” [Sci. Total Environ. Volume 730, 15 August 2020, 138932]

The Collective Thomson Scattering (CTS) diagnostic system will be used at ITER to provide spatial and temporal measurements of fast ion velocity distributions. The diagnostic is based on the CTS principle, where a microwave beam scatters off electrons in the plasma. The scattered radiation is then collected and measured, providing information about the fast ions. The system components are either considered in-vessel or ex-vessel depending on their location in the port plug. In this work, thermo-structural analyses were performed on four in-vessel components using the finite-element method (FEM) and the commercial software ANSYS Mechanical v18.0. The analyses indicate that active cooling will be required for most of the analysed components. The thermal stresses will be used to perform the structural assessment of these components based on the RCC-MR code.

An Al-Zn-Mg-Cu, Al 7075, alloy was subjected to friction stir processing (FSP) using several processing conditions, two different backing anvils and three initial precipitation states in order to reach the maximum feasible processing severity to produce ultrafine grain sizes. Microstructures formed by fine, equiaxed and highly misoriented grains were obtained. Grain sizes were situated in the range of 200-1000 nm, making FSP competitive with other severe plastic deformation techniques. No influence of the initial precipitation state in the processed grain size was perceived. In fact, the processing conditions and the cooling rate determine the observed grain size. It was found that the selection of the appropriate processing conditions delivered an ultrafine grain size, thus allowing suitable microstructural control.

A key characteristic of a friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir processing (FSP) technique was applied to modify the through thickness microstructure of a monolithic plate of a magnesium alloy. Grain structure refinement in these alloys could have a significant impact on their strength and ductility opening up their use for high-performance defense applications. EWI has been investigating the use of the FSP technique to achieve nano-sized grains in a magnesium alloy, AZ31B. Heat input estimations have enabled the prediction of welding parameters and tool geometries that could achieve significant grain refinement. This presentation will summarize the experimental procedures using active cooling and theoretical efforts undertaken in order to achieve an average stir zone grain size of 500 nm. This work was performed under a cooperative agreement between EWI and the U.S. Army Research Laboratory., Proceedings of TMS 142nd Annual Meeting and Exhibition, San Antonio, TX, 3-7 March 2013. The original document contains color images.

A micro-electro-mechanical-system (MEMS) based, temperature triggered, switch is developed as a cost-effective solution for smart cooling control of solid-state-lighting systems. The switch (1.0x0.4 mm2) is embedded in a silicon substrate and fabricated with a single-mask 3D micro-machining process. The device switches on at a designed temperature threshold (130 °C) with a contact resistance of < 2 ohm, and switches off when the temperature drops below that limit. In this way, automatic control of a cooling system is possible, without any need of additional electronic components. The research is a part of the Enlight project., Delft Institute of Microsystems and Nanoelectronics, Electrical Engineering, Mathematics and Computer Science

A micro-electro-mechanical-system (MEMS) based, temperature triggered, switch is developed as a cost-effective solution for smart cooling control of solid-state-lighting systems. The switch (1.0x0.4 mm2) is embedded in a silicon substrate and fabricated with a single-mask 3D micro-machining process. The device switches on at a designed temperature threshold (130 °C) with a contact resistance of < 2 ohm, and switches off when the temperature drops below that limit. In this way, automatic control of a cooling system is possible, without any need of additional electronic components. The research is a part of the Enlight project., Delft Institute of Microsystems and Nanoelectronics, Electrical Engineering, Mathematics and Computer Science

The computational modeling and design of an actively-cooled microvascular fin specimen is presented. The design study is based on three objective functions: (i) minimizing the maximum temperature in the thermally loaded fin, (ii) optimizing the flow efficiency of the embedded microchannel, and (iii) minimizing the void volume fraction of the microvascular material. A recently introduced Interface-enriched Generalized Finite Element Method (IGFEM) is employed to evaluate the temperature field in a 2D model of the specimen, allowing for the accurate and efficient capturing of the gradient discontinuity along the fluid/solid interface without the need of meshes that conform to the geometry of the problem. Finding the optimal shape of the embedded microchannel is thus accomplished with a single non-conforming mesh for all configurations. Prior to the optimization study, the IGFEM solver is validated through comparison with infrared measurements of the thermal response of an epoxy fin with a sinusoidal microchannel, Published in the International Journal of Heat and Mass Transfer, v55 p5309 5321, 14 Jun 2012. Prepared in collaboration with the Depts of Civil and Environmental Engineering, Aerospace Engineering, and Materials Science and Engineering, University of Illinois at Urbana-Champaign.

To allow better machining heat transfer through mist evaporation, a new active cooling method is proposed. It is based on variable strength activation of coolant together with active cooling. A key issue in the proposed method is the use of multiple actuators of high frequency vibration for extra strength increase. This will rely on the idea of focusing and superposition. In this project, experimental tests were conducted to test the idea for the proposed variable strength activation of coolant in precision machining. Experimental test results show that the effects of ejection distance de on the vibration sensor output amplitude Aa and output frequency f a are not significant. The output amplitude Aa has a linear relationship with the number of actuator na. The effects of na on fa is not obvious. Based on the results, the idea of using multiple actuators for focusing and constructive superposition in variable strength activation is confirmed.

A new active cooling method is proposed for increased cooling effectiveness of coolant in grinding. It is based on variable strength activation of coolant together with active cooling to allow better machining heat transfer through mist evaporation. Multiple actuators are used through superposition and focusing. A device of variable strength coolant activation has been developed. Preliminary experimental tests were conducted to test the feasibility of the proposed cooling method. It is found that, using the proposed variable strength activation, an improvement of 87.6% in Ra value and 71.9% in R q value were obtained when compared with the existing activated and cooled coolant cooling method.

An actively cooled and activated cooling approach is proposed and examined in this project in order to deal with the problems associated with methods such as the cryogenic cooling method. It is also aimed to further improve the surface quality of the workpiece after grinding by combining the advantages of the existing cooling methods. Both computational and experimental studies were conducted for grinding the brittle materials with the proposed approach. Optical examinations were used to study the surface morphology. The experimental results show that the surface quality can be improved by up to 23.75% on average in terms of surface roughness Ra. The computational test reveals that the heat can be taken away more effectively by the proposed approach.

To allow better machining heat transfer through mist evaporation, a new active cooling method is proposed. It is based on variable strength activation of coolant together with active cooling. A key issue in the proposed method is the use of multiple actuators of high frequency vibration for extra strength increase. This will rely on the idea of focusing and superposition. In this project, experimental tests were conducted to test the idea for the proposed variable strength activation of coolant in precision machining. Experimental test results show that the effects of ejection distance de on the vibration sensor output amplitude Aa and output frequency f a are not significant. The output amplitude Aa has a linear relationship with the number of actuator na. The effects of na on fa is not obvious. Based on the results, the idea of using multiple actuators for focusing and constructive superposition in variable strength activation is confirmed.

A new active cooling method is proposed for increased cooling effectiveness of coolant in grinding. It is based on variable strength activation of coolant together with active cooling to allow better machining heat transfer through mist evaporation. Multiple actuators are used through superposition and focusing. A device of variable strength coolant activation has been developed. Preliminary experimental tests were conducted to test the feasibility of the proposed cooling method. It is found that, using the proposed variable strength activation, an improvement of 87.6% in Ra value and 71.9% in R q value were obtained when compared with the existing activated and cooled coolant cooling method.

An actively cooled and activated cooling approach is proposed and examined in this project in order to deal with the problems associated with methods such as the cryogenic cooling method. It is also aimed to further improve the surface quality of the workpiece after grinding by combining the advantages of the existing cooling methods. Both computational and experimental studies were conducted for grinding the brittle materials with the proposed approach. Optical examinations were used to study the surface morphology. The experimental results show that the surface quality can be improved by up to 23.75% on average in terms of surface roughness Ra. The computational test reveals that the heat can be taken away more effectively by the proposed approach.

In order to enhance the cooling performance, better understanding of the effects of coolant parameters is necessary. In this project, a total of five input parameters for actively cooled and activated cutting fluid were studied. An aerosol spectrometer was used to measure the particle size spatial distribution of the cooling mist in the fluid. Taguchi method was used in the design of experiments. It was found that the unit volume net specific particle counts exhibit the behavior of oscillation and attenuation of a second order dynamic system. Cooling mist particle spatial frequency ranges from 0.01269/u.m to 2.5/u.m, the weighted average size ranges from 0.3051μm to 3.714μm and the particle size difference for 99.8% count attenuation ranges from 0.5μm to 19.7μm. The order of importance of the input parameters was studied and the coolant concentration was found as the most important input parameter for the unit volume net particle counts.

A new active cooling method is proposed for increased cooling effectiveness of coolant in grinding. It is based on variable strength activation of coolant together with active cooling to allow better machining heat transfer through mist evaporation. Multiple actuators are used through superposition and focusing. A device of variable strength coolant activation has been developed. Preliminary experimental tests were conducted to test the feasibility of the proposed cooling method. It is found that, using the proposed variable strength activation, an improvement of 87.6% in Ra value and 71.9% in R q value were obtained when compared with the existing activated and cooled coolant cooling method.

To allow better machining heat transfer through mist evaporation, a new active cooling method is proposed. It is based on variable strength activation of coolant together with active cooling. A key issue in the proposed method is the use of multiple actuators of high frequency vibration for extra strength increase. This will rely on the idea of focusing and superposition. In this project, experimental tests were conducted to test the idea for the proposed variable strength activation of coolant in precision machining. Experimental test results show that the effects of ejection distance de on the vibration sensor output amplitude Aa and output frequency f a are not significant. The output amplitude Aa has a linear relationship with the number of actuator na. The effects of na on fa is not obvious. Based on the results, the idea of using multiple actuators for focusing and constructive superposition in variable strength activation is confirmed.

An actively cooled and activated cooling approach is proposed and examined in this project in order to deal with the problems associated with methods such as the cryogenic cooling method. It is also aimed to further improve the surface quality of the workpiece after grinding by combining the advantages of the existing cooling methods. Both computational and experimental studies were conducted for grinding the brittle materials with the proposed approach. Optical examinations were used to study the surface morphology. The experimental results show that the surface quality can be improved by up to 23.75% on average in terms of surface roughness Ra. The computational test reveals that the heat can be taken away more effectively by the proposed approach.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling and chilled air-cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve the surface quality by up to 36.68\% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the X-Ray Diffraction (XRD) tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and Scanning Electron Microscope (SEM) examinations also confirmed that the proposed approach is advantageous.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling and chilled air-cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve the surface quality by up to 36.68\% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the X-Ray Diffraction (XRD) tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and Scanning Electron Microscope (SEM) examinations also confirmed that the proposed approach is advantageous.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling and chilled air-cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve the surface quality by up to 36.68\% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the X-Ray Diffraction (XRD) tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and Scanning Electron Microscope (SEM) examinations also confirmed that the proposed approach is advantageous.

An active cooling approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance surface quality and to enhance productivity. The problem associated with the cryogenic cooling approach and the one with the chilled air approach are addressed. An active cooling prototype was developed utilizing a compact heat pump design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding ductile materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality by up to 29.95% on average in terms of surface roughness Ra. Computational testing results show that the heat can be taken away more effectively by using the proposed approach. The results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

An active cooling approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance surface quality and to enhance productivity. The problem associated with the cryogenic cooling approach and the one with the chilled air approach are addressed. An active cooling prototype was developed utilizing a compact heat pump design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding ductile materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality by up to 29.95% on average in terms of surface roughness Ra. Computational testing results show that the heat can be taken away more effectively by using the proposed approach. The results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

An active cooling approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance surface quality and to enhance productivity. The problem associated with the cryogenic cooling approach and the one with the chilled air approach are addressed. An active cooling prototype was developed utilizing a compact heat pump design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding ductile materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality by up to 29.95% on average in terms of surface roughness Ra. Computational testing results show that the heat can be taken away more effectively by using the proposed approach. The results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling, and chilled air cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve surface quality by up to 36.68% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the XRD tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling, and chilled air cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve surface quality by up to 36.68% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the XRD tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

An active cooling and activation approach for coolant during ductile material grinding is proposed and examined. The aim is to enhance the surface quality of the workpiece being machined by the grinding process. Problems in the existing cooling approaches, such as activation, cryogenic cooling, and chilled air cooling, are discussed. Experimental and computational studies of the effects of actively cooled and activated coolant for ductile material grinding were conducted. Experimental results show that the proposed approach is able to improve surface quality by up to 36.68% on average in terms of surface roughness R-a. In addition, it was found that surface roughness could be reduced if the coolant temperature is reduced. The results of the XRD tests show that the proposed method could, in general, produce low residual stress values. Further studies of this topic are necessary. Results of optical and SEM examinations also confirmed that the proposed approach is advantageous.

To solve the problem associated with the cryogenic cooling approach and the one with the chilled air approach, an actively cooled coolant approach is proposed and examined. The proposed cooling system is also able to reduce the time period to reach the equilibrium state to enhance productivity. An active cooling prototype was developed that utilizes a compact air conditioner design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding brittle materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality for up to 13.1\% on average in terms of surface roughness R-a. The results of optical and SEM examinations confirmed that the proposed approach is advantageous. Computational testing results show that the heat can be taken away more effectively by using the proposed approach.

To solve the problem associated with the cryogenic cooling approach and the one with the chilled air approach, an actively cooled coolant approach is proposed and examined. The proposed cooling system is also able to reduce the time period to reach the equilibrium state to enhance productivity. An active cooling prototype was developed that utilizes a compact air conditioner design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding brittle materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality for up to 13.1\% on average in terms of surface roughness R-a. The results of optical and SEM examinations confirmed that the proposed approach is advantageous. Computational testing results show that the heat can be taken away more effectively by using the proposed approach.

In many precision machining processes such as surface grinding, coolant is typically used to provide functions such as lubrication and cooling. In order to reduce surface grinding temperatures effectively, an active coolant cooling system is proposed. The system is based on the use of forced convection of the heat generated during the machining process. The coolant cooling system utilizes a commonly used air conditioner for ease of use and to reduce costs. In the proposed design, the evaporator of the heat pump is connected to the coolant tank of a surface grinding machine to reduce grinding temperatures for improved stability of accuracy and surface quality. This can be done without compromising production efficiency. System structure is explained, and a coolant temperature model presented. Experimental testing on a prototype active cooling system is presented. The coolant temperature can be reduced to approximately -2 degreesC under no load condition, and to approximately 3 degreesC under loaded condition. The time constants of the cooling system were estimated The results of the experimental tests demonstrated the effectiveness of the proposed system for applications in surface grinding for active coolant cooling in comparison with passive cooling. (C) 2003 Elsevier Science Ltd. All rights reserved.

In many precision machining processes such as surface grinding, coolant is typically used to provide functions such as lubrication and cooling. In order to reduce surface grinding temperatures effectively, an active coolant cooling system is proposed. The system is based on the use of forced convection of the heat generated during the machining process. The coolant cooling system utilizes a commonly used air conditioner for ease of use and to reduce costs. In the proposed design, the evaporator of the heat pump is connected to the coolant tank of a surface grinding machine to reduce grinding temperatures for improved stability of accuracy and surface quality. This can be done without compromising production efficiency. System structure is explained, and a coolant temperature model presented. Experimental testing on a prototype active cooling system is presented. The coolant temperature can be reduced to approximately -2 degreesC under no load condition, and to approximately 3 degreesC under loaded condition. The time constants of the cooling system were estimated The results of the experimental tests demonstrated the effectiveness of the proposed system for applications in surface grinding for active coolant cooling in comparison with passive cooling. (C) 2003 Elsevier Science Ltd. All rights reserved.

In many precision machining processes such as surface grinding, coolant is typically used to provide functions such as lubrication and cooling. In order to reduce surface grinding temperatures effectively, an active coolant cooling system is proposed. The system is based on the use of forced convection of the heat generated during the machining process. The coolant cooling system utilizes a commonly used air conditioner for ease of use and to reduce costs. In the proposed design, the evaporator of the heat pump is connected to the coolant tank of a surface grinding machine to reduce grinding temperatures for improved stability of accuracy and surface quality. This can be done without compromising production efficiency. System structure is explained, and a coolant temperature model presented. Experimental testing on a prototype active cooling system is presented. The coolant temperature can be reduced to approximately -2 degreesC under no load condition, and to approximately 3 degreesC under loaded condition. The time constants of the cooling system were estimated The results of the experimental tests demonstrated the effectiveness of the proposed system for applications in surface grinding for active coolant cooling in comparison with passive cooling. (C) 2003 Elsevier Science Ltd. All rights reserved.

Phase I demonstrated that ion beam microtexturing of metal surfaces enhances heat transfer under three conditions: (1) thermal radiation emission at relatively high temperatures, (2) forced convection, and (3) nucleate boiling. Features were too small to significantly affect heat transfer under non-flowing constant phase conditions. For nucleate boiling, combining microtexture with large scale structures, and after optimizing the texturing process, it should be possible to achieve a composite enhancement better than 20 times the nucleate- boiling heat transfer from a smooth surface. Ion texturing processes produce rugged broadband light absorbers, completely black from the visible to long wavelength IR. At higher temperature ranges, enhanced radiation adds significantly to total heat transferred. Thus, heat pipes, capillaries, and higher temperature radiators would all perform better with microtextured surfaces.

This report presents the results of a study to design and fabricate a radiative actively cooled panel. The panel assembly consists of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure.

Cílem této diplomové práce je navrhnout druhý stupeň základní školy s téměř nulovou spotřebou energie v Brně-Bosonohy. Práce se skládá ze 3 částí. První část obsahuje stavebně-konstrukční návrh. Budova je nepodsklepená a má dvě nadzemní podlaží. Konstrukční systém budovy je tvořen podélnými stěnami z keramických tvarovek a předpjatými prefabrikovanými stropními panely. V nižší části budovy se nachází jídelna, nad kterou je umístěna provozní střecha s edukačními záhony. Ve vyšší části budovy se nachází 4 kmenové třídy pro celkem 120 žáků, jazyková učebna, laboratoř a ateliér. Druhá část se zabývá návrhem koncepcí technických systémů. Objekt je vytápěn tepelným čerpadlem země-voda s hlubinnými vrty, které slouží i pro ohřev teplé vody. Tento systém umožňuje také aktivní i pasivní chlazení. Nucené větrání je zajištěno VZT jednotkami s vysokou účinností rekuperace. Pro pokrytí spotřeby elektřiny z OZE jsou na střeše instalovány fotovoltaické panely. Třetí část analyzuje data naměřená na existující základní škole, ve které si její uživatelé stěžují na komfort vnitřního prostředí. Analýza je zaměřena na teplotu v místnosti v letním období. Následně je optimalizováno řízení technických systémů a pasivních prvků ochrany pro zlepšení vnitřního prostředí z hlediska přehřívání. Poznatky ze třetí části byly aplikovány při návrhu školy, která je předmětem první a druhé části této diplomové práce., The aim of this master thesis is to design a nearly-zero energy primary school in Brno-Bosonohy. The thesis consists of 3 parts. The first part contains architectural and structural design. The second part deals with the design of the concept of building services. The building is designed without a basement and has three above-ground floors. The structural system includes longitudinal masonry wall and prestressed prefabricated floor panels. In the lower part of the building there is a lunchroom, above which there is an operating roof. In the higher part of the building, there are 4 form classes for a total of 120 children, a language lab, a laboratory and a atelier. The building is heated by a ground-water heat pump with deep bore holes, which are also used for hot water heating. The ventilation has a heat recovery system with high efficiency. Photovoltaic panels are installed on the roof. The third part analyses data from a local survey at the primary school. The analysis is focused on the temperature in the room in the summer season, and then the management of building services is optimized to energy consumption. The conclusions from the third part were applied to the design of the school, which is the subject of the first and second parts of this master thesis.

Cílem této diplomové práce je navrhnout druhý stupeň základní školy s téměř nulovou spotřebou energie v Brně-Bosonohy. Práce se skládá ze 3 částí. První část obsahuje stavebně-konstrukční návrh. Budova je nepodsklepená a má dvě nadzemní podlaží. Konstrukční systém budovy je tvořen podélnými stěnami z keramických tvarovek a předpjatými prefabrikovanými stropními panely. V nižší části budovy se nachází jídelna, nad kterou je umístěna provozní střecha s edukačními záhony. Ve vyšší části budovy se nachází 4 kmenové třídy pro celkem 120 žáků, jazyková učebna, laboratoř a ateliér. Druhá část se zabývá návrhem koncepcí technických systémů. Objekt je vytápěn tepelným čerpadlem země-voda s hlubinnými vrty, které slouží i pro ohřev teplé vody. Tento systém umožňuje také aktivní i pasivní chlazení. Nucené větrání je zajištěno VZT jednotkami s vysokou účinností rekuperace. Pro pokrytí spotřeby elektřiny z OZE jsou na střeše instalovány fotovoltaické panely. Třetí část analyzuje data naměřená na existující základní škole, ve které si její uživatelé stěžují na komfort vnitřního prostředí. Analýza je zaměřena na teplotu v místnosti v letním období. Následně je optimalizováno řízení technických systémů a pasivních prvků ochrany pro zlepšení vnitřního prostředí z hlediska přehřívání. Poznatky ze třetí části byly aplikovány při návrhu školy, která je předmětem první a druhé části této diplomové práce., The aim of this master thesis is to design a nearly-zero energy primary school in Brno-Bosonohy. The thesis consists of 3 parts. The first part contains architectural and structural design. The second part deals with the design of the concept of building services. The building is designed without a basement and has three above-ground floors. The structural system includes longitudinal masonry wall and prestressed prefabricated floor panels. In the lower part of the building there is a lunchroom, above which there is an operating roof. In the higher part of the building, there are 4 form classes for a total of 120 children, a language lab, a laboratory and a atelier. The building is heated by a ground-water heat pump with deep bore holes, which are also used for hot water heating. The ventilation has a heat recovery system with high efficiency. Photovoltaic panels are installed on the roof. The third part analyses data from a local survey at the primary school. The analysis is focused on the temperature in the room in the summer season, and then the management of building services is optimized to energy consumption. The conclusions from the third part were applied to the design of the school, which is the subject of the first and second parts of this master thesis.

Cílem této diplomové práce je navrhnout druhý stupeň základní školy s téměř nulovou spotřebou energie v Brně-Bosonohy. Práce se skládá ze 3 částí. První část obsahuje stavebně-konstrukční návrh. Budova je nepodsklepená a má dvě nadzemní podlaží. Konstrukční systém budovy je tvořen podélnými stěnami z keramických tvarovek a předpjatými prefabrikovanými stropními panely. V nižší části budovy se nachází jídelna, nad kterou je umístěna provozní střecha s edukačními záhony. Ve vyšší části budovy se nachází 4 kmenové třídy pro celkem 120 žáků, jazyková učebna, laboratoř a ateliér. Druhá část se zabývá návrhem koncepcí technických systémů. Objekt je vytápěn tepelným čerpadlem země-voda s hlubinnými vrty, které slouží i pro ohřev teplé vody. Tento systém umožňuje také aktivní i pasivní chlazení. Nucené větrání je zajištěno VZT jednotkami s vysokou účinností rekuperace. Pro pokrytí spotřeby elektřiny z OZE jsou na střeše instalovány fotovoltaické panely. Třetí část analyzuje data naměřená na existující základní škole, ve které si její uživatelé stěžují na komfort vnitřního prostředí. Analýza je zaměřena na teplotu v místnosti v letním období. Následně je optimalizováno řízení technických systémů a pasivních prvků ochrany pro zlepšení vnitřního prostředí z hlediska přehřívání. Poznatky ze třetí části byly aplikovány při návrhu školy, která je předmětem první a druhé části této diplomové práce., The aim of this master thesis is to design a nearly-zero energy primary school in Brno-Bosonohy. The thesis consists of 3 parts. The first part contains architectural and structural design. The second part deals with the design of the concept of building services. The building is designed without a basement and has three above-ground floors. The structural system includes longitudinal masonry wall and prestressed prefabricated floor panels. In the lower part of the building there is a lunchroom, above which there is an operating roof. In the higher part of the building, there are 4 form classes for a total of 120 children, a language lab, a laboratory and a atelier. The building is heated by a ground-water heat pump with deep bore holes, which are also used for hot water heating. The ventilation has a heat recovery system with high efficiency. Photovoltaic panels are installed on the roof. The third part analyses data from a local survey at the primary school. The analysis is focused on the temperature in the room in the summer season, and then the management of building services is optimized to energy consumption. The conclusions from the third part were applied to the design of the school, which is the subject of the first and second parts of this master thesis.

This paper presents the experimental investigation of a novel cross-compound parabolic concentrator (CCPC). For the first time, a CCPC module was designed to simultaneously work as an electricity generator and collect the thermal energy present in the module which is generated due to the incident irradiation. This CCPC module consists of two regions: an absorber surface atop the rig and a reflective region below that to reflect the irradiation onto the photovoltaic (PV) cell, coupled together to form an absorptive/reflective CCPC (AR-CCPC) module. A major issue in the use of PV cells is the decrease in electrical conversion efficiency with the increase in cell temperature. This module employs an active cooling system to decrease the PV cell temperature, optimizing the electrical performance and absorbing the heat generated within the module. This system was found to have an overall efficiency of 63%, which comprises the summation of the electrical and thermal efficiency posed by the AR-CCPC module.

Předkládaná bakalářská práce se zabývá koncentrátorovými fotovoltaickými systémy. Je popsána historie jejich vzniku, vývoje a aplikace, princip činnosti a popis technologie konstrukcí, optiky, speciálních fotovoltaických článků a jejich chlazení. V praktické části je popsána konstrukce experimentálního koncentrátorového fotovoltaického systému postaveného u firmy Solartec s.r.o.. Tento systém slouží pro ověření hypotéz a studium chování systému za provozu. Cílem je změření reálných koncentračních, teplotních a elektrických vlastností systému a porovnání výhodnosti aktivního a pasivního chlazení článků., The subject of this bachelor´s thesis is to introduce concentrator photovoltaic systems, history of their foundation, evolution and application, principles of function and description of technology including its construction, optics, special photovoltaic cells and their cooling. The practical part of thesis describes the experimental concentrator photovoltaic system build in cooperation with Solartec s.r.o. company. The system is used to test hypotheses and study the behavior during its operation. The aim is to measure concentration ratio, temperature and electrical characteristics and to compare advantages of active and passive cooling of photovoltaic cells.

Předkládaná bakalářská práce se zabývá koncentrátorovými fotovoltaickými systémy. Je popsána historie jejich vzniku, vývoje a aplikace, princip činnosti a popis technologie konstrukcí, optiky, speciálních fotovoltaických článků a jejich chlazení. V praktické části je popsána konstrukce experimentálního koncentrátorového fotovoltaického systému postaveného u firmy Solartec s.r.o.. Tento systém slouží pro ověření hypotéz a studium chování systému za provozu. Cílem je změření reálných koncentračních, teplotních a elektrických vlastností systému a porovnání výhodnosti aktivního a pasivního chlazení článků., The subject of this bachelor´s thesis is to introduce concentrator photovoltaic systems, history of their foundation, evolution and application, principles of function and description of technology including its construction, optics, special photovoltaic cells and their cooling. The practical part of thesis describes the experimental concentrator photovoltaic system build in cooperation with Solartec s.r.o. company. The system is used to test hypotheses and study the behavior during its operation. The aim is to measure concentration ratio, temperature and electrical characteristics and to compare advantages of active and passive cooling of photovoltaic cells.

Předkládaná bakalářská práce se zabývá koncentrátorovými fotovoltaickými systémy. Je popsána historie jejich vzniku, vývoje a aplikace, princip činnosti a popis technologie konstrukcí, optiky, speciálních fotovoltaických článků a jejich chlazení. V praktické části je popsána konstrukce experimentálního koncentrátorového fotovoltaického systému postaveného u firmy Solartec s.r.o.. Tento systém slouží pro ověření hypotéz a studium chování systému za provozu. Cílem je změření reálných koncentračních, teplotních a elektrických vlastností systému a porovnání výhodnosti aktivního a pasivního chlazení článků., The subject of this bachelor´s thesis is to introduce concentrator photovoltaic systems, history of their foundation, evolution and application, principles of function and description of technology including its construction, optics, special photovoltaic cells and their cooling. The practical part of thesis describes the experimental concentrator photovoltaic system build in cooperation with Solartec s.r.o. company. The system is used to test hypotheses and study the behavior during its operation. The aim is to measure concentration ratio, temperature and electrical characteristics and to compare advantages of active and passive cooling of photovoltaic cells.