Fluid Circuit Research Articles

System of fractional differential algebraic equations with applications

Abstract One of the important classes of coupled systems of algebraic, differential and fractional differential equations (CSADFDEs) is fractional differential algebraic equations (FDAEs). The main difference of such systems with other class of CSADFDEs is that their singularity remains constant in an interval. However, complete classifying and analyzing of these systems relay mainly to the concept of the index which we introduce in this paper. For a system of linear differential algebraic equations (DAEs) with constant coefficients, we observe that the solvability depends on the regularity of the corresponding pencils. However, we show that in general, similar properties of DAEs do not hold for FDAEs. In this paper, we introduce some practical applications of systems of FDAEs in physics such as a simple pendulum in a Newtonian fluid and electrical circuit containing a new practical element namely fractors. We obtain the index of introduced systems and discuss the solvability of these systems. We numerically solve the FDAEs of a pendulum in a fluid with three different fractional derivatives (Liouville–Caputo’s definition, Caputo–Fabrizio’s definition and with a definition with Mittag–Leffler kernel) and compare the effect of different fractional derivatives in this modeling. Finally, we solved some existing examples in research and showed the effectiveness and efficiency of the proposed numerical method.

Combined and fast computable thermal models for situationally optimal tempering of machine tool components

The focus of this paper is on the modeling of an existing machine frame with its cooling structures. An overview is given of all the modeling methods used, their respective sub-targets and their interactions with each other. The modeling workflow encompasses both the mechanical and fluidic properties of the machine frame, including the fluid circuits and their control. The study results are the different requirements for modeling and the achievable result accuracy with regard to the temperature and deformation field. It forms the basis for the subsequent investigation of various temperature control variants, which are not part of this paper.

CFD Simulation Studies on Integrated Approach of Solar Chimney and Borehole Heat Exchanger for Building Space Conditioning

In this communication, integrated approach of solar chimney and borehole heat exchanger has been studied by using computational fluid dynamics software. It is observed that, the room temperature can be maintained at 25-30 °C, at 4.9 ACH with this integrated approach in both peak summer and winter conditions. The cooling and heating effects are evaluated as 4.73-5.55 kW at 40 °C in summer and 8.27-10.56 kW at 5 °C in winter. The SC-BHE integrated system approach produced 21-37 % higher heating effect than the BHE alone system. In cooling mode SC fitted after the room in fluid circuit and it produces the induce effect for air suction from BHE along the air blower. So, integrated approach is a feasible solution for building space conditioning.

Geometry Measurement of Submerged Metallic Micro-Parts Using Confocal Fluorescence Microscopy

The in situ geometry measurement of microstructures in the laser chemical machining (LCM) manufacturing process places high demands on measurement systems because the specimen is submerged in a closed fluid circuit. The steep slopes of the manufactured micro-components and the general lack of accessibility hinder the use of standard techniques such as tactile measurement or conventional confocal microscopy. A technique based on confocal fluorescence microscopy shows promise for increasing the measurability on metallic surfaces with large curvatures. By applying an intensely scattering fluorescent coating to the specimen, the surface position can be determined by the change in fluorescence signal at the boundary between specimen and coating. In contrast to the currently tested thin coatings ( $$< 100\, \upmu \hbox {m}$$ ) the measurements in layers thicker than $$ 1\, \hbox {mm}$$ , as required for in situ application at the LCM process, show distinct dependencies on the fluorescent medium in terms of concentration and index of refraction. Hence, a fundamentally different signal evaluation approach based on a physical model of the fluorescence signal is needed to extract the surface position information from the detected fluorescence intensity signal. For the purpose of validation, the measurement of a step geometry is performed under the condition of a thick fluid layer and referenced with a tactile measurement. As a result, the model-based approach is shown to be suitable to detect the geometry parameter step height with an uncertainty of $$ 8.8\, \upmu \hbox {m}$$ for a step submerged in a fluid layer with a thickness of $$2.3\, \hbox {mm}$$ .

Integration of the Neutral Beam Injector System Into the DCLL Breeding Blanket for the EU DEMO

The integration of plant systems involving penetrations into the in-vessel components, such as heating and current drive, fuel cycle, and diagnostics, is a complex task constrained by top-level requirements of remote maintainability and high reliability. Within the EUROfusion Power Plant Physics and Technology Program, some activities are ongoing to assess the integration of different systems into the breeding blanket (BB), specifically neutral beam injector (NBI), electron cyclotron resonance heating launchers, diagnostics sightlines, fueling lines, and specific protections for the first wall (like startup limiters). This paper describes the integration of the NBI system into the Dual-Coolant Lithium-Lead (DCLL) BB for the EU DEMO. After identifying the major issues impacting the mechanical, thermal-hydraulic and neutronic behavior of the blanket, the integration efforts have been focused on minimizing the invasiveness of the NBI system and exploring different NBI options for the best compromise between plasma heating and BB performance. This paper describes the adaptation of the DCLL BB design to allocate the neutral beam duct. A particular attention is devoted to the redistribution of breeding and shielding functions, the new path of fluid circuits, and the additional cooling needs. The consequences of design modifications on key neutronic aspects like tritium breeding ratio and shielding capability are addressed. Besides, the thermal loads transferred to the BB walls from the neutral beam and the plasma are discussed, and a preliminary thermal assessment of the proposed solution is presented.

Modeling and dynamic simulation of a steam generation system for a parabolic trough solar power plant

Abstract In a parabolic trough solar power plant, the steam generation system is the junction of the heat transfer fluid circuit and the water/steam circuit. Due to the discontinuous nature of solar radiation, the dynamic characteristics of working fluid physical parameters, such as mass flow rate, temperature, and pressure, are more evident in the steam generation system in this kind of plant, increasing the complexity of system operation. In this paper, a zero-dimension dynamic model of an oil/water steam generation system was developed based on the lumped parameter method. Based on the developed model, four typical single-parameter disturbance processes were simulated, and then the control strategy was obtained. System-level simulations on different days (clear and cloudy) and in different seasons (spring, summer, autumn, and winter) were also conducted on a STAR-90 simulation platform using real meteorological data. The simulation results show that PI control can be used to adjust the water level, that system operation on cloudy days should be avoided, and that the system can continue to generate steam after the sun sets. The simulation results can provide a useful reference for plant operators.

ISIS TS1 Project mock-ups and testing

The ISIS TS1 target station has operated with the current tantalum clad tungsten design of target for over a decade with only minor changes to the accompanying moderators and reflector since ISIS’s creation in the 1980s. The TS1 upgrade project is currently being undertaken to redesign the target, moderators, and reflector (TRaM), as well as their associated support structure, and also the services located in the target services area (TSA). This paper will detail the work being undertaken to underpin design, verify and validate through an on-site testing programme. As the area that the new equipment will be installed in is already radiologically active, everything must be comprehensively tested for fit and function before installation. Most of the testing will be performed on a full scale representation of the remote handling cell (RHC), complete with the remote handling manipulator arms. There will also be rigs in place for testing the new water pumps and instrumentation prior the installation into the TSA. In addition to these testing mock-ups, there is also work planned to support and verify various aspects of the fluid circuits that are required for operation of the target station. Presently, all ISIS targets are flow-tested on a dedicated rig to ensure that the cooling channels are clear and can achieve the required cooling flow rate. This rig is to be replaced with a dual purpose rig that will also allow cooling testing to be performed while improving the operability of the rig’s design. Testing is scheduled to begin in summer 2017 and will continue until installation in 2019/2020.

Dynamic Characteristics Analysis of Vehicle Incorporating Hydraulically Interconnected Suspension System with Dual Accumulators

A novel roll‐resistant hydraulically interconnected suspension with dual accumulators on each fluid circuit (DHIS) is proposed and dynamic characteristics of vehicle incorporating DHIS subsystem are studied in this paper. A 10‐degrees‐of‐freedom (DOFs) vehicle model coupled with DHIS subsystem is established and validated. Four physical parameters of DHIS subsystems which are crucial to vehicle responses are selected with prescribed variation ranges to explore their relationships with the vehicle performance. Simulations of vehicle conducting sine‐wave steering maneuvers are carried out to evaluate handling performance with roll angle and vertical tyre force for DHIS subsystem with the parameters varying, compared with the results for vehicle with the original spring‐damper suspension and conventional hydraulically interconnected suspension (HIS). On the other hand, ride comfort performance indicated by total weighted root mean square accelerations at the center of gravity is studied when vehicle is excited by three different types of road pavements when the four parameters vary in the prescribed ranges. Simulation results are compared to investigate the special merits of DHIS subsystem, and the parameters that influence the handling performance and ride comfort most are identified. Overall, the DHIS subsystem can effectively enhance the vehicle handling performance compared with the original spring‐damper suspension, and it can also benefit much to the ride comfort in contrast to the HIS subsystem.

Issues on the Testing of Small Cryogenic Recuperators and Experimental Studies on Perforated Plate Heat Exchangers

ABSTRACTThis paper deals with various issues on testing heat exchangers at cryogenic temperatures, the test setup and experimental studies on perforated plate heat exchangers. A number of fluid flow circuits are used in practice for testing a heat exchanger at cryogenic temperatures. These circuits are reviewed and a simplified fluid circuit is proposed with justifications. Effects of the fluid inlet/outlet tubes on the performance evaluation of the heat exchanger were investigated numerically. It is found that convection heat transfer between fluid and the tube as well as conduction heat transfer through the tube walls can cause significant errors in the evaluation. These errors are considered while designing the inlet/outlet tubes for the test setup. Details of the test setup including mounting of temperature sensors, instrumentation and data acquisition are discussed. Some selected data from our experimental studies on perforated plate heat exchangers are presented. Transient study on the heat exchanger by using the setup is also demonstrated. For pressure drop studies, a separate test setup is used.

The hydraulic hammer effect in solar tower fluid circuit temperature controller

This article addresses the possible occurrence of hydraulic hammer effects in solar power towers and the limitations they impose on the response bandwidth of the control loop that governs the valve actuating on heating fluid flow. The partial differential equations that model the traveling waves associated to the hammer effect are solved with different methods. A finite dimensional approximation of the exact solution, by a transfer function with a finite number of poles is obtained. It is concluded that, for the speed of response of the temperature controller associated to the valve, there is no danger of inducing hydraulic hammer effects that can damage the equipment.

Cascade system using both trough system and dish system for power generation

This paper represents a novel solar thermal cascade system using both trough and dish systems for power generation. An effective structure using the condensed fluid of Rankine cycle to cool the Stirling engines to use the heat released by Stirling engines was proposed. The cascade system model with different fluid circuits was developed. The models of some important components of the system, such as dish collector, trough collector and Stirling engine array, are presented with detail explanation in this paper. Corresponding stand-alone systems were also developed for comparison. Simulations were conducted with the models to find out efficiency difference between cascade system and corresponding stand-alone systems. The directions to increase the efficiency difference were also considered. Results show that the cascade system can achieve a higher efficiency with a high solar irradiance (>550W/m2). The flow type of fluids between heating and cooling Stirling engine array is also required to concern on designing a cascade system with Stirling engine array.

A novel filtration system for point of care washing of cellular therapy products.

The cell therapy industry would greatly benefit from a simple point of care solution to remove dimethylsulphoxide (DMSO) from small-volume thawed cell suspensions before injection. A novel dead-end filtration device has been designed and validated, which takes advantage of the higher density of thawed cell suspensions to remove the DMSO and protein impurities from the cell suspension without fouling the filter membrane. The filter was designed to avoid fluid circuits and minimize the surface area that is contacted by the cell suspension, thus reducing cell losses by design. The filtration process was established through optimization of the fluid flow configuration, backflush cycles and filter geometry. Overall, this novel filtration device allows for a 1ml of thawed cryopreserved cell suspensions, containing 107 cells of a fetal lung fibroblast cell line (MRC-5), to be washed in less than 30min. More than 95% of the DMSO and up to 94% of the albumin-fluorescein-isothiocyanate content can be removed while the viable cell recovery is higher than 80%. It is also demonstrated that this system can be used for bone marrow-derived human mesenchymal stem cells with more than 73% cell recovery and 85% DMSO reduction. This is the first time that a dead end (normal) filtration process has been used to successfully wash high-density human cell suspensions. In practice, this novel solid-liquid separation technology fills the need for small-volume washing in closed processing systems for cellular therapies. Copyright © 2016 John Wiley & Sons, Ltd.

Recent Development of Droplet Microfluidics in Digital Polymerase Chain Reaction

Digital polymerase chain reaction (PCR) has been experiencing a rapid development during the past few years. Compared with the traditional qPCR, the accuracy of digital PCR for the absolute quantification of target gene has been significantly improved with the same primer and probe as qPCR. The development of digital PCR is directly related to the development of microfluidics. The integrated fluid circuit, which has a complicated fabrication process with high cost, is an early integration of the microfluidics and digital PCR. Recently, researchers are trying to apply the droplet microfluidics in digital PCR. A droplet microfluidic chip is able to generate millions of droplets within a short time. Each of these droplets containing no more than one target gene is a reaction chamber during the amplification process. After amplification, each droplet is tested to obtain the absolute quantification of the target gene. This paper reviews the recent progress of droplet digital PCR and the application of droplet digital PCR in biological, medical and environmental area.

Design and performance of a novel magnetocaloric heat pump

The design and preliminary results of an active magnetic refrigeration prototype for room temperature cooling applications are investigated. The physical prototype along with its operational and measurement envelopes are described. General design goals included: A wide range of cycle parameter control, independent fluid and magnetic circuits, extensive measurement capability, and compact overall design. An initial set of measurements has been made with Gadolinium particulate of an industrial purity. The maximum no-load span recorded was 21 K and the maximum power recorded was 26 W at a span of 1 K. Additionally, three different cyclical parameters have been varied to help determine the optimal cycle for such a machine. The unique modularity and control of this system will allow for a detailed understanding of the operation of commercial active magnetic regeneration designs.

Butane Heat Pipes for Stagnation Temperature Reduction of Solar Thermal Collectors

Heat pipes in solar thermal collectors enable to reduce the temperature loads in the solar circuit during stagnation periods by exploiting their dry out limit. Typically water, pentane or acetone are used as heat transfer media in collector heat pipes. Butane is very suitable to reach a high temperature gradient of the dry out even if the maximum temperature in the fluid circuit should be designed to 120 ̊C or below. The paper presents experimental results with butane heat pipes that operate up to a maximum temperature of 120 ̊C with a high temperature gradient in the dry-out region. This ensures that the collector performance in the operating range (typically up to 100 ̊C) is not affected negatively by the dry-out. Different approaches to increase the thermal conductance of butane heat pipes by enhancing the inner surface of the condenser or of both, the condenser and the evaporator are experimentally assessed and discussed. Measurement results report an increase of the heat pipes’ thermal conductance from 3 W/K (standard geometry) to 23 W/K.

Performance comparison of improvised prehospital blood warming techniques and a commercial blood warmer

IntroductionPrehospital transfusion of packed red blood cells (PRBC) may be life saving for hypovolaemic trauma patients. PRBCs should preferably be warmed prior to administration but practical prehospital devices have only recently become available. The effectiveness of purpose designed prehospital warmers compared with previously used improvised methods of warming has not previously been described. Materials and methodsExpired units of PRBCs were randomly assigned to a warming method in a bench study. Warming methods were exposure to body heat of an investigator, leaving the blood in direct sunlight on a dark material, wrapping the giving set around gel heat pads or a commercial fluid warmer (Belmont Buddy Lite). Methods were compared with control units that were run through the fluid circuit with no active warming strategy. ResultsThe mean temperature was similar for all methods on removal from the fridge (4.5°C). The mean temperatures (degrees centigrade) for all methods were higher than the control group at the end of the circuit (all P≤0.001). For each method the mean (95% CI) temperature at the end of the circuit was; body heat 17.2 (16.4–18.0), exposure to sunlight 20.2 (19.4–21.0), gel heat pads 18.8 (18.0–19.6), Buddy Lite 35.2 (34.5–36.0) and control group 14.7 (13.9–15.5). ConclusionsAll of the warming methods significantly warmed the blood but only the Buddy Lite reliably warmed the blood to a near normal physiological level. Improvised warming methods therefore cannot be recommended.

Experimental study on the heat transfer of MWCNT/water nanofluid flowing in a car radiator

This study is concerned with an experimental evaluation of the thermal performance of multi-walled carbon nanotubes (MWCNT) dispersed in distilled water flowing inside an automotive radiator. A two-step method called high-pressure homogenization was used to disperse the MWCNT nanoparticles in water, in concentrations varying between 0.05 and 0.16wt%. Experiments have been carried out in an experimental set up composed by a wind tunnel that simulates the air flow through a car radiator, and a hot fluid circuit, that circulates the nanofluid inside the radiator. The air flow rate was maintained constant at 0.175kg/s. The mass flow rate of the hot fluid varied from 30 up to 70g/s and the inlet temperature was maintained constant at 50, 60, 70 and 80°C, respectively. The temperature drop and heat transfer rate have been investigated. A slight-decrease on the heat transfer rate, up to 5%, was found for all test conditions. On the other hand as the nanoparticle concentration increased, the heat transfer rate decreased.

Dynamic modelling of a low-concentration solar power plant: A control strategy to improve flexibility

This paper deals with a dynamic analysis on a low concentration solar power plants coupled with Organic Rankine Cycles (ORC), which can be an alternative to PV systems because of their capability of providing a smoother electricity production due to their thermal inertia. At least within certain restraints, moreover they are able to exploit diffused solar radiation.The dynamic model of a plant with static Compound Parabolic Collectors and an ORC system, using a rotary volumetric expander, was developed using the simulation tool AMESim. All the main components of the plant are modelled: solar collectors field, heat transfer fluid circuit, heat exchangers and the ORC system. The plant response to the radiation of different days was analyzed to quantify the daily production and the trend of various plant parameters. Real ambient conditions were employed for the simulations by using data obtained by historical series.The results showed that the employment of a volumetric expansion device with variable rotating speed allows the plant to operate at different radiations and ambient temperatures without the need of any storage system or external heat sources. Results can be extended to other applications, such as low temperature waste heat recovery or geothermal systems.

Growth of a Pleistocene giant carbonate vein and nearby thermogene travertine deposits at Semproniano, southern Tuscany, Italy: Estimate of CO2 leakage

A giant carbonate vein (≥50m thick; fissure ridge travertines) and nearby travertine plateaus in the Semproniano area (Mt. Amiata geothermal field, southern Tuscany, Italy) are investigated through a multidisciplinary approach, including field and laboratory geochemical analyses (U/Th geochronology, C, Nd, O and Sr isotope systematics, REE abundances, and fluid inclusion microthermometry). The main aim of this work is to understand: (1) modes and rates for the growth of the giant vein and nearby travertine deposits within a Quaternary volcano-tectonic domain; (2) implications in terms of the CO2 leakage; and (3) possible relationships with Quaternary paleoclimate and hydrological oscillations. Results show that the giant vein was the inner portion of a large fissure ridge travertine and grew asymmetrically and ataxially through repeated shallow fluid injections between >650 and 85ka, with growth rates in the 10−2–10−3mm/a order. The giant vein developed mainly during warm humid (interglacial) periods, partially overlapping with the growth of nearby travertine plateaus. Estimated values of CO2 leakage connected with the vein precipitation are between about 5×106 and 3×107mola−1km−2, approximately representing one millionth of the present global CO2 leakage from volcanic areas. Temperature estimates obtained from O-isotopes and fluid inclusion microthermometry indicate epithermal conditions (90–50°C) for the circulating fluid during the giant vein growth, with only slight evidence of cooling with time. Geochemical and isotope data document that the travertine deposits formed mainly during Pleistocene warm humid periods, within a tectonically-controlled convective fluid circuit fed by meteoric infiltration and maintained by the regional geothermal anomaly hosted by the carbonate reservoir of the Mt. Amiata field.

Increasing thermal drying temperature of biosolids reduced nitrogen mineralisation and soil N2O emissions.

Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood. This will be of importance for the value of the biosolids when used to fertilise crops. We sourced AD biosolids from a Danish waste water treatment plant (WWTP) and dried it in the laboratory at 70, 130, 190 or 250°C to >95% dry matter content. Also, we sourced biosolids from the WWTP dried using its in-house thermal drying process (input temperature 95°C, thermal fluid circuit temperature 200°C, 95% dry matter content). The drying process reduced the ammonium content of the biosolids and reduced it further at higher drying temperatures. These findings were attributed to ammonia volatilisation. The percentage of mineralisable organic N fraction (min-N) in the biosolids, and nitrous oxide (N2O) and carbon dioxide (CO2) production were analysed 120days after addition to soil. When incubated at soil field capacity (pF 2), none of the dried biosolids had a greater min-N than the AD biosolids (46.4%). Min-N was lowest in biosolids dried at higher temperatures (e.g. 19.3% at 250°C vs 35.4% at 70°C). Considering only the dried biosolids, min-N was greater in WWTP-dried biosolids (50.5%) than all of the laboratory-dried biosolids with the exception of the 70°C-dried biosolids. Biosolid carbon mineralisation (CO2 release) and N2O production was also the lowest in treatments of the highest drying temperature, suggesting that this material was more recalcitrant. Overall, thermal drying temperature had a significant influence on N availability from the AD biosolids, but drying did not improve the N availability of these biosolids in any case.