Smart Flow Control Processes in Micro Scale

In recent years, microfluidic devices with a large surface-to-volume ratio have witnessed rapid development, allowing them to be successfully utilized in many engineering applications. A smart control process has been proposed for many years, while many new innovations and enabling technologies have been developed for smart flow control, especially concerning “smart flow control” at the microscale. This Special Issue aims to highlight the current research trends related to this topic, presenting a collection of 33 papers from leading scholars in this field. Among these include studies and demonstrations of flow characteristics in pumps or valves as well as dynamic performance in roiling mill systems or jet systems to the optimal design of special components in smart control systems

Supercritical carbon dioxide power cycles for waste heat recovery applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThe growing energy demand and the increasingly stringent regulations on pollutant and greenhouse gas emissions are driving academia and industry to seek new approaches to increase the overall energy efficiency of existing industrial facilities. Among them, the recovery and utilisation of industrial waste heat is currently considered as one of the most effective approaches to reduce the energy demand of industrial processes as they are characterised by thermal energy losses, through high temperature exhausts above 300°C, that account for nearly 11.4% of primary energy consumption. For these high temperature waste heat sources, the use of conventional heat to power conversion systems based on bottoming thermodynamic cycles is limited by technological and economic constraints. Most of the state-of-the-art working fluids are indeed not able to perform safely and efficiently at high temperatures. Supercritical Carbon Dioxide (sCO2) power systems allow to overcome these limitations because of the chemical stability of CO2 at high temperatures. Furthermore, the favourable CO2 thermo-physical properties in the supercritical state, including high density, allow to achieve superior performance and lower footprint and cost compared to Organic Rankine Cycles and other more conventional technologies. With the aim of giving a broad overview of the potential of sCO2 power cycles in high temperature waste heat recovery (WHR) applications, this research firstly investigates the theoretical capabilities of several Joule-Brayton cycle configurations. The analysis involves performance indicators and economic metrics, which are calculated using cost correlations and budgetary quotations to estimate the investment costs of equipment. This aspect represents one of the main novel contributions of the research. Among the investigated layouts, the simple regenerative cycle showed the highest competitiveness for industrial uptake of the sCO2 technology at small-scales (<0.5 MWe) in high-grade waste heat to power applications. For this reason, such cycle layout has been adopted as reference for the design and construction of a 50 kWe state-of-the-art experimental facility. The facility comprises an 830 kW process air heater able of providing an exhaust mass flow rate of 1.0 kg/s at 70 mbarg and maximum temperature of 800°C, and a water dry cooler of 500 kW heat rejection capacity as heat sink. The sCO2 heat to power conversion block utilises a single-shaft Compressor-Generator-Turbine unit and three types of heat exchanger technology. The main design features of the test facility as well as operation and safety considerations are discussed. This research activity allowed to retrieve accurate geometrical and performance data by component manufacturers which have been used to develop a detailed numerical model of the facility with the objective of investigating the steady-state and transient performance of the sCO2 system. Operating maps of the unit have been obtained which can form the baseline for the setting up of optimisation and control strategies. The dynamic analysis showed that the system is able to quickly adapt to transient heat load profiles, proving the flexible nature of the sCO2 unit investigated. Start-up and shut-down strategies able to achieve a safer build-up and decline of pressures and temperatures in the circuit, thus eliminating the risk of flow shocks and excessive mechanical stresses, have also been identified. A further novel contribution is assessment of the advantages of having the turbine and compressor driven independently as opposed to being mounted on the same shaft that dictates operation at the same speed. The results show only a small benefit at design conditions, but a power increase of 27% at 10% increase in heat source temperature, highlighting the advantage of independent drive at off design conditions. The adoption of an inventory control strategy to regulate the sCO2 system during transient operations showed that the imposed variation in the CO2 mass circulating in the loop allows to achieve a 30% variation in the turbine inlet temperature with lower penalties on system performance compared to turbomachinery speed control.EPSR

Fifteenth Space Simulation Conference: Support the Highway to Space Through Testing

The Institute of Environmental Sciences Fifteenth Space Simulation Conference, Support the Highway to Space Through Testing, provided participants a forum to acquire and exchange information on the state-of-the-art in space simulation, test technology, thermal simulation and protection, contamination, and techniques of test measurements

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018

High Performance Light Water Reactor : Design and Analyses

The High Performance Light Water Reactor is a nuclear reactor concept of the 4th generation which is cooled and moderated with supercritical water. The concept has been worked out by a consortium of European partners, co-funded by the European Commission. It features a once through steam cycle, a pressure vessel type reactor, and a compact containment with pressure suppression pool. The conceptual design enables to assess its feasibility, its safety features and its economic potential

Numerical Heat Transfer and Fluid Flow 2021

This reprint focuses on experiments, modellings, and simulations of heat transfer and fluid flow. Flowing media comprise single- or two-phase fluids that can be both compressible and incompressible. The reprint presents unique experiments and solutions to problems of scientific and industrial relevance in the transportation of natural resources, technical devices, industrial processes, etc. In the presented works, the formulated physical and mathematical models together with their boundary and initial conditions and numerical computation methods for constitutive equations lead to solutions for selected examples in engineering

14th International Conference on Turbochargers and Turbocharging

14th International Conference on Turbochargers and Turbocharging addresses current and novel turbocharging system choices and components with a renewed emphasis to address the challenges posed by emission regulations and market trends. The contributions focus on the development of air management solutions and waste heat recovery ideas to support thermal propulsion systems leading to high thermal efficiency and low exhaust emissions. These can be in the form of internal combustion engines or other propulsion technologies (eg. Fuel cell) in both direct drive and hybridised configuration. 14th International Conference on Turbochargers and Turbocharging also provides a particular focus on turbochargers, superchargers, waste heat recovery turbines and related air managements components in both electrical and mechanical forms

Advanced Microturbine Systems

In July 2000, the United Technologies Research Center (UTRC) was one of five recipients of a US Department of Energy contract under the Advanced Microturbine System (AMS) program managed by the Office of Distributed Energy (DE). The AMS program resulted from several government-industry workshops that recognized that microturbine systems could play an important role in improving customer choice and value for electrical power. That is, the group believed that electrical power could be delivered to customers more efficiently and reliably than the grid if an effective distributed energy strategy was followed. Further, the production of this distributed power would be accomplished with less undesirable pollutants of nitric oxides (NOx) unburned hydrocarbons (UHC), and carbon monoxide (CO). In 2000, the electrical grid delivered energy to US customers at a national average of approximately 32% efficiency. This value reflects a wide range of powerplants, but is dominated by older, coal burning stations that provide approximately 50% of US electrical power. The grid efficiency is also affected by transmission and distribution (T&D) line losses that can be significant during peak power usage. In some locations this loss is estimated to be 15%. Load pockets can also be so constrained that sufficient power cannot be transmitted without requiring the installation of new wires. New T&D can be very expensive and challenging as it is often required in populated regions that do not want above ground wires. While historically grid reliability has satisfied most customers, increasing electronic transactions and the computer-controlled processes of the 'digital economy' demand higher reliability. For them, power outages can be very costly because of transaction, work-in-progress, or perishable commodity losses. Powerplants that produce the grid electrical power emit significant levels of undesirable NOx, UHC, and CO pollutants. The level of emission is quoted as either a technology metric or a system-output metric. A common form for the technology metric is in the units of PPM {at} 15% O2. In this case the metric reflects the molar fraction of the pollutant in the powerplant exhaust when corrected to a standard exhaust condition as containing 15% (molar) oxygen, assuring that the PPM concentrations are not altered by subsequent air addition or dilution. Since fuel combustion consumes oxygen, the output oxygen reference is equivalent to a fuel input reference. Hence, this technology metric reflects the moles of pollutant per mole of fuel input, but not the useful output of the powerplant-i.e. the power. The system-output metric does embrace the useful output and is often termed an output-based metric. A common form for the output-based metric is in the units of lb/MWh. This is a system metric relating the pounds of pollutant to output energy (e.g., MWh) of the powerplant

Heat Transfer in Engineering

The advancements in research related to heat transfer has gathered much attention in recent decades following the quest for efficient thermal systems, interdisciplinary studies involving heat transfer, and energy research. Heat transfer, a fundamental transport phenomenon, has been considered one of the critical aspects for the development and advancement of many modern applications, including cooling, thermal systems which contain symmetry analysis, energy conservation and storage, and symmetry-preserving discretization of heat transfer in a complex turbulent flow. The objective of this book is to present recent advances, as well as up-to-date progress in all areas of heat transfer in engineering and its influence on emerging technologies