The air-liquid flow in a microfluidic airway tree

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Microfluidic techniques are employed to investigate air-liquid flows in the pulmonary airway tree. A network of microchannels with five generations is made and used as a simplified model of the pulmonary airway tree. Liquid plugs are injected into the network and pushed by air flow to divide at every bifurcation before reaching the exits. The resistance associated with the presence of one plug in a given generation is defined to establish a linear relation between the driving pressure and the total flow rate in the network. Based on this resistance, we have good predictions of the flow of two successive plugs in the network. For two-plug flows under the same driving pressure, the total flow rate depends not only on the lengths of the plugs but also the initial distance between the two. Strong long range interactions are found between daughter plugs, especially when they are flowing through the bifurcations. We also observe different flow patterns under different pushing conditions. Under a constant pressure forcing, the flow develops symmetrically while a constant flow rate push achieves an asymmetric flow.This study is funded by the ANR under the “Sante-Environnement et Sante-Travail” programme

Data-driven approaches for techno-economic assessment of waste heat recovery and utilisation in the industrial sector

The industrial sector is a critical element in the sustainability transition as it is currently the largest consumer of fossil fuels, and the consumption is forecasted to continue to increase. Approximately one-fifth of the total industrial primary energy consumption is wasted due to the lack of proven attractive schemes for effective recovery. When addressing the opportunities of industrial waste heat recovery (WHR), it is found that the feasibility depends on multiple factors, including the forms and capacities of the heat sources, the potential heat sinks, and the effectiveness, technological maturity, and economic impact of available technologies. Developing systematic approaches to identify optimal WHR options for different applications is key to effectively reduce plant-scale energy consumption. In particular, power consumption accounts for more than half of the industrial energy use, and its share is expected to grow with the expansion of electrification aspirations. In this paper, industrial WHR technologies are investigated, and tools are developed to understand the sustainability and techno-economic impact of integrating these technologies within industrial processes. We specifically propose a data-driven technology-agnostic approach to evaluate the use of heat engines, which can in practice be organic Rankine cycle (ORC) systems, and of thermally- driven (i.e., absorption) heat pumps in the context of industrial WHR for plant-scale power demand reduction. The scope of this work explores three pathways to achieving efficiency improvements in bulk chemicals plants, represented by olefins production facilities, which are: (i) direct onsite power generation; (ii) enhancement of existing power generation processes; and (iii) reduction in power consumption by compressor efficiency improvements through waste-heat-driven cooling. The techno-economic performance of these technologies is assessed, with particular attention to industrial facilities that reside in hot climates, using fine-tuned technology-agnostic thermodynamic and market-based costing models. Finally, decision-aiding performance maps are derived by varying the quantity and the quality of waste-heat sources and heat sinks, offering application- specific guidelines for selecting appropriate waste-heat recovery schemes. These findings reveal valuable factors for selecting such integration schemes for various industries and scenarios

A γA-Crystallin Mouse Mutant Secc with Small Eye, Cataract and Closed Eyelid

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Techno-economic assessment of integrated spectral-beam-splitting photovoltaic-thermal (PV-T) and organic Rankine cycle (ORC) systems

Promising solar-based combined heating and power (CHP) systems are attracting increasing attention thanks to the favourable characteristics and flexible operation. For the first time, this study explores the potential of integrating a novel spectral-beam-splitting (SBS), hybrid photovoltaic-thermal (PVT) collector and organic Rankine cycle (ORC) technologies to maximise solar energy utilisation for electricity generation, while also providing hot water/space heating to buildings. In the proposed collector design, a parabolic trough concentrator (PTC) directs light to a SBS filter. The filter reflects long wavelengths to an evacuated tube absorber (ETA), which is thermally decoupled from the cells in the PVT tube, subsequently enabling a high-temperature fluid stream to be provided by the ETA to an ORC sub-system for secondary power generation. The SBS filter’s optical properties are a key determinant of the system’s performance, with maximum electricity generation attained when the filter transmits wavelengths between 485 and 860 nm onto the PVT tube, while the light outside this range is reflected onto the ETA. The effect of key design parameters and system capacity on techno-economic performance is investigated, considering Spain (Sevilla), the UK (London) and Oman (Muscat) as locations to capture climate and economic impacts. When operated for maximum electricity generation, the combined system achieves a ratio of heat to power of ∼1.3, which is comparable to conventional CHP systems. Of the total incident solar energy, 24% and 31% is respectively converted to useful electricity and heat, with 54% of the electricity being generated by the PV cells. In Spain, the UK and Oman, respective electricity generation of 1.8, 0.9 and 2.1 kWhel/day per m2 of PTC area is achieved. Energy prices are found to be pivotal for ensuring viable payback times, with attractive payback times as low as 4–5 years obtained in the case of Spain at system capacities over 2.7 kWel. Integrating the ORC sub-system with the concentrating SBS-PVT collector design reduced the levelised cost of electricity (LCOEel). A LCOEel of 0.10 £/kWh is attained in Spain at an electrical capacity of only 4 kWel, demonstrating the significant potential of exploiting the proposed systems in practical applications, as highly competitive with established combustion-based CHP systems

Thermodynamic investigation of latent-heat stores for pumped-thermal energy storage

As a large-scale energy storage technology, pumped-thermal energy storage uses thermodynamic cycles and thermal stores to achieve energy storage and release. In this paper, we explore the thermodynamic feasibility and potential of exploiting cascaded latent-heat stores in Joule-Brayton cycle-based pumped-thermal energy storage systems. A thermodynamic model of cascaded latent-heat stores is developed, and the effects of the heat store arrangement (i.e., total stage number and stage area) and fluid velocity in the thermal store tubes as key parameters that affect the heat storage and release rates, as well as the roundtrip efficiency, are evaluated. A pure electricity-storage mode and a combined heating and power mode are proposed and investigated, which allows such technologies to transform from a pure electricity storage system to an energy management system supplying power and multi-grade thermal and cold energy, and also to integrate with external waste heat and/or cold sources. Results show that the roundtrip efficiency of cascaded latent-heat stores is higher in the combined heating and power mode than in the pure electricity-storage mode, and that roundtrip efficiencies ranging from 62 % to 100 % can be achieved in the combined heating and power mode, accompanied by a corresponding pressure loss gradient ranging from 10 Pa/m to 2270 Pa/m. A comparison with packed-bed and liquid sensible-heat stores is also performed, and the results indicate that if these can be well designed, cascaded latent-heat stores can deliver comparable performance in terms of the total heat storage and release rates, roundtrip efficiency and flow resistance loss. Therefore, it is concluded that cascaded latent-heat stores can be considered for use in Joule-Brayton cycle-based pumped-thermal energy storage systems aimed at intelligent energy management for the provision of power and multi-grade heat and cold, if the costs can justify this decision

Advanced exergy analysis of a Joule-Brayton pumped thermal electricity storage system with liquid-phase storage

Pumped thermal electricity storage is a thermo-mechanical energy storage technology that has emerged as a promising option for large-scale (grid) storage because of its lack of geographical restrictions and relatively low capital costs. This paper focuses on a 10 MW Joule-Brayton pumped thermal electricity storage system with liquid thermal stores and performs detailed conventional and advanced exergy analyses of this system. Results of the conventional exergy analysis on the recuperated system indicate that the expander during discharge is associated with the maximum exergy destruction rate (13%). The advanced exergy analysis further reveals that, amongst the system components studied, the cold heat exchanger during discharge is associated with the highest share (95%) of the avoidable exergy destruction rate, while during charge the same component is associated with the highest share (64%) of the endogenous exergy destruction rate. Thus, the cold heat exchanger offers the largest potential for improvement in the overall system exergetic efficiency. A quantitative analysis of the overall system performance improvement potential of the recuperated system demonstrates that increasing the isentropic efficiency of the compressor and turbine from 85% to 95% significantly increases the modified overall exergetic efficiency from 37% to 57%. Similarly, by increasing the effectiveness and decreasing the pressure loss factor of all heat exchangers, from 0.90 to 0.98 and from 2.5% to 0.5% respectively, the modified overall exergetic efficiency increases from 34% to 54%. The results of exergy analyses provide novel insight into the innovation, research and development of pumped thermal electricity storage technology

A combination of left ventricular noncompaction and double orifice mitral valve

A 24-year-old woman admitted with mild chest distress associated with activity without chest complaint for twenty days. Two orifices were visible at the level of the mitral valve with a transthoracic short-axis view of the two-dimensional and three-dimensional echocardiography. The left ventricle was mildly dilatated and the left ventricular wall was thickened, especially at the apex and anterolateral wall, and appeared sponge-like. There were numerous, excessively prominent trabeculations associated with intertrabecular recesses. Although the coexistence of NVM and DOMV could be a coincidence, we believe that both defects were probably caused by a developmental arrest of the left ventricular myocardium in the present case

Inhibition of cell proliferation, migration and colony formation of LS174T Cells by carbonic anhydrase inhibitor

Background: Metastasis is the leading cause of cancer deaths. Migration of tumor cells is an important stage in metastasis. Therefore, recent studies have focused on clarifying migration and migration-dependent cell functions such as angiogenesis, wound healing, and invasion. Objectives: In the present study, we aimed to investigate the effect of acetazolamide, which is a classical carbonic anhydrase inhibitor, on the cell viability, migration, and colony forming capacity of human LS174T colorectal cancer cells. Methods: Three different cell culture techniques (MTT test, wound healing and clonogenic assay) were performed in this in vitro study on colorectal cancer cells. Results: Acetazolamide reduced the cell viability, migration and colony formation ability of cells depending on dose. There was no significant difference between the cells treated with acetazolamide with 1 \u3bcM dose and the control. However, it can be concluded that acetazolamide exerts its effect on human colorectal cancer cells at 10-1000 \ub5M concentrations. Conclusion: Acetazolamide was observed to significantly inhibit the cell viability, colony forming capacity, and migration ability in the culture medium of LS174T cells. This inhibitor effect of acetazolamide was observed to be dependent on the concentration in medium

Operational optimisation of a non-recuperative 1-kWe organic Rankine cycle engine prototype

Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140 ∘ C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120 ∘ C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140 ∘ C. For a 100- ∘ C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander components are all significant for the three heat-source conditions, while the exergy destroyed in the pump is negligible by comparison (below 4%). The data can be used for the development and validation of advanced models capable of steady-state part-load and off-design performance predictions, as well as predictions of the transient/dynamic operation of ORC systems.</jats:p