Mechanistic Model Of An Oil-Flooded Single-Screw Expander

The power generated from Organic Rankine Cycles (ORCs) is directly related to the performance of the expander used, which in many cases it is adapted from the original compressor. The efficiency of positive displacement expanders depends on several aspects such as internal volume ratio and pressure ratio (under- and over-expansion), leakages, non-adiabatic expansion and heat losses to the ambient and mechanical losses. Thus, lubrication is often required to reduce friction and to seal leakage gaps. In this paper, the effect of oil-flooding on the performance of a single-screw expander is investigated. By varying the oil fraction, it is possible to analyze the combined effects of reducing the leakages and the possibility to achieve a quasi-isothermal expansion. The flooding of the expander is realized by adding an independent oil loop to the conventional ORC as proposed by Woodland et al. (2013). The mechanistic model developed by Ziviani et al. (2014) for a single-screw expander has been extended to include liquid-flooding. The multi-chamber model with the associated governing equations of conservation of mass and energy for the flooded-expansion process is described along with the overall energy balance model of the expander. Insights on the calculation of the working fluid and lubricant oil mixture properties and the solubility effects are provided. The working fluid considered is R245FA and the lubricant oil is ACD100FY. The mechanistic model is implemented in the Python programming language and an example of oil-flooded singlescrew expander model is integrated in the open-source simulation package PDSim (v3.0). REFRENCES Woodland, B. J., Krishna, A., Groll, E. A., Braun, J. E., Horton, W. T., and Garimella, S. V. (2013). Thermodynamic comparison of organic rankine cycles employing liquid-flooded expansion or a solution circuit. Applied Thermal Engineering, 61:859-65. Ziviani, D., Bell, I. H., De Paepe, M., and van den Broek, M. (2014). Comprehensive model of a single screw expander for orc-systems applications. In 22th Int.Compressor Engineering Conf. at Purdue, number 1506

Recessive osteogenesis imperfecta caused by LEPRE1 mutations: clinical documentation and identification of the splice form responsible for prolyl 3-hydroxylation

Abstract: Background: Recessive forms of osteogenesis imperfecta (OI) may be caused by mutations in LEPRE1, encoding prolyl 3-hydroxylase-1 (P3H1) or in CRTAP, encoding cartilage associated protein. These proteins constitute together with cyclophilin B (CyPB) the prolyl 3-hydroxylation complex that hydroxylates the Pro986 residue in both the type I and type II collagen alpha 1-chains. Methods: We screened LEPRE1, CRTAP and PPIB (encoding CyPB) in a European/Middle Eastern cohort of 20 lethal/severe OI patients without a type I collagen mutation. Results: Four novel homozygous and compound heterozygous mutations were identified in LEPRE1 in four probands. Two probands survived the neonatal period, including one patient who is the eldest reported patient (17(7/12) years) so far with P3H1 deficiency. At birth, clinical and radiologic features were hardly distinguishable from those in patients with autosomal dominant (AD) severe/lethal OI. Follow-up data reveal that the longer lived patients develop a severe osteochondrodysplasia that overlaps with, but has some distinctive features from, AD OI. A new splice site mutation was identified in two of the four probands, affecting only one of three LEPRE1 mRNA splice forms, detected in this study. The affected splice form encodes a 736 amino acid (AA) protein with a "KDEL'' endoplasmic reticulum retention signal. While western blotting and immunocytochemical analysis of fibroblast cultures revealed absence of this P3H1 protein, mass spectrometry and SDS-urea-PAGE data showed severe reduction of alpha 1(I) Pro986 3-hydroxylation and overmodification of type I (pro) collagen chains in skin fibroblasts of the patients. Conclusion: These findings suggest that the 3-hydroxylation function of P3H1 is restricted to the 736AA splice form

Update on single-screw expander geometry model integrated into an open-source simulation tool

In this paper, a mechanistic steady-state model of a single-screw expander is described with emphasis on the geometric description. Insights into the calculation of the main parameters and the definition of the groove profile are provided. Additionally, the adopted chamber model is discussed. The model has been implemented by means of the open-source software PDSim (Positive Displacement SIMulation), written in the Python language, and the solution algorithm is described. The single-screw expander model is validated with a set of steady-state measurement points collected from a 11 kWe organic Rankine cycle test-rig with SES36 and R245fa as working fluid. The overall performance and behavior of the expander are also further analyzed

Experimental investigation of solidification in metal foam enhanced phase change material

A major challenge for the use of phase change materials (PCMs) in thermal energy storage (TES) is overcoming the low thermal conductivity of PCM’s. The low conductivity gives rise to limited power during charging and discharging TES. Impregnating metal foam with PCM, however, has been found to enhance the heat transfer. On the other hand, the effect of foam parameters such as porosity, pore size and material type has remained unclear. In this paper, the effect of these foam parameters on the solidification time is investigated. Different samples of PCM-impregnated metal foam were experimentally tested and compared to one without metal foam. The samples varied with respect to choice of material, porosity and pore size. They were placed in a rectangular cavity and cooled from one side using a coolant flowing through a cold plate. The other sides of the rectangular cavity were Polymethyl Methacrylate (PM) walls exposed to ambient. The temperature on the exterior walls of the cavity was monitored as well as the coolant flow rate and its temperature. The metal foam inserts reduced the solidification times by at least 25 %. However, the difference between the best performing and worst performing metal foam is about 28 %. This shows a large potential for future research.This study has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 657466 (INPATH-TES)

Development of a non-functional pancreatic neuroendocrine tumor and a duodenal ulceration after cholecystoduodenostomy in a cat

A six-year-old Ragdoll with previous extrahepatic biliary tract obstruction due to cholangio-hepatitis, treated with cholecystoduodenostomy, was presented for acute vomiting, hyporexia, and weight loss. Abdominal ultrasound examination revealed randomly distributed hepatic nodules and dilated biliary ducts. Gastroduodenoscopy showed a patent cholecystoduodenostoma but disclosed a perforated duodenal ulceration. Conversion to celiotomy revealed extensive liver pathology, a discrete pancreatic nodule, and a duodenal ulcer opposite to the cholecystoduodenostoma. The cat was euthanized intra-operatively and necropsy was performed. The intrahepatic biliary tract of the right liver lobes was obstructed and severely dilated, whereas bile from the left lobes drained through the cholecystoduodenostoma. Histopathologic diagnoses were a primary pancreatic tumor, positive for glucagon on immunohistochemistry, with liver meta-stases, chronic purulent cholecystitis, and duodenal ulceration. To the authors' knowledge, this is the first report in which the development of pancreatic neoplasia is described in a cat with a history of biliary tract disease

Successful management of a solitary simple renal cyst in a dog

In this report, a dog is described that was referred to the Small Animal Department, Faculty of Veterinary Medicine (Ghent University) for further work-up and treatment of a solitary renal cyst. The cyst was treated successfully with ultrasound-guided drainage and percutaneous sclerotherapy. The dog was followed-up during twenty-four months post procedure with renal sonography. The complaints of intermittent lethargy disappeared after the first treatment. The ultrasonographic appearance of the cyst evolved from a round, anechoic, sharply demarcated lesion to an ill-defined, hyperechoic lesion

Short-term health effects in the general population following a major train accident with acrylonitrile in Belgium

Background: Following a train derailment, several tons of acrylonitrile (ACN) exploded, inflamed and part of the ACN ended up in the sewage system of the village of Wetteren. More than 2000 residents living in the close vicinity of the accident and along the sewage system were evacuated. A human biomonitoring study of the adduct N-2-cyanoethylvaline (CEV) was carried out days 14-21 after the accident. Objectives: (1) To describe the short-term health effects that were reported by the evacuated residents following the train accident, and (2) to explore the association between the CEV concentrations, extrapolated at the time of the accident, and the self-reported short-term health effects. Methods: Short-term health effects were reported in a questionnaire (n=191). An omnibus test of independence was used to investigate the association between the CEV concentrations and the symptoms. Dose-response relationships were quantified by Generalized Additive Models (GAMs). Results: The most frequently reported symptoms were local symptoms of irritation. In non-smokers, dose-dependency was observed between the CEV levels and the self-reporting of irritation (p=0.007) and nausea (p=0.007). Almost all non-smokers with CEV concentrations above 100 pmol/g globin reported irritation symptoms. Both absence and presence of symptoms was reported by non-smokers with CEV concentrations below the reference value and up to 10 times the reference value. Residents who visited the emergency services reported more symptoms. This trend was seen for the whole range of CEV concentrations, and thus independently of the dose. Discussion and conclusion: The present study is one of the first to relate exposure levels to a chemical released during a chemical incident to short-term (self-reported) health effects. A dose-response relation was observed between the CEV concentrations and the reporting of short-term health effects in the non-smokers. Overall, the value of self-reported symptoms to assess exposure showed to be limited. The results of this study confirm that a critical view should be taken when considering self-reported health complaints and that ideally biomarkers are monitored to allow an objective assessment of exposure

Semantics in the wild : a digital assistant for Flemish citizens

Public service fragmentation across more than 800 digital channels of government administrations in the region of Flanders (Belgium), causes administrative burden and frustrations, as citizens expect a coherent service. Given the autonomy of the various entities, the fragmentation of information and budget constraints, it is not feasible to rewire the entire e-gov ecosystem to a single portal. Therefore, the Flemish Government is building a smart digital assistant, which supports citizens on the governmental portals, by integrating status information of various transactions. This paper outlines our ongoing research on a method for raising semantic interoperability between different information systems and actors. In this approach, semantic agreements are maintained and implemented end-to-end using the design principles of Linked Data. The lessons learned can speed-up the process in other countries that face the complexity of integrating e-government portals

Estimation of ontogeny functions for renal transporters using a combined population pharmacokinetic and physiology-based pharmacokinetic approach : application to OAT1,3

To date, information on the ontogeny of renal transporters is limited. Here, we propose to estimate the in vivo functional ontogeny of transporters using a combined population pharmacokinetic (popPK) and physiology-based pharmacokinetic (PBPK) modeling approach called popPBPK. Clavulanic acid and amoxicillin were used as probes for glomerular filtration, combined glomerular filtration, and active secretion through OAT1,3, respectively. The predictive value of the estimated OAT1,3 ontogeny function was assessed by PBPK predictions of renal clearance (CLR) of other OAT1,3 substrates: cefazolin and piperacillin. Individual CL(R)post-hoc values, obtained from a published popPK model on the concomitant use of clavulanic acid and amoxicillin in critically ill children between 1 month and 15 years, were used as dependent variables in the popPBPK analysis. CLR was re-parameterized according to PBPK principles, resulting in the estimation of OAT1,3-mediated intrinsic clearance (CLint,OAT1,3,invivo) and its ontogeny. CLint,OAT1,3,invivo ontogeny was described by a sigmoidal function, reaching half of adult level around 7 months of age, comparable to findings based on renal transporter-specific protein expression data. PBPK-based CLR predictions including this ontogeny function were reasonably accurate for piperacillin in a similar age range (2.5 months-15 years) as well as for cefazolin in neonates as compared to published data (%RMSPE of 21.2 and 22.8%, respectively and %PE within +/- 50%). Using this novel approach, we estimated an in vivo functional ontogeny profile for CLint,OAT1,3,invivo that yields accurate CLR predictions for different OAT1,3 substrates across different ages. This approach deserves further study on functional ontogeny of other transporters