Thermodynamic and Experimental Analysis of a Biomass Steam Power Plant: Critical Issues and their Possible Solutions with CCGT Systems☆

Abstract This paper shows the experimental and numerical analysis of a biomass steam power plant from maximum power of 2.3 MW with a maximum pressure of 48 bar and a turbine inlet temperature of about 430 °C at the design point. The analysis has been conducted using experimental data, collected directly on the power plant, at the design point, and they have been afterwards used to validate a thermodynamic model. The analysis of the biomass power plant pointed out some critical issues that can be summarized in three points: low plant efficiency due to the small size, biomass supply range and continuous variation of the operating point. In order to solve this problem, different plant configurations were numerically evaluated. The first solution to these problems consists of a 100 kWe micro gas turbine (MGT) fueled by natural gas, whose exhaust gas were sent to the steam generator of the biomass power plant in order to evaluate the benefits on the power fluctuations and on global electric efficiency. A thermodynamic model of the MGT has been developed and validated with experimental data from technical literature, creating a CCGT (Combined Cycle Gas Turbine) system. The analysis of the results of this system showed improvement in terms of efficiency and operational stability. The second option was to fuel the previously validated method of MGT with four different alternative fuels and to evaluate the integration with the biomass plant for all of them. Furthermore, to emphasize the benefits of this integration, the power of the micro turbine has been increased assuming the use of more MGT at the same time. These analyses show an increase of the system efficiency, it could been also used the biomass, not suitable for direct combustion (high humidity), to produce biogas that fuels the MGT, reducing the range of biomass supply

Multi-objective Optimization and Sensitivity Analysis of a Cogeneration System for a Hospital Facility☆

Abstract Combined heat and power plants are recognized as very effective solutions to achieve the increasingly stringent requirements in primary energy saving. The paper addresses the use of a specifically developed methodology to conduct several analyses on the basis of the loads of a specific hospital facility and through the study of the cogeneration system-user interaction. Predictive analyses are carried out using a multi-objective approach to find optimized plant configurations that approaches the best energetic results while ensuring a reasonable profit. Optimized plant configurations and management strategies indicate primary energy savings exceeding 17%. Finally, a sensitivity analysis is carried out to evaluate the robustness of the result

Reciprocating Compressor 1D Thermofluid Dynamic Simulation: Problems and Comparison with Experimental Data

The authors here extend a 0D-1D thermofluid dynamic simulation approach to describe the phenomena internal to the volumetric machines, reproducing pressure waves' propagation in the ducts. This paper reports the first analysis of these phenomena in a reciprocating compressor. The first part presents a detailed experimental analysis of an open-type reciprocating compressor equipped with internal sensors. The second part describes a 0D-1D thermofluid dynamic simulation of the compressor. Comparison of computed and measured values of discharge mass flow rate shows a good agreement between results for compression ratio < 5 . Then, to improve the model fitting at higher pressures, a new scheme has been developed to predict the blow-by through the ring pack volumes. This model is based on a series of volumes and links which simulate the rings' motions inside the grooves, while the ring dynamics are imposed using data from the literature about blow-by in internal combustion engines. The validation is obtained comparing experimental and computing data of the two cylinder engine blowby. After the validation, a new comparison of mass flow rate on the compressor shows a better fitting of the curves at higher compression ratio

Effects of Pre-Lift Intake Valve Strategies on the Performance of a DISI VVA Turbocharged Engine at Part and Full Load Operation☆

Abstract In the paper, the potentialities offered by an advanced valve lift design are numerically analyzed. In particular, the study is carried out by a 1D approach and regards the characterization of a VVA strategy named " pre-lift" applied to a downsized turbocharged four-cylinder engine. The pre-lift consists of a small, almost constant lift of the intake valve during the exhaust stroke, so to increase the valves overlapping. The results show a benefit on the fuel economy and on the gas-dynamic noise at part load and a substantial increase in the delivered torque at full load, while preserving the fuel consumption

The tumor suppressor gene TRC8/RNF139 is disrupted by a constitutional balanced translocation t(8;22)(q24.13;q11.21) in a young girl with dysgerminoma

<p>Abstract</p> <p>Background</p> <p><it>RNF139/TRC8 </it>is a potential tumor suppressor gene with similarity to PTCH, a tumor suppressor implicated in basal cell carcinomas and glioblastomas. <it>TRC8 </it>has the potential to act in a novel regulatory relationship linking the cholesterol/lipid biosynthetic pathway with cellular growth control and has been identified in families with hereditary renal (RCC) and thyroid cancers. Haploinsufficiency of <it>TRC8 </it>may facilitate development of clear cell-RCC in association with <it>VHL </it>mutations, and may increase risk for other tumor types. We report a paternally inherited balanced translocation t(8;22) in a proposita with dysgerminoma.</p> <p>Methods</p> <p>The translocation was characterized by FISH and the breakpoints cloned, sequenced, and compared. DNA isolated from normal and tumor cells was checked for abnormalities by array-CGH. Expression of genes <it>TRC8 </it>and <it>TSN </it>was tested both on dysgerminoma and in the proposita and her father.</p> <p>Results</p> <p>The breakpoints of the translocation are located within the LCR-B low copy repeat on chromosome 22q11.21, containing the palindromic AT-rich repeat (PATRR) involved in recurrent and non-recurrent translocations, and in an AT-rich sequence inside intron 1 of the TRC8 tumor-suppressor gene at 8q24.13. <it>TRC8 </it>was strongly underexpressed in the dysgerminoma. Translin is underexpressed in the dysgerminoma compared to normal ovary.</p> <p><it>TRC8 </it>is a target of Translin (TSN), a posttranscriptional regulator of genes transcribed by the transcription factor CREM-tau in postmeiotic male germ cells.</p> <p>Conclusion</p> <p>A role for <it>TRC8 </it>in dysgerminoma may relate to its interaction with Translin. We propose a model in which one copy of <it>TRC8 </it>is disrupted by a palindrome-mediated translocation followed by complete loss of expression through suppression, possibly mediated by miRNA.</p

Myocardial stress perfusion scintigraphy for outcome prediction in patients with severe left ventricular systolic dysfunction

Abstract: Coronary angiography has been recommended in all patients with suspected chronic coronary syndrome and left ventricular ejection fraction (LVEF) ≤35%. The role of ischemia testing, for example, through stress-rest myocardial perfusion scintigraphy (MPS), for risk prediction is not well established. Methods: We evaluated 1576 consecutive patients referred to MPS and stratified into 3 LV ejection fraction (LVEF) categories: ≤35%, 36–49%, and ≥ 50%. Results: Patients with LVEF ≤35% were oldest, most often men, and with the highest likelihood of prior early (elective or urgent) coronary revascularization. They had also the highest values or summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS), as well as the highest frequency of significant coronary artery disease, and a greater number of diseased vessels. Follow-up: In this subgroup, 32 cardiovascular death or non-fatal myocardial infarction (MI) (21%), 35 all-cause deaths (22%), and 37 cardiovascular deaths, non-fatal MI, or late revascularizations (27%) were recorded with the shortest survival among all LVEF classes. SRS, SSS, and SDS had very low area under the curve values for the prediction of the 3 endpoints, with very high cut-offs, respectively. SRS and SSS cut-offs predicted a worse outcome in Cox regression models including the number of diseased vessels and early revascularization. Conclusions: In patients with LVEF ≤35%, SRS and SSS are less predictive of outcome than in patients with better preserved systolic dysfunction, but their cut-offs retain independent prognostic significance from the number of vessels with significant stenoses and from early revascularization

Altered intra-nuclear organisation of heterochromatin and genes in ICF syndrome.

The ICF syndrome is a rare autosomal recessive disorder, the most common symptoms of which are immunodeficiency, facial anomalies and cytogenetic defects involving decondensation and instability of chromosome 1, 9 and 16 centromeric regions. ICF is also characterised by significant hypomethylation of the classical satellite DNA, the major constituent of the juxtacentromeric heterochromatin. Here we report the first attempt at analysing some of the defining genetic and epigenetic changes of this syndrome from a nuclear architecture perspective. In particular, we have compared in ICF (Type 1 and Type 2) and controls the large-scale organisation of chromosome 1 and 16 juxtacentromeric heterochromatic regions, their intra-nuclear positioning, and co-localisation with five specific genes (BTG2, CNN3, ID3, RGS1, F13A1), on which we have concurrently conducted expression and methylation analysis. Our investigations, carried out by a combination of molecular and cytological techniques, demonstrate the existence of specific and quantifiable differences in the genomic and nuclear organisation of the juxtacentromeric heterochromatin in ICF. DNA hypomethylation, previously reported to correlate with the decondensation of centromeric regions in metaphase described in these patients, appears also to correlate with the heterochromatin spatial configuration in interphase. Finally, our findings on the relative positioning of hypomethylated satellite sequences and abnormally expressed genes suggest a connection between disruption of long-range gene-heterochromatin associations and some of the changes in gene expression in ICF. Beyond its relevance to the ICF syndrome, by addressing fundamental principles of chromosome functional organisation within the cell nucleus, this work aims to contribute to the current debate on the epigenetic impact of nuclear architecture in development and disease