Thermodynamic Analysis of ORC for Energy Production from Geothermal Resources

Abstract This study concerns a thermodynamic analysis of Organic Rankine Cycles for energy conversion from geothermal resources. A numerical flow-chart tool based on a lumped parameters approach is adopted to compute values of thermodynamic variables during each transformation composing the cycle. The equation of state is expressed by the Peng-Robinson formulation. The different plant components are outlined by single blocks, linked each other by connections through balance equations. Analyses are carried-out considering two working fluids (isopentane and isobutane). Results are obtained for several sets of operating parameters, such as the evaporation and condensation pressure for the working fluid, the mass flow rate of the geothermal fluid and the cooling water temperature. From results, thermodynamic cycles are built-up in the T-s plan, allowing to quantify effectiveness and energy benefit related to the investigated functional scenarios

Radiating effect of participating media in a flameless industrial reactor

A 3D multi-physical numerical model concerning fluid-dynamical and thermo-chemical behaviour of a flameless reactor is presented in this communication. The analysed industrial device exploits a recent combustion technique that seems to largely hinder thermal NO x formation. Modelling and computations are carried-out by using a multi-physical FEM commercial software. The swirling jet used for combustive injection is firstly analysed, then the entire reactor volume is considered for simulations. The fluid-dynamics of the process is based on a k - e turbulence model, coupled with four diffusion-transport equations whose the first one characterises the temperature, while the remaining three are related to the concentrations of the chemical species involving in the process. In order to consider the radiating effects of participating media inside the combustion chamber, the Rosseland approximation is invoked in solving the energy equation. Results principally highlight the occurrence of a Reverse Flow Zone closed to the inlet section of the swirling injection system and a flat temperature profile characterising thermal distribution throughout the control volume of the reactor. These findings are in good agreement with experimental data concerning similar operating devices

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Thermal dissipation of DIMM in Tower-BTX configuration

Natural convection for Dual In-Line Memory Module (DIMM) systems, disposed as predicted by the recent Balanced Technology Extended (BTX) form factor in tower configuration, is numerically studied in this article. The considered physical system is modelled by horizontal air-filled layers bounded by parallel walls in which multiple heat sources are arranged. Three-dimensional simulations are carried-out by using a multi-physical FEM software. The results, obtained for imposed ambient temperature and operative conditions (power supplied to memories), show as thermoconvective instabilities may be produced and consequently complex fluid motion field could be detected. Simulated temperature fields show good agreement with thermal design data proposed by DIMM leading constructors. In order to improve computational performance of the numerical model, a simplified geometry is also proposed and tested for solving the physical problem. The present study contributes in investigation on critical cooling conditions for BTX form factor and in innovative projects of fan-less computer architecture

Experimental and numerical investigation on airflow and climate in a real operating theatre under effective use conditions

In the present study microclimate and airflow patterns in a real operating theatre (OT) under effective use conditions are investigated. Surgical staff movements and sliding door opening/closing effects on the air thermal distribution and velocity fields are considered. Experimental measurements and numerical simulations are carried out for the "at rest" and "operational" conditions of the OT. Two "operational" use conditions are considered: "correct" and "incorrect" during a simulated hip surgery. Numerical and experimental results comparisons are used to check their compliance with the standard limits. Results mainly show the ventilation system effectiveness in providing the expected conditions, even though local perturbations due to operational conditions are clearly pointed out