Development and Approbation of Methodology Aimed to Define the Reasons for Turbine Unit Capacity Limitation Based on the Specified Mathematical Model of its Condenser

The purpose of this work is to develop and test the methodology of elucidation of the reasons for turbine unit capacity limitations based on a mathematical model of its condenser. This pur-pose is achieved by using a mathematical model of the condenser as part of the developed methodology, taking into account the separate effects of contamination of the heat exchange surfaces, air suction into the vacuum system and the operating mode of the main ejector. Based on operational data sampling, the value of the limiting pressure in the condenser, excess of which leads to limitation of turbine unit capacity, was determined. It was established that the cause of power limitation is the abnormal operation of the main ejector due to inadmissible high temperature in the intermediate cooler of its first stage. For regimes that were not pressure-limited, using a mathematical model, the degree of tubes contamination, its influence on the condenser pressure and the power generated by the turbine unit, and the influence of actual air suctions on the condenser pressure were determined. The most important result of the study is to determine the possibility and feasibility of using the developed and tested methodology for solv-ing similar problems for any type of turbine unit equipped with a condenser. The significance of the work lies in the fact that the proposed approach expands the possibilities of using mathemat-ical models of this class in terms of solving such problems.

Techno-commercial study of a solar hybrid renewable energy generator with an initial sizing strategy

Solar energy based hybrid renewable energy generators are techno-economically designed for various standalone uses like, far distance area electrification, commercial building electrification, polygeneration, industrial application, etc. This paper attempts to address the problem of high cost of energy of such generators, which needs to be optimized. The research gap is that there is hardly any work on techno-economic optimization of such generators using an initial sizing technique, thereby resulting in a design with higher cost of energy. In this work, a hybrid renewable energy generator comprising of solar PV-biogas-battery storage is techno-economically optimized with the aim of minimizing its cost of energy for electrification of a radio-broadcasting station in India by using simulation software named hybrid optimization model for electric renewables. An initial sizing strategy has been proposed in the modelling of the hybrid system. Optimal designs are obtained under different scenarios, like in standalone mode with and without capacity shortage fraction, and in grid connected mode with scheduled and random outages. The results show that during initial sizing in standalone mode, consideration of larger size (25 kW) of the component with lower unit capacity cost (biogas unit), and higher load sharing by it (102625 kWh/year) in the energy management of the hybrid design with a small capacity shortage (5%) reduces the levelized cost of energy to 0.0956 /kWh compared to some of the literature designs. Out of all the optimal designs, the grid connected system has the lowest levelized cost of energy of 0.0873/kWh with a renewable fraction of 0.821. The present work contributes in the component size planning of hybrid renewable energy generator to generate lower levelized cost of energy. The novelty of the present work is that in the component size planning in standalone mode, following the initial sizing strategy, if the component with lower unit capacity cost shares majority of the load, then the levelized cost of energy with or without grid connected mode can be further reduced compared to some existing designs, which can be verified from the simulation results. Therefore, the present results will be useful for component planning and sizing of hybrid renewable generators so as to preset the size of its components as per their unit capacity cost to result in a lower cost of energy.

Missed Nursing Care in Intensive Care Patients Subjected to Interhospital Capacity Transfers: A Retrospective Matched Case–Control Chart Review

Background The number of patients undergoing an interhospital intensive care unit-to-unit capacity transfer has dramatically increased. These transfers are complex, pose a risk for the patients and have been linked to increased intensive care unit length of stay and mortality, but the reasons for this are not known. We hypothesised that there was a difference in the incidence of missed nursing care among patients subjected to capacity transfer compared with patients not subjected to any transfer during their intensive care stay. Methods A retrospective case–control chart review was conducted on adult patients who between January 1, 2009, and January 31, 2020, underwent an interhospital intensive care unit-to-unit capacity transfer. We applied a matched control group by 1:2 matching. Missed nursing care was based on four variables: mobilisation, tooth brushing, oral care and nutrition. Data were retrieved from the local database and the patient’s medical charts at two general level 3 ICUs. Results The case group (n = 63) received significantly less mobilisation ( p < 0.05), mean 5.94 (2.36), compared with the control group (n = 126), mean 7.74 (2.96). In a subanalysis of the patients treated with invasive positive pressure ventilation and noninvasive positive pressure ventilation, the case group (n = 56) was found to receive significantly less oral care ( p < 0.05), median 3.50 (1.00–6.00), compared with the control group (n = 80), median 5.00 (2.00–7.75). None of the other variables were significantly related to interhospital intensive care unit-to-unit capacity transfers. Conclusion In critically ill patients, interhospital intensive care unit-to-unit capacity transfers were associated with missed nursing care. Future studies, focusing on capacity transfers should consider missed nursing care when the causes of increased intensive care unit length of stay and mortality are to be investigated.

Modelling intensive care unit capacity under different epidemiological scenarios of the COVID-19 pandemic in three Western European countries

Background The coronavirus disease 2019 (COVID-19) pandemic has placed enormous strain on intensive care units (ICUs) in Europe. Ensuring access to care, irrespective of COVID-19 status, in winter 2020–2021 is essential. Methods An integrated model of hospital capacity planning and epidemiological projections of COVID-19 patients is used to estimate the demand for and resultant spare capacity of ICU beds, staff and ventilators under different epidemic scenarios in France, Germany and Italy across the 2020–2021 winter period. The effect of implementing lockdowns triggered by different numbers of COVID-19 patients in ICUs under varying levels of effectiveness is examined, using a ‘dual-demand’ (COVID-19 and non-COVID-19) patient model. Results Without sufficient mitigation, we estimate that COVID-19 ICU patient numbers will exceed those seen in the first peak, resulting in substantial capacity deficits, with beds being consistently found to be the most constrained resource. Reactive lockdowns could lead to large improvements in ICU capacity during the winter season, with pressure being most effectively alleviated when lockdown is triggered early and sustained under a higher level of suppression. The success of such interventions also depends on baseline bed numbers and average non-COVID-19 patient occupancy. Conclusion Reductions in capacity deficits under different scenarios must be weighed against the feasibility and drawbacks of further lockdowns. Careful, continuous decision-making by national policymakers will be required across the winter period 2020–2021.