Fluid Selection Research Articles

Fluid resuscitation with balanced crystalloids versus normal saline in critically ill patients: a systematic review and meta-analysis

BackgroundIntravenous fluids are used commonly for almost all intensive care unit (ICU) patients, especially for patients in need of resuscitation. The selection and use of resuscitation fluids may affect the outcomes of patients; however, the optimal resuscitative fluid remains controversial.MethodsWe systematically searched PubMed, Embase, and CENTRAL. Studies comparing balanced crystalloids and normal saline in ICU patients were selected. We used the Cochrane Collaboration tool to assess the risk of bias in studies. The primary outcome was mortality at the longest follow-up. Secondary outcomes included the incidence of acute kidney injury (AKI) and new renal replacement therapy (RRT).ResultsA total of 35,456 patients from eight studies were included. There was no significant difference between balanced crystalloid solutions and saline in mortality (risk ratio [RR]: 0.96; 95% confidence interval [CI]:0.92–1.01). The subgroup analysis with traumatic brain injury (TBI) showed lower mortality in patients receiving normal saline (RR:1.25; 95% CI 1.02–1.54). However, in patients with non-TBI, balanced crystalloid solutions achieved lower mortality than normal saline (RR: 0.94; 95% CI 0.90–0.99). There was no significant difference in moderate to severe AKI (RR: 0.96; 95% CI 0.90–1.01) or new RRT (RR: 0.94; 95% CI 0.84–1.04).ConclusionsCompared with normal saline, balanced crystalloids may not improve the outcomes of mortality, the incidence of AKI, and the use of RRT for critically ill patients. However, balanced crystalloids reduce the risk of death in patients with non-TBI but increase the risk of death in those with TBI. Large-scale rigorous randomized trials with better designs are needed, especially for specific patient populations.

Novel decision-making strategy for working fluid selection in Organic Rankine Cycle: A case study for waste heat recovery of a marine diesel engine

The Organic Rankine Cycle (ORC) is receiving increasing attention as a waste heat recovery system. However, it is still a major challenge to quickly and practically choose the appropriate one among dozens of working fluids, considering many criteria. In this study, the comprehensive decision-making strategy for working fluid selection in ORC applications was proposed. The selection of working fluid was evaluated not only in terms of thermodynamics and economics but also considering safety and environmental concerns. A container ship was chosen for the case study. Optimization was carried out for the design condition using the Multi-Objective Gray Wolf Algorithm (MOGWA). The results obtained for 10 different working fluids were evaluated with a comprehensive decision-making strategy and R245fa was determined as the final working fluid. Moreover, off-design analyses and operational profile-based simulation were performed. The net work was calculated as 439.5772 kW and 420.1741 kW for the design condition and the overall operating condition, respectively. The electricity generation cost for the design operating condition was 0.0570 $/kWh, and this value for all conditions was calculated as 0.0596 $/kWh. Lastly, MOGWA and NSGA-II were compared to each other, and their performance was analyzed. The results showed that both algorithms had similar performance.

Cascaded model predictive controller performance for the selection of robust working fluids in absorption refrigeration cycles

• Evaluation of the dynamic performance of 13 novel working fluids. • Cascade model predictive control is of superior performance than cascade PI control. • Systematic ranking of ABR fluids based on setpoint tracking and resource utilization. • A multi-criteria assessment approach for working fluid selection is presented. • Acetaldehyde/Dimethylformamide exhibits superior steady state and dynamic performance. Current working fluid selection approaches for the absorption refrigeration cycle are based exclusively on steady-state cycle performance. In real operating conditions, the cycle is subject to exogenous disturbances, with detrimental effects on their performance, resulting in increased resource utilization or even failure to meet load demands. In the present work, the problem of working fluid evaluation for the absorption refrigeration cycle is investigated, by considering both the steady state and the dynamic performance of the system. The evaluation of 13 novel, organic working fluids is performed utilizing a cascaded proportional-integral and a cascaded model predictive controller, implemented on a single-effect absorption refrigeration cycle. A set of previously validated non-linear, dynamic process models, developed in ASPEN Plus are used to create the linear models required for the model predictive controller. The closed loop dynamic performance is evaluated based on speed of response, resource utilization and deviations from the desired operating point (setpoint), while operating under a disturbance scenario involving load demand changes. Multi-criteria assessment results indicate that the cascaded model predictive control is considerably more consistent than the cascade PI controller. The novel mixture of acetaldehyde/dimethylformamide exhibits superior performance than the conventional NH 3 /H 2 O mixture, by 57% in speed of response and 76% in resource utilization. The mixture ιs also 25% and 12% better than NH 3 /H 2 O in steady-state cost per ton of cooling and coefficient of performance, indicating high economic potential and robustness for single-effect ABR systems.

A bibliometric analysis of the application of solar energy to the organic Rankine cycle

Solar Thermal is one of many heat sources that support the organic Rankine cycle (ORC) system. The advantage of using solar thermal as a heat source when combined with the ORC system is that it can provide affordable energy supplies in remote areas and it is suitable in disaster territories. Growth in solar-ORC research is not only on a lab/workshop scale but also on an industrial scale. Most articles refer to methods and tools in the design process, combining heat and improvement of the cycle, working fluids selection, and case studies based on primary or secondary data. The paper reports the newest trends on the research of solar application on ORC using bibliometric analysis. The study of bibliometric using VOSviewer was recognized as a captivating method in the literature that allows examining the scientific progress of a particular topic. Moreover, a qualitative approach can be performed by analyzing the keywords contained in different documents to identify a circumstance that features the research trend and to understand future viewpoints.

Medication and Fluid Management of Pediatric Sepsis and Septic Shock.

Sepsis is a life-threatening response to infection that contributes significantly to neonatal and pediatric morbidity and mortality worldwide. The key tenets of care include early recognition of potential sepsis, rapid intervention with appropriate fluids to restore adequate tissue perfusion, and empiric antibiotics to cover likely pathogens. Vasoactive/inotropic agents are recommended if tissue perfusion and hemodynamics are inadequate following initial fluid resuscitation. Several adjunctive therapies have been suggested with theoretical benefit, though definitive recommendations are not yet supported by research reports. This review focuses on the recommendations for medication and fluid management of pediatric sepsis and septic shock, highlighting issues related to antibiotic choices and antimicrobial stewardship, selection of intravenous fluids for resuscitation, and selection and use of vasoactive/inotropic medications. Controversy remains regarding resuscitation fluid volume and type, antibiotic choices depending upon infectious risks in the patient's community, and adjunctive therapies such as vitamin C, corticosteroids, intravenous immunoglobulin, and methylene blue. We include best practice recommendations based on international guidelines, a review of primary literature, and a discussion of ongoing clinical trials and the nuances of therapeutic choices.

Working fluid selection for heat pumps in solar district heating systems

In the context of the global energy transition, solar energy holds a promising potential as an energy source for a sustainable heat supply. Solar thermal collector in combination with heat pump technology utilizing electricity from renewable sources, such as photovoltaic, opens the possibility for the transformation of many existing residential areas into zero-emissions districts. However, according to the EU F-Gas Regulation No. 517/2014, the use of many commercial working fluids with high GWP is restricted in future refrigeration systems. Here, we present the results of current research on existing heat pump applications in Germany with a heating capacity over 20 kW, and then we evaluate possible refrigerants for a typical heat-pump-based solar district heating system with a tank store in the scenario of a residential area in Germany considering two different heat pump configurations: system A (two-stage compression with an open-flash-economizer) with nine candidate refrigerants, and system B (low-temperature-cycle and high-temperature-cycle in series) with 90 pairs of refrigerants as candidates. Two criteria – the coefficient of performance for heating COPh and the volumetric flow rate of the suction gas V̇Sg – were applied to assess optimal working fluids. The simulation results demonstrate a trade-off between low GWP and good safety properties (nonflammability, nontoxicity). Based on the simulation results, we also discuss the corresponding restrictions and necessary precautions for the application of our refrigerant candidates considering safety issues and potential environmental effects. For the heat-pump-based solar district heating system (referred to in the following as “HP-SDH system”) in this exemplary residential area, the commercially available refrigerant R1234ze(E) exhibits the best combination of thermodynamic, environmental and safety properties; it is mildly flammable, and its application must comply with the safety and environmental requirements of the relevant German and European regulations.

An investigation on organic Rankine cycle incorporating a ground-cooled condenser: Working fluid selection and regeneration

This research presents an optimization of a power generation system incorporating a ground-cooled condenser. It focuses on the mitigation of the adverse effects of critical parameters such as low mass flow rates and large ground loops. This includes an investigation of different configurations (basic and regenerative cycles) and working fluids to ascertain their effects on the performance of the system. Three refrigerants, R123, R124 and R245fa, were compared in terms of working fluid's performance. The purpose of the system optimization is to increase the net output power whilst reducing the capital cost of installation. At an inlet expander pressure of 3 MPa, as the condensation temperature was decreased from 25 °C to 15 °C the enhancements in net output power were 7.35%, 12.13% and 8.77% for R123, R124 and R245fa, respectively in the case of basic organic Rankine cycle. However, the highest performance in terms of net output power was recorded for R123 in both configurations under the investigated conditions. Based on the calculations of net output power and heat rejection, the regenerative cycle is highly recommended since it provides significant increase in the output power without considerably changing the amount of heat rejected to the ground.

Microchannel flow and heat transfer enhancement via ribs arrangements

Enhanced heat transfer rates in microchannel flow remain challenging in terms of channel design, proper selection of carrier fluid, and setting the appropriate flow conditions. Introducing extended surfaces, such as ribs, in microchannel design, and the use of nanofluids enable to enhance the thermal performance of the flow system. In the present study, heat transfer characteristics in a microchannel flow incorporating the ribs arrangements on the channel wall are considered and the influence of the ribs location and carrier fluid on the thermal performance of the channel is examined. Temperature and velocity variations in the channel are predicted numerically and the findings of the Nusselt number are compared with that obtained from the experiments. The location of ribs along the channel wall is altered and the resulting variation of the Nusselt number and pressure drop along the microchannel is assessed. Al2O3 and TiO2 nanofluids are incorporated as a working fluid and water are also considered for the comparison. Temperature parameters are introduced to scale the rise of the maximum fluid temperature and temperature difference across the channel length. It is found that locating the ribs in the close region of the channel exit improves the Nusselt number by 25% and increases the pressure drop along the microchannel by 10% as compared to those corresponding to no-ribs arrangements. In addition, nanofluids improve the heat transfer rates and slightly alter the pressure drop across the microchannel.

Adoption of the CO2 + SO2 mixture as working fluid for transcritical cycles: A thermodynamic assessment with optimized equation of state

This paper focuses on the use of the CO2 + SO2 binary mixture as innovative working fluid for closed transcritical power cycles with a minimum temperature above 50 °C. Starting from a literature review of the available experimental data on the mixture, the PC-SAFT EoS is identified as a suitable model to characterize the mixture behavior. Once the proper thermodynamic model is selected for this mixture, a comparison between the innovative transcritical cycle and the sCO2 cycle is proposed for various plant layouts in order to find out the advantages of the innovative mixture. The analysis is presented fixing the cycle maximum temperature at 700 °C and the maximum pressure at 250 bar: the results depict an increment in cycle electric efficiency and cycle specific work, along with a lower temperature of heat introduction in the cycle for any considered configuration of transcritical CO2 + SO2 cycle, when compared to pure sCO2.An economic analysis of the power block is then performed to support the selection of the innovative working fluid. Two of the most promising plant layouts are evidenced: the recompression layout is selected for highly efficient power blocks, while the dual recuperated layout works effectively in applications characterized by higher hot source exploitation. The recompression layout adopting the CO2 + SO2 mixture presents a power block electric efficiency of 48.67% (2.33% higher than the respective sCO2 cycle) and a reduction of the power block CAPEX from 1160 $/kWel to 1000 $/kWel when compared to the sCO2 configuration for a 100MWel size, while the dual recuperated layout exploiting the CO2 + SO2 mixture shows a power block electric efficiency of 39.58% (0.69% above the same sCO2 cycle), a decrease of power block CAPEX from 795 $/kWel to 718 $/kWel and 70 °C of additional heat recovery from the hot source with respect to the analogous sCO2 cycle.

Selection of working fluid for organic Rankine cycle used in low temperature geothermal power plant

In this paper, for the low-temperature geothermal organic Rankine (ORC) power generation system, the subcritical saturated vapor cycle is selected as the key research object, the mathematical and physical model of the thermal process of the ORC system is established, and five organic working fluids are selected. With the net power produced per unit mass of geothermal water(PPH) as the optimization target, the optimal parameters of the ORC system are determined. Based on the selection of the best organic working fluid, various parameters that affect the performance and economic performance of the ORC system are analyzed. After simulation calculation, the results show that: when the system takes PPH as the optimization target, the working fluid R245fa can be selected as the best applicable working fluid.

Performance analysis and working fluid selection of organic Rankine steam compression air conditioning driven by ship waste heat

In order to effectively use the waste heat of ship flue gas and cooling water, in this paper, the organic Rankine-vapor compression refrigeration system is used for air conditioning for ships, and the thermodynamic model of the system is established. The system performance corresponding to the five commonly used working fluids R22, R141b, R236ea, R218 and R601 is analyzed and compared. The working fluid is optimized with the goal of the best system performance. Calculations proves that: regardless of the organic Rankine cycle and vapor compression refrigeration cycle, or for the entire system, R601 is the most suitable working fluid. The temperature of the heat source and the condensing temperature have an important effect on the performance of the system. The hot water temperature can be controlled and adjusted by changing the hot water flow rate, thereby optimizing system performance. At the same time, the determination of the condensing temperature should comprehensively consider the system performance, cooling water pump power, heat exchanger area and system investment to achieve the best overall system performance.

Modeling and test of a thermosyphon loop for the cooling of a megawatt-range power electronics converter

A thermosyphon loop, designed for the thermal management of a large Medium voltage power converter 5 MW overall, corresponding to a 2.4 kW thermal load per cooling unit) is presented. The device is mainly made of an evaporator, a condenser and a reservoir connected with plastic liquid and vapor lines. Novec 649 (3M) has been chosen as the working fluid due to environmental and electrical concerns. A model of the loop is described, and its predictions are compared with experiments. A first comparison yields a maximum mean deviation of 20 % between experimental results and numerical simulation at the maximum coolant temperature. The main sources of errors are identified, and improvements are proposed for better model accuracy. • Selection of an environment-friendly fluid (Novec 649). • Entire model of the loop thermo-syphon is presented. • Experimental validation on a full-scale protype (up to 2400 W thermal load) shows < 20% deviation.

Multi-objective optimization and fluid selection of organic Rankine cycle (ORC) system based on economic-environmental-sustainable analysis

Global issues such as the energy crisis and environmental pollution impulse the development of waste heat recovery technologies. Organic Rankine cycle (ORC) systems are a promising solution to utilize renewable energies and recover waste heat. However, the different heat source temperatures often force the ORC to use different working fluids. Matching the heat source temperatures with suitable fluids is important to enhance the system performance and promote the marketability of this technology. In this work, a double-layer multi-objective optimization framework is proposed for subcritical ORC systems applied in the geothermal field. Four kinds of objective functions are selected in the optimization model, including net power output, total product unit cost, greenhouse gas emissions, and ecological life cycle cost to characterize system thermodynamic, exergoeconomic, environmental, and sustainable performances, respectively. The feature of the established model allows simultaneous system comprehensive design and fluid screening under specific geothermal temperatures. Results showed that the impacts of decision variables, including evaporation pressure and condensation temperature, on system performances were different under the different performance indicators. According to the balanced weighting factor case study, it is found that R134a had excellent thermodynamic and sustainable performances while R600a performed better from economic and environmental aspects at 393.15 K geothermal temperature. In addition, it was observed that the obtained optimal point shifted regularly on the Pareto curve with the change of geothermal temperature and weighting factor. Finally, under different weighting factor schemes, the optimal plans of fluid selection were obtained at certain geothermal temperatures. HCs fluids showed superior overall performance in the double-layer optimization framework considering ecological impacts, while R152a exhibited excellent comprehensive performance among the selected safe fluids under the premise of strict consideration of system security.

Performance analysis and working fluid selection of an Organic Rankine Cycle Power Plant coupled to an Enhanced Geothermal System

This paper presents a coupled Wellbore-Reservoir-Organic Rankine Cycle (ORC) power plant model for sustainable and efficient use of multiple-fractures Enhanced Geothermal System with simulations conducted over 40 years of operation time. A multi-objective optimization of the ORC under off-design conditions was conducted using constrained NSGA-II technique considering specific investment cost, energy and exergy efficiencies as objective functions. Twenty working fluids were considered to select the best one based on the turbine inlet superheated vapor condition, the lowest specific investment cost, the best energy and exergy efficiencies. Optimal operations conditions were determined for each working fluid considering turbine inlet temperature, turbine inlet pressure, condenser temperature, refrigerant mass flow rate, and length, tubes number, inner diameter and outer diameter of evaporator and condenser, isentropic turbine efficiency, isentropic pump efficiency as decision variables. The results show that the working fluids have a significant effect on the reinjection geofluid temperature and slight effect on the production temperature. The best performing working fluid was R1233zd(E) providing an energy efficiency of 19.2–19.32% and the exergy efficiency found is between 56.4% and 58.44% over the 40 years of production in off-design conditions and optimal operation conditions. The energy efficiency and the exergy efficiency decrease with increasing condenser temperature.

Zeotropic working fluid selection for an organic Rankine cycle bottoming with a marine engine

Organic Rankine cycle (ORC) is an effective approach for low-grade energy utilization. It is important to improve the efficiency of an ORC when the heat source temperature varies. In this study, a method of selecting zeotropic mixture for a bottoming ORC with changeable heat source temperature is presented. The effects of the operation conditions of the marine engine and the ambient temperature are investigated. First, the optimal performances of the ORC using 40 pure working fluids are determined and compared. Then, two zeotropic mixtures benzene/m-xylene and cyclopentane/toluene are selected and the mechanism of temperature match with the heat source and sink is explored. Finally, the performance improvement with benzene/m-xylene using the composition adjustment method is evaluated. The results indicate that the suitable pure working fluids are isopentane and R245ca for a low exhaust temperature while toluene and m-xylene are the best when the exhaust temperature is high. Using the zeotropic mixtures benzene/m-xylene and cyclopentane/toluene can obtain a high performance over the operation range of the marine engine. When the exhaust temperature is 225 °C, the net power and exergy efficiency of benzene/m-xylene are improved by 6.9%–21.9% and 6.5%–22.0%, respectively, compared with the pure fluids benzene and m-xylene. When the exhaust temperature increases to 380 °C, these improvements decrease to 1.9%–6.8%. If a zeotropic mixture is used, the critical temperature of the component with a high-boiling point should be close to the maximum operation temperature of the heat source, and the temperature glide should first match with the temperature increase of the heat sink. If the heat sink temperature is fixed, it is impossible to enhance the ORC performance using the composition adjustment method. However, the composition adjustment method is effective when the temperature of the heat sink varies with the ambient temperature. The net power and exergy efficiency of the ORC are improved by up to 21.9% and 22% in winter using benzene/m-xylene. However, these improvements are less than 6.8% in summer.

Influence of thermal stability on organic Rankine cycle systems using siloxanes as working fluids

• An off-design model with fluid decomposition parameters was established. • The influence of MM thermal decomposition on the ORC system was evaluated. • MM decomposition reduced the net power and efficiency of ORC system obviously. • MM decomposition may lead to incomplete evaporation and evaporator acid corrosion. The organic Rankine cycle (ORC) is an efficient power generation technology that has been widely used in renewable energy utilization and industrial waste heat recovery. The thermal stability of working fluids has a significant effect on the fluid selection and system design of ORC systems. In this study, an off-design model of an ORC system was established with hexamethyldisiloxane (MM) as the working fluid, and the effects of the MM thermal stability on the system were analyzed. The results showed that the effect of MM thermal decomposition on the cold source and working fluid pump was limited. The outlet temperature of the evaporator decreased with MM decomposition, which might lead to incomplete evaporation of working fluids and possible damage to the expander. The outlet temperature of the heat source also decreased with MM decomposition, which led to lower outlet temperatures than the acid dew point limit temperature. Both of these results can affect the safe operation of ORC systems. The net power and thermal efficiency of the system decreased with increasing thermal decomposition ratios of MM. The net power and thermal efficiency decreased by 7.48% and 10.72% respectively in the model of this study with a 10% decomposition ratio.

Thermal-Economic Optimization and Working Fluid Selection of Subcritical Organic Rankine System for Low-Temperature Waste Heat Recovery

Thermal-Economic Optimization and Working Fluid Selection of Subcritical Organic Rankine System for Low-Temperature Waste Heat Recovery

Working Fluid Selection for Organic Rankine Cycle Under Real Expansion Conditions

Working Fluid Selection for Organic Rankine Cycle Under Real Expansion Conditions

Working Fluid Selection for the Geothermal-Solar Hybrid Cycle at Olkaria Ii Power Plant in Kenya

Working Fluid Selection for the Geothermal-Solar Hybrid Cycle at Olkaria Ii Power Plant in Kenya

Laboratory Investigation of Impact of Slickwater Composition on Multiphase Permeability Evolution in Tight Sandstones

Summary Fracturing fluid filtrate that leaks off during injection is imbibed by strong capillary forces present in low-permeability sandstones and may severely reduce the effective gas permeability during cleanup and post-fracture production. This work aims to investigate the role fracturing fluid filtrate from slickwater has on rock-fluid and fluid-fluid interactions and to quantify the resulting multiphase permeability evolution during imbibition and drainage of the filtrate by means of specialized core laboratory techniques. Three suites of experiments were conducted. In the first suite of experiments, a fluid leakoff test was conducted on selected core samples to determine the extent of polymer invasion and leakoff characteristics. In the second suite, multigas relative permeability measurements were conducted on sandstone plugs saturated with fracturing fluid filtrate. A combination of controlled fluid evaporation and pulse decay permeability technique was used to measure liquid and gas effective permeabilities for both drainage and imbibition cycles. These experiments aim to capture dynamic permeability evolution during invasion and cleanup of fracturing fluid (slickwater). The final suite of experiments consists of adsorption flow tests to investigate, identify, and quantify possible mechanisms for adsorption of the polymeric molecules of friction reducers present in the fluid filtrate to the pore walls of the rock sample. Imbibition tests and observations of contact angles were conducted to validate possible wettability changes. Results from multiphase permeability flow tests show an irreversible reduction in endpoint brine permeability and relative permeability with increasing concentration of friction reducer. Our results also show that effective gas permeability during drainage/cleanup of the imbibed slickwater fluid is controlled to a large degree by trapped gas saturation than by changes in interfacial tension. Adsorption flow tests identified adsorption of polymeric molecules of the friction reducer present in the fluid to the pore walls of the rock. The adsorption friction reducer increases the wettability of the rock surface and results in the reduction of liquid relative permeability. The originality of this work is to diagnose formation damage mechanisms from laboratory experiments that adequately capture multiphase permeability evolution specific to a slickwater fluid system, during imbibition and cleanup. This will be useful in optimizing fracturing fluid selection.