Mixing Valve Research Articles

Numerical Calculation of Oil Dispersion through the Air Flow Applied to the Inner Surface of Slim Tubes

One simple, efficient, reliable, and inexpensive method to protect the inner surface of slim tubes prior to exposure to corrosion is to apply a dispersed oil fraction through a nozzle and a mixing valve to prepare a mixture of air and oil applied on the texture in a suitable form. The problem, in particular, is in transporting the oil micro particles to the distal end of the lean tube. The method also has an ecological effect, since other known “soaking” methods of oil application onto the inner surface of slim tubes require long and laborious cleaning methods with higher oil consumption. This method was experimentally verified by measurement and modal simulation in Ansys CFX 19.1 software. The results indicate the possibilities of using the method in practice. However, there are a few rules and recommendations to follow when applying this solution strategy.

Real-Time Continuous Surveillance of Temperature and Flow Events Presents a Novel Monitoring Approach for Hospital and Healthcare Water Distribution Systems.

Within hospitals and healthcare facilities opportunistic premise plumbing pathogens (OPPPs) are a major and preventable cause of healthcare-acquired infections. This study presents a novel approach for monitoring building water quality using real-time surveillance of parameters measured at thermostatic mixing valves (TMVs) across a hospital water distribution system. Temperature was measured continuously in real-time at the outlet of 220 TMVs located across a hospital over a three-year period and analysis of this temperature data was used to identify flow events. This real-time temperature and flow information was then compared with microbial water quality. Water samples were collected randomly from faucets over the three-year period. These were tested for total heterotrophic bacteria, Legionella spp. and L. pneumophila. A statistically significant association with total heterotrophic bacteria concentrations and the number of flow events seven days prior (rs[865] = −0.188, p < 0.01) and three days prior to sampling (rs[865] = −0.151, p < 0.01) was observed, with decreased heterotrophic bacteria linked to increased flushing events. Only four samples were positive for Legionella and statistical associations could not be determined; however, the environmental conditions for these four samples were associated with higher heterotrophic counts. This study validated a simple and effective remote monitoring approach to identifying changes in water quality and flagging high risk situations in real-time. This provides a complementary surveillance strategy that overcomes the time delay associated with microbial culture results. Future research is needed to explore the use of this monitoring approach as an indicator for different opportunistic pathogens.

Oil/Water Pipe-Flow Dispersions: From Traditional Flow Loops to Real Industrial-Transport Conditions

Summary In this paper we present a study on oil/water pipe-flow dispersions. There are two main objectives of this work: The first objective is to gain more knowledge on the behavior of oil/water dispersions in pipe flow; the second objective is to validate a new methodology to characterize dispersion properties at realistic industrial conditions. The characteristics of oil/water flows such as the development of the phase-fraction profiles, droplet-chord lengths, and pressure gradient were studied in a 0.069-m-diameter and 50-m-length horizontal pipe at the Multiphase Flow Laboratory of SINTEF in Norway. The fluid system consisted of a model oil (Exxsol® D80) with and without surfactants, and tap water. A comparison of the experiments with and without a mixing valve was performed. The experiments were conducted at different superficial liquid velocities (Usl) and five different water-cut (WC) values (with WC defined as the ratio of the water superficial velocity to the liquid superficial velocity). In addition, experiments on a wheel-shaped flow loop were conducted at selected conditions. The wheel mimics realistic pipe-flow conditions for the oil/water dispersions. This methodology allows us to identify flow-developing time scales and long-term behavior, which cannot be studied in a shorter test section. Furthermore, it is possible to have an indication of the viscosity increment when dispersions form. The results from the pipe-flow experiments show that the effective viscosity of the mixed flow increases by the dispersion formation promoted by the valve. As a result, the pressure gradient in the downstream pipe increases dramatically compared with the same conditions without premixing. For the studied cases, the surfactant concentration did not have any significant effect on the pressure drop in the pipe. However, differences in the phase-fraction profiles were observed, especially with respect to flow development along the pipe. A possible explanation is that the effective viscosity of the created dispersion is not high enough to produce an increase in the pressure drop. Flow development along the pipeline (oil/water separation) is observed only for selected cases without surfactant. For the rest of the experiments, especially with surfactant, the test section was not long enough to observe flow development. With the wheel, it is simple and fast to study both the formation and the stability of dispersions with real fluids at realistic conditions. There are indications that the energy-dissipation rate could be used as a scaling parameter between pipe-flow experiments and the wheel experiments. Wheel experiments can be used cost-efficiently to investigate dispersion characteristics and long-term flow development, which cannot be observed in traditional pipe-flow loops because of their restrictions.

A novel wall water system for cardiopulmonary bypass may reduce the risk of aerosolized infection

ObjectiveOxygenators for cardiopulmonary bypass require water flow for their integral heat exchanger. Heater-cooler units are nearly universally used for this requirement. Heater-cooler units pose the risk of aerosolized infection. The Centers for Disease Control and Prevention recommended discontinuing use of Stöckert 3T heater-cooler units (LivaNova PLC, London, United Kingdom) in October 2016 because of this risk. We aimed to reduce the risk of aerosolized infection posed by heater-cooler units by eliminating those devices from our operating rooms. MethodsThe cardiac surgery division collaborated with in-house specialties to engineer a novel wall water system. The design called for service to 4 operating rooms with the actual water mixing valve in an operating room closet. Remote temperature control was mounted next to the heart-lung machine. Primary safety systems built into the water system include 5 μm filtration, pressure regulating and relief valves, flow quantifiers, limits to the hot and chilled input temperatures, and a novel bridge near the heart-lung machine that allows the perfusionist to test the system before patient use and to quickly disconnect the patient in case of system malfunction. In addition, all water line connections can be made with the tubing drained and never under pressure. ResultsThis novel wall water system has successfully provided heat exchanger water flow on 625 patients undergoing congenital heart surgery requiring cardiopulmonary bypass during its first 9 months of use. ConclusionsWall water systems are an option for oxygenator heat exchangers that allow for improved heat exchange performance while reducing the risk of heater-cooler unit–associated infection during cardiac surgery.

Microfluidic dual loops reactor for conducting a multistep reaction

Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carried out in a stepwise manner in each reactor without any cross-contamination issue. To precisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanoparticles are successfully synthesized in a microfluidic dual loops reactor through a fully automated multistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.

Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.

Heat integration of alternative Ca-looping configurations for CO2 capture

The best option to overcome the energy penalty in Ca-looping is to take advantage of the surplus heat by external integration to produce additional power and increase net efficiency. As calciner represents the main energy consumption, another possibility is to internally use the surplus heat to preheat the solids entering this reactor. The objective of internal integration is to reduce the energy demand per captured tonne of CO2. It represents a reduction of the coal and oxygen needs and also a total decrease in the CO2 generation regarding the ordinary configuration. However, the amount of available heat for extra power generation by external integration, essential for the viability of this technology, is also reduced. This is the case of the configurations including a cyclonic preheater or a mixing seal valve. This study assess the energy penalty minimization that may be reached by external integration of these internal energy integration configurations. A methodological process has been applied to obtain a reduction of the energy penalty with respect to the ordinary configuration. This energy saving combined with the lower size of equipment and reduced capital cost would make the cyclonic preheater the most suitable configuration to improve the viability of this technology.

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease—North America, 2000–2014

Background The number of reported cases of Legionnaires’ disease, a severe pneumonia caused by the bacterium Legionella, is increasing in the United States. During 2000–2014, the rate of reported legionellosis cases increased from 0.42 to 1.62 per 100 000 persons; 4% of reported cases were outbreak-associated. Legionella is transmitted through aerosolization of contaminated water. A new industry standard for prevention of Legionella growth and transmission in water systems in buildings was published in 2015. CDC investigated outbreaks of Legionnaires’ disease to identify gaps in building water system maintenance and guide prevention efforts. Methods Information from summaries of CDC Legionnaires’ disease outbreak investigations during 2000–2014 was systematically abstracted, and water system maintenance deficiencies from land-based investigations were categorized as process failures, human errors, equipment failures, or unmanaged external changes. Results During 2000–2014, CDC participated in 38 field investigations of Legionnaires’ disease. Among 27 land-based outbreaks, the median number of cases was 10 (range = 3–82) and median outbreak case fatality rate was 7% (range = 0–80%). Sufficient information to evaluate maintenance deficiencies was available for 23 (85%) investigations. Of these, all had at least one deficiency; 11 (48%) had deficiencies in ≥2 categories. Fifteen cases (65%) were linked to process failures, 12 (52%) to human errors, eight (35%) to equipment failures, and eight (35%) to unmanaged external changes. Conclusions and Implications for Public Health Practice Multiple common preventable maintenance deficiencies were identified in association with disease outbreaks, highlighting the importance of comprehensive water management programs for water systems in buildings. Properly implemented programs, as described in the new industry standard, could reduce Legionella growth and transmission, preventing Legionnaires’ disease outbreaks and reducing disease.

Effect of current frequency on crude oil dehydration in an industrial electrostatic coalescer

The main aim of the present study is to develop a detail mathematical model to investigate the performance of an industrial electrostatic desalting process. The dehydration process consists of a mixing valve and an electrostatic coalescer drum. The equipments are modeled based on the population balance equation considering a detail circuit model in the coalescer drum. The electrode plates and crude oil emulsion are considered as a complex of parallel capacitors and dielectric material, respectively. To prove the accuracy of the model and assumptions, the outlet water cut from the coalescer drum is compared with the plant data. Then the effect of temperature, fresh water rate and current frequency on the strength of applied electric field on the emulsion, voltage decay, size distribution of water droplets and outlet water cut in the treated crude oil is investigated based on the developed model. The simulation results show that increasing current frequency from 50 to 300 Hz reduces water cut in the treated crude oil from 0.12% to 0.09%, respectively.

English

Water resources play an important role in the development of the socio-economic status of a country. The world&rsquo;s population increased from one billion to six billions in less than 200 years. With the rapid increase in population and advancement in technology, demand for water increases steadily and the limited amount of available fresh water sources are subjected to severe environmental problems. Available fresh water in the world, which is less than 1% of the total volume of water on the Earth, is unevenly distributed. Therefore, management of water resources is very important. Limited fresh water resources are to be conserved against growing demands. In arid regions, it is extremely important to use water efficiently. This article aims to draw attention to the errors in the design of some shower mixers and disk type faucets, that cause excessive water consumption, and offers a retrofit and compression type faucets, respectively for having better water utilization efficiency. Additionally, in this article, considering the errors in the design of shower mixers and some other products, which are formed by the graduates of industrial design departments of faculties, it is commented that to be able to prevent or at least minimize errors in conceptual designs, the industrial design departments should be restructured to offer only 2nd tier programs for the graduates of engineering faculties. Key words: Water conservation, shower mixer valve, faucet valve, industrial design departments

Mixed-integer MPC for the temperature control of the batch reactor

Discrete Model Predictive Control (MPC) became one of the most widespread modern control principles. Process controls with a finite number of admissible values are common in a large number of relevant applications. For this type of optimization problems, the computational complexity is exponential in the number of binary optimization variables. The solver is based on a standard branch-and-bound method and interior point method is used for solution of the relaxed problem. The simulation experiment involved controlling the temperature of a batch reactor by using two on/off input valves and a discrete-position mixing valve.

Modeling and operability analysis of water separation from crude oil in an industrial gravitational coalescer

The main aim of present study is to develop a mathematical model to analyze the performance of an industrial gravitational coalescer to separate water from crude oil. The considered process consists of a mixing valve and coalescer tank that connected in series. Gravitational coalescer is a huge two-phase separator that separates free water from crude oil based settling time. In this research, the water removal from crude oil is simulated based on a two-dimensional model at steady state condition. The population balance method is used to predict drop size distribution in mixing and coalescence stages considering breakage and coalescence terms. To prove accuracy of the considered model and considered assumptions, the outlet water cut, water removal efficiency and salt content from gravitational coalescer are compared to plant data. Then, effect of temperature, fresh water rate, and mixing pressure drop is studied on water and salt removal efficiencies. The simulation results show that there is an optimum condition to maximize water and salt removal efficiency in desalting process.

Modeling electrostatic separation for dehydration and desalination of crude oil in an industrial two-stage desalting plant

The aim of present study is to develop a mathematical model to predict water and salt separation efficiencies in an industrial two stages crude oil desalting process. The considered process consists of mixing valve and electrostatic drums connected in series. The desalting plant is modeled based on the population balance method considering water droplet breakage and coalescence terms to predict droplet size distribution. The class method as a common mathematical technique is selected to solve population balance equation. The accuracy of the developed mathematical model and considered assumption is evaluated using taken data from an industrial desalting plant. Then, the effect of mixing valve pressure drop, flow rate of fresh water and strength of electric field is studied on the desalting and dehydration efficiencies. The simulation result shows that increasing flow rate of fresh water from 3% to 6% decreases salt content in the treated crude oil from 2.06 to 0.71 PTB.

Modeling and simulation of crude oil desalting in an industrial plant considering mixing valve and electrostatic drum

The aim of present study is development of a mathematical model to predict water and salt removal efficiencies in an industrial crude oil desalting plant at steady state condition. The considered desalting process consists of the mixing valve and AC electrostatic desalting drum that were connected in series. The mixing valve and desalting drum are modeled based on population balance method considering water droplet breakage and coalescence to predict the droplet size distribution. The class method as a common mathematical technique is selected to solve population balance equation. The accuracy of the developed mathematical model and considered assumptions are evaluated via industrial data from a desalting plant. Then, the effect of pressure drop in the mixing valve, flow rate of fresh water and strength of electric field on the desalting and dehydration efficiencies are assessed. The results show that electric field has a significant effect on the process efficiency, so increasing electric field strength from 1.0kV/cm to 2.0kV/cm improves water separation efficiency from 93.92% to 97.85%.

Energy Intensity Reduction of Ca-Looping CO2 Capture by Applying Mixing Loop Seals and Cyclonic Systems

Abstract This work faces the challenge of cutting the specific energy demand in the CO2 capture process based on Ca-looping technology. The use of high-temperature sorbents allows an efficient integration of the excess heat flows. Up to now, several investigations studied the Ca-looping integration with external systems such as a steam cycle. In this research, a further step is done by comparing technological solutions for the internal heat integration with the aim of reducing the energy needs. Particles preheating before entering the regeneration reactor appears as an opportunity for energy saving since solids have to be heated up around 250–300°C from one reactor to another. Two different internal heat integration possibilities making use of a particle separation device and a mixing valve are presented and compared. The former consists of the inclusion of a cyclonic preheater. This configuration presents the a priori advantage of a more developed technology since it is widely used in the cement industry but the drawback of a worse gas–solid heat exchange. Although there is a lack of practical experience regarding the use of a single seal valve to feed two reactors, this configuration presents a promising prospective related to the excellent heat exchange features of the solid flows. The aim is to obtain comparative results by means of implementing advanced thermochemical models, in order to make progress on the development of less energy-intensive configurations of the calcium looping.

Environmental sampling for legionella proliferation risk in three long-term care facilities in Vancouver, British Columbia

&#x0D; Background: Legionella is a pathogen that causes Legionnaires’ disease in high risk populations. The pathogen is known to exist in plumbing systems that do not have preventative factors in place to prevent its growth and proliferation. Legionella grows between 25˚C and 42˚C and is killed at 60˚C, yet long-term care facilities (LTCFs) reduce accessible hot water temperatures from 60˚C at the hot water tank to less than 49˚C at the taps in order to prevent scalding of their residents. Currently, prevention against scalding takes precedence as temperature at accessible taps is regulated within the Residential Care Regulation (RCR) of the Community Care and Assisted Living Act. It is thought that Legionella proliferation risk can be balanced with scalding in-part through the appropriate installation location of thermostatic mixing valves (TMVs). Methods: Three LTCFs in Vancouver, British Columbia were selected for environmental sampling for Legionella proliferation risk. At each LTCF the author recorded the type of hot water tank, temperature of water within the hot water tank, the presence of a TMV and temperature of pipes before and after the TMV. As well, the author recorded hot water temperatures after one minute and free available chlorine concentration ([FAC]) at numerous resident-accessible taps throughout each LTCF. Results: The hot water tank temperatures were set at 60.6˚C, 73.0˚C and 62.0˚C for LTCF #1, LTCF #2 and LTCF #3, respectively. All three LTCFs had installed a TMV within the boiler room immediately after the hot water tank. It was found that LTCF #1’s plumbing system water temperature was reduced from 60.6˚C (at the tank) to 48.9˚C after the TMV. LTCF #2’s plumbing system water temperature was reduced from 73.0˚C (at the tank) to 43.3˚C after the TMV. LTCF #3 was an older plumbing system that did not have thermometers within the boiler room to check the drop in temperature after the TMV. Water temperatures at taps were compared to a standard of 49°C and [FAC] levels at taps to a standard of 0.2 mg/L. The mean hot water temperature and mean [FAC] residual for all three LTCFs were 40.2˚C and 0.27 mg/L, respectively. For all three LTCFs, it was statistically significant that mean water temperatures were less than the comparison value of 49˚C (LTCF #1 p = 0.00000, LTCF #2 p = 0.00022, LTCF #3 p = 0.00110). It was also statistically significant that the mean [FAC] of all three LTCFs were greater than the comparison vale of 0.20 mg/L (LTCF #1 p = 0.00042, LTCF #2 p = 0.00000, LTCF #3 p = 0.00107). Conclusion: It was found that all three LTCFs had set preventive measures in place to protect their residents. Water was heated to at least 60˚C to prevent Legionella and lowered to less than 49˚C to prevent scalding. [FAC] residual was also adequate to prevent growth of Legionella. However, the location of the TMV in the boiler room was suspected to be a possible contributing factor to Legionella growth, especially if cold water temperatures were to reach 20˚C or above, as they could in warm summer months. Further research is needed to determine the significance of the TMV location and the presence of Legionella.&#x0D;

Preventing childhood scalds within the home: Overview of systematic reviews and a systematic review of primary studies

ObjectiveTo synthesise and evaluate the evidence of the effectiveness of interventions to prevent scalds in children. MethodsAn overview of systematic reviews (SR) and a SR of primary studies were performed evaluating interventions to prevent scalds in children. A comprehensive literature search was conducted covering various resources up to October 2012. Experimental and controlled observational studies reporting scald injuries, safety practices and safety equipment use were included. ResultsFourteen systematic reviews and 39 primary studies were included. There is little evidence that interventions are effective in reducing the incidence of scalds in children. More evidence was found that inventions are effective in promoting safe hot tap water temperature, especially when home safety education, home safety checks and discounted or free safety equipment including thermometers and thermostatic mixing valves were provided. No consistent evidence was found for the effectiveness of interventions on the safe handling of hot food or drinks nor improving kitchen safety practices. ConclusionEducation, home safety checks along with thermometers or thermostatic mixing valves should be promoted to reduce tap water scalds. Further research is needed to evaluate the effectiveness of interventions on scald injuries and to disentangle the effects of multifaceted interventions on scald injuries and safety practices.

Numerical Simulation on Indoor Thermal Comfort of a new Integrated Rural Heating System

INTRODUCTIONThis paper presents a new rural energy usage mode based on biomass briquette boiler,which integrated cooking, water heating Kang, water heating bed, water heater into a system. The biomass briquette boiler produces hot water with high efficiency and low emission, the hot water can be sent directly into the heating system for room heating, sent into a special water heater for domestic hot water, and sent to water heating Kang or water heating bed for heating and ensure the comfortable of Kang's or bed's surface after reductions of temperature through mixing valve. METHODSIn order to verify the feasibility and the comfort of thisnewsystem, Airpark software was used to simulate these two living rooms based on the measured data. Simulated the indoor temperature of new heating system room and traditional heating room, analyzed PMV and PPD of these two living rooms, and quantify their thermal comfort. RESULTSSimulation results show that the average PMV of traditional heating room is around -1.19, while the average PMV of new heating model room is -0.10; and the average PPD of traditional heating room is 39.8%, while the average PPD of the new heating model room is 13.47%. CONCLUSIONSIt is obviously that the room with new heating system is more comfortable than the room with traditional heating system. In addition, comparing the economy analysis of these two heating systems, the new one has better economic performance through the life cycle. If this new system be widely used it will produce huge social and economic benefits.

Temperature stratification using an air-cooled heat pump system with a mixing valve

The main factor determining the performance of a thermal storage method is the temperature stratification in the storage tank. At the ideal stratification, the energy efficiency of the storage tank is extremely high. However, when the heat pump is applied, the stratification is disrupted by heat exchange between the layers of the heat medium, and consequent convection in the tank. Therefore, this study analyzed the influence of stratification-related design factors in the water-piping facility area outside a tank heated by a heat pump. In particular, it assessed the thermal stratification and energy efficiency in the storage tank installed with a mixing valve. In the system using the mixing valve, hot water of constant temperature was supplied to the top of the storage tank, reducing the mixing effect of the hot and cold waters; consequently, the stratification index was maximized at 0.42. Comparing the times at which the temperature of the uppermost part reached 70°C in the systems with and without the mixing valve (30 and 75 min, respectively), we find that the mixing valve reduced the time of obtaining effectively hot water by approximately 60%.

Seeking the source of Pseudomonas aeruginosa infections in a recently opened hospital: an observational study using whole-genome sequencing

ObjectivesPseudomonas aeruginosa is a common nosocomial pathogen responsible for significant morbidity and mortality internationally. Patients may become colonised or infected with P. aeruginosa after exposure to contaminated sources within the...