Holding Tube Research Articles

In the Eye of the BBHolder: A Look into Recent Trends in Blood Bank Hold Order Utilization

Abstract The transfusion service at a large academic institution provides transfusion support to the regional cancer center in inpatient and outpatient settings. This center has a large patient population many of whom require frequent blood count monitoring. To reduce the number of blood draws and port accesses, it is standard of care to collect a blood bank hold (BBHold) tube simultaneously with routine CBC samples. The BBHold tube is routed to the transfusion services lab and stored in case a type and crossmatch (TXM) is needed in preparation for transfusion; it is valid for 72 hours. While advantages to this system are eliminating the need for a secondary blood draw and ready access to a sample for transfusion testing, disadvantages include drawing an additional tube, increased cost and storage, and increased specimen mislabeling in the conversion of a BBHold to a TXM. Our objectives were to analyze trends in BBHold usage, make recommendations to reduce unnecessary utilization, and create an algorithm to predict which patients would need transfusion. We collected data from March 2016 to June 2019 including hemoglobin values, BBHold orders, and TXM orders, and used the statistical programming language R for data analysis. Approximately 1,000 BBHold samples were collected monthly, with 64.2% taking place in the outpatient setting. Our analysis focused on this outpatient population. A total of 31.1% of BBHold orders were unnecessary, as they were re-collected within the 72-hour window of sample viability. Of all the BBHold orders, including the previously mentioned unnecessary orders, only 32.7% were converted to a TXM, which was used as a surrogate marker for transfusion. Unexpectedly, 28.2% of the last hemoglobin values collected prior to a BBHold (either concurrently with the BBHold or up to 3 days prior) were ≥10 g/dL. Notably, only 44.6% of these hemoglobin orders occurred concurrently with a BBHold, indicating that over 55% of BBHold orders were placed after the hemoglobin order. Once a hemoglobin value is resulted, a BBHold has minimal use since the hemoglobin value would determine if a transfusion is indicated. If transfusion is indicated, a TXM order should be placed directly, rather than a BBHold. Next, the average hemoglobin values were compared between patients who did and did not receive a transfusion within 7 days, and these were 8.8 and 9.1 g/dL, respectively. In conclusion, the trends illustrated here indicate overutilization of BBHold orders and highlight potential areas for optimization. Hemoglobin values within 7 days of a BBHold may not be enough to design a robust algorithm to stratify patients based on need for transfusion. Recommendations moving forward may include improving the EHR interface to display the expiration date of the current BBHold sample or displaying the patient’s last hemoglobin if ≥10 g/dL.

Modeling high protein liquid beverage fouling during pilot scale ultra-high temperature (UHT) processing

Ultra-high temperature (UHT) processing is where liquid foods are sterilized at temperatures at or near 135°C. Because of the relatively high temperature, UHT processes are known for developing severe foulants on heat exchange surfaces. Furthermore, there is ambiguity (and commercial variation) in the exact process temperature when UHT processing. Therefore, it was the goal of this research to quantify the effects of process temperature changes on fouling rates in a pilot UHT system. The research performed evaluated fouling when processing 20% (wt./wt.) reconstituted non-fat dry milk as a model high protein beverage. The variables of interest were process temperature (127, 132 and 138°C) and run time. Each thermal process was designed to maintain equivalent thermal processing of a model microbe (F0=7.5) by adjusting the hold tube length at each temperature. After a defined run time, foulant from the pilot system was extracted into a sodium hydroxide solution. Compositional changes in this solution were indirectly associated with the pickup of foulant from the pilot system. Statistical differences (α=0.05) in fouling rates were observes as a function of process temperature using 4 foulant indicators (active alkali, electrical conductivity, protein content and color). The temperature dependence of fouling rate fit significantly to Arrhenius models (r2 range 0.95–0.99) with activation energies ranging from 116.6 to 154.5 kJmol−1. Results provide evidence that reduction in process temperatures can significantly decrease fouling rates, therefore increasing product run times.

Flash Pasteurization of Filtered and Unfiltered Beer (Wheat Beer or Craft Made Beer) with One Heated Holding Tube: A Process Comparison with Shortened Heat Holding

Flash Pasteurization of Filtered and Unfiltered Beer (Wheat Beer or Craft Made Beer) with One Heated Holding Tube: A Process Comparison with Shortened Heat Holding

MON-P035: Prediction of Oral Intake and Pneumonia of the Patients with Dysphagia Holding Tube Feeding

MON-P035: Prediction of Oral Intake and Pneumonia of the Patients with Dysphagia Holding Tube Feeding

Mathematical modeling and microbiological verification of ohmic heating of a solid–liquid mixture in a continuous flow ohmic heater system with electric field perpendicular to flow

To ensure sterility of a solid–liquid mixture processed in continuous-flow ohmic systems, the slowest-heating solid particle needs to receive sufficient heat treatment at the outlet of the holding section. We describe herein, the development of a mathematical model for solid–liquid mixtures in a commercial ohmic heater with electric field oriented perpendicular to the flow. The fastest moving particle velocity was identified using over 299 particles and a radio-frequency identification technique, and used as an input to the model for the worst-case heating scenario. Thermal verification was conducted by comparing predicted and measured fluid temperatures at heater and hold tube outlets; the model showed good agreement between calculated and experimental fluid temperatures (P>0.05) with a maximum error of 0.4°C. The model predicted a hold tube length of 15.85m at 134.0°C process temperature to achieve a target lethal effect at the cold spot of the slowest-heating particle. Using this length of hold tube, microbiological tests were conducted using at least 299 chicken/alginate particles inoculated with Clostridium sporogenes spores per run. These tests showed the absence of viable microorganisms at the target treatment and positive growth when temperatures were below target, thereby verifying model predictions.

Determination of food particle residence time distributions in coiled tube and straight tube with bends at high temperature using correlation analysis

The effects of tube geometry (coiled and straight), particle concentration (0–30% v/v), average product flow rate, and carrier fluid temperature (96–124 °C) on residence time distributions of model food particles in the holding section of an aseptic processing system were investigated by means of correlation analysis. Hold tube geometry and flow rate exerted significant effects on the mean normalized residence time. Minimum normalized residence time was significantly influenced by the fluid temperature and the interaction between hold tube geometry and particle concentration. In the coiled tube, standard deviation of normalized residence time decreased with an increase in particle concentration. The fastest-moving particles in the coiled tube possessed a velocity of 1.96 times the average product velocity, whereas the velocity of fastest-moving particle in the straight tube was 1.8 times the average product velocity. Based on empirical expressions of the residence time parameters as functions of particle concentration and dimensionless groups ( Fr f, Re gp, and Ar f), variable influence of several forces on particle residence time of particulate food suspensions in different settings was deduced.

Fluid to Particle Heat Transfer Coefficients in Holding Tube Having Noncircular Cross Section

ABSTRACT: Convective heat transfer coefficient (hp) between fluid and particle in continuous tube flow were compared for 2 configurations of holding tubes: one conventional having a circular cross section (CHT) and the other having noncircular cross section (NCHT). A stream of plastic spheres was fed into the holding tube to simulate a food system with particulates. Live vegetative cells of Bacillus stearothermophilus were immobilized in aqueous gellan cubes and injected into the holding tubes with water as a carrier medium. The observed inactivation levels were compared with predicted values calculated from transient heat transfer equations solved by an explicit finite difference technique. Mean effective hp values ranged from 400 to 2500 W/m2.K for the NCHT and 350 to 1700 W/m2.K for the CHT at a Reynolds numberrpanging from 6000 to 13000. The difference in hp levels between the 2 configurations increased with the flow rate and temperature. Although no relation was observed between hp values and liquid to particle relative velocity, a trend between pipe Reynolds number and hp values was observed. The presence of a large number of particles in the holding tube significantly influenced hp values. Keywords: heat transfer coefficients, holding tube, Reynolds number, particle

Flow Characteristics of a Pilot-Scale High Temperature, Short Time Pasteurizer

In this study, we present a method for determining the fastest moving particle (FMP) and residence time distribution (RTD) in a pilot-scale high temperature, short time (HTST) pasteurizer to ensure that laboratory or pilot-scale HTST apparatus meets the Pasteurized Milk Ordinance standards for pasteurization of milk and can be used for obtaining thermal inactivation data. The overall dimensions of the plate in the pasteurizer were 75×115mm, with a thickness of 0.5mm and effective diameter of 3.0mm. The pasteurizer was equipped with nominal 21.5- and 52.2-s hold tubes, and flow capacity was variable from 0 to 20 L/h.Tracer studies were used to determine FMP times and RTD data to establish flow characteristics. Using brine milk as tracer, the FMP time for the short holding section was 18.6s and for the long holding section was 36s at 72°C, compared with the nominal times of 21.5 and 52.2s, respectively. The RTD study indicates that the short hold section was 45% back mixed and 55% plug flow for whole milk at 72°C. The long hold section was 91% plug and 9% back mixed for whole milk at 72°C. This study demonstrates that continuous laboratory and pilot-scale pasteurizers may be used to study inactivation of microorganisms only if the flow conditions in the holding tube are established for comparison with commercial HTST systems.

COMPUTATIONAL FLUID DYNAMICS MODELING OF FLUID FLOW IN HELICAL TUBES

ABSTRACTThe effect of different processing parameters on the degree of mixing and axial and radial pressure drops, during single‐phase flow in helical tubes was investigated by using CFD software. Correlations were developed to calculate axial and radial pressure drops, and also the ratio of maximum to average fluid velocities. All of these quantities were found to be dependent on curvature ratio (ratio of tube diameter to coil diameter). Flow visualization experiments were performed to assess the degree of mixing in different configurations. At identical conditions, the degree of mixing was higher in the system with the large curvature ratio, which is in agreement with the simulation results. A minimum ratio of maximum to average fluid velocities of 1.61 was achieved, representing a 20% reduction in hold tube length for Newtonian fluid in laminar flow.

Fluid-to-particle Heat Transfer Coefficients for Continuous Flow of Suspensions in Coiled Tube and Straight Tube with Bends

Fluid-to-particle heat transfer coefficient (h fp ) for spherical particles in continuously flowing food suspensions (0–30% v/v green peas in 1.5% sodium carboxymethylcellulose solution) in the holding section of an aseptic processing system was determined. The effects of hold tube geometry, temperature, flow rate, and particle concentration were investigated. The h fp values ranged from 538 to 1450 W/m 2·°C in the coiled tube and from 204 to 1220 W/m 2·°C in the straight tube. Significantly, higher h fp value was observed for particles in the coiled tube as compared to that in the straight tube. The h fp value increased with temperature, flow rate, and particle concentration. Dimensionless correlations relating the Nusselt number to Reynolds and Prandtl numbers were developed. Estimation of h fp values based on the particle resistance temperature device (RTD) data and dimensionless correlations indicated a reduction in the degree of overprocessing of average particles when a coiled tube was used instead of a straight tube for the holding section.

Secondary Flow and Residence Time Distribution in Food Processing Holding Tubes with Bends

ABSTRACTResidence times of nearly neutrally buoyant polystyrene particles flowing with an aqueous solution of carboxymethylcellulose were measured in each of 4 straight sections of holding tubes that were connected by 180° bends. Equations were developed to predict mean, minimum, and standard deviations of residence times in individual tubes and in the entire assembly as a function of viscosity, particle size, particle concentration, and flow rate. The residence time distribution in the 4th tube was always narrower than that in the 1st tube, and the ratio of the mean to minimum residence time was always between 1.07 and 1.20. These results can help in the design of appropriate holding tubes for food processing.

Bulk Average Heat Transfer Coefficient of Multiple Particles Flowing in a Holding Tube

Amethodology was developed to measure the bulk average heat transfer coefficient of a large number of particles flowing in a holding tube. This technique is based on energy balance on the fluid and the analytical solution of transient heat conduction within a sphere. Particles at concentrations up to 18% v/v and fluid, at different initial temperatures, were mixed while flowing in the holding tube. The range of measured heat transfer coefficient ( h fp ) was from 180 to 800Wm− 2 2 K, based on particle concentration and flow rate. The value of h fp was found to decrease significantly as the particle concentration increased. This could be attributed to the restriction of particle movement in the holding tube as the particle concentration increased. Although bulk flow rate, as expected, was found to increase h fp , the increase was not significant at all levels.

Distribution of Liquid‐Solid Heat Transfer Coefficient among Suspended Particles in Vertical Holding Tubes of an Aseptic Processing System

ABSTRACTMass transfer coefficients between sucrose coated particles and water as the suspending fluid, were measured to obtain values of the heat transfer coefficient by analogy with mass transfer. In a vertical holding tube configuration, the mass transfer coefficient spanned considerable range for those particles with comparable residence time. At Reynolds number 26100, the average mass transfer Sherwood number expressed in terms of residence time was Sh= ‐110.4t+215.1, and it scattered normally with standard deviation 19.2. The results indicated that heat transfer coefficients vary among particles with different residence times and may be significantly different even for particles with the same residence time.

Residence time distribution of liquids in a continuous tubular thermal processing system part II: Relating hold tube efficiency to processing conditions

The concept of efficiency of a holding tube is essential to guarantee the safety of continuously processed fluid foods. A good prediction of efficiency allows a better control of the processing conditions, guaranteeing product safety while decreasing product quality losses due to overprocessing. Different published methods were compared to data obtained in this work and to reported data, to assess their ability to predict tube efficiency in a range of Reynolds number (Re) covering laminar, transient and turbulent flow. Furthermore, a model assuming dispersed plug flow and a power-law relation between Peclet number (Pe) and Re was developed and evaluated. Published models were shown to be, in general, conservative for both laminar and turbulent flow, but often overpredicted the experimental efficiency in the zone of 2100 <Re < 4000. Deviations between predicted and experimental values were very considerable (errors from −25% to 90%). The model proposed has proved to be conservative over the whole range, but more accurate (errors up to 15%).

Residence Time Distribution of Particles during Two‐Phase Non‐Newtonian Flow in Conventional as compared with Helical Holding Tubes

ABSTRACTThe residence times of multiple particles during the flow of a non‐Newtonian suspension through a conventional holding tube assembly were compared with that in a helical holding tube assembly of identical length and tube diameter. The residence times were measured for different combinations of process parameters (viscosity, flow rate of fluid, size and concentration of particles). The effects of these parameters on Residence Time Distribution (RTD) of particles was determined and dimensionless equations were developed to predict the mean, minimum and standard deviation of residence times. The RTDs in the helical holding tube were found to be narrower than in the conventional holding tube. The RTD of particles at all combinations of process parameters were normally distributed. The ratio of mean to minimum residence time was within 1.05 to 1.11 in the helical holding tube and 1.06 to 1.16 in the conventional holding tube for the range of parameters studied.

Residence Time Distributions of Meat and Carrot Cubes in the Holding Tube of an Aseptic Processing System

Residence time distribution (RTD) of meat and carrot cubes in the holding tube of a commercial pilot scale aseptic processing system was evaluated using a full factorial design of experiments employing holding tube length (4·6, 9·2, 13·8 and 18·4 m), flow rate (10, 15 and 20 kg/min), particle size (10 and 20 mm meat cubes and 6 and 13 mm carrot cubes) and concentration of the carrier fluid (40 and 60 g/100 g starch) as factors. All test factors significantly ( P< 0·05) influenced the fastest particle residence time and its normalized counterpart, the mean particle residence time and standard deviation of RTD. Experimental RTD was well described by a generalized logistic model ( r 2> 0·95). The model parameters were responsive to test factors and could be well described using multiple regression analyses of test factors and their interactions.

A model for conduction heat transfer to particles in a hold tube using a moving mesh finite element method

Holding mixtures of solid and liquids at a high temperature is a common process in sterilising food material. It is difficult to measure the temperature of a particle flowing down the holding tube. Differences in velocity and temperature between different particles must however be estimated in order to allow prediction of process times. Experiments show that some particles may spend extended periods of time at or near the walls of the tube; the thermal behaviour of particles propagating along the wall may differ from those in the bulk. A mathematical model has considered this problem for the case of a rectangular shaped particle sliding on the pipe wall. Analytical solutions of the conduction equations are not available; a two-dimensional finite element program, using a novel dynamic moving mesh, has been developed to simulate the moving particle. Temperature differences between wall and bulk have been shown by the model.

Determination of Fluid-particle Convective Heat Transfer Coefficient

Fluid-to-particle convective heat transfer coefficient (hfp) was determined by continuous particle center temperature measurements in a hold tube by a temperature sensor system using the transmitter particle technique. The fluid used was carboxy methyl cellulose (CMC) at concentrations of 0.5, 1.0, and 1.2% (w/w). The carrier fluid temperatures were 22.22, 65.56, 76.67, and 82.22 C. Temperature dependent viscosity parameters of CMC were determined and used in calculating hfp. Specific heat and thermal resistance of the sensor were experimentally determined and used in solving the energy balance equation to obtain hfp values. Values of hfp ranged from 108.08 to 195.83 W/m2 C. The results are expressed as a correlation of dimensionless numbers. The fluid viscosity significantly affected hfp at high temperatures. Decreasing fluid viscosity (by increasing fluid temperatures) increased hfp.

Residence Time Distribution of Multiple Particles in Non‐Newtonian Holding Tube Flow: Statistical Analysis

ABSTRACTResidence times of multiple particles in aqueous solutions of carboxy‐methylcellulose (CMC) in a holding tube arrangement were measured at different conditions of fluid viscosity, suspension flow rate, particle sizes and particle concentrations. Nearly neutrally buoyant polystyrene spheres were used to simulate food particles. Residence time distribution functions, E(t), applicable to lethality calculations in aseptic processing were developed along with equations to predict the mean (RTmean), minimum (RTmin) and standard deviation (RT std) of the residence times as a function of process parameters. Results showed that viscosity, flow rate and particle concentrationhad significant (a = 0.05) effects on RTmean) RT min and RT std while particle size affected only RT std. The ratio of mean residence time to minimum residence time was 1.06 to 1.16.

Food sterilization by electrical heating: Sensitivity to process parameters

AbstractThe design of efficient continuous sterilization equipment for flowing solid‐liquid food mixtures requires that temperature and velocity distributions within the fluid are known. In electrical (ohmic) heating, electric current is passed through a two‐sterilize it. This allows rapid sterilization of solid‐liquid mixtures which minimizes quality loss. A computational process model simulates the effect of realistic physical property changes. The effect of variations in physical properties can have a significant effect on the temperature of the product and thus on its sterility. Realistic designs will have to cope with temperature differences between phases. Experimental data for velocities in a food flow have been incorporated into an enthalpy balance model for heat transfer in solid‐liquid mixtures. The effect of inlet temperature on the length of hold tube required to give the necessary process sterility calculated shows the variation in output conditions that might results in real systems.