Compartment Temperatures Research Articles

Determination of stability indicating assay method for eszopiclone in pharmaceutical drug substances a comparative study by UPLC and HPLC

Eszopiclone is a nonbenzodiazepine hypnotic used as a treatment for insomnia . Eszopiclone is the active dextrorotatory stereoisomer of zopiclone , and belongs to the class of drugs known as cyclopyrrolones . A simple, Isocratic, rapid and selective RP-UPLC method was developed for the quantification of Capecitabine in active pharmaceutical ingredients (API’S) using a simple mobile phase of solution A (5.0g of sodium dodecyl sulfate and 2.0 g of monobasic sodium phosphate were dissolved in one liter of water and adjusted the pH to 3.8 with 10% phosphoric acid) and solution B acetonitrile in the ratio of 65:35 at a flow rate of 0.50 mL/min. The chromatographic separation was achieved on a Poroshell C18 column of dimension 4.6 X 50 mm, 2.7µm. The column and sample compartment temperatures were maintained at ambient. UV detector was monitored at 303nm. The retention time (RT) of Eszopiclone was about 8.4min at an overall runtime of 12min. The developed method was validated as per the requirements of ICH guidelines. Finally a comparison of the method was done against conventional HPLC. The developed method was superior with respect to analysis time , efficiency and sensitivity. The runtime of Eszopiclone in conventional hplc method was about 60.0min. Compare to HPLC method the developed method is cost effective and more rugged. The method can be used for routine analysis of assay in Quality Control laboratory on regular basis.

Calculation of radiant heat flux from compartment fires in various ventilation conditions

Radiant heat flux calculation methods from a compartment fire to an adjacent structure have been previously developed using different techniques [1–7]. All of these methods consider post-flashover, ventilation controlled compartment fire scenarios where internal compartment temperatures and external flames through openings contribute to the overall radiation received at the target locations. However, the applicability of these methods for compartments with different ventilation conditions such as fuel controlled or forced-flow ventilation is unknown due to insufficient experimental data. These conditions may be necessary for design scenarios where wind conditions can affect burning in the room and the resulting heat transfer to adjacent buildings. New data from large-scale compartment fire tests is used in this paper to explore the development of calculation methods for different ventilation conditions.

Travelling fires for structural design–Part I: Literature review

Close inspection of accidental fires in large, open-plan compartments reveals that they do not burn simultaneously throughout the whole enclosure. Instead, these fires tend to move across floor plates as flames spread, burning over a limited area at any one time. These fires have been labelled travelling fires. Current structural fire design methods do not account for these types of fires. Despite these observations, fire scenarios most commonly used for the structural design of modern buildings are based on traditional methods that assume uniform burning and homogenous temperature conditions throughout a compartment, regardless of its size.This paper is Part I of a two part article and is a literature review of the research on the new topic of travelling fires. A brief background to the traditional methods that assume uniform fires is given along with critiques of that assumption, such as the observation of heterogeneity among compartment temperatures and the travelling nature of fires in both accidental events and controlled tests. The research in travelling fires is reviewed, highlighting the pioneering work in the field to date, and compared to the state of the art. The main challenge in developing tools for incorporating travelling fires into design is the lack of large scale test data. Nonetheless, significant progress in the field has been made and two methodologies using travelling fires to characterise the thermal environment for structural analysis have recently been developed. The research in quantifying the structural response to travelling fires is also reviewed, demonstrating the benefit of collaboration between fire engineers and structural fire engineers.

Alternative test method to assess the energy performance of frost-free refrigerating appliances

This paper outlines an alternative test method to evaluate the energy consumption of frost-free refrigerators and freezers for residential applications. While the standardized methods require the refrigerating appliance to be kept running according to its onboard control system, which usually drives the refrigerator through an on–off cycling pattern, the proposed approach assesses the refrigerator energy performance in the steady-state regime, being therefore much faster and more reliable. In this procedure, the cooling capacity is matched to the cooling loads by PID-controlled electrical heaters installed within the refrigerated compartments, so that the compartment temperatures are kept at the desired standardized levels. Comparisons between the experimental results obtained using the steady-state energy test and the standardized procedures showed that the former follows closely the trends observed for the latter.

Assessment of the Use of Fire Dynamics Simulator in Performance-Based Design

This paper discusses a procedure for the use of fire modelling in the performance-based design environment to quantify design fires for commercial buildings. This procedure includes building surveys, medium-and full-scale experiments and computer modelling. In this study, a survey of commercial premises was conducted to determine fire loads and types of combustibles present in these buildings. Statistical data from the literature were analysed to determine the frequency of fires, ignition sources, and locations relevant to these premises. Based on the results of the survey and the statistical analyses a number of fuel packages were designed that represent fire loads and combustible materials in commercial buildings. The fuel packages were used to perform medium- and full-scale, post-flashover fire tests to collect data on heat release rates, compartment temperatures and production and concentration of toxic gases. Based on the experimental results, input data files for the computational model, Fire Dynamics Simulator (FDS), were developed to simulate the burning characteristics of the fuel packages observed in the experiments. Comparative analysis between FDS model predictions and experimental data of HRR, carbon monoxide (CO), and carbon dioxide (CO2), indicated that FDS model was able to predict the HRR, temperature profile in the burn room, and the total production of CO and CO2 for medium- and large-scale experiments as well as real size stores.

Development of Design Fires for Performance-Based Fire Safety Designs

This paper discusses a procedure for the development of design fires for buildings and presents a study undertaken to quantify design fires for commercial buildings. This procedure includes building surveys, full-scale experiments and computer modelling. In this study, a survey of commercial premises was conducted to determine fire loads and types of combustibles present in these buildings. Based on the results of the survey a number of fuel packages were designed that represent fire loads and combustible materials in commercial buildings. The fuel packages were used to perform full-scale, post-flashover fire tests to collect data on heat release rates, compartment temperatures and production and concentration of toxic gases. Results from these experiments are presented and discussed. The paper also discusses a computer modelling study in which a computational fluid dynamics model was used to simulate the tests and to model a fire in a real-scale commercial store.

Replacing international temperature–time curves with BFD curve

From The World Trade Centre Investigation Draft Report by NIST [National Institute of Standards and Technology. World Trade Centre performance study: data collection, preliminary observations and recommendations. FEMA (Federal Energy Management Association), 2002.], one of the recommendations was to “improve the century-old standard for the testing of building components, assembles and systems”. NIST believes that it is essential to complete a comprehensive review that will establish a firm technical basis for future fire-rating requirements. The purpose of this paper is to describe and demonstrate how a single log-normal equation (such as BFD curve [Barnett CR. BFD curve: a new empirical model for fire compartment temperatures. Fire Safety J 2002; 37: 437–63]) can be used to replace international temperature–time curves such as ISO 834, BS 476, ASTM 119, NFPA 251, the external, the hydrocarbon and the Eurocode parametric curve. There are five main reasons for such a replacement. Firstly, BFD curve is a “natural” fire curve that fits the results of actual fire tests closer than previously known fire modelling methods. Secondly, the shape of the curve bears a strong relationship to both the pyrolysis coefficient ( R/ A v. h v 0.5) and the opening factor ( F O2). Thirdly, the shape of the curve is related to the thermal properties of the firecell. Fourthly, contrary to a number of other fire modelling curves, BFD curve does not need the use of a time shift. Finally, it uses a single equation to model the temperature of both the growth and decay phases of a fire in a building whereas a curve such as Eurocode 1 curve requires two equations. Only three factors are required to model a BFD curve: maximum gas temperature, the time at which this maximum temperature occurs, and a shape constant for the curve. Ref. [2] shows how these factors can be derived.

Estimation of Mean Body Temperature from Mean Skin and Core Temperature

Mean body temperature (MBT) is the mass-weighted average temperature of body tissues. Core temperature is easy to measure, but direct measurement of peripheral tissue temperature is painful and risky and requires complex calculations. Alternatively MBT can be estimated from core and mean skin temperatures with a formula proposed by Burton in 1935: MBT = 0.64 x TCore + 0.36 x TSkin. This formula remains widely used, but has not been validated in the perioperative period and seems unlikely to remain accurate in dynamic perioperative conditions such as cardiopulmonary bypass. Therefore, the authors tested the hypothesis that MBT, as estimated with Burton's formula, poorly estimates measured MBT at a temperature range between 18 degrees and 36.5 degrees C. The authors reevaluated four of their previously published studies in which core and mass-weighted mean peripheral tissue temperatures were measured in patients undergoing substantial thermal perturbations. Peripheral compartment temperatures were estimated using fourth-order regression and integration over volume from 18 intramuscular needle thermocouples, 9 skin temperatures, and "deep" hand and foot temperature. MBT was determined from mass-weighted average of core and peripheral tissue temperatures and estimated from core temperature and mean skin temperature (15 area-weighted sites) using Burton's formula. Nine hundred thirteen data pairs from 44 study subjects were included in the analysis. Measured MBT ranged from 18 degrees to 36.5 degrees C. There was a remarkably good relation between measured and estimated MBT: MBTmeasured = 0.94 x MBTestimated + 2.15, r = 0.98. Differences between the estimated and measured values averaged -0.09 degrees +/- 0.42 degrees C. The authors concluded that estimation of MBT from mean skin and core temperatures is generally accurate and precise.

Quantitative comparison of FDS and parametric fire curves with post-flashover compartment fire test data

This paper presents a comparison of two parametric fire modelling techniques (Eurocode 1, and the BFD curve method) and one field model (fire dynamics simulator) against large-scale post-flashover test data. Using a method of the product moment correlation coefficient, it is shown that the BFD curve predictions are most closely representative of reality. For the computational test data, two grid resolutions are adopted in the FDS field model, the finer of which having comparable results in terms of regression analysis to the BFD method. Both the field model and the BFD curve method were found to give better predictions compared to the Eurocode method over the duration of the test. However, a direct comparison of the maximum gas temperatures shows the field model to be poorer in its predictive capability than the parametric methods, under-predicting the maximum gas temperatures. In addition, a more in-depth analysis of the FDS predictions indicates that by considering simply average compartment temperatures the more inaccurate spatially specific temperature predictions were disguised. This study provides useful quantitative data on the three techniques presented and discusses more general issues concerning fire modelling.

Temperature and time-sharing running combination control strategy of two-circuit cycle refrigerator–freezer with parallel evaporators

A two-circuit cycle refrigerator/freezer (RF) with parallel evaporators is more efficient than a single-loop RF and a bypass two-circuit cycle RF, and its cost is less than that of a dual-loop RF with two compressors. The existed control strategies for this kind of RFs are only based on the temperature control with freezer compartment (FZC) prior to fresh food compartment (FFC) or FFC prior to FZC. When a lot of foods are put into FFC or FZC at a time, the compartment temperatures will go up very high and the food will be damaged. In order to solve this problem, the combination control strategy based on both the temperature control and the time-sharing running control is put forward in this paper. The rules to determine the maximum set on-time of FFC loop and that of FZC loop are presented based on theoretically analyses. The new control strategy is validated in a two-circuit cycle RF with parallel evaporators, and the compartment temperature fluctuations can be controlled within rational ranges under the conditions that a lot of food are put into FFC or FZC at a time, or the ambient temperature is very high. The daily energy consumption of the tested RF with the new control strategy is about 0.99% larger than that with the existed control strategies, which may be caused by the frequent shifts between FZC loop and FFC loop.

Simulating the effects of fuel type and geometry on post-flashover fire temperatures

This paper discusses the effect of fuel type and geometry on predicted compartment temperatures derived from computer modelling of post-flashover compartment fires. Many previous studies have investigated post-flashover fires with either wood crib or liquid pool fuels, but very few analytical or experimental studies have considered realistic wood-based fuels with different ratios of surface area to volume, combined with plastic-based fuels. A simple single zone fire model was used to calculate the temperatures in post-flashover compartment fires. The program includes a catalogue of furniture items, each with fuel mass loss rate evaluated on the basis of a constant regression rate on all exposed surfaces. The program also includes a pool-burning model and considers wood fuels and thermoplastic fuels burning together inside a compartment. Use of the model shows that the total fuels load alone is not sufficient to characterise a post-flashover fire. The fire temperature is highly dependent on the fuel type and geometry. For given ventilation and total fuel load, the resulting temperature depends greatly on the average thickness of the wood fuels and the presence of thermoplastic fuels. The ratio of the available fuel surface area to the ventilation opening is particularly important. Several fire scenarios involving different fuel types and characteristics are simulated and compared with Eurocode parametric fires.

Experimental investigation of a comfort heating system for a passenger vehicle with an air-cooled engine

This study describes a novel approach utilizing waste heat from the exhaust gas for comfort heating of the passenger compartment of a vehicle with an air-cooled engine. In the devised system, a water stream heated by the hot exhaust gas was sent to the passenger compartment of a commercial minibus with an air-cooled engine, and the system was tested under various operating conditions. Variations of the temperatures at several locations inside the vehicle were monitored while ambient temperatures were −3, 0, 5 and 10 °C and there were various numbers of passengers on board. It is found that the system shows a reasonable heating performance while consuming no extra fuel for this purpose, and experimental data is in good agreement with numerical results based on heat loss calculations. Results show that when the ambient temperature is above 0 °C and the engine speed is above 2500 rpm, the system yielded comfortable compartment temperatures. Compared with alternative methods using extra fuel for comfort heating, the proposed system decreases vehicle operating costs and environmental pollution caused by the heating system as well as causing a lower global warming.

BFD curve: a new empirical model for fire compartment temperatures

The purpose of this paper is to describe and demonstrate the potential of a new and unique fire engineering design tool, which for discussion purposes in this paper has been given the name of “BFD Curve”. The research for this paper revealed four important facts. Firstly, BFD curve is a natural fire curve in that it fits the results of actual fire tests closer than previous known fire modelling methods. Secondly, the shape of the curve bears a strong relationship to both the pyrolysis coefficient ( R/ A v h v 0.5) and the opening factor F O 2 . Thirdly, contrary to a number of other fire modelling curves, BFD curve does not need the use of time shifts. Finally, it uses a single equation to model the temperature of both the growth and decay phases of a fire in a building whereas the well publicised Eurocode 1 and Swedish curves require two equations. Only three factors are required: maximum gas temperature, the time at which this temperature occurs, and a shape constant for the curve.

A quasi-steady-state model for predicting fire suppression in spaces protected by water mist systems

A quasi-steady-state model was developed to predict the effectiveness of a water mist system for extinguishing fuel spray and pool fires. The model was developed for obstructed fires where extinguishment primarily occurs as a result of a reduction in oxygen concentration due to the consumption of oxygen by the fire and due to dilution of the oxygen with water vapor. Interactions between the mist and the flame are neglected resulting in limiting case predictions. The model is based on conservation of energy and requires the following input parameters: fire size, compartment geometry, vent area, and water flow rate. The steady-state temperatures and oxygen concentrations predicted by the model can be used to determine the smallest fire that can be extinguished. The predictions made by the model compared favorably to the results of three full-scale test series conducted for the US Coast Guard. These tests were conducted in shipboard machinery spaces with compartment volumes ranging from 100 to 500 m 3 with a wide range of ventilation rates and openings. The model was able to accurately predict the compartment temperatures during the tests where steady-state conditions were produced. The model was also able to accurately predict the extinguishment times for a wide range of fire sizes and was used to identify the smallest fire that could be extinguished for a given set of conditions.

A two-dimensional numerical investigation of the oscillatory flow behaviour in rectangular fire compartments with a single horizontal ceiling vent

This paper presents a comparison of fire field model predictions with experiment for the case of a fire within a compartment which is vented (buoyancydriven) to the outside by a single horizontal ceiling vent. Unlike previous work, the mathematical model does not employ a mixing ratio to represent vent temperatures but allows the model to predict vent temperatures a priori. The experiment suggests that the flow through the vent produces oscillatory behaviour in vent temperatures with puffs of smoke emerging from the fire compartment. This type of flow is also predicted by the fire field model. While the numerical predictions are in good qualitative agreement with observations, they overpredict the amplitudes of the temperature oscillations within the vent and also the compartment temperatures. The discrepancies are thought to be due to three-dimensional effects not accounted for in this model as well as using standard ‘practices’ normally used by the community with regards to discretization and turbulence models. Furthermore, it is important to note that the use of the k–e turbulence model in a transient mode, as is used here, may have a significant effect on the results. The numerical results also suggest that a linear relationship exists between the frequency of vent temperature oscillation (n) and the heat release rate (Q0) of the type n∝Q0.290, similar to that observed for compartments with two horizontal vents. This relationship is predicted to occur only for heat release rates below a critical value. Furthermore, the vent discharge coefficient is found to vary in an oscillatory fashion with a mean value of 0.58. Below the critical heat release rate the mean discharge coefficient is found to be insensitive to fire size.

Modelling Post-Flashover Fires With FASTLite

This paper describes the post-flashover use of the FASTLite program and illustrates typical output for a post-flashover fire in a single room. The program is shown to model heat release and fire duration in a rational way, but some calculated compartment temperatures appear to be too high. Suggestions are made for using the program in its current form and for future improvements. Language: en

Ventilation Effects On Compartment Fire Characterization

Compartment fire experiments were performed using either natural or overhead forced ventilation to assess the effect of ventilation on the compartment fire environment. The ventilation rate was varied by changing the vent size in natural ventilation tests and mechanically in forced ventilation tests. Three fuels were used: diesel fuel, wood cribs, and polyurethane slabs. For naturally ventilated fires, it was noted that the vent size and geometry had a significant impact on the vertical temperature and oxygen concentration profiles. Both the temperature and oxygen concentration measurements were representative of two-layer environments. However, in terms of oxygen concentration, forced ventilation fires resulted in a well-mixed compartment regardless of the ventilation rate. In contrast, temperature measurements showed either a two-layer or linear variation with respect to compartment height, depending on the scenario. These results defy the conventional assumption that compartment temperatures and gas concentrations have the same vertical distribution. Furthermore, these results identify the need to go beyond the classic twolayer paradigm. In addition, reduced oxygen concentrations at the flame base resulted in reduced mass loss rates. The relationship between these burning rates and the oxygen concentration at the flame base was examined, and a correlation was developed. The results show that temperature and flashover potential assessments based on furniture calorimeter data may be significantly overestimated.

AGGRESSIVE WATER FOG ATTACK REDUCES HEAT STRAIN DURING SHIPBOARD FIREFIGHTING1182

This study compared the use of two shipboard firefighting water attack methods, direct straight-stream (DIR) and aggressive fog (FOG), on heat strain of naval firefighting personnel. Eight males and four females aged 31 ± 4 yrs served as subjects. Portable data logger recordings were made of heart rate (HR), and rectal (Tre), chest (Tch), arm (Tar), hand(Tha), index finger (Tfi), thigh (Tth), foot(Tfo), and big toe (Tto) temperatures during altematingly ordered DIR and FOG tests. Subjects wore cotton work clothes underneath the standard Navy firefighting ensemble plus oxygen breathing apparatus. Fire compartment temperatures at the time of entry averaged (±SD) 591± 43°C. Firefighters entered into the fire compartment 1.2 to 1.8 m, took a crouched position, and set the nozzle angle to either 60° for FOG or 30° for DIR. During both FOG and DIR, water was discharged in a series of 2 or 3 short bursts lasting 2-3 sec in duration. During pre-activities and actual firefighting, HR and all body temperatures increased progressively. Time to extinction of flames was significantly (p<.05) less for FOG (9.1 ± 0.6 min) compared to DIR (10.9 ± 0.6 min). Analysis of covariance (adjusted for pre-entry values) showed no differences for Tha ([horizontal bar over]X=38.2°C), Tfi ([horizontal bar over]X=41.6°C), and Tth ([horizontal bar over]Xs=38.2°C). However, FOG Tre ([horizontal bar over]X=38.2°C), Tch([horizontal bar over]X=39.6°C), Tar ([horizontal bar over]X=40.0°C) and Tfo ([horizontal bar over]X=36.0°C) were lower (p<.05) compared to DIR (38.5°C, 40.4°C, 41.0°C, 37.4°C, respectively). HR for FOG ([horizontal bar over]X=185 bpm) was also lower (p<.05) than DIR ([horizontal bar over]X=171 bpm). Our findings suggest that use of the FOG attack method reduces heat strain in personnel conducting shipboard firefighting.

Temperature changes during strenous exercise in different body compartments of the horse

In order to evaluate metabolic heat generation and heat dissipation of strenuously exercising horses, thermal response in various body compartments was simultaneously and continuously monitored. Two horses were subjected to a long-term incremental exercise protocol with progressive increase of treadmill speed, slope and draught load. The temperatures were determined in the following structures and cavities using implanted thermocouple probes: middle gluteal, semitendinosus and masseter muscles, right cardiac ventricle, jugular vein, abdomen, rectum and subcutaneous tissue. The kinetics of temperature increases were similar for locomotor muscles, right ventricle (body core), abdomen and subcutaneous tissue. At peak exercise the highest temperatures were measured in locomotor muscle (43.3 degrees C). The blood temperature in the jugular vein was approximate to 1 degrees C below body core temperature at rest and approximate to 3 degrees C below at peak exercise. During and after exercise the rectal temperature never accurately assessed core and compartment temperatures. Maximal rectal temperatures peaked approximate to 1 degrees C below body core temperature with a lag time of 10-15 minutes.

The role of temperature on carbon monoxide production in compartment fires

Abstract The objective of this study was to assess the effect of temperature on carbon monoxide production in compartment fires in order to resolve the difference between global equivalence ratio-yield correlations obtained in simplified upper layer environments and more realistic compartment fires. The chemical reactivity of upper layer gases was studied using a detailed chemical kinetics model. An analysis of the modeling and experimental data in the literature provided insights into the effect of temperature on carbon monoxide production. The effect of changing temperature on compartment fire upper layer composition is twofold: (1) the generation of species in the fire plume is changed; and (2) oxidation of post-flame gases in the layer is affected. Elevated compartment temperatures correlate with increased fire plume temperatures and more complete oxidation of the fuel to CO 2 and H 2 O within the plume. The layer temperature dictates post-flame oxidation in the layer. For most situations, upper layer temperatures below 800K indicate chemically unreactive layers. As such, combustion within the fire plume dictates final CO production in the compartment. Reactions in the upper layer dictate final CO levels when upper layer temperatures are about 900K and higher.