Compartment Temperatures Research Articles

Large-scale fire experiments in a cross-laminated timber compartment with an adjacent corridor – Partly and fully protected with a water sprinkler system

Two fire experiments have been conducted to study sprinkler system extinguishing performance in a compartment (13 m2) with an adjacent corridor (12 m2), both with exposed cross-laminated timber (CLT). Four nozzles were installed in the corridor and two in the compartment. In Experiment 1, the sprinkler system was fully functional and successfully controlled a concealed fire. In Experiment 2, nozzles in the compartment were disconnected, while the corridor nozzles were operative, giving flashover after 5 min with large flames emerging into the corridor, rapidly worsening evacuation conditions. Despite four activated nozzles in the corridor, the temperatures remained high, and flames spread through the corridor along the CLT ceiling and the upper parts of the wall, an area that was not effectively protected by the nozzles. After flashover, the compartment temperatures remained stable at ∼1000 °C until experiment termination at 96 min. This continued fire in the compartment can be explained by water from the corridor sprinklers not reaching this area, extensive radiative feedback by the CLT surfaces and delamination of CLT elements of the 20 mm layers. The charring rate was ≥1.1 mm/min for large parts of the exposed CLT wall and ceiling in the compartment during the fire.

Exploring Overpressure Events in Compartment Fires

For more than a century, smoke explosions have been documented in the fire research literature. Yet even with this long history, smoke explosions have received very little attention in the fire research community. The few review articles on unexplained explosions (overpressure events) have adopted the conventional names of smoke explosions, backdraft, smoke gas explosions or rapid fire progression. Anecdotal evidence from firefighters have shown a number of overpressure events that cannot be explained as a gas leak or flammable liquids ignition. In this study, experiments were conducted in a plywood lined compartment with a timber crib as a sustained fire source and the ignition source. The compartment had a single vent that was open for the entire time. After an extended period of burning, the flames detached from the crib, traveled around the compartment, and finally self-extinguished. Sometime after the flames self-extinguished, the compartment erupted in flames culminating in a large horizontal flame projecting more than 2 m from the vent opening. In this study, a consistent cycle that leads to an overpressure event has been identified. A total of 29 overpressure events were created in 13 experiments with many experiments experiencing multiple overpressure events. Gas species, compartment temperatures, vent velocities, and compartment pressure were all recorded during the experiments. Conditions in the compartment immediately prior to the overpressure event are reported. Having demonstrated that an overpressure event within a combustible compartment can be reproduced, future research is recommended to better quantify the conditions leading to an overpressure event.

A computational method to study heat transfer in a helicopter turboshaft engine compartment for waste energy recovery purposes

It is important to take action to make aviation more energy-efficient and less pollutant. One of the approaches currently under development is waste energy recovery. This would be specially advantageous in turboshaft engines, which present an exhaust flow that is not being used for propulsive purposes and with high thermal residual energy that increases infrared signature of helicopters.To evaluate where to locate waste energy recovery devices such as thermoelectric generators or organic Rankine cycles the following is needed: temperatures of exhaust gas flow temperature and exhaust ducts wall temperature, i.e. hot source temperature, and engine compartment temperature, i.e. heat sink temperature. This variables are usually not known beforehand. The present paper develops a method that, with minimal data input, translates flight conditions and engine operation into conditions inside the engine compartment that are later applied to obtain heat transfer in the exhaust ducts, where the waste energy recovery should take place to minimize the influence on the engine. The procedure is based on an algorithm that uses Computational Fluid Dynamics (CFD) simulations validated with experiments.The main findings of this work are: (i) cruise flight velocity has minimal impact on engine compartment temperatures, but hover operation increases it by 5–16 K, (ii) cruise altitude significantly affects engine compartment temperature, with a 12 K difference between 2500 ft and 10000 ft, (iii) considering only the axial component of velocity in exhaust ducts may underestimate wall temperature, (iv) heat transfer in exhaust ducts can be estimated using empirical correlations for natural convection, multiplied by a specific factor, (v) non-invasive methods can recover 23.6 to 31.2 kW of heat from exhaust duct walls, potentially converting up to half of it into useful work.

Stress Response and Safe Driving Time of Bus Drivers in Hot Weather.

Purpose: To evaluate the impact of high-temperature environments on bus drivers’ physiology and reaction times, and to provide a basis for driver occupational health management. Methods: The physiological and reaction indexes of 24 bus drivers under different temperatures were investigated. The statistical analysis method was used to analyze the changes in drivers’ physiological stress, the relationship between stress and response ability, and a safe driving time. The Kaplan–Meier survival function was used to analyze the survival rate of bus drivers under different temperatures and driving times. Results: The results showed that body temperature, heart rate, physiological strain index (PSI), and reaction ability were significantly different among different compartment temperatures. PSI was positively correlated with reaction ability. The safe driving time was 80 min, 73 min, and 53 min, respectively, at 32 °C, 36 °C, and 40 °C. The survival rate decreased to less than 60% at 36 °C when driving continuously for 73 min; it decreased to 20% at 40 °C when driving for 53 min, and it was 0 for 75 min. Conclusions: High-temperature environments lead to heat stress of bus drivers, physiological indexes have changed significantly, and behavioral ability is also decreased. The higher the temperature, the lower the survival rate. Improvement measures can be taken from the aspects of convection, conduction, and behavior to ensure the bus driver’s physiological health and driving safety under high temperatures and to improve the survival rate.

Heat transfer rates in hot shell, cold tube inclined baffled small shell, and tube heat exchanger using CFD and experimental approach

The work presented is an effort to realize the changes occurring for convective coefficients of heat transfer in STHX fitted with inclined baffles. Effort has been undertaken using Fluent, a commercially available CFD code ona CAD model of small STHX with inclined baffles with cold liquid flowing into the tubes and hot liquid flowing in the shell. Four sets of CFD analysis have been carried out. The hot liquid flow rate through shell compartments varied from 0.2 kg/sec to 0.8 kg/sec in steps of 0.2 kg/sec, while keeping the cold liquid flow condition in tube at 0.4 kg/sec constant. Heat transfer rates, compartment temperatures, and overall heat transfer coefficients, for cold liquid and hot liquid, were studied. The results given by the software using CFD approach were appreciable and comparatively in agreement with the results available by the experimental work, which was undertaken for the same set of inlet pressure conditions, liquid flow rates, and inlet temperatures of liquid for both hot and cold liquids. The experimental output results were also used to validate the results given by the CFD software. The results from the CFD analysis were further used to conclude the effect of baffle inclination on heat duty. The process thus followed also helped realize the effects of baffle inclination on convective heat transfer coefficient of the liquid flow through the shell in an inclined baffle shell and tube heat exchanger. The temperature plots for both cold and hot liquid were also generated for understanding the compartmental temperature distributions inclusive of the inlet and outlet compartments. The heat duty for a heat exchanger has been found to increase with the increase in baffle inclinations from zero degree to 20 degrees. Likewise, the convective heat transfer coefficients have also been found to increase with the increase in baffle inclinations.

Wall and Corner Effects on Fire Plumes as a Function of Offset Distance

A series of compartment fire experiments is described in which a square natural gas burner was positioned in a corner or against a wall and gradually moved towards the room center to assess the relative effects on the plume and compartment temperatures. The experiments were conducted to validate computational fluid dynamics simulations that were performed to provide guidance for probabilistic risk assessments in nuclear power plants. The measurements consist of one dimensional vertical thermocouple arrays to measure the hot gas layer temperature and height, and a three dimensional thermocouple array to measure the temperature of the fire plume as the burner is moved away from the corner or wall. As a result of the modeling and experiments, recommendations have been made that quantify wall and corner effects as a function of offset distance.

Cooling Performance Analysis of the Lab-Scale Hybrid Oyster Refrigeration System

Compared with the waste-to-heat and electricity-based hybrid refrigeration system, the innovative lab-scale refrigeration system integrated with the DC and AC cooling units that able to use solar and electricity as energy resources. Previous studies found that temperature control and uniform temperature distribution in refrigeration systems are both critical factors reducing vibrio growth on raw oysters and saving energy consumption. Therefore, this refrigeration system also equipped a specially designed divider and was used to test various air circulation strategies to achieve uniform temperature distribution in six individual compartments. The objective is to investigate and evaluate the effects of air circulation strategies and operating conditions on the cooling performance, including temperature distribution, standard deviation of compartment temperatures, and cooling time using a factorial design method. Results indicated the maximum temperature difference between the compartments was 8.9 ± 2.0 °C, 6.7 ± 2.0 °C, and 4.8 ± 2.0 °C in the scenarios of no air circulation, natural air circulation, and combined natural and forced air circulation, respectively. The interaction of fan location and fan direction showed a significant effect on the compartment temperatures while there was no significant effect on cooling time. A circulation fan on the lower part of the 12-volt section with an air supply from the 12- to 110-volt section was determined as the optimal condition to achieve relatively uniform temperature distribution. Refrigeration system also achieved a cooling temperature of 7.2 °C within 150 min to meet regulations. To that end, the innovative hybrid oyster refrigeration system will benefit oyster industries, as well as the aquaculture farmers in terms of complying with regulations and energy savings.

Cabin temperature during prehospital patient transport \u2013 a prospective observational study

BackgroundFew studies have investigated the patient compartment temperatures during ambulance missions or its relation to admission hypothermia. Still hypothermia is a known risk factor for increased mortality and morbidity in both trauma and disease. This has special relevance to our sub-arctic region’s pre-hospital services, and we prospectively studied the environmental temperature in the patient transport compartment in both ground and air ambulances.MethodsWe recorded cabin temperature during patient transport in two ground ambulances and one ambulance helicopter in the catchment area of the University Hospital of North Norway using automatic temperature loggers. The data were collected for one month in each of the four seasons. We calculated the sum of degrees Celsius below 18 min by minute to describe the patient exposure to unfavourably low cabin temperature, and present the data as box plots. The statistical differences between transport mode and season were analysed with ANCOVA.ResultsThe recorded cabin temperatures were higher during the summer than the other three seasons. However, we also found that helicopter transports were performed at lower cabin temperatures and with significantly more exposure to unfavourably low temperatures than the ground ambulance transports. Furthermore, the helicopter cabin reached the final temperature much slower than the ground ambulance cabins did or remained at a lower than comfortable temperature.ConclusionsHelicopter cabin temperature during ambulance missions should be monitored closer, particularly for patients at risk for developing admission hypothermia.

Compartment temperature estimation of a multiple-layer cable tray fire with different cable arrangements in a closed compartment

Fire hazard analysis of multiple-layer cable tray is an important part of nuclear safety analysis. Large-scale cable fire experiments with a three-layer horizontal cable tray were conducted in a closed compartment. The vertical temperature profile in the middle of the room was acquired. Distinctive stratification phenomena were found in the vertical temperature distribution. The interface between the upper and lower layer was located at approximately the height of the top cable layer. Heat transfer between the smoke and compartment walls occurred mainly above the smoke interface. A modified non-steady energy balance model in a closed compartment which included the effect of smoke interface height was used to estimate the compartment temperatures. Compared with the experimental results, the modified model for the multiple-layer cable tray fire in a closed compartment provides better estimation than the original model.

Transport phenomena of fire-induced smoke flow in a semi-open vertical shaft

PurposeThe purpose of this study is to investigate the transport phenomena of smoke flow in a semi-open vertical shaft.Design/methodology/approachThe large eddy simulation (LES) method was used to model the movement of fire-induced thermal flow in a full-scale vertical shaft. With this model, different fire locations and heat release rates (HRRs) were considered simultaneously.FindingsIt was determined that the burning intensity of the fire is enhanced when the fire attaches to the sidewall, resulting in a larger continuous flame region in the compartment and higher temperatures of the spill plume in the shaft compared to a center fire. In the initial stage of the fire with a small HRR, the buoyancy-driven spill plumes incline toward the side of the shaft opposite the window. Meanwhile, the thermal plumes are also directed away from the center of the shaft by the entrained airflow, but the inclination diminishes as HRR increases. This is because a greater HRR produces higher temperatures, resulting in a stronger buoyancy to drive smoke movement evenly in the shaft. In addition, a dimensionless equation was proposed to predict the rise-time of the smoke plume front in the shaft.Research limitations/implicationsThe results need to be verified with experiments.Practical implicationsThe results could be applied for design and assessment of semi-open shafts.Originality/valueThis study shows the transport phenomena of smoke flow in a vertical shaft with one open side.

Effects of exposed cross laminated timber on compartment fire dynamics

A series of compartment fire experiments has been undertaken to evaluate the impact of combustible cross laminated timber linings on the compartment fire behaviour. Compartment heat release rates and temperatures are reported for three configuration of exposed timber surfaces. Auto-extinction of the compartment was observed in one case but this was not observed when the experiment was repeated under identical condition. This highlights the strong interaction between the exposed combustible material and the resulting fire dynamics. For large areas of exposed timber linings heat transfer within the compartment dominates and prevents auto-extinction. A framework is presented based on the relative durations of the thermal penetration time of a timber layer and compartment fire duration to account for the observed differences in fire dynamics. This analysis shows that fall-off of the charred timber layers is a key contributor to whether auto-extinction can be achieved.

Evaluation of Conditions during Weaned Pig Transport

Abstract.Transport of weaned pigs poses special challenges because of their size and thermal needs as well as the extended distances and transport times. The resultant economic impact can be substantial. Compared to transport of market pigs, weaned pigs generally encounter much farther travel distances with different adapting abilities to the environmental conditions. The objectives of this study were: 1) to characterize the environmental conditions within a typical transport trailer for weaned piglets to determine if current management practices and trailer design provides an acceptable environment as evidenced by mortality rates and environmental parameters, and 2) to analyze airflow patterns of the tranport trailer using a scale model in a wind tunnel. Data from 78 usable transport trips were collected for air temperature in each trailer compartment, ambient temperature,distance traveled, time traveled, stocking density, and mortality by compartment. The 78 trips had an average distance of 778 km (range of 264 to 1016 km), travel time of 8.51 h (range of 3.4 to 12.3 h), and mortality rate of 0.031% (range of 0 to 1.11%). There was no significant difference in mortality by compartment (p>0.05). The results indicate that if pigs are transported at a higher stocking density, the compartment temperatures would be similar during cold weather (e.g., 2°C). Under mild weather condition (e.g., 16°C), significant differences could exist in compartment temperature between part of the upper deck (Upper 1) and the lower deck (Lower 4) (p<0.05). In comparison, no significant differences were found at warm conditions (e.g., 29°C) (p>0.05). In addition to the weather influence, in-trailer environment is affected by the side openings which may be adjusted by the driver. Keywords: Click here to enter keywords and key phrases, separated by commas, with a period at the end

Temperature, relative humidity, and dew point of 6 commercial trailer compartments during summer transportations of beef calves in the mid-South

ABSTRACT Improving animal welfare during transit may reduce morbidity and improve subsequent animal health. The objective of this study was to determine whether temperature, relative humidity, dew point, and temperature–relative humidity index differed among 4 compartments of a commercial trailer while transporting beef calves during the summer within the mid-South region. A temperature–relative humidity data logger was fastened to the ceiling of each trailer compartment during June and July for 12 loads of cattle (BW = 344.5 ± 96.60 kg, mean ± SD) transported 542.9 ± 408.38 km. Compartment temperatures averaged 31.6 ± 0.79°C and did not differ (P > 0.10). Relative humidity in the belly (64.1 ± 2.74%), tail (62.5 ± 2.74%), and bottom nose (62.1 ± 2.74%) were not different (P > 0.10), and all were greater than the top deck (58.5 ± 2.74%; P 0.10); however, they differed from the dew point in the tail compartment (23.4 ± 0.59°C; P 0.10) and averaged 82.1 ± 0.89. The percentage of time temperature–relative humidity index was in the danger and emergency categories was 93.9, 86.6, 84.2 and 68.3 ± 0.04% for the bottom nose, top deck, belly, and tail compartments, respectively (P

Time-dependent smoke yield and mass loss of pool fires in a reduced-scale mechanically ventilated compartment

Technical and pure grades of the combustibles heptane and dodecane were used in a series of small-scale fire tests conducted in a 1m3 compartment that was mechanically ventilated at 5 and 8 air changes per hour (ACH). Combustible mass loss rates, soot mass concentrations, soot size distributions, several gas species concentrations, and compartment temperatures were measured during the fire. Results for the two pure-grade hydrocarbons were compared with results obtained for their respective technical grades. Technical-grade dodecane produced the highest soot emissions; pure n-heptane produced the lowest. Soot size distributions of all four combustibles attained a steady profile whose modal diameter was about 200nm. Underventilated fires showed higher carbon monoxide yields than soot yields. Both compartment ventilation rates produced similar results, although the fire self-extinguished earlier for 5ACH.

인텔리전트빌딩 단위가연물의 구획화재실험을 통한 화재특성 연구

In this study, real fire tests have been performed for the fire behavior and temperature analysis of the compartment. The size of Mock-up experiments were 3 m length, 3.2 m wide, 2.5 m height m. The BFD curve method of C.R. Barnett is adopted to study a empirical model for fire compartment temperatures. The fire load was with office combustible supplies including access floors. The temperatures in the Mock-up compartment were measured using two different locations of thermocouple trees. These conclusions and experiment data obtained in this paper could be helpful in reference for the fire simulation, fire hazard assessment and fire protection design (including PBD). Based on experimental data, BFD curve and mathematical models need to be discussed to predict temperature curve in flashover and fire spread in the compartment. Also, this empirical model study needs more test to verify and optimize.

Transient simulation of a two-door frost-free refrigerator subjected to periodic door opening and evaporator frosting

Abstract This paper describes a quasi-steady-state simulation model for predicting the transient behavior of a two-door household refrigerator subjected to periodic door opening and evaporator frosting. A semi-empirical steady-state model was developed for the refrigeration loop, whereas a transient model was devised to predict the energy and mass transfer into and within the refrigerated compartments, and also the frost build-up on the evaporator. The key empirical heat and mass transfer parameters required by the model were derived from a set of experiments performed in-house in a climate-controlled chamber. In general, it was found that the model predictions followed closely the experimental trends for the power consumption (deviations within ±10%) and for the compartment temperatures (deviations within ±2 K) when the doors are opened periodically and frost is allowed to accumulate over the evaporator.

Temperature influencing permeation pattern of alfuzosin: An investigation using DoE

Background and objectiveThere has been relatively little investigation of the effect of temperature on skin permeation compared to other methods of penetration enhancement. A principal physicochemical factor which controls the passive diffusion of a solute from a vehicle into the skin arises from the skin temperature. The aim of this ex vivo study was to probe into the effect of heat on transdermal absorption of alfuzosin hydrochloride from ethyl cellulose-polyvinyl pyrrolidone (EC-PVP) based transdermal systems. Materials and methodsPrinciples of design of experiment (DoE) were used to systematically study the influence of temperature on transdermal permeation of alfuzosin. Ex vivo transdermal permeation studies were carried out at varied donor compartment temperatures. Permeation data analysis was carried out and activation energy for transdermal permeation was estimated. ResultsTemperature found to enhance ex vivo permeation parameters of alfuzosin hydrochloride from its transdermal systems. It was also noted that chemical permeation enhancers potentiate permeation enhancing effect of temperature. The permeation flux values approximately doubled after exposure to 45°C. The activation energy for transdermal permeation was found lower for the runs with chemical permeation enhancers indicating existence of a lower energy barrier in the presence of chemical permeation enhancers. ConclusionThe method reported here is a simple and useful tool for studying the effect of heat on percutaneous absorption. Such temperature dependent enhancement of flux can be more pronounced at skin surface temperatures >45°C.

Effects of fire-fighting on a fully developed compartment fire: Temperatures and emissions

This study evaluates the effects and consequences of fire-fighting operations on the main characteristics of a fully-developed compartment fire. It also presents data and evaluation of the conditions to which fire-fighters are exposed. A typical room enclosure was used with ventilation through a corridor to the front access door. The fire load was wooden pallets. Flashover was reached and the fire became fully developed before the involvement of the fire-fighting team. The progression of the fire-fighters through the corridor and the main-room suppression attack – in particular the effect of short, medium and long water pulses on either the hot gas layer or the fire seat – was charted against the compartment temperatures, heat release rates, oxygen levels and toxic species concentrations. The fire fighting team was exposed to extreme conditions, heat fluxes in excess of 35kW/m2 and temperatures of the order of 250°C even at crouching level. The fire equivalence ratio showed rich burning with high toxic emissions in particular of CO and unburnt hydrocarbons very early in the fire history and a stabilisation of the equivalence ratio at about 1.8. The fire fighting operations made the combustion temporarily richer and the emissions even higher.

Compartment fire temperature – a new simple calculation method

In this paper a new simple calculation method for compartment temperatures is derived. The method is applicable to post-flashover ventilation controlled fires. A parameter termed the ultimate compartment fire temperature is defined as the temperature obtained when thermal equilibrium is reached and thick compartment boundaries cannot absorb any more heat from the fire gases. This temperature depends only on the product of the heat of combustion and the combustion efficiency over the specific heat capacity of air. It is, however, independent of the air mass flow rate, and of the fire compartment geometry and the thermal properties of the compartment boundary materials. These parameters on the other hand govern the rate at which the fire temperature is increasing towards the ultimate temperature. It is shown how the fire temperature development as a function of time in some idealized cases may be calculated by a simple analytical closed form formula.The fire temperature developments of two types of compartment boundaries are presented, semi-infinitely thick and thin structures. It is also shown that for the semi-infinite case, the solution resembles the standard ISO 834/EN 1363-1 curve and the parametric fire curves according to Eurocode 1, EN 1991-1-2.

Theoretical modelling and experimental investigation of a thermal energy storage refrigerator

Numerical simulations using the computational fluid dynamics (CFD) software ANSYS Fluent were undertaken to characterize the airflow and temperature distribution in a natural convection thermal energy storage refrigerator. The model compared the household refrigerator temperature stability with different phase change materials (PCM) incorporated into the storage compartment. Scenarios investigated included the PCM orientation (vertical or horizontal), PCM temperature (use of water or eutectics) and compartment designs (conventional or drawer type appliance). The results suggested that a horizontal PCM configuration produces lower compartment temperatures than a vertical configuration. The temperature distribution with a horizontal PCM was tested experimentally and the results were in agreement with the CFD predictions. Both the simulation and the experimental results suggest that a eutectic with a phase change temperature below 0 °C must be employed to maintain the compartment temperature within acceptable limits. The model indicated that combining horizontal and vertical PCMs in a full height compartment or dividing the same compartment into two drawers with a horizontal PCM configuration for each drawer are feasible design options for the household thermal storage refrigerator.