An analytical model to estimate the time delay to reach spontaneous ignition considering heat loss in oil reservoirs

During air injection into an oil reservoir,an oxidation reaction generates some heat to raise the reservoir temperature.When the reservoir temperature reaches an ignition temperature,spontaneous ignition occurs.There is a time delay from the injection to ignition.There are mixed results regarding the feasibility of spontaneous ignition in real-field projects and in laboratory experiments.No analytical model is available in the literature to estimate the oxidation time required to reach spontaneous ignition with heat loss.This paper discusses the feasibility of spontaneous ignition from theoretical points and experimental and field project observations.An analytical model considering heat loss is proposed.Analytical models with and without heat loss investigate the factors that affect spontaneous ignition.Based on the discussion and investigations,we find that it is more difficult for spontaneous ignition to occur in laboratory experiments than in oil reservoirs;spontaneous ignition is strongly affected by the initial reservoir temperature,oil activity,and heat loss;spontaneous ignition is only possible when the initial reservoir temperature is high,the oil oxidation rate is high,and the heat loss is low.

Analysis of the Pipe Heat Loss of the Water Flow Calorimetry System in EAST Neutral Beam Injector

Neutral beam injection heating is one of the main auxiliary heating methods in controllable nuclear fusion research. In the EAST neutral beam injector, a water flow calorimetry （WFC） system is applied to measure the heat load on the electrode system of the ion source and the heat loading components of the beamline. Due to the heat loss in the return water pipe, there are some measuring errors for the current WFC system. In this paper, the errors were measured experimentally and analyzed theoretically, which lay a basis for the exact calculation of beam power deposition distribution and neutralization efficiency.

Analysis on Transmission Heat Loss in Hot Water System of Residential Building

Based on the data of China Statistical Yearbooks, the current situation and development trend of the energy consumption of residential hot-water was discussed in this paper. Two hundred and sixty eight apartments were surveyed on the installation and operation situations of residential water heaters in five cities. Based on survey data, the proportion of pipeline heat loss was calculated in the energy consumption of a shower/bath. The influence factors of heat loss in residential hot-water pipeline network were discussed, and the measures were suggested for reducing the transport heat loss. The statistics and analysis conclusion have directive significance to reducing the transport heat loss.

Influence of heat loss through probe electrical leads on thermal conductivity measurement with TPS method

The transient plane source(TPS)method is developed recently to measure the thermal conductivity of materials.In the measurement,the heating power is influenced by the heat which is transferred via the probe electrical leads.This fact further influences the measurement accuracy of thermal conductivity.To solve this problem,the influence of heat loss through the electrical leads on the heating power is studied theoretically.The mathematical formula of heat loss is deduced,and the corresponding correction model is presented.A series of measurement experiments on different materials have been conducted by using the hot disk thermal constant analyzer.The results show that the influence of the heat loss on the measurement is sensitive to different test materials and probes with different sizes.When the thermal conductivity of the material is greater than 0.2 W/(m·K),the influence of the heat loss is less than 0.16%,which can be ignored.As to the lower thermal conductivity materials,it is necessary to compensate the heat loss through the electrical leads,and the accuracy of thermal conductivity measurement can be effectively improved.

Analytical Model for Predicting the Heat Loss Effect on the Pyrolysis of Biomass Particles

This paper presents the combined influence of heat-loss and radiation on the pyrolysis of biomass particles by considering the structure of one-dimensional, laminar and steady state flame propagation in uniformly premixed wood particles. The assumed flame structure consists of a broad preheat-vaporization zone where the rate of gas-phase chemical reaction is small, a thin reaction zone composed of three regions: gas, tar and char combustion where convection and the vaporization rate of the fuel particles are small, and a broad convection zone. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number is large and the equivalence ratio is larger than unity(i.e.u≥1). The principal attention is made on the determination of a non-linear burning velocity correlation. Consequently, the impacts of radiation, heat loss and particle size as the determining factors on the flame temperature and burning velocity of biomass particles are declared in this research.

Analysis and optimization of heat loss for water-cooled furnace roller

A heat transfer model of furnace roller cooling process was established based on analysis of furnace roller＇s structure. The complicated model was solved with iteration planning algorithm based on Newton search. The model is proved logical and credible by comparing calculated results and measured data. Then, the relationship between water flow velocity, inlet water temperature, furnace temperature and roller cross section temperature, outlet water temperature, water temperature rise, cooling water heat absorption was studied. The conclusions and recommendations are mainly as follows： l） Cooling water temperature rise decreases with the increase of water flow velocity, but it has small relationship with inlet water temperature; 2） In order to get little water scale, inlet water temperature should be controlled below 30 ℃. 3） The cooling water flow velocity should be greater than critical velocity. The critical velocity is 0.07 m/s and water flow velocity should be controlled within 0.4-0.8 m/s. Within this velocity range, water cooling efficiency is high and water temperature rise is little. If cooling water velocity increases again, heat loss will increase, leading to energy wasting.

Numerical and Experimental Evaluation of Shine-Through Loss and Beam Heating Due to Neutral Beam Injection on EAST

This research applies experimental measurements and NUBEAM,ONETWO and TRANSP modules to investigate the shine-through(ST)loss ratio and beam heating percentage of neutral beam injection on EAST.Measurements and simulations confirm that the ST loss ratio increases linearly with beam energy,and decreases exponentially with plasma density.Moreover,using the multi-step fitting method,we present analytical quantitative expressions of ST loss ratio and beam heating percentage,which are valuable for the high parameter long-pulse experiments of EAST.

Mathematical Model Prediction of Heat Losses from a Pilot Sirosmelt Furnace

A mathematical model was developed for simulating heat transfer through the sidewall, bottom and top of a pilot scale TSL （Top-Submerged-Lance） Sirosmelt furnace. With a feed rate of about 50 kg/h, the furnace has been used for investigating the technical feasibility of a variety of pyrometallurgical processes for smelting nonferrous and ferrous metals and for high temperature processing of solid wastes including electronic scraps, etc. The model was based on numerical solution of energy transport equations governing heat conduction in multi-layered linings in the sidewall, bottom and top lid of the furnace as well as convection and radiation of heat from the furnace outer surfaces to the ambient. Imperfect contacts between two neighboring solid lining layers due to air gap formation were considered. Temperature profiles were determined across the furnace bottom, top lid and three sections of the furnace sidewall, from which the heat loss rates through the corresponding parts of the furnace were calculated. The modelling results indicate that approximately 88% of heat is lost from the furnace sidewall, 7-8% from the bottom and 4-5% from the top lid. With increasing melt bath temperature, the proportion of total heat loss from the bottom decreases whereas that from the top lid increases and that from the sidewall is little changed. For a bath temperature of 1,300℃, total absolute heat loss rate from the furnace was found to be close to 12 kW.

Molecular screening of patients with nonsyndromic hearing loss from Nanjing city of China

Hearing loss is the most frequent sensory disorder involving a multitude of factors, and at least 50% of cases are due to genetic etiology. To further characterize the molecular etiology of heating loss in the Chinese population, we recruited a total of 135 unrelated patients with nonsyndromic sensorineural hearing loss （NSHL） for mutational screening of GJB2, GJB3, GJB6, SLC26A4, SLC26A5 IVS2-2A〉G and mitochondrial 12SrRNA, tRNASer（t/CN） by PCR amplification and direct DNA sequencing. The carrier frequencies of deafness-causing mutations in these patients were 35.55% in GJB2, 3.70% in GJB6, 15.56% in SLC26A4 and 8.14% in mitochondrial 12SrRNA, respectively. The results indicate the necessity of genetic screening for mutations of these causative genes in Chinese population with nonsyndromic heating loss.

Heat calculation and numerical simulation in steam mining of permafrost gas hydrate

Steam mining method was injecting hot steam into the borehole to heat the hydrate strata at the same time of depressurization mining,which could promote further decomposition and expand mining areas of gas hydrate. Steam heat calculation would provide the basis for the design of heating device and the choice of the field test parameters. There were piping heat loss in the process of mining. The heat transfer of steam flowing in the pipe was steady,so the heat loss could be obtained easily by formula calculation. The power of stratum heating should be determined by numerical simulation for the process of heating was dynamic and the equations were usually nonlinear. The selected mining conditions were 500-millimeter mining radius,10 centigrade mining temperature and 180 centigrade steam temperature. Heat loss and best heating power,obtained by formula calculation and numerical simulation,were 21. 35 W/m and 20 kW.

Thermal Loss Analysis of a Flat Plate Solar Collector Using Numerical Simulation

In this paper,we studied theoretically and numerically heated losses of a flat solar collector to model the solar water heating system for the Kazakhstan climate condition.For different climatic zones with a growing cost for energy or lack of central heating systems,promising is to find ways to improve the energy efficiency of the solar system.The mathematical model(based on ordinary differential equation)simulated the solar system work process under different conditions.To bridge the modeling and real values results,we studied the important physical parameters such as loss coefficient,Nu,Ra,and Pr values.They impacted the efficiency of flat solar collectors and heat losses of the system.The developed mathematical models,the design and composition of the software and hardware complex,and automated control and monitoring systems allow solar hot water heating systems to increase the energy efficiency of life support systems and heat supply of buildings by reducing energy consumption for heat supply.The simulation result showed that during the daytime,the temperature of water in the collector is 70°C;the storage of heated water since heated water is cooled at night.We defined that a work period of the system can be extended with high efficiency(April-October)for Almaty region.

Influence of the position relationship between gas–liquid interface and laser focus on plasma evolution characteristics in jet LIBS technology

In order to understand the characteristics of breakdown process,plasma evolution and spectral emission in liquid jets laser-induced breakdown spectroscopy methods under the influence of the position variation between laser focus and gas–liquid interface,this work takes the plasma generated by laser-induced liquid jets as the object of study and discusses the changes in the spatial and temporal evolution characteristics and spectral radiation of the plasma when the position parameters between the laser focal point and the gas–liquid interface are different.The initial breakdown position is always between the front interface and the focus when the laser focus moves along the vertical direction of the interface,forming a phenomenon like’interface effect’.The relationship between laser pulse energy and breakdown probability exhibits a law similar to a‘hysteresis curve’in the study of breakdown threshold.In this work,plasma with smaller size,rounder shape,stronger radiation,higher temperature,and higher density can be produced when the focus position is in the liquid column 0.2 mm away from the front interface.Simultaneously,the spectral signal intensity and signal-to-back ratio of the characteristic peaks of target elements in water reach maximum values,and the spectral signal becomes more stable(relative standard deviation value reaches 2%).The Ca element’s ion radiation at 393.366 nm and atomic radiation at 422.673 nm are studied using narrow-band filtering imaging and time-space resolution spectroscopy.The findings demonstrate that the laws of ion and atomic radiation are not perfectly consistent in space and time.

Evaluation of Heat and Current Characteristics of Bypass Diodes for Fault Detection in Photovoltaic Module

In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.

Structure and stability of non-adiabatic reverse smolder waves

The structure and stability of non-adiabatic reverse smolder waves are investigated numerically. First, the 1D steady-state responses of reverse smolder waves in the presence of convective heat losses are studied with the rate of incoming air flow as the control parameter. Based on the 1D steady solutions, the linear stability and the Lewis number effects on the stability are examined by a numerical normal mode analysis. Finally, the dynamical evolution processes of unstable reverse smolder waves are studied by direct numerical simulations. It is shown that, in comparison with the adiabatic case, the presence of heat losses leads to a backward shift of the extinction limit. For varying Lewis numbers, the extinction limit shifts forward with the increase of the Lewis number while the smolder temperature remains unchanged. Furthermore, results of a linear stability analysis show that the maximum growth rate decreases with the increasing Lewis number, implying that increasing the Lewis number tends to weaken the thermal-diffusive instability of non-adiabatic reverse smolder waves. Direct numerical simulation results show that, on the fuel-rich branch, the unstable plane reverse smolder wave gradually develops to a regular steady fingering pattern, whereas on the fuel-lean branch, similar to the adiabatic case, vigorous fragmentation instability occurs, and is accompanied by a substantial local temperature rise, which may be sufficiently high to trigger the transition to flaming combustion.

Technological,environmental and biological factors:referent variance values for infrared imaging of the bovine

Background： Despite its variety of potential applications, the wide implementation of infrared technology in cattle production faces technical, environmental and biological challenges similar to other indicators of metabolic state. Nine trials, divided into three classes （technological, environmental and biological factors） were conducted to illustrate the influence of these factors on body surface temperature assessed through infrared imaging. Results： Evaluation of technological factors indicated the following： measurements of body temperatures were strongly repeatable when taken within ]0 s; appropriateness of differing infrared camera technologies was influenced by distance to the target; and results were consistent when analysis of thermographs was compared between judges. Evaluation of environmental factors illustrated that wind and debris caused decreases in body surface temperatures without affecting metabolic rate; additionally, body surface temperature increased due to sunlight but returned to baseline values within minutes of shade exposure. Examination/investigation/exploration of animal factors demonstrated that exercise caused an increase in body surface temperature and metabolic rate. Administration of sedative and anti-sedative caused changes on body surface temperature and metabolic rate, and during late pregnancy a foetal thermal imprint was visible through abdominal infrared imaging. Conclusion： The above factors should be considered in order to standardize operational procedures for taking thermographs, thereby optimizing the use of such technology in cattle operations.

Study on the Pyrolysis Behavior of Polycarbosilane

The pyrolysis behavior of polycarbosilane （PCS） and chemical reaction mechanism during the pyrolysis process were studied by thermogravimetric-mass spectrometry （TG-MS） combined with X-ray diffraction and infrared spectroscopic analysis methods. The experimental results indicate that the main gas phase products generated during pyrolysis of PCS in nitrogen atmosphere include H2, -CH3 and CH4. The heating rate has a large effect on the pyrolysis process of PCS, the lower heating rate releases more small molecule gases and gets bigger rate of pyrolysis mass loss, demonstrating that the lower heating rate is beneficial to fully pyrolysis of PCS and obtain ceramics products with better microstructure.

Effects of wall thickness and material on flame stability in a planar micro-combustor

Flame is prone to lose its stability in micro-combustors due to the large amount of heat loss from the external walls. On the other hand, heat recirculation through the upstream combustor walls can enhance flame stability. These two aspects depend on the structural heat transfer, which is associated with the thickness and thermal conductivity of the combustor walls. In the present study, the effects of wall thickness and material on flame stability were numerically investigated by selecting two thicknesses (δ=0.2 and 0.4 mm) and two materials (quartz and SiC). The results show that when δ=0.2 mm, flame inclination occurs at a certain inlet velocity in both combustors, but it happens later in SiC combustor. For δ=0.4 mm, flame inclination still occurs in quartz combustor from a larger inlet velocity compared to the case of δ=0.2 mm. However, flame inclination in SiC combustor with δ=0.4 mm does not happen and it has a much larger blowout limit. Analysis reveals that a thicker wall can enhance heat recirculation and reduce heat loss simultaneously. Moreover, SiC combustor has larger heat recirculation ratio and smaller heat loss ratio. In summary, the micro-combustor with thicker and more conductive walls can harvest large flame stability limit.

Modeling of Rotary Kiln in Cement Industry

Cement production is a highly energy-intensive process, and the rotary kiln is the most important part of the process. Having a comprehensive model of the kiln in order to reduce manufacturing costs, better performance can be created. In this paper, the influence processes in a simulated cement rotary kiln and operating parameters on the output of the study were to develop and validate the systems using the same batch. The followings were examined: solid phase, gas and coating temperature change in a rotary kiln.

Conceptual Design of 25-Barrel Pellet Injector with Cycle Refrigerator for HL-2A Tokamak

The preliminary design of a multi-barrels pellet injector with cycle refrigerator as an advanced plasma-fuelling tool for HL-2A tokamak has been proposed. The design aims at precise temperature control, easy operation with high reliability and high flexibility. GM-cycle refrigerator and pipe-gun structure have been employed to produce 25 pellets in 25 gun barrels simultaneously and the design aims. have been accomplished. Prime design principle, engineering parameters, structure and layout of the cryostat components as well as calculation of heat load for the cryostat are presented.

Measurements of Static Heat Loss and Unloaded Q_0 on the BEPCⅡ SRF Cavities

The static heat loss and unloaded Q_0 are the most important values for both the cryogenic and the RF systems.The BEPCⅡ SRF cavity operates in a liquid helium bath contained in a vacuum insulated,liquid nitrogen cooled radiation shielded vessel.During the horizontal test at the test station,thermodynamic method is used to measure and calculate the static loss and Q_0 value of the SRF cavity.This paper has briefly introduced the method and process to measure the static loss and Q_0 value of the SRF cavity.The results under different experimental conditions are presented as important data for acceptance test of the SRF cavity.