Rate Of Temperature Reduction Research Articles

Performance analysis of a nitrogen-based Brayton cryocooler prototype

When very low temperatures are needed for industrial applications, reverse Brayton cryocoolers can be adopted. This paper reports the results of an energy analysis in which the performance of a Brayton cryocooler prototype was studied. The prototype is innovative in both the cycle configuration and the pressure and temperature levels. Moreover, nitrogen, an eco-friendly gas that is safe for people, was used as the working fluid.Simultaneous measurements of the pressure and temperature at the inlet and outlet of the main thermodynamic cycle components, nitrogen flow rate, and power consumption were taken during the experimental tests. The prototype was tested at design operating conditions (maximum and minimum pressure of 18.5 and 8 bar respectively, and minimum temperature of −120 °C), obtaining a cooling effect of 15.6 kW, a temperature reduction rate at the turbine outlet of 8 °C min−1, and a coefficient of performance of 0.29, which rises to 1.34 when including the waste heat (about 55 kW) that can be recovered at low temperatures (<100 °C). Also, a sensitivity analysis was carried out by testing the prototype at different maximum pressure and minimum temperature levels. The higher the maximum pressure, the higher the prototype performance is, and a minimum temperature of about −140 °C was reached. Our findings demonstrated that the tested prototype shows great promise for several industrial applications where low temperatures are required.

Analysis of the Heat Transfer Design and Thermal Management Performance for Battery Modules Combined with Liquid‐ and Forced‐Air‐Cooling Methods

Liquid‐cooling techniques are commonly employed for battery thermal management (BTM) in commercial vehicles and energy storage applications, typically incorporating a cooling plate positioned beneath the casing of the battery pack. However, this heat transfer structural design results in smaller temperature drop in the terminal batteries located distantly from the plate, leading to an increased temperature difference. The integration of supplementary media into BTM systems holds the potential to enhance thermal management performance, thereby offering a viable solution to this issue. Herein, a fan is incorporated into the liquid‐cooling system to induce air circulation and augment convective heat transfer onto the battery surface. In the findings, it is revealed that the implementation of a reverse airflow path beneath the cooling plate result in a temperature decreasing rate of 0.59 K min−1, indicating a notable enhancement of 23% compared to solely employing a liquid‐cooling configuration. In the results, it is demonstrated that 1) reducing the inlet temperature can effectively enhance the rate of temperature reduction and 2) increasing the fan speed can reduce the temperature difference and promote temperature uniformity. In conclusion, in this present study, comprehensive guidelines and references are provided for the future design of BTM.

1G and microgravity tank self-pressurization: Research on cryogenic fluid thermal stratification

A correlation numerical model was constructed, and relevant experiments were simulated to investigate the influence of gravity level on the self-pressurization process of the cryogenic fluid of liquid nitrogen. The calculated results agreed well with the experimental data. On this basis, the influences of a normal gravity environment and a microgravity environment on the self-pressurization process of liquid nitrogen in the normal-temperature fluid Perfluoro-n-Pentane (PnP, or C5F12) tank of National Aeronautics and Space Administration (NASA) were analyzed. According to the calculation results, an explicit horizontal interface is formed between the gas and liquid phases in the tank during the 1G (G = 9.81 m/s2) self-pressurization process. The ullage pressure increases as time progresses, and obvious thermal stratification phenomena are observed in the ullage along the axial and radial directions. However, the thermal stratification of the liquid zone is not obvious. The ullage near the gas‒liquid interface shifts from counterclockwise movement to clockwise movement, while the liquid changes from clockwise movement to counterclockwise movement. In the process of microgravity self-pressurization, the gas‒liquid interface in the tank presents an irregular shape, and the ullage pressure increases continuously before 400 s and then tends to be stable. The axial thermal stratification of fluid in the tank tends to disappear as time progresses, but obvious radial thermal stratification is observed. The ullage in the tank moves up and down as a response to the Marangoni migration effect. The temperature of the liquid zone in the tank during 1G self-pressurization tends to be consistent more quickly than that during microgravity self-pressurization, and the average temperature is higher. However, the temperature reduction rate of the ullage in the tank during microgravity self-pressurization is higher than that during 1G self-pressurization. Numerical simulation results can provide references to further study the on-orbit pressure control technique of cryogenic liquid tanks.

Analysis of combustion characteristics of wood stack and absolute ethanol in fire extinguishing experiment

For the purpose of researching the rules of combustion heat release, ammonium phosphate dry powder extinguishing agent and water-based fire extinguishing agent were utilized before and after the class A fire common wood stack ignition fuel and class B fire anhydrous ethanol ignition fuel fire extinguishing. For wood stack fire, 0.5A wood stack was used for blank combustion test, and the pan fire ignition method for the same type and scale of wood stack fire extinguishing experiment. For absolute ethanol fire, fire suppression was studied using a 13B scale. The change characteristics of the combustion field before and after action of the dry powder extinguishing agent and water system extinguishing agent were measured by thermocouple, heat flow meter and digital camera. The findings of the experiment demonstrated that in the combustion experiment of wood stack, the temperature of 0.5A wood stack of the blank group could reach 800 °C, and the temperature reduction rate of free combustion was 2.62 °C/s. It took an average of 36.5s and 2.25 kg of ammonium phosphate dry powder to put out the fire，and the temperature reduction rate was 4.18 °C/s. The average amount of water-based extinguishing agent used to extinguish a fire was 1.21 kg, yet the average time to do so was just 12.5 s, and the average rate of temperature drop was 10.14 °C/s. In the experiment where an ethanol pool fire was being burned, the typical amount of water-based fire extinguishing chemical used was 3.44 kg, and the typical extinguishing time was 18 s, the maximum temperature drop rate could reach 35.6 °C/s in the initial stage of fire extinguishing, despite the fact that the dry powder fire extinguisher containing ammonium phosphate was used, the fire was not properly controlled.

Microconvection of MHD solarized nanofluid in the presence of double slip and surface suction

Refrigeration systems are becoming more efficient as a result of nanofluids. Cooling and heating process improvements can lead to enhanced industrial efficiency, reduced processing times, energy conservation, and improved heating and cooling processes. A study is being conducted on the effects of magnetohydrodynamics (MHD) in nanofluids by adding double slip and thermal radiation to the governing model. It is numerically simulated using bvp4c code in MATLAB. Analyzing temperature, concentration, and velocity requires the evaluation of multiple parameters. A more uniform distribution of temperatures can be achieved by increasing the Biot number, thermal radiation, and thermophoretic motion parameters. The use of suction is an effective method of controlling the rate of temperature reduction in various manufacturing processes. A product's mechanical properties and overall quality can be enhanced if one is able to control how quickly it cools during the process of melting and condensing raw materials. As a consequence of the emergence of quadratic and linear slip factors, the flow velocity decreases. A distinguishing feature of this research is the use of boundary conditions that are tailored to the geometry that is being investigated.

Preparation of fluorine-free foam extinguishing agent based on silicone and hydrocarbon surfactants for markedly suppressing the pool fire

To solve the serious environmental hazard of fluorinated aqueous film-forming foam (AFFF), it is urgently to develop environmental-friendly fluorine-free foam extinguishing agents. In this study, a highly effective phosphate betaine silicone surfactant (PPSS) was prepared successfully, and then combined with various hydrocarbon surfactants to prepare the fluoride-free foam extinguishing agents. The effect of PPSS on the surface tension, foaming ability, foam stability and fire-extinguishing efficiency of fluoride-free foam extinguishing agents were investigated. The results show that the surface tension of PPSS is as slow as 20.68 mN/m, which imparts a lower surface tension to the mixed systems of PPSS and hydrocarbon surfactants. Especially, the mixture of PPSS and sodium alpha-olefin sulfonate (AOS) possess the lowest surface tension of 22.95 mN/m compared to the CTAB/PPSS and LAD-30/PPSS mixed systems. Moreover, AOS/PPSS mixture presents the excellent comprehensive performance with the critical micelle concentration (CMC) of 0.165 g/L, the surface tension at CMC value of 22.95 mN/m, the initial foam height of 111.9 mm, and the foam stability of 83.45%. Fire-extinguishing tests show that the foam obtained from AOS and PPSS exerts a wonderful fire-extinguishing efficiency compared to two commercial fire-fighting foams. In addition, the fire-extinguishing efficiency of foam extinguishing agents is closely related to the gas–liquid ratio. When the gas–liquid ratio is 17, the foam shows the maximum temperature reduction rate of 6.05 °C/s as well as the minimum extinguishing time of 38.9 s.

Performance improvement of the dry chemical-based fire extinguishers using nanocalcium silicate synthesised from biowaste

Herein, we investigated nanocalcium silicate (nCa2SiO4) prepared from clam shells and rice husks for its utilisation as a chemical agent in a fire-extinguishing mixture comprising ABC dry powder. The fire-extinguishing performance was evaluated with Class A and B fires. The prepared mixture was compared with commercial mono-ammonium phosphate powder based on different parameters, namely extinguishing time, amount of extinguishing agent used, fire temperature reduction rate, powder coating on the fuel and a reburn incident. It was found that the mixture of nCa2SiO4 and ABC dry powder could extinguish Class A and B fires within 10.67 and 9 s, respectively, while commercial mono-ammonium phosphate powder required 11 and 11.33 s to extinguish Class A and B fires, respectively. Thus, the mixture of nCa2SiO4 and ABC dry powder was more effective and less consumed as compared to commercial mono-ammonium phosphate powder (Class B only). This study demonstrates the efficacy of nCa2SiO4 to improve the performance of dry chemical-based fire extinguishers.

A novel sustainable cooling system in a tunnel with high geotemperature: Concept and thermal performance

An increasing number of tunnels pass through the anomaly geothermal zones and inevitably encounter thermal engineering geological problems during tunnel operation. In order to efficiently eliminate the thermal damage, an efficient and energy-saving cooling system composed of borehole heat exchangers (BHEs) and thermal insulation layer in a high geotemperature tunnel is proposed. Taking Sangzhuling tunnel as an example, a 3D numerical model is established for analyzing the thermal performance of the cooling system, and is validated by the field measured data. The cooling effect of the cooling system in the high-geotemperature tunnels is proved to be remarkable in comparison with the tunnel having thermal insulation layer. Moreover, the effects of design parameters on the thermal performance are revealed during a 180-day heat extraction. The results show that a lower inlet temperature contributes to a shorter drop to the target tunnel ambient temperature. The effect of the cooling system is significantly improved as the borehole depth increases within a limited extent because the cooling effect cannot be infinitely improved by increasing the borehole depth. The thermal insulation layer plays a beneficial role in reducing the maximum ambient temperature and an adverse effect on the temperature reduction rate. These findings contribute to preliminary thermal performance estimation of the BHE cooling system in high-geotemperature tunnels without large-scale simulation.

Study on the changing pattern of the salt-freeze swelling force of sulfate saline soil containing sodium chloride under variable temperature environment

The salt-freeze swelling forces generated by sulfate saline soils when experiencing changes in ambient temperature can cause a large degree of damage to building foundations, endangering the safety of people's lives and property. We performed an experimental study on the change of salt-freeze swelling force under different conditions of salt content, cooling rate, and chlorine-sulfur ratio by using the self-developed salt-freeze swelling force test device in combination with the methods of indoor tests and mathematical statistics. The findings revealed that: The growth rate of the salt-freeze swelling force was positively correlated with the salt content. The salt-freeze swelling force of soils increased first and then decreased as the temperature decreased, and the maximum reduction reached 71.7%, which could be divided into three stages: rapid growth, slow growth, and fallback. The rate of temperature reduction had a significant impact on the deviation of the salt-freezing swelling force, and the two were positively correlated. The addition of sodium chloride could effectively inhibit the occurrence of salt-freeze swelling. Considering the economy and applicability, 0.3 is recommended to be considered as the chlorine-to-sulfur ratio in soils with CSR≥0.3; in soils with CSR<0.3, 0.3 and 0.1 are recommended to be considered for soils with high salt content (S>2%) and low salt content (S ≤ 2%), respectively. The final salt-freeze swelling force of sulfate-saline soils and sulfate-saline soils containing sodium chloride was predicted using a specific model, and its accuracy was confirmed by comparing it with previous studies.

Analisis perubahan sifat fisis (viskositas, kerapatan, tegangan permukaan dan koefisien laju penurunan suhu) minyak kelapa (coconut oil) terhadap beberapa kali pemanasan

The purpose of this study was to ascertain the impact of repeated heating of coconut oil on the value of viscosity, density (mass density), surface tension, and the coefficient of temperature reduction rate (Newton cooling constant). The coconut oil sample used was the result of my own production. The heating repetition was carried out at most five times with a peak temperature of 90oC. The physics quantities were respectively determined by the methods of the falling ball, the directly measuring the mass and volume with the measuring cylinder, the raising fluid in a capillary tube, and the Newton cooling.From this study, it was found that there was an effect of repeated heating of coconut oil on the value of viscosity, mass density, surface tension, and the Newton cooling constant. This effect is indicated by the presence of a functional relationship between the heating test and the value of the four physical quantities. The relationship between heating repetition and viscosity is a quadratic function, the relationship between heating repetition and mass density is a linear function, the relationship between heating repetition and surface tension is a quadratic function, and the relationship between heating repetition and Newton cooling constant is a quartic function. The four functional relationships are empirical equations that state the laws of nature in a certain heating range and can be used as material for further studies to reveal the physical mechanisms that build them, including determining the general equations that unite them.

Investigating a citrus fruit supply chain network considering CO2 emissions using meta-heuristic algorithms

AbstractAccording to the increasing carbon dioxide released through vehicles and the shortage of water resources, decision-makers decided to combine the environmental and economic effects in the Agri-Food Supply Chain Network (AFSCN) in developing countries. This paper focuses on the citrus fruit supply chain network. The novelty of this study is the proposal of a mathematical model for a three-echelon AFSCN considering simultaneously CO2 emissions, coefficient water, and time window. Additionally, a bi-objective mixed-integer non-linear programming is formulated for production–distribution-inventory-allocation problem. The model seeks to minimise the total cost and CO+ emission simultaneously. To solve the multi-objective model in this paper, the Augmented Epsilon-constraint method is utilised for small- and medium-sized problems. The Augmented Epsilon-constraint method is not able to solve large-scale problems due to its high computational time. This method is a well-known approach to dealing with multi-objective problems. It allows for producing a set of Pareto solutions for multi-objective problems. Multi-Objective Ant Colony Optimisation, fast Pareto genetic algorithm, non-dominated sorting genetic algorithm II, and multi-objective simulated annealing are used to solve the model. Then, a hybrid meta-heuristic algorithm called Hybrid multi-objective Ant Colony Optimisation with multi-objective Simulated Annealing (HACO-SA) is developed to solve the model. In the HACO-SA algorithm, an initial temperature and temperature reduction rate is utilised to ensure a faster convergence rate and to optimise the ability of exploitation and exploration as input data of the SA algorithm. The computational results show the superiority of the Augmented Epsilon-constraint method in small-sized problems, while HACO-SA indicates that is better than the suggested original algorithms in the medium- and large-sized problems.

Experimental investigation on the start-up behaviors of a Joule–Thomson refrigeration system with pressure control

• Start-up behaviors of the J-T refrigeration system with pressure control were explored. • Reducing the pressure control time could accelerate pull-down rate. • Increasing control pressure and expansion valve opening decreases pull-down time. • Reducing compressor speed and R1150 concentration could reduce pull-down time. The excessively high discharge pressure of mixture-based Joule–Thomson (J–T) refrigeration system for low-temperature freezers at the start-up process without active control leads to the reduction of operation reliability of compressors. Start-up characteristics of a J–T refrigeration system with an expansion tank for pressure control were investigated in this study. The binary mixture R1150/R600a was selected as the working fluid, and influences of the control pressure, compressor speed, throttle valve opening, and mixture concentration on the system’s dynamic performances were experimentally explored. Results demonstrated that the discharge pressure could be effectively limited below the compressor’s safety pressure with an expansion tank. Meanwhile, the close relationship between pull-down rate and time of the pressure control phase was associated with the control pressure, compressor speed, throttle valve opening, and mixture concentration. The pull-down rate can be accelerated by increasing the control pressure and throttle valve opening and reducing the compressor speed and the R1150 concentration at the start-up process. The excessively rich R1150 concentration caused the continuous action of the pressure switch and the malfunction of the low-temperature freezing at an acceptable time range. The build-up of the heat recuperation played a significant role in pressure control time and freezing temperature reduction rate.

선박 화재시 제연경계벽 설치가 온도 감소 및 가시거리 향상에 미치는 연구

Maritime accidents caused by a ship include collisions, sinking, stranding and fire etc. This study is intending to consider fire accidents among such diverse marine accidents. Since ships load assorted cargoes and operate at sea for a long time, the possibility of various types of fires is high. Accordingly, different equipment and facilities are installed on ships to increase the survival rate of passengers and crew. Among these facilities, in the residential area where passengers and crew live, fire doors are installed and operated to prevent the spread of fire. In other words, the fire door is automatically closed in case of a fire alarm to prevent the spread of fire. Fire doors are very effective not only in preventing the spread of fire itself, but also in preventing the spread of smoke, which accounts for most of the casualties. However, it can be fatal for passengers and crew members located inside the fire doors who have not yet completed their evacuation. In the event of a fire, the temperature and soot rise upward and move through the ceiling. In this study, since draft curtains are not installed on ships, the effect on the increase in effective evacuation time, which is the lifespan time, was analyzed. As a result, in the case of temperature, when the draft curtain is 30cm, compared to the case without the draft curtain, the temperature reduction rate is improved by 6.6% by decreasing 2.2℃. Also, when the draft curtain was 40cm, the temperature decreased by 6.3℃, which improved by 18.9%. In the case of visibility, when the draft curtain is 20cm, 57.0% is improved from 13.5m to 21.2m compared to the case without the draft curtain. In particular, when the draft curtain is 30cm or more, there is no decrease in the visible distance due to smoke.

Thermal energy storage inside the chamber with a brick wall using the phase change process of paraffinic materials: A numerical simulation

Phase change materials are one of the potential resources to replace fossil fuels in regards of supplying the energy of buildings. Basically, these materials absorb or release heat energy with the help of their latent heat. Phase change materials have low thermal conductivity and this makes it possible to use the physical properties of these materials in the tropical regions where the solar radiation is more direct and concentrated over a smaller area. In this theoretical work, an attempt has been made to study the melting process of these materials by applying constant heat flux and temperature. It was found that by increasing the thickness of phase change materials’ layers, due to the melting, more thermal energy is stored. Simultaneously it reduces the penetration of excessive heat into the chamber, so that by increasing the thickness of paraffin materials up to 20 mm, the rate of temperature reduction reaches more than 18%. It was also recognized that increasing the values of constant input heat flux increases buoyancy effects. Increasing the Stefan number from 0.1 to 0.3, increases the temperature by 6%.

Research on the residual tensile strength of composite reinforcing bars exposed to elevated temperatures

Paper describes a testing procedure for the determination of tensile strength of the composite reinforcing bars subjected to elevated temperatures. Experimentally obtained results on GFRP bars with different diameter are presented and discussed. Moreover, a brief comparison with an analytical approach was included. Almost identical temperature reduction rate of tensile strength was observed for all tested specimens, regardless diameter of the bar. Therefore, it can be expected, that different bar diameter should not significantly affect the results especially if steady state conditions were assumed.

Study on transient boiling heat transfer of coal with different bedding angles quenched by liquid nitrogen

Liquid nitrogen (LN2) cracking is a new waterless cracking technology, and the efficiency of cracking coal from different angles is obviously different. Therefore, the boiling heat transfer of LN2 in contact with media with different stratification angles is studied in this paper. It is found that the longitudinal and transverse wave velocities of ultrasonic waves are positively correlated with the bedding angle of coal samples. With the increase of bedding angle of coal samples, the rate of temperature reduction of coal samples at the initial stage of LN2 quenching first drops and then rises, and the coal temperature decreases fastest in parallel bedding direction. The central temperature of coal samples from different bedding angles has experienced four stages: rapid decline-slow decline-rapid linear decline-slow decline, among which stage 3 lasts the longest and the temperature reduction rate exceeds 50%. The quenching effect parameters are defined, and the quenching effect of four stages is stage 3 > stage 4 > stage 2 > stage 1. Prolonging the time of stage 3 can improve the quenching efficiency of LN2. According to the RPI model, the change of the side wall temperature of coal sample is rapidly decreasing-slowly decreasing, and a low temperature layer with high thermal resistance is formed after rapid decrease, which can inhibit the heat transfer from coal to LN2.

Analisis Laju Penurunan Temperatur di Dalam Ruangan Menggunakan AC Low Watt 0,5 HP

Heat absorb ability split AC is the most important factor in the cooling speed on room temperature. The rate of temperature drop is determined by many factors, including compressor power. Nowadays, there are many Split AC are produced that have low power (low Watt), so that research is needed to determine the cooling speed in a room.&#x0D; This study uses a low watt split AC with a power of 0.5 HP. The distance from the evaporator and the outside temperature are used as independent variables, while the rate of temperature reduction or cooling speed in the room is used as the dependent variable. The results showed that the distribution of room temperature and the rate of temperature reduction in the room varied based on the position of the distance to the location of the AC Split Low Watt. The lowest temperature and reduction rate in the room occurs at a distance of 2 m and 3 m in front of the AC location. The outside temperature or the temperature around the location of the AC condenser affects the temperature distribution at each distance in front of the AC. When the outside temperature is low, the temperature conditions at a distance of 1 m, 4 m, and 5 m have a significant difference. While the high outside temperature conditions, the temperature at a distance of 1 m, 4 m, and 5 m, namely the positions close to the wall, is almost the same.&#x0D; &#x0D; Kata kunci: AC, split, low watt, evaporator

Mathematical design and performance investigation of evaporator water cooled storage‐cum‐mobile thermoelectric refrigerator for preservation of fruits and vegetables

AbstractA storage‐cum‐mobile thermoelectric refrigeration system was designed for passive, active, and total load of refrigeration on the basis of thermo‐physical properties of polyurethane sheet, heat generated by axial fan, and internal heat of commodities stored for refrigeration. A prototype of mobile thermoelectric refrigeration system of capacity 100 L (40 kg per batch) was designed and developed for maintaining the temperature of 15 ± 2°C and relative humidity of 80 ± 5%. The developed system of dimension (45 × 50 × 50 length × width × height), composed of four thermoelectric modules, liquid cooled evaporator, axial fan, diaphragm water pump, fogger, and water tank. The system was operated by 12 V DC power source. Results obtained from experimental performance evaluation indicated that 20.8°C temperature reduction was achieved in 210 min under no load operation, whereas, 23.6°C temperature reduction was obtained in 360 min when the system was loaded with 30 kg of bitter gourd. The temperature was reduced at the rate of 9.65°C/h till temperature of 20°C was attained which latter reduced to 2.23°C/h under no load condition, whereas, rate of temperature reduction was 7.44°C/h till attainment of 20°C and then reduced to 1.43°C/h under loading condition. The techno‐economic feasibility of the system exhibited COP 0.85 which was significantly higher than those reported by several scientists in the range of 0.15–0.50. Developed refrigeration system can be effectively utilized as an eco‐friendly technology for small scale cold storage of fruits and vegetables with causing detrimental effect to environment.Practical ApplicationsDeveloped thermoelectric refrigeration technology is climate friendly without generating any global warming potential and can be commercially used for small scale cold storage of fruits and vegetables to enhance the shelf life of produce. A developed refrigeration system is helpful for fruits and vegetable vendors to maintain the quality of commodity during transportation to minimize the decay of food and fetch good value to the commodity.

Investigating the effect of process parameters on the mechanical properties and temperature distribution in fiber laser welding of AISI304 and AISI 420 sheet using response surface methodology

Fiber laser welding of austenitic and ferritic stainless steel was performed based on response surface methodology to systemically analyze the effect of process parameters on the weld characterizations. The laser welding input parameters were selected (laser power, welding speed and nozzle stand of distance) while the tensile strength of the joint and temperature near the molten pool were considered as the main responses. Variation of nozzle distance about 5 mm had less effect on the temperature domain near the molten pool and weld tensile strength. Increasing the nozzle distance and moving the focal point position to the upper surface of the sheet surface led to the notable improvement of the tensile strength about 20 percent. In other words, transition of the focal point thorough the material thickness clearly reduced the joint strength due to creating more volume of martensitic micro-structure and finally cracking during the tensile test from HAZ region of ferritic steel. The interaction of the laser power and welding speed had noticeable impact on the molten pool temperature. Evidently, the rate of temperature reduction due to an increased welding speed is greater at higher laser power. Among the investigated parameters, the welding speed had the highest effects on the tensile strength of the joint. Increasing the laser power from 300 to 360 W raised the tensile strength about 20%. Interaction of the laser power and welding speed resulted in about 300 °C of the temperature reduction due to an increased welding speed at higher laser power of 395 W variation of nozzle distance at different lase power levels less effect about 5 percent in comparison to the welding speed versus nozzle distance although the similar trend was observed for both of them.

Numerical Studies on the Heat Effect of Explosion Suppression by a Heat Pipe

A composite structure with a heat pipe and foamed iron-nickel composite fire suppression is proposed on the basis of the phase-change heat transfer of the heat pipe, which simultaneously attenuates the metal foam explosion energy. A numerical simulation is conducted to evaluate the feasibility of the designed construction for suppressing explosions under various thicknesses and pore diameters of the metal foam. The results demonstrate that when the foam iron-nickel metal is installed in the pipeline, the temperature reduction rate in the pipeline can reach 8.9%. The new heat pipe foam composite structure can reduce the flame temperature to 1600 K within 0.095 s. It is concluded that the heat pipe composite metal foam structure pipeline has a strong effect on suppressing combustion and explosion overpressure. Due to the combined effect of the heat pipe vacuum chamber suction energy and the foamed iron-nickel, the flame temperature decay rate increases. The maximum attenuation rate of the foamed iron-nickel for the gas explosion shock wave reaches 41.76%, and the maximum flame temperature attenuation rate reaches 64.7%. The composite heat pipe structure can quickly disperse and transfer heat, thereby effectively destroying the heat storage environment as soon as possible to prevent a secondary explosion from occurring.