Cooling Thin Parts of Pressure Casting Moulds by Means of Liquid CO2

2015 ◽  
Vol 669 ◽  
pp. 71-78
Author(s):  
Iva Nováková ◽  
Martin Seidl ◽  
Pavel Brdlík ◽  
Jan Štverák ◽  
Jaromír Moravec
Keyword(s):  
Cooling System ◽  
Heat Removal ◽  
Pressure Casting ◽  
Optimal Temperature ◽  
Heat Transfer Medium ◽  
Cooling Systems ◽  
Start Up ◽  
Casting Cycle ◽  
Heat Processes ◽  
Heat Amount

To ensure optimal temperature conditions during casting cycle the pressure casting moulds are equipped with cooling systems. These days the cooling systems used in the most of Czech foundry plants enable pre-heating of pressure casting moulds to the working temperature before start-up of production and during casting operation to keep optimal temperature balance among the casting and the mould. Pressure casting mould temperature balance is provided by system of mutually connected channels which are mostly parallel with parting line and inside those the heat transfer medium flows. However such a system allows removal only limited heat amount from the most overheated places of the casting mould and does not allow heat removal from cores of small diameters. This inhomogeneous heat removal causes porosity of the casting in certain areas and also lifetime of the pressure casting mould is dramatically reduced. Cooling by means of liquid CO2 was developed as one of the new cooling possibilities for such places in the pressure casting mould where the heat is concentrated and for standard cooling systems it is too complicated to fully control the heat processes there. The paper deals with the behaviour monitoring of the new cooling system utilizing the potential of liquid CO2. This system was applied into pressure casting mould core and its final impact on the casting quality in the close surrounding was observed.

scholarly journals Improving the cooling system of ship equipment

2020 ◽  
Author(s):  
А.В. Фомин ◽  
Е.В. Фомин
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cooling System ◽  
Heat Removal ◽  
Normal Operation ◽  
Water Cooling ◽  
Cooling Systems ◽  
Start Up ◽  
Membrane Type ◽  
Water Cooling System

В статье представлены результаты исследования эффективности работы системы охлаждения корабельного оборудования и предложены конструктивные решения, позволяющие модернизировать данную систему. В настоящее время, для обеспечения нормальной работы корабельного оборудования, применяются системы охлаждения. В корабельных энергетических установках распространены системы водяного охлаждения из-за целого ряда преимуществ. К ним относится и высокая эффективность теплоотвода, и меньшее влияние внешней среды, а также более надежный пуск и возможность использования энергии отводимого тепла для других нужд. Одним из основных элементов в таких системах является расширительный бак гравитационного типа, обеспечивающий правильную циркуляцию дистиллированной воды во внутреннем контуре и расположенный в верхней точке системы. Однако практика испытаний и эксплуатации показала, что есть и серьезный недостаток в таком расположении бака – в случаи его перелива или разрыва может пострадать дорогостоящее оборудование, расположенное ниже. В связи с этим, определены направления по совершенствованию системы водяного охлаждения корабельного оборудования, которые связаны с применением расширительного бака мембранного типа и использования воздухоудаляющих клапанов. The article presents the results of a study of the efficiency of the cooling system of ship equipment and offers design solutions that allow to modernize this system. Currently, to ensure the normal operation of ship's equipment, cooling systems are used. Water cooling systems are common in ship power plants due to a number of advantages. These include high efficiency of heat removal, less influence of the external environment, as well as more reliable start-up and the ability to use the energy of the heat being withdrawn for other needs. One of the main elements in such systems is a gravity-type expansion tank that ensures proper circulation of distilled water in the internal circuit and is located at the top of the system. However, the practice of testing and operation has shown that there is a serious drawback in this arrangement of the tank – in cases of overflow or rupture, expensive equipment located below may suffer. In this regard, the directions for improving the water cooling system of ship equipment, which are associated with the use of an expansion tank of the membrane type and the use of air-removing valves, have been identified.

scholarly journals Perfection of cooling systems of overhead tuyeres heads of 250-t BOFs

2019 ◽  
Vol 75 (3) ◽  
pp. 327-336
Author(s):  
S. P. Panteikov ◽  
L. M. Uchitel’ ◽  
V. V. Ivko ◽  
Yu. I. Kharchenko ◽  
Yu. P. Makhlai ◽  
...  
Keyword(s):  
Cooling System ◽  
Heat Removal ◽  
Internal Surface ◽  
Side Surface ◽  
Operating Characteristics ◽  
Blow Down ◽  
Cooling Systems ◽  
Nozzle Block ◽  
Heat Removal Efficiency ◽  
Positive Effect

Deterioration of tips cooling as a result of number of nuzzles increase in tuyere heads does not allow to use multinozzle (six and more) overhead tuyeres for increasing of steel melting technical and economical indices and operating characteristics of technological equipment. The main reason of it is as follows: deterioration ofcooling results in over-heating and burnt-outof tips material in the farthest nozzle zone following the overhead tuyeres breakage. To avoid the water stagnant areas in the farthestnozzle zones of the heads cooling route and therefore to increase the overheads oxygen tuyeres of 250-t BOF operation life, a new design of the six-nozzle tuyere head with asymmetric cooling of tips farthest zones elaborated, manufactures and tested. The perfection of the six-nozzle heads cooling system included asymmetric (relating the side surface of the nozzle block) installation behind every nozzle (in the water direction) a guidingblade of special design. It enabled to increase to a maximum degree the heat removal efficiency from the internal surface in the tip farthest zones and had a positive effect on the overhead tuyeres heads resistance. The workability of the proposed design of the six-nozzle tuyere head with asymmetric cooling of farthest zones was confirmed during test-industrial heats at 250-t BOFs of OJSC “Dneprovskysteel-works”. The heats were carried out with oxygen consumption of 800–1200 m 3/min and regime of partial afterburning ofexit gases. The water consumption for tuyeres cooling decrease from 320–340 m 3 /h, at that the  water temperature difference at the tuyere entry and exit varied in the range of 11–16 °C depending on blow-down duration. Application of the new design of the six-nozzle tuyere head with asymmetric farthest zones cooling enabled to increase the sixnozzle heads resistance by a factor 1.287 comparing with six-nozzle heads without farthest zones cooling and by a factor of 3.327 comparing with regular five-nozzle tuyere heads. The effect reached thanks to more rational cooler distribution and increase ofits velocity. The metal pick up of shafts of the six-nozzle tuyere head with asymmetric farthest zones cooling: while the five-nozzle tuyeres were taken off for salamander cutting off after 1–5 heats, the six-nozzle tuyeres were taken off for the salamander cutting off after 79–81 heats. It indicated a higher efficiency of heat running blow-down and slag regimes with application of proposed design of the six-nozzle tuyere head with asymmetric farthest zones cooling.

scholarly journals Experimental Study to Performance Improvement of Vapor Compression Cooling System Integrated Direct Evaporative Cooler and Condenser

2018 ◽  
Vol 215 ◽  
pp. 01017
Author(s):  
Arfidian Rachman ◽  
Lisa Nesti
Keyword(s):  
Energy Use ◽  
Cooling System ◽  
Electricity Consumption ◽  
Weather Condition ◽  
Heat Removal ◽  
Cooling Capacity ◽  
Cooling Power ◽  
Cooling Systems ◽  
Evaporative Cooler ◽  
And Performance

For areas with very hot and humid weather condition increased latent and sensible load are a major problem in cooling systems that will increase compressor work so that electricity consumption will also increase. Combined condenser with direct evaporate cooling will increase the heat removal process by using an evaporative cooler effect that will increase the efficiency of energy use. This paper presents the study of the use of evaporator cooling and condenser. This paper mainly calculated energy consumption in steam compression cooling systems and related problems. From the results of this study, the use of condensers with evaporative cooling, power consumption can be reduced to 46% and performance coefficient (COP) can be increased by about 12%, with 1,2 kW cooling capacity.

Effect of the Technological Parameters on the Thermal Conditions of Die-Casting Tool

2013 ◽  
Vol 752 ◽  
pp. 183-192 ◽  
Author(s):  
Jenő Dúl ◽  
Zsolt Leskó ◽  
Borbála Juhász
Keyword(s):  
Cooling System ◽  
Die Casting ◽  
Thermal Conditions ◽  
Technological Parameters ◽  
Cooling Systems ◽  
Casting Tool ◽  
Casting Cycle ◽  
And Function ◽  
The Heat Balance ◽  
Short Times

The heat balance of a casting cycle can be ensured in short times by the annealing of the die-casting tool, by which the well-constructed and well-functioned cooling system can enhance productivity. Incorrect cooling, however, can lead to heat unbalance in the die casting tool, thus causing the destruction of casting quality, reduction of the lifetime of die casting tool and irreversible production-reduction. Beside the theoretical examination of construction and function of cooling system, the evaluation of the effectively removed heat quantities has great importance. The paper presents an analysis of the function of the cooling system of a scraggy thin casting of AlSi9Cu3 alloy, in case of different cooling parameters. Based on the measured results of the inlet and outlet temperatures and the volume flow of the cooling agents, the heat quantities belonging to the cooling circles are determined and an optimization of the cooling system is proposed. The findings of the analysis can be utilized for the construction and optimum operation of die-casting cooling systems.

Study of the Behaviors of an Open-Loop Heat-Removal System

2018 ◽  
Author(s):  
Xianmao Wang ◽  
Yonggang Shen ◽  
Jiang Yang ◽  
Yong Ouyang ◽  
Min Rui ◽  
...  
Keyword(s):  
Cooling System ◽  
Natural Circulation ◽  
Heat Removal ◽  
Calculation Model ◽  
Open Loop ◽  
Cooling Systems ◽  
Core Cooling ◽  
Passive Cooling Systems ◽  
Heat Removal System ◽  
Removal System

In the third generation of nuclear reactors, passive systems have been widely used such as passive core cooling system and passive containment cooling system, which usually relay on natural circulation induced by buoyancy force to remove heat. Most of these passive cooling systems are closed-loop natural circulations. In recent years, some open-loop heat-removal systems have also been put forward. Open-loop heat-removal systems have its own advantages such as its simplification and low costs. However, the thermal-hydraulic behaviors of open-loop heat-removal systems are still not totally clear and need further study. In this study, a simplified open-loop passive containment cooling system is studied. A calculation model is built based on RELAP SCDAPSIM code. The thermal-hydraulic behaviors of the system are studied. By changing some key parameters of the system, the influences of these parameters on the system are evaluated.

Three Dimensional CFD Simulation of Condensation Inside Inclined Tubes

2017 ◽  
Author(s):  
Amirhosein Moonesi Shabestary ◽  
Eckhard Krepper ◽  
Dirk Lucas ◽  
Thomas Höhne
Keyword(s):  
Heat Transfer ◽  
Annular Flow ◽  
Cfd Simulation ◽  
Cooling System ◽  
Heat Removal ◽  
Normal Operation ◽  
Cooling Systems ◽  
Horizontal Pipes ◽  
Subcooled Water ◽  
Operation Conditions

The current paper comprises CFD-modelling and simulation of condensation and heat transfer inside horizontal pipes. Designs of future nuclear boiling water reactor concepts are equipped with emergency cooling systems which are passive systems for heat removal. The emergency cooling system consists of slightly inclined horizontal pipes which are immersed in a tank of subcooled water. At normal operation conditions, the pipes are filled with water and no heat transfer to the secondary side of the condenser occurs. In the case of an accident the water level in the core is decreasing, steam comes in the emergency pipes and due to the subcooled water around the pipe, this steam will condense. The emergency condenser acts as a strong heat sink which is responsible for a quick depressurization of the reactor core when any accident happens. The actual project is defined in order to model all these processes which happen in the emergency cooling systems. The most focus of the project is on detection of different morphologies such as annular flow, stratified flow, slug flow and plug flow. The first step is the investigation of condensation inside a horizontal tube by considering the direct contact condensation (DCC). Therefore, at the inlet of the pipe an annular flow is assumed. In this step, the Algebraic Interfacial Area Density (AIAD) model is used in order to simulate the interface. The second step is the extension of the model to consider wall condensation effect as well which is closer to the reality. In this step, the inlet is pure steam and due to the wall condensation, a liquid film occurs near the wall which leads to annular flow. The last step will be modelling of different morphologies which are occurring inside the tube during the condensation via using the Generalized Two-Phase Flow (GENTOP) model extended by heat and mass transfer. By using GENTOP the dispersed phase is able to be considered and simulated. Finally, the results of the simulations will be validated by experimental data which will be available in HZDR. In this paper the results of the first part has been presented.

scholarly journals CFD Analysis of the ESFR Reactor Pit Cooling System in Case of Sodium Leakage

2021 ◽  
Author(s):  
Aleksander Grah ◽  
Haileyesus Tsige-Tamirat ◽  
Joel Guidez ◽  
Antoine Gerschenfeld ◽  
Konstantin Mikityuk ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Cooling System ◽  
Heat Removal ◽  
Strong Line ◽  
Cooling Systems ◽  
Decay Heat ◽  
Cooling Loops ◽  
Heat Removal System ◽  
Removal System ◽  
Residual Heat

Abstract The Decay Heat Removal System (DHRS) for the ESFR Concept consists of three cooling systems, which provide highly reliable, redundant and diversified decay heat removal function. Two of the systems provide strong line of defense, whereas the third system provides a weak line of defense. This third DHR system, DHRS-3, involves separate oil and water cooling loops integrated in the reactor pit, which is installed instead of the safety vessel. It is hoped that the proposed DHR concept enables a robust demonstration of the practical elimination. For its confirmation, detailed numerical analysis is needed as a basis for further investigation. Supporting this approach, the current CFD computation provides a preliminary thermal analysis of the capability of the oil cooling system in the reactor to be used for residual heat removal pit in case of an emergency. For the evaluation, different heat flux values are assumed at the vessel wall to examine the range of the resulting temperatures. The temperature of the main vessel wall should remain below 800°C. Furthermore, a sodium leakage at 500°C into the reactor pit is assumed. The concrete structure should remain below 70°C.

An Evaluation of Cooling Systems for PEMFCs in Transport Applications

2003 ◽  
Author(s):  
K. M. Oseen-Senda ◽  
J. Pauchet ◽  
M. Feidt ◽  
O. Lottin
Keyword(s):  
Fuel Cells ◽  
Cooling System ◽  
Combustion Engine ◽  
Current System ◽  
Polymer Electrolyte Fuel Cells ◽  
Cooling Systems ◽  
Start Up ◽  
Dry Out ◽  
Transportation Applications ◽  
System Designs

Polymer Electrolyte Fuel Cells in transportation applications require specific cooling systems. Inside the cell itself, the temperature must remain relatively constant to avoid problems of condensation or dry out that would adversely affect its efficiency. The cooling system must also deal with several challenges unique to fuel cells: it must not conduct electricity across the cells, and it must withstand freezing and cold start-up. Moreover, the cooling system must be compact and light to keep the energy density of the stack as high as possible. Unlike the conventional internal combustion engine in today’s cars, the fuel cell engine works at a low temperature. This means that the entire automobile cooling system must be redesigned to dissipate this low quality heat. To better compare various cooling systems, we have done a patent search of current system designs.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

scholarly journals Performance Analysis of Hybrid Desiccant Cooling System with Enhanced Dehumidification Capability Using TRNSYS

2021 ◽  
Vol 11 (7) ◽  
pp. 3236
Author(s):  
Ji Hyeok Kim ◽  
Joon Ahn
Keyword(s):  
Thermal Comfort ◽  
Cooling System ◽  
Operation Mode ◽  
Heat Removal ◽  
Simulation Models ◽  
Coefficient Of Performance ◽  
Dimensional Structure ◽  
Dominant Factor ◽  
Exhaust Heat ◽  
Chp System

In a field test of a hybrid desiccant cooling system (HDCS) linked to a gas engine cogeneration system (the latter system is hereafter referred to as the combined heat and power (CHP) system), in the cooling operation mode, the exhaust heat remained and the latent heat removal was insufficient. In this study, the performance of an HDCS was simulated at a humidity ratio of 10 g/kg in conditioned spaces and for an increasing dehumidification capacity of the desiccant rotor. Simulation models of the HDCS linked to the CHP system were based on a transient system simulation tool (TRNSYS). Furthermore, TRNBuild (the TRNSYS Building Model) was used to simulate the three-dimensional structure of cooling spaces and solar lighting conditions. According to the simulation results, when the desiccant capacity increased, the thermal comfort conditions in all three conditioned spaces were sufficiently good. The higher the ambient temperature, the higher the evaporative cooling performance was. The variation in the regeneration heat with the outdoor conditions was the most dominant factor that determined the coefficient of performance (COP). Therefore, the COP was higher under high temperature and dry conditions, resulting in less regeneration heat being required. According to the prediction results, when the dehumidification capacity is sufficiently increased for using more exhaust heat, the overall efficiency of the CHP can be increased while ensuring suitable thermal comfort conditions in the cooling space.

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