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Wyszukujesz frazę "cooling rate" wg kryterium: Temat


Tytuł:
The influence of incondensible gases on the refrigeration capacity of the reliquefaction plant during ethylene carriage by sea
Autorzy:
Nanowski, D.
Tematy:
ethylene carrier
cargo cooling rate
reliquefaction plant
Pokaż więcej
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/246338.pdf  Link otwiera się w nowym oknie
Opis:
This paper presents a performance of the reliquefaction cascade plant during ethylene carriage by sea. Parameters of this plant are discussed because of dramatic low cooling rate of the cargo. Ability to decrease ethylene temperature from approx. minus 96°C to minus 103°C on board the ship is essential. Modern ethylene carriers are able to keep cooling rate about 2K per day, on the other hand old ones do it with rate approx. 0,2 K per day and require weeks to achieve proper temperature of ethylene for discharging. Of course, economic issue of such journey is not very satisfying but many factors influence on this. In this paper almost new one – nine months – old ship is considered, with capacity 21 000m3. Main reason of problem is analysed, including heat ingress through the cargo tanks insulation. Gassing-up of the ship is explained and influence of presence incondensable gases in the cargo tanks described. Operation of the reliquefaction plant is shown, especially with the vent valve of LPG condenser. Analysis of pressures in the cargo tanks is carried out – on board the ship and with help of ProSimPlus – thermodynamic simulator. Conclusions contain discussion of the reliquefaction plant problems and remarks what should be improved on board the ethylene carrier to avoid such problems.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The operation limitation of the two-stage reliquefaction cycle employed on board the ethylene carrier
Autorzy:
Nanowski, D.
Tematy:
ethylene carrier
cargo-cooling rate
reliquefaction plant
Pokaż więcej
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/242707.pdf  Link otwiera się w nowym oknie
Opis:
Ethylene, propane, commercial propane or HD-5 is cargoes very often carried by sea. In order to reduce the time of loading and later cooling down to required parameters of temperature and pressure in the cargo tanks two-stage reliquefaction cycle is used. For above-mentioned cargoes, two-stage cycle with liquid subcooling and interstage cooler is one of the most often utilized. In this paper operation of this cycle is discussed, based on parameters of the reciprocating cargo compressor and its cycle used on board the one of the biggest – 21 500 m3 – ethylene carrier in the world. It is explained how some vapour mixtures decrease cooling rate during reliquefaction of the cargo and some parameters of pressure and temperature of these mixtures are calculated with help of ProSimPlus – thermodynamic simulator. In this way, changes of the mixtures composition across reliquefaction plant are discussed. Increased pressure of the cargoes condensing as a way of solving of explained problem is analysed. Three stage – cycle of reliquefaction plant used for pure propane or ethylene is shown and some of its disadvantages are explained. Based on this discussion, three-stage cycle with liquid injection is proposed to fulfil operation requirements of the cargoes and improve their loading and cooling processes on board the ethylene carrier. Analysis of refrigeration capacity for both cycles is carried out.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Rapid Cooling on the Corrosion Resistance of As-Cast Aluminium Alloy 5052
Autorzy:
Szklarz, Z.
Krawiec, H.
Rogal, Ł.
Tematy:
aluminium alloys
cooling rate
EIS
passive films
pitting corrosion
Pokaż więcej
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:
https://bibliotekanauki.pl/articles/106959.pdf  Link otwiera się w nowym oknie
Opis:
The effect of rapid cooling by the vacuum suction casting method (VSC) on the microstructure and electrochemical response of the as-cast 5052 aluminium alloy is presented. The VSC method allowed us to obtain massive samples with a very high cooling rate (102 – 103)oC/s. The microstructure of the quick-cooled sample (QC) has been significantly changed. Finer grains and more-homogeneous intermetallic phase distribution has been observed. Corrosion potential (OCP) and polarization measurements (LSV) revealed a higher activity of the QC alloy than ingot (IN), which leads to a denser and thicker corrosion-product formation on the surface. Electrochemical Impedance Spectroscopy (EIS) indicates higher resistance values, which suggests a greater thickness of the corrosion products.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Cooling Rates and Intermediate Slab Blank Thickness on the Microstructure and Mechanical Properties of the X70 Pipeline Steel
Autorzy:
Xu, Haijian
Han, Chufei
Yan, Pingyuan
Zhao, Baochun
Li, Weijuan
Tematy:
cooling rate
microstructure
pipe steel
acicular ferrite
low-alloy
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Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:
https://bibliotekanauki.pl/articles/28099617.pdf  Link otwiera się w nowym oknie
Opis:
In this study, the microstructures and mechanical properties of X70 pipeline steels produced with varying Mo contents, accelerated cooling rate and intermediate slab blank thickness are systematically investigated. Results showed that the microstructures and mechanical properties of the X70 pipeline steels were strongly affected by Mo addition. The pearlite and proeutectoid ferrite formation is obviously inhibited in containing-Mo steel and the acicular ferrite (AF) is obtained in a wide range of cooling rates. With the increasing the cooling rates, the AF constituent amount increases. The grains can be refined by increasing the thickness of intermediate slab for enhancing the cumulative reduction rates, and meanwhile increase the number density of precipitates. It was proved by simulation and industrial trials that the low-alloy X70 pipeline steels can be produced increasing cooling rates and the thickness of intermediate slab without strength and toughness degradation which also reduce alloy cost.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Cooling Rate on Microstructure and Mechanical Properties According to Heat Treatment Temperature of Inconel 625
Autorzy:
Park, Minha
Lee, Gang Ho
Kim, Hyo-Seong
Kim, Byoungkoo
Noh, Sanghoon
Kim, Byung Jun
Tematy:
Inconel 625
heat treatment
cooling rate
microstructure
mechanical property
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:
https://bibliotekanauki.pl/articles/59110919.pdf  Link otwiera się w nowym oknie
Opis:
Inconel 625 is typically used in extreme environments due to excellent mechanical properties such as high strength, corrosion resistance, abrasion resistance and low-temperature toughness. When manufacturing a hot forged flange with a thick and complex shape, the cooling rate varies depending on the location due to the difference in thermal gradient during the cooling process after hot forging. In this study, to evaluate the microstructure and mechanical properties of Inconel 625 according to the cooling rate, we performed heat treatment at 950°C, 1050°C, and 1150°C for 4 hours followed by water cooling. Additionally, temperature data for each location on the flange were obtained using finite element method (FEM) simulation for each heat treatment temperature, revealing a discrepancy in the cooling rate between the surface and the center. Therefore, the correlation between microstructure and mechanical properties according to cooling rate was investigated.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The cooling rate of the heated vapor compression cycle in case of using refrigerants R134a, R22, and R600a
Autorzy:
Abd-Elhady, Mohamed Salama
Melad, Emmanoueil Bishara
Abd-Elhalim, Mohamed
Seif Alnasr, Ahmed
Tematy:
compression
cycle
power saving
refrigerant
refrigerating cycle
cooling rate
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/1845463.pdf  Link otwiera się w nowym oknie
Opis:
The most power consuming part in the vapor compression cycle (VCC) is the gas compressor. Heating the refrigerant under constant volume after the compressor increases the condenser pressure, which consequently increases the cooling rate of the VCC. This study examined the influence of heating different refrigerants, i.e. R143a, R22, and R600a on the cooling rate of the VCC. Four experiments have been performed: the first experiment is a normal VCC, i.e. without heating, while in the second, third, and fourth experiments were carried out to raise the temperature of the refrigerant to 50◦C, 100◦C, and 150◦C. It has been found that heating raises the refrigerant pressure in VCC and thereby improves the refrigerant’s mass flow rate resulting in an improvement in the cooling power for the same compressor power. Heating the refrigerant after the mechanical compressor increases the temperature of the condenser as well as the temperature of the evaporator when using refrigerant R134a, which prevents the refrigeration cycle to be used in freezing applications, however using refrigerant R22 or refrigerant R600a promotes the heated VCC to be used in freezing applications. Refrigerant R600a has the lowest operating pressure compared to R134a and R22, which promotes R600a to be used rather than R134a and R22 from a leakage point of view.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
To Study the Microstructural Evolution of EN353 Steel under Different Heat Treatment Conditions
Autorzy:
Sharma, Lochan
Chaubey, Sandeep Kumar
Tematy:
CCT curves
cooling rate
heat treatment
bainite
ferrite
pearlite
microstructure
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:
https://bibliotekanauki.pl/articles/27313870.pdf  Link otwiera się w nowym oknie
Opis:
Steel is basically used in construction, automobile, buildings, infrastructure, tools, ships, appliances, machines and weapons due to its good mechanical as well as metallurgical properties. Heat treatment of steels significantly enhance its mechanical and metallurgical properties due to the formation of various phases depending upon the type of steel used for specific application. In present study, blank of EN353 grade steel having different sizes were used to investigate the effect of heat treatment and microstructural changes. JMat-Pro software was used to predict the continuous cooling transformation behaviour of EN353 steel. Different phases such as bainite, perlite and other carbide inclusion can be observed in the microstructural examination. Pearlitic microstructure developed for the specimen of size 40×40×40 mm heated at 870°C for 2 hrs and then isothermal heating was performed for same specimen at 600°C for 73 min followed by air cooling. Relevance Statement: Steel is an important material which is frequently used in almost all areas such as structure building, pressure vessels, transportation and many more other applications. Addition of alloying elements in parent steel significantly improve the metallurgical as well as mechanical properties. Steel properties like tensile strength, toughness, ductility, corrosion resistance, wear resistance, hardness, hot hardness, weldability, fatigue etc. significantly improved with the addition of alloying and heat treatment. Heat treatment processes can be used to improve the properties of steel which are frequently used in many manufacturing industries. Different grades of steels which are heat treated under a set of sequence of heating and cooling to change their physical and mechanical properties so that it can fulfil its function under loading condition. With the help of heat treatment process desired microstructure has been achieved which exhibit good mechanical properties of steels.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Modeling of the Phenomenon of Air-Cooled Solid
Autorzy:
Pluta, Z.
Hryniewicz, T.
Tematy:
phenomenon of body cooling
thermal space-time
potential field
time constant
cooling rate
temperature
time
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/411916.pdf  Link otwiera się w nowym oknie
Opis:
The paper turns the attention to the thermal problems of the solid cooling in air. The physical aspect of mathematic approach has been underlined. The analysis and critical evaluation of Newton's Law concerning the solid air-cooling have been performed. The cognitive path leading to the solution is presented with the result being the body temperature dependence on time of cooling down in the air. Then the course of solution concerning the result of the adequate dependence of temperature of the cooled body on time has been presented. In the study, the stress is put on constant magnitudes chich characterize the susceptibility of solid to the cooling in the air. In the end, the synthetic formulation of all functional characteristics of the thermal phenomenon discussed in the paper, have been presented.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties of Al-Si-Mg alloy castings as a function of structure refinement and porosity fraction
Autorzy:
Hajkowski, M.
Bernat, Ł.
Hajkowski, J.
Tematy:
właściwości mechaniczne
silumin
szybkość chłodzenia
porowatość
mechanical properties
cooling rate
structure
porosity
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/380306.pdf  Link otwiera się w nowym oknie
Opis:
During design of the casting products technology, an important issue is a possibility of prediction of mechanical properties resulting from the course of the casting solidification process. Frequently there is a need for relations describing mechanical properties of silumin alloys as a function of phase refinement in a structure and a porosity fraction, and relations describing phase refinement in the structure and the porosity fraction as a function of solidification conditions. The study was conducted on castings of a 22 mm thick plate, made of EN AC-AlSi7Mg0,3 alloy in moulds: of quartz sand, of quartz sand with chill and in permanent moulds. On the basis of cooling curves, values of cooling rate in various casting parts were calculated. The paper also presents results of examination of distance between arms in dendrites of a solid solution \alfa (DASL), precipitations length of silicon in an eutectic (DlSi) and gas-shrinkage porosity (Por) as a function of cooling rate. Statistical relations of DASL, DlSi, Por as a function of cooling rate and statistical multiparameter dependencies describing mechanical properties (tensile strength, yield strength, elongation) of alloy as a function of DASL, DlSi and Por are also presented in the paper.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Cooling Rate on the Microstructure and Mechanical Properties of Al-33 wt.% Cu Alloy
Autorzy:
Lee, Yeon-Joo
Kwon, Do-Hun
Cha, Eun-Ji
Song, Yong-Wook
Choi, Hyun Joo
Kim, Hwi-Jun
Tematy:
laser melting
cooling rate
lamellar spacing
hardness
Al-33wt.%Cu alloy
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/2203708.pdf  Link otwiera się w nowym oknie
Opis:
Directed energy deposition (DED) is an additive manufacturing process wherein an energy source is focused on a substrate on which a feedstock material is simultaneously delivered, thereby forming a small melt pool. Melting, solidification, and subsequent cooling occur at high rates with considerable thermal gradients compared with traditional metallurgical processes. Hence, it is important to examine the effects of cooling rates on the microstructures and properties of the additive manufactured materials. In this study, after performing DED with various energy densities, we investigated the changes in the microstructures and Vickers hardness of cast Al-33 wt.% Cu alloy, which is widely used to estimate the cooling rate during processing by measuring the lamellar spacing of the microstructure after solidification. The effects of the energy density on the cooling rate and resultant mechanical properties are discussed, which suggests a simple way to estimate the cooling rate indirectly. This study corresponds to the basic stage of the current study, and will continue to apply DED in the future.
Dostawca treści:
Biblioteka Nauki
Artykuł

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