Simulation and Real-World Investigation of the Vacuum Pumping Process for Liquid Nitrogen Vapour

2020 ◽  
pp. 95-108
Author(s):  
A.A. Ustsov ◽  
M.Yu. Kupriyanov
Keyword(s):  
Liquid Nitrogen ◽  
Test Bench ◽  
Vacuum Pump ◽  
Saturated Liquid ◽  
Evacuation Time ◽  
Point Temperature ◽  
System Temperature ◽  
Temperature And Pressure ◽  
Time Required ◽  
Triple Point Temperature

We performed the required theoretical computations to simulate the process of pumping saturated liquid nitrogen vapours, accounting for the assumptions adopted. The paper provides a schematic of the test bench and describes the sequence of experiment stages. We checked whether the storage Dewar and volumetric vacuum pump were selected correctly so as to ensure the required evacuation level above the liquid nitrogen surface. We built our test bench and conducted an experiment involving thermostatting in the 63 to 77 K temperature range, and achieved a phase transition in the nitrogen, it turning from liquid to solid. We computed the mass of the nitrogen evaporated required to reach its triple point temperature. We calculated the effective evacuation rate in the system, taking into account the conductivity of separate components. We determined the minimum vapour evacuation time required. We plotted system temperature and pressure as functions of time. The paper describes possible modernisation of the experimental installation, that is, introducing additional crystallisation centres and monitoring the liquid nitrogen mass using electronic scales

scholarly journals Reply to “Comments on ‘MSE minus CAPE is the True Conserved Variable for an Adiabatically Lifted Parcel’”

2016 ◽  
Vol 73 (6) ◽  
pp. 2577-2583
Author(s):  
David M. Romps
Keyword(s):  
Triple Point ◽  
Specific Energy ◽  
Liquid Water ◽  
Thermodynamic System ◽  
Numerical Calculations ◽  
Two Phase ◽  
Point Temperature ◽  
Dry Air ◽  
Temperature And Pressure ◽  
Triple Point Temperature

Abstract A standard convention in moist thermodynamics, adopted by D. M. Romps and others, is to set the specific energy and entropy of dry air and liquid water to zero at the triple-point temperature and pressure. P. Marquet claims that this convention leads to physically incorrect results. To support this claim, Marquet presents numerical calculations of a lifted parcel. It is shown here that the claim is false and that the numerical calculations of Marquet are in error. In the context of a simple two-phase thermodynamic system, an analysis is presented here of the freedoms one has to choose additive constants in the definitions of energy and entropy. Many other misconceptions are corrected as well.

scholarly journals The risk of static electricity at handling diesel fuel

2021 ◽  
Vol 343 ◽  
pp. 10013
Author(s):  
Mihaela Părăian ◽  
Emilian Ghicioi ◽  
Niculina Vătavu ◽  
Dan Gabor ◽  
Sorin Iuliu Mangu
Keyword(s):  
Electrical Conductivity ◽  
Diesel Fuel ◽  
Static Electricity ◽  
Fuel Type ◽  
Point Temperature ◽  
Flammability Characteristics ◽  
Fuel Tanks ◽  
Temperature And Pressure ◽  
A Company

Diesel fuel in motion when is transporting by pipes when is mixing, pumping, filtering, agitating or by pouring them from one vessel to another can generate static charges. Also, static electricity may occur if the liquid is splashes and forms a mist inside the tank. Accumulation of static electricity can, under certain conditions, be discharge and ignite the flammable/explosive atmosphere. Ignition hazards from static discharges can be eliminated by controlling the generation or accumulation of static charges or by eliminating a flammable mixture where static electricity may be discharged. Factors that need to be considered to reduce the risk of ignition sunt flammability characteristics of explosive atmosphere (the vapor pressure, flash point, temperature, and pressure) and the factors that determine the charging of static electricity (fuel type, electrical conductivity, sulfur content, viscosity, vehicle process: flow rate, pipe diameter, filters, pumps, spark promoters). In this paper are presented some aspects regarding the technical, organizational requirements and responsibilities of the personnel designated to prevent the formation and accumulation of static electricity when loading diesel fuel tanks, starting from a case study, respectively some explosions which occurred to a company during the loading operation.

scholarly journals The succinonitrile triple-point standard: a fixed point to improve the accuracy of temperature measurements in the clinical laboratory.

1983 ◽  
Vol 29 (7) ◽  
pp. 1380-1384 ◽  
Author(s):  
B W Mangum
Keyword(s):  
Fixed Point ◽  
Triple Point ◽  
Temperature Scale ◽  
Clinical Laboratory ◽  
Freezing Behavior ◽  
Temperature Measurements ◽  
Point Temperature ◽  
Practical Temperature ◽  
Practical Temperature Scale ◽  
Triple Point Temperature

Abstract In an investigation of the melting and freezing behavior of succinonitrile, the triple-point temperature was determined to be 58.0805 degrees C, with an estimated uncertainty of +/- 0.0015 degrees C relative to the International Practical Temperature Scale of 1968 (IPTS-68). The triple-point temperature of this material is evaluated as a temperature-fixed point, and some clinical laboratory applications of this fixed point are proposed. In conjunction with the gallium and ice points, the availability of succinonitrile permits thermistor thermometers to be calibrated accurately and easily on the IPTS-68.

scholarly journals Formation of microcrystals under the influence of femtosecond laser radiation on carbon samples in liquid nitrogen

2019 ◽  
Vol 220 ◽  
pp. 02005
Author(s):  
Kirill Khorkov ◽  
Dmitry Kochuev ◽  
Anton Chernikov ◽  
Valery Prokoshev ◽  
Sergey Arakelian
Keyword(s):  
Experimental Study ◽  
Laser Radiation ◽  
Liquid Nitrogen ◽  
Subsurface Layer ◽  
Laser Action ◽  
Target Surface ◽  
Femtosecond Laser Radiation ◽  
Carbon Target ◽  
Direct Laser ◽  
Temperature And Pressure

In this paper, we present the results of an experimental study of the carbon microcrystals formation by direct laser action on the carbon target surface at temperature of liquid nitrogen. It is demonstrated that the formation of microcrystals occurs in the subsurface layer and is caused by the achievement of critical temperature and pressure.

Reduction of Campylobacter jejuni on Poultry by Low-Temperature Treatment

2003 ◽  
Vol 66 (4) ◽  
pp. 652-655 ◽  
Author(s):  
TONG ZHAO ◽  
GABRIEL O. I. EZEIKE ◽  
MICHAEL P. DOYLE ◽  
YEN-CON HUNG ◽  
RHONDA S. HOWELL
Keyword(s):  
Liquid Nitrogen ◽  
Campylobacter Jejuni ◽  
The United States ◽  
Temperature Treatment ◽  
Epidemiologic Studies ◽  
Human Infection ◽  
Internal Temperature ◽  
Low Temperature Treatment ◽  
Different Temperatures ◽  
Time Required

Campylobacter jejuni is a leading cause of acute bacterial gastroenteritis in the United States, with epidemiologic studies identifying poultry as a leading vehicle in human infection. Studies were conducted to determine rates of C. jejuni inactivation on poultry exposed to different cooling and freezing temperatures. A mixture of three strains of C. jejuni originally isolated from poultry was inoculated onto chicken wings at ca. 107 CFU/g. The results of the study revealed that the storage of wings at −20 and −30°C for 72 h reduced the population of C. jejuni on wings by 1.3 and 1.8 log10 CFU/g, respectively. The results with regard to long-term freezing for 52 weeks revealed C. jejuni reductions of ca. 4 and 0.5 log10 CFU/g on wings held at −20 and −86°C, respectively. Protocols were developed to superchill wings in Whirl-Pak bags with liquid nitrogen at −80, −120, −160, and −196°C such that the internal portion of each wing quickly reached −3.3°C but did not freeze. The results with regard to the superchilling of wings at different temperatures for 20 to 330 s (the time required for the wings to reach an internal temperature of −3.3°C) revealed C. jejuni reductions of 0.5 log10 CFU/g for wings held at −80°C, 0.8 log10 CFU/g for wings held at −120°C, 0.6 log10 CFU/g for wings held at −160°C, and 2.4 log10 CFU/g for wings held at −196°C. The superchilling of wings to quickly cool meat to −3.3°C (internal temperature) can substantially reduce C. jejuni populations at −196°C when the wings are submerged in liquid nitrogen, but not at −80 to −160°C when the wings are treated with vapor-state liquid nitrogen. The results of this study indicate that freezing conditions, including temperature and holding time, greatly influence the rate of inactivation of C. jejuni on poultry. The conditions used in the poultry industry to superchill poultry to a nonfrozen-state internal temperature are not likely to substantially reduce Campylobacter populations on fresh products.

Sign in / Sign up

Export Citation Format

Share Document