https://orcid.org/0000-0002-3005-614X
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ABSTRACT
This paper discusses the evolution of stratification and self-pressurization in a cryogenic storage tank. The heat ingress due to the large temperature difference between ambient and cryogen leads to thermal stratification and self-pressurization. The prediction of the thermodynamic state of cryogen is required for the successful execution of any space mission. An experimental cryogenic test tank which is a combination of an evacuated vacuum jacket and multilayered insulation has been designed, fabricated and is used for stratification studies using liquid nitrogen as the model propellant. Stratification at two conditions were tested; ‘venting’ and ‘non-venting’. During venting condition, only saturated boiling occurs, and the degree of thermal stratification is very less. Whereas during non-venting condition, there is a significant amount of thermal stratification and the degree of thermal stratification increases with working pressure. For a deeper understanding of the phenomenon and better prediction of the state of cryogen, a numerical model had been developed and validated with the experimental result. A stratification parameter has been used to quantify the degree of stratification for both “venting” and “non-venting” conditions. The model developed can be used for accurate prediction of the state of cryogen.
Nomenclature
| C | = | Specific heat, J/kg.K |
| F | = | Body force, N/m3 |
| g | = | Acceleration due to gravity, m/s2 |
| K | = | Thermal conductivity, W/(m.K) |
| = | Mass flow rate, kg/s | |
| n | = | Normal direction |
| P | = | Pressure, Pa |
| Sh | = | Energy source term |
| T | = | Temperature, K |
| t | = | Time, s |
| = | Velocity vector, m/s |
Greek symbols
| α | = | Volume fraction |
| β | = | Thermal expansion coefficient, K−1 |
| μ | = | Absolute viscosity, Pa.s |
| ρ | = | Density, kg/m3 |
| λ | = | Thermal stratification parameter |
Subscripts
| l | = | Liquid |
| v | = | Vapour |
Additional information
Funding
Notes on contributors
Vishnu S B
Vishnu S B is a Ph.D student in the Department of Mechanical Engineering, National Institute of Technology Calicut, India. He received his Master’s and Bachelor’s degree from Kerala University, India in 2014 and 2012 respectively. Currently he is working on thermal stratification in Cryogen storage tanks.
Soumyajit Bhowmick
Soumyajit Bhowmick is a Masters student in the Department of Mechanical Engineering, National Institute of Technology Calicut. He received his Bachelors degree in Mechanical Engineering from Heritage Institute of Technology Kolkata. Currently he is working on thermal stratification phenomenon during cryogen storage.
Biju T. Kuzhiveli
Biju T. Kuzhiveli received his Doctoral degree in the field of cryogenic refrigerators for onboard space craft applications from the department of mechanical engineering, Indian Institute of Technology Bombay in the year 1993, subsequently he proceeded with his post-doctoral work in the Institut de recherche sur l'hydrogène, Canada and worked with the development of magnetic refrigeration systems. Served for two terms as a visiting faculty in Université du Québec Canada, continued to work in the field of cryogenics, hydrogen technologies, fuel cells, and gasoline engines for quick hydrogen conversion. Also worked with prestigious national organsations in India; Defense research and development organization and Indian space research organization as an officer/Scientist for more than a decade in the field of various Cryogenic systems, Cryogenic rocket engines and Cryogenic upper stage design and continue to work as a consultant also to Nuclear centers. Presently working with National institute of Technology Calicut as a Professor and look after Centre for advanced studies in Cryogenics.