This document discusses the thermodynamic analysis of a nitrogen liquefaction system based on the Kapitza cycle, which is a modified Claude cycle. Some key points:
- The Kapitza cycle was modified from the Claude cycle by eliminating the third heat exchanger and using a rotary expander instead of a reciprocating one.
- A mathematical model of the Kapitza cycle was developed using EES to evaluate parameters like expander flow fraction, isentropic efficiency, and the figure of merit (FOM) of the cycle.
- The FOM is defined as the ratio of theoretical minimum work to actual work and provides a measure of how close the real system comes to ideal performance.
REVIEW OF CASCADE REFRIGERATION SYSTEM WITH DIFFERENT REFRIGERANT PAIRSijiert bestjournal
A Comparative assessment of a cascade refrigeration cycle with different refrigerant pair is presented in this paper. R744 is used in Low-temper ature (LT) cycle whereas R134a,R290,R717 and R404A (R125(44%)/R143a(52%) /R134a(4%)) are use d in the High-temperature (HT) cycle. The effects of the thermodynamic parameters on the cascade system are evaluated with an objective to find the best working fluid pair based on COP. R 744-717 is selected based on thermodynamic and environmental performance. A parametric evaluation is also presented for R744-R717 working pair by varying parameters like sub cooling,superheatin g,evaporating,condensing temperature and temperature difference in the cascade condenser of the system.
Design Calculation of Main Components for Lab Based Refrigeration Systemijtsrd
The purpose of this paper is for the students to know the basic function of main components of refrigeration system. Theoretical and experimental of design calculation of main components and their results are reported in this paper. During the performance of testing, the length of expansion device is varied and the result data are also described. In this system, R134a refrigerant is used as working substance. Because it is now being used for a replacement of R 12 CFC refrigerant. It can be handled safely because it is not toxic, corrosive and flammable. Moreover, it has no damage effect to ozone layer and greenhouse. Ko Ko | Aye Aye San | Khin Maung Than "Design Calculation of Main Components for Lab Based Refrigeration System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-6 , October 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29212.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/29212/design-calculation-of-main-components-for-lab-based-refrigeration-system/ko-ko
REVIEW OF CASCADE REFRIGERATION SYSTEM WITH DIFFERENT REFRIGERANT PAIRSijiert bestjournal
A Comparative assessment of a cascade refrigeration cycle with different refrigerant pair is presented in this paper. R744 is used in Low-temper ature (LT) cycle whereas R134a,R290,R717 and R404A (R125(44%)/R143a(52%) /R134a(4%)) are use d in the High-temperature (HT) cycle. The effects of the thermodynamic parameters on the cascade system are evaluated with an objective to find the best working fluid pair based on COP. R 744-717 is selected based on thermodynamic and environmental performance. A parametric evaluation is also presented for R744-R717 working pair by varying parameters like sub cooling,superheatin g,evaporating,condensing temperature and temperature difference in the cascade condenser of the system.
Design Calculation of Main Components for Lab Based Refrigeration Systemijtsrd
The purpose of this paper is for the students to know the basic function of main components of refrigeration system. Theoretical and experimental of design calculation of main components and their results are reported in this paper. During the performance of testing, the length of expansion device is varied and the result data are also described. In this system, R134a refrigerant is used as working substance. Because it is now being used for a replacement of R 12 CFC refrigerant. It can be handled safely because it is not toxic, corrosive and flammable. Moreover, it has no damage effect to ozone layer and greenhouse. Ko Ko | Aye Aye San | Khin Maung Than "Design Calculation of Main Components for Lab Based Refrigeration System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-6 , October 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29212.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/29212/design-calculation-of-main-components-for-lab-based-refrigeration-system/ko-ko
Air separation units: technology on the move!BRONSWERK
Several industries require pure nitrogen, oxygen or argon for their production processes. Cryogenic Air Separation is the process that enables the separation of these compounds. Interested in this technology? Have a look at this content and contact us if we can help!
Refrigeration and its Terminologies;
(i) Capacity or Units of refrigeration,
(ii) COP,
(iii) Types of Refrigerants
(iv) Refrigerants and their desirable properties,
Refrigeration Cycles:
(i) Vapor compression refrigeration system; description, analysis, refrigerating effect.
(ii) Vapor compression refrigeration system Special Case 1,2,3;
(iii) Deviation of the Actual Vapor Compression Refrigeration Cycle from the Ideal Cycle
Air cycle refrigeration;
a) reversed Carnot cycle,
b) reversed Brayton cycle,
c) Vapor absorption refrigeration system.
Previous Year Problems with Solution
ANALYSIS OF VAPOR COMPRESSION REFRIGERATION SYSTEM WITH DIFFERENT CONFIGURATI...ijiert bestjournal
A capillary tube is widely used as throttling device in small sized refrigeration and air - conditioning applications having capacity less than 3 TR. This research paper provides a set of capillary tube performance data in a vapor compression refrigeration system using R - 134a as working fluid. Several capillary tubes with different length and inner diameter were selected as test sections. Mass flow rate and Pressure drop through capillary tube was measured for several inlet temperatures of each capillary tube. The sub cooling and superheating temperatures are maintained constant throughout the experimentation. Experimental condit ions for the condensing temperatures were selected from 38 to 54� C in the interval of 2� C. The effect of above given parameters on the Pressure difference,Power input,Evaporating capacity and Coefficient of performance for R - 134a through the helically coiled capillary tube has been analyzed.
There are many applications where
refrigeration plant is required to meet the various refrigerating
loads at different temperatures. For example, systems for hotels,
large restaurant, institutions and food preservation industries. In
these cases, it is necessary that each location is cooled by separate
evaporators to maintain the particular temperature and produce
the required refrigeration load. Hence it requires different
refrigerating units with single evaporator for each location.
Instead it will be beneficial to use a refrigerating unit with
multiple evaporators working at different temperatures.
Therefore, it is the purpose of this paper to introduce vapor
compression system which uses a single compressor and
individual expansion devices to provide the concurrent testing.
Also we have to analyse the performance of the refrigeration
system when different refrigerants are used in the same system
with changing suction and discharge pressure. The performance
parameters will be COP & the refrigerating effect obtained at
evaporator.
Aircraft refrigeration system (air cooling system)Ripuranjan Singh
Aircraft air refrigeration systems are required due to heat transfer from many external and internal heat sources (like solar radiation and avionics) which increase the cabin air temperature. With the technological developments in high-speed passenger and jet aircraft's, the air refrigeration systems are proving to be most efficient, compact and simple. Various types of aircraft air refrigeration systems used these days are.
Simple air cooling system
Simple air evaporative cooling system
Boot strap air cooling system
Boot strap air evaporative cooling system
Reduced ambient air cooling system
Regenerative air cooling system
COMPRESSOR EFFICIENCY AND TURBINE EFFICIENCY.
Comparison of Various Air Cooling Systems used for Aircraft ON basis of dart
Presentation of Refrigeration SimulationShafiul Munir
This presentation is the aftermath of a laboratory experiment to understand the refrigeration cycles and functions in detail. It also shows the various uses and modifications refrigeration system accounts to.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
Air separation units: technology on the move!BRONSWERK
Several industries require pure nitrogen, oxygen or argon for their production processes. Cryogenic Air Separation is the process that enables the separation of these compounds. Interested in this technology? Have a look at this content and contact us if we can help!
Refrigeration and its Terminologies;
(i) Capacity or Units of refrigeration,
(ii) COP,
(iii) Types of Refrigerants
(iv) Refrigerants and their desirable properties,
Refrigeration Cycles:
(i) Vapor compression refrigeration system; description, analysis, refrigerating effect.
(ii) Vapor compression refrigeration system Special Case 1,2,3;
(iii) Deviation of the Actual Vapor Compression Refrigeration Cycle from the Ideal Cycle
Air cycle refrigeration;
a) reversed Carnot cycle,
b) reversed Brayton cycle,
c) Vapor absorption refrigeration system.
Previous Year Problems with Solution
ANALYSIS OF VAPOR COMPRESSION REFRIGERATION SYSTEM WITH DIFFERENT CONFIGURATI...ijiert bestjournal
A capillary tube is widely used as throttling device in small sized refrigeration and air - conditioning applications having capacity less than 3 TR. This research paper provides a set of capillary tube performance data in a vapor compression refrigeration system using R - 134a as working fluid. Several capillary tubes with different length and inner diameter were selected as test sections. Mass flow rate and Pressure drop through capillary tube was measured for several inlet temperatures of each capillary tube. The sub cooling and superheating temperatures are maintained constant throughout the experimentation. Experimental condit ions for the condensing temperatures were selected from 38 to 54� C in the interval of 2� C. The effect of above given parameters on the Pressure difference,Power input,Evaporating capacity and Coefficient of performance for R - 134a through the helically coiled capillary tube has been analyzed.
There are many applications where
refrigeration plant is required to meet the various refrigerating
loads at different temperatures. For example, systems for hotels,
large restaurant, institutions and food preservation industries. In
these cases, it is necessary that each location is cooled by separate
evaporators to maintain the particular temperature and produce
the required refrigeration load. Hence it requires different
refrigerating units with single evaporator for each location.
Instead it will be beneficial to use a refrigerating unit with
multiple evaporators working at different temperatures.
Therefore, it is the purpose of this paper to introduce vapor
compression system which uses a single compressor and
individual expansion devices to provide the concurrent testing.
Also we have to analyse the performance of the refrigeration
system when different refrigerants are used in the same system
with changing suction and discharge pressure. The performance
parameters will be COP & the refrigerating effect obtained at
evaporator.
Aircraft refrigeration system (air cooling system)Ripuranjan Singh
Aircraft air refrigeration systems are required due to heat transfer from many external and internal heat sources (like solar radiation and avionics) which increase the cabin air temperature. With the technological developments in high-speed passenger and jet aircraft's, the air refrigeration systems are proving to be most efficient, compact and simple. Various types of aircraft air refrigeration systems used these days are.
Simple air cooling system
Simple air evaporative cooling system
Boot strap air cooling system
Boot strap air evaporative cooling system
Reduced ambient air cooling system
Regenerative air cooling system
COMPRESSOR EFFICIENCY AND TURBINE EFFICIENCY.
Comparison of Various Air Cooling Systems used for Aircraft ON basis of dart
Presentation of Refrigeration SimulationShafiul Munir
This presentation is the aftermath of a laboratory experiment to understand the refrigeration cycles and functions in detail. It also shows the various uses and modifications refrigeration system accounts to.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
EXPERIMENTAL INVESTIGATION OF WASTE HEAT RECOVERY SYSTEM FOR DOMESTIC REFRIGE...IAEME Publication
The objective of this project was to determine the energy savings associated with improved utilization of waste heat from a domestic refrigerator. Domestic refrigerators maybe operate
continuously to maintain proper food storage condition. The continual operation of this equipment accounts more electrical energy consumption. Furthermore, a significant amount of waste heat is rejected by the condensers of refrigerator.
The COP of the refrigeration increasing the performance and to get high efficiency of the refrigeration system. By using nano coating over the evaporator of the refrigeration component the objective can be achieved. The improper heat dissipation occurred in the heat exchanger components causes effect in performance. The vapour compression refrigeration system consuming the high power. Though the energy taken for the refrigeration process has increased and leads to more power consumption. In order to increase the performance, Nano coating Copper Oxide has been applied over the evaporator. By applying the Nano coating Copper Oxide over the evaporator the COP increased. In result the energy required for the refrigeration process and global warming problems has been reduced. By addition of nanoparticles to the refrigeration results in improvements in the COP of the refrigeration, thereby improving the performance of the refrigeration system. In this experiment the effect of using CuO-R134a in the vapour compression system expected COP will be increased by 5% with nano coating.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Design Calculation of Lab Based Vapour Compression Systemijtsrd
This paper deals with experimental investigation to calculate the value of main components of vapor compression refrigeration system and experimental results by using three different length of the capillary tube. At present, there are many types of refrigeration systems but the most widely used is vapor compression refrigeration system. This system is mainly used in air conditioning in buildings, electronic materials, automobile air conditioners, freezers, household refrigerators and even in supermarkets. This lab based refrigeration system is used R 134a because it can be replaced successfully for R 12 refrigerant and useful for many applications now. Moreover, it can be handling safely and has no damage effect to ozone layer. Ko Ko | Khin Maung Than | Aye Aye San "Design Calculation of Lab Based Vapour Compression System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-6 , October 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29213.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/29213/design-calculation-of-lab-based-vapour-compression-system/ko-ko
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
"Impact of front-end architecture on development cost", Viktor TurskyiFwdays
I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...
G04563844
1. IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 04, Issue 05 (May. 2014), ||V6|| PP 38-44
International organization of Scientific Research 38 | P a g e
Thermodynamic Analysis of Kapitza Cycle based on Nitrogen
Liquefaction
Vijay Singh Bisht
Assistant Professor Department of Mechanical Engineering, Uttaranchal University,
Dehradun ,Uttarakhand, India
Abstract: - Cryogenic technology is used for liquefaction of many gases and it has several applications in food
process engineering. The thermodynamic analysis of various cryogenic systems for liquefaction of different
gases has been done by many researchers. Thermodynamic analysis of a nitrogen liquefaction system based on
Kapitza cycle which is a modified Claude cycle has been carried out to evaluate various vital parameters of the
system.
Parametric evaluation using EES Commercial helps to identify the effects of expander flow fraction,
isentropic efficiency of expander on the FOM (figure of merit) of the liquefaction cycle.
The study computes helps in selecting expander flow fraction, operating temperature levels of expanders, and
approach temperature of the heat exchangers through them. Results from the analysis may help evolving
guidelines for designing appropriate thermodynamic cycles for practical nitrogen liquefaction systems.
I. INTRODUCTION
The word cryogenics stems from Greek and means "the production of freezing cold". The science and
technology of producing a low-temperature environment is generally referred to as cryogenics. It is perhaps
appropriate to start with some definitions. The word cryogenics has its origin in the Greek language where
"cryos" means frost or cold and "gen" is a common root for the English verb to generate. However, the term is
used today as a synonym for the low-temperature state. It is not well-defined at what point on the temperature
scale refrigeration ends and cryogenics begins, but most scientists assume it starts at or below -150 °C or 123 K
(about -240 °F). The National Institute of Standards and Technology at Boulder, Colorado has chosen to
consider the field of cryogenics as that involving temperatures below −180 °C (-292 °F or 93.15 K). This is a
logical dividing line, since the normal boiling points of the so-called permanent gases (such as helium,
hydrogen, neon, nitrogen, oxygen, and normal air) lie below −180 °C while the Freon refrigerants, hydrogen
sulfide, and other common refrigerants have boiling points above −180 °C.
The cryogenic mean literally, the production of ice cold, however the term is used today as a for low
temperatures. Cryogenics is defined as that branch of physics which deals with the production of very low
temperatures and their effect on matter a formulation which addresses both aspects of attaining low temperatures
which do not naturally occur on Earth, and of using them for the study of nature or the human industry. In a
more operational way it is also defined as the science and technology of temperatures below 123 K.
1). 0.01-.1k = Dilution refrigerator
2). 1-10 k = Magnetic refrigerator
3). 10-50 k = Liquid helium
4). 50-123 k = Air liquefies
APPLICATION OF LIQUID NITROGEN IN FOOD PROCESSING [4][5][7][8][9]
1.Freezing of baked goods, shrimp, meats, soups, and so on requires a process known as CRYO-QUICK in the
food processing industry.
2.Liquid nitrogen is widely used in food processing and food transportation because of minimum production
costs.
3. Cryogenic (i.e., very low-temperature) freezing results in smaller weight losses from dehydration than
traditional mechanical freezing. Frozen food processors can thus preserve the quality of. Their products with a
freezing system that uses environmentally friendly liquid nitrogen.
4. Due to its own extremely cold temperature, liquid nitrogen can enable a cryogenic system to freeze food
within minutes instead of the hours traditionally required with other systems The faster freezing causes the
formation of small ice crystals, which then help ensure product moisture and quality are maintained longer.
5.In freezing on microbial flora of ground beef patties. It was observed that LN2 freezing produced significantly
greater reduction in microbial activity than the mechanical air blast freezer. Patties containing 30% fat provided
greater.
2. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 39 | P a g e
6.LN2 freezing of prawns over. It was reported that the beneficial effect of LN2 freezing over conventional plate
freezing can exist even after 59 days at a commercial storage temperature of 255 K.
7.The use of LN2 as a secondary refrigerant along with ice for transportation of wet fish. It is found that the ice
melting rate can be reduced by about 50%.
8. The freezing point and freezing rate of tilapia meat in LN2 freezers at186 and 145K. It is found that the
freezing rate in LN2 freezing is independent of thickness of the product to be frozen.
9. Liquid nitrogen used in polar stream system for refrigerated transportation of frozen fish.
II. KAPITZA LIQUEFACTION SYSTEM[2]
Kapitza (1939) modified the basic Claude system by eliminating the third heat exchanger or low
temperature heat exchanger. Several notable practical modifications were also introduced in this system a rotary
expansion engine was instead of reciprocating expander. The first or high temperature heat exchanger in the
kapitza system was actually a set of valved regenerators, which combined the cooling process with the
purification process. The incoming warm gas was cooled in one unit and impurities were deposited there, while
the outgoing stream warmed up in the other unit and flushed out the frozen impurities deposited in it. Kapitza
did a careful analysis of turbo-refrigeration and developed radial flow turbines for air refrigeration.
2.1 Components Used[2]
1. COMPRESSOR: - It is a device used to reduce the volume of gaseous air and increase the pressure.
Generally for cryogenic application compressor with high compression ratio are used. To achieve high stage
compression ratio a number of compressor are used in series rather using a single compressor. It also reduces
work consumption. For present work isothermal compression process is used.
2. Expander: - A rotary expansion engine was used have high efficiency than reciprocating engine and the loss
also less in rotary expender.
3. HEAT EXCHANGER: - Heat exchangers are devices which transfer heat from hot fluid stream to cold fluid
stream. In heat exchanger hot fluid temperature decreases and there is increase in temperature of cold fluid. By
losing heat hot fluid is prepared for throttling process and similarly by gaining heat cold fluid heated up for
compression process.
4. VALVE: - A throttling valve is used to reduce the pressure of the compressed air so that liquid air can be
produced and stored. The process is assumed to be isenthalpic expansion.
5.SEPARATOR/DISTILLATION COLUMN: - In this chamber air is separated into desired components like
liquid N2, liquid O2 etc. and the gaseous part is again recirculated.
6. MIXER: - It is a device helps to maintain a constant flow rate of air into the compressor. The extra amount of
air is added into incoming stream from separator. The process is assumed to be isobaric.
2.2 Advantages [3]
1. A rotary expansion engine of high isentropic efficiency is used instead of reciprocating engine as in
Claude cycle.
2.First heat exchanger replaced by a set of valved regenerators which combined the cooling process with
purification process.
3.Kapitza cycle can be operate at relatively low pressure is lower than critical pressure of nitogen gas.
III. MATHEMATICAL MODEL
A computer program has been developed depending upon the requirements of engineering equation solver
(EES). The equations are written in the equation window of EES in the FORTRAN LANGUAGE. EES solves
these equations itself on giving „calculate‟ command [10].
Assumptions:
1. The system is at steady state condition. All processes are steady flow processes.
2. Neglecting the effects of kinetic and potential energy in analysis of all the components of system
3.There is no heat in-leak to the system.
Mass balance
Let m = mass flow rate of N2 compressed = 0.1kg/s
m e = mass flow rate of N2 bypassed to the expander = 0.06m kg/s
m 4 = mass flow rate of N2 passing through the second heat exchanger = 0.04m kg/s
3. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 40 | P a g e
m = m e+ m 4 (1)
xe =
me
m
= fraction of nitrogen gas going to expander
m 6 = mass flow rate of liquid N2 produced
y =
m6
m
= liquid yield
Applying First Law for steady flow to the heat exchangers, the expansion valve and the liquid receiver as a unit
excluding compressor, for no external heat transfer to the control volume then
m − m6 h10 + m6h6 + m11h11 − mh2 − meh3 = 0 (2)
On arranging terms and putting value of xeand y we get
y =
m6
m
=
h10−h2
h10−h6
− xe ×
h3−h11
h10−h6
(3)
In case of actual system we consider isentropic efficiency of turbine
Ƞ 𝐞
=
𝐡 𝟑−𝐡` 𝟏𝟏
𝐡 𝟑−𝐡 𝟏𝟏
Then yield becomes
y =
m6
m
=
h10−h2
h10−h6
− xe ×
h3−h11
h10−h6
(4)
Theoretical minimum work requirement or the system [1]
wi = T1 s1 − s6 − h1 − h6 (5)
work requirement for the system
𝐰 =
𝟏
𝐲
𝐓𝟏 𝐬 𝟏 − 𝐬 𝟐 − (𝐡 𝟏 − 𝐡 𝟐) − 𝐱 𝐞(𝐡 𝟑 − 𝐡 𝟏𝟏) (6)
Considering isentropic efficiency of turbine, the actual work requirement
w=
1
y
T1 s1 − s2 − (h1 − h2) − Ƞe
xe(h3 − h11) (7)
3.1 Figure of merit (FOM) [1]
It is defined as the ratio of theoretical work requirement and actual work requirement for the system.
The figure of merit is a number between 0 and 1.It gives measure of how closely the actual system approaches
the ideal system performance .If the figure of merit greater than unity, it would be in violation of the second law
of thermodynamics. The above equation is of FOM is for liquefaction system.
𝐅𝐎𝐌 =
𝐖𝐈
𝐖
Kapitza system
Fig. 1 Kapitza system
4. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 41 | P a g e
z
Fig.2 Kapitza cycle on T-s plane
Fig.3 Plot Variation of for with efficiency of expander and FOM
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.5 0.6 0.7 0.8
FOM
expanderisentropic efficiency
FOM
atDTHX_1=5K,D
THX_2=10K
FOM
atDTHX_1=10K,
DTHX_2=15K
FOM
atDTHX_1=15K,
DTHX_2=20K
FOM
atDTHX_1=20K,
DTHX_2=25K
5. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 42 | P a g e
Fig. 4 Plot of Yield and FOM with different fraction of nitrogen going to expander.
Fig. 5 Plot of Yield and FOM at different expander tempretures.
6. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 43 | P a g e
Fig. 6 Plot of Yield against expander efficiency.
Fig. 7 Plot of pressure ratio at different heat capacity ratio of heat exchangers.
IV. RESULTS AND DISCUSSION
A mathematical model has been developed for theestimation of yield of liquid nitrogen produced and FOM
(figure of merit) of Kapitza system for varying compressor exit pressure,expander flow rate ratio, and isentropic
efficiency of expander, approach temperature of regenerator and heat exchanger and inlet temperature of
expander
1. From figure 3 the plot between expander efficiency and FOM at different approach temperatures of
regenerator and heat exchanger, we conclude at given expander efficiency that the best FOM is achieved at 5
K and 10K approach temperature of regenerator and heat exchanger respectively.As shown in graph by
considering various approach tempratures for regenerator and heat exchanger the curve of 5 K and 10K
approach temperature of regenerator and heat exchanger have highest value of FOM obtained is approximately
.78.
.
0.6 0.65 0.7 0.75 0.8 0.85 0.9
0.09
0.1
0.11
0.12
0.13
0.14
0.15
0.16
ne [-]
y[-]
yy
5 10 15 20 25 30 35
0.1
1
10
Pr [-]
CR,2,CR,1
7. Thermodynamic analysis of Kapitza cycle based on nitrogen liquefaction
International organization of Scientific Research 44 | P a g e
2 From fig. 4 Plot of Yield and FOM with different fraction of nitrogen going to expander, shows that both yield
and FOM increases. It appears that to maximize the y(yield) x(expander flow rate ratio) should take on its
maximum value, however conservation of mass flow requires that y+x≤1 , because some gas also returned
from lower pressure side for cooling of heat exchangers.
3. plot between expander inlet temperature as input parameter or independent parameter,yield and FOM are
dependent parameters both yield and FOM increases with increase in expander inlet temperature. The liquid
yield rise is more sensitive than the fom,we here take care the range of expander inlet temperature from 260 to
280 k because we also have taken care of cooling done by regenerator at given approach temperature.
4. As from figure 6 to study the impact of expander efficiency on the performance of Kapitza liquefaction cycle,
isentropic efficiency of the expanders is varied in a practically possible range 55–85%. When varying the
isentropic efficiency of expander observed from the Fig. 6 that the relationships between the liquid production
and the isentropic efficiency of expanders are almost linear and the trends are very similar to each other.
5.It is been found that for HX1 Heat Capacity Ratio CR1 is less than 1 which is resulting from the reduced
return stream flow due to withdrawal of liquid from the cycle. For HX2 that are connected in parallel to the
expander, the return stream flow is higher, and therefore, they always have CR greater than 1. This is due to the
reason that a part of the high pressure stream (forward stream) before HX2 is diverted through EXP1 and the
expander stream finally join the return flow after these two heat exchangers.
V. CONCLUSIONS
1 The best FOM is achieved at 5 K and 10K approach temperature of regenerator and heat exchanger
respectively. The highest value of FOM obtained is approximately .78.
2. The relationships between the liquid production and the isentropic efficiency of expanders are almost linear .
3. Both yield and FOM increases with increase in expander inlet temperature. The liquid yield rise is more
sensitive than the fom,
REFERENCES
[1] Barron R F “Cryogenic Systems‟, second edition, New York, Oxford University Press,1985.
[2] S.Prasad “Study Cryogenics Cycles with ASPEN - HYSYS simulation” N.I.T Rourkela 2009.
[3] SciverS.W.V.“Heliumcryogenics”,Timmerhaus K.D.,RizzutoC.“International cryogenics monograph
series Pentium publishing corporationNew York, 1986.
[4] Ventura G,RisegariL.“The art of cryogenics low-temperature experimental techniques” published in
Elsevier Ltd, 2008.
[5] Kraft AA et al. Effect of composition and method of freezing on microbial flora of ground beef patties. J
Food Sci 1979; 44:350–5.
[6] Chakrabarti R, Chaudhary DR. Advantages of liquid nitrogen freezing of penaeusmonodon over
conventional plate freezing Fishery Techno 1987;24:44–7.
[7] Chattopadhyay P, Roy AK, Lala S. Studies on Transportation of wet fish IV. Use of liquid nitrogen as a
secondary refrigerant. J Food SciTechnol 1987;24:178–80.
[8] Chen YL, Bonnie SP. Freezing tilapia by airblast and liquid nitrogen––freezing point and freezing ate. Int
J Food Sci Technol1995;30:159–66.
[9] Goswami TK, Das H, Bose AN. A system design for transportation of frozen fish using liquid nitrogen.
In: Proceedings of INCONCRYO‟85. 1985, p. 332–41.
[10] Klein, S.A. 2012. Engineering Equation Solver.VersionV9.205 3-D. F Chart Software.