k10798 ashok rac me 6th sem

“Theoritical analysis of cascade refrigeration system for cooling

application”PRESENTED BY:- Ashok kumar singhUid- k10798course – B.techBranch –mechanicalYear/Sem- 3rd/6th

PRESENTED TO:-Mr. Aditya MishraAssistant professor Mechanical Deptt.

CAREER POINT UNIVERSITY, KOTAMAJOR ASSIGNMENT OF RAC

CONTENT1. Introduction.2. Types.3. Description.4. Assumptions.5. Graphs.6. Conclusion.7. References.

• It is a freezing system• Two kinds of refrigerants are

used having different boiling points

• Both refrigerants run in their own independent freezing cycle

• Both cycles are joined by heat exchanger

INTRODUCTION

• Natural refrigerant have low ODP and GWP in nature

• Low temperature cycle R744

• High temperature cycle R134a,R290,R717, R404a

TYPES OF REFRIGERANT S

During process 1-2 the low temperature cycle refrigerant is compressed isentropically. It is then passes through cascade condenser where it gives heat to refrigerant of higher temperature cycle (process 2-3). It is expands in throttling device (process 3-4) and further passes to evaporator (process 4-1) to produce necessary refrigerating effect. In higher stage refrigerant is compressed in high temperature cycle compressor (process 5-6), then it passed through condenser where it rejects heat (process 6-7). It expands isentropically in throttling device (process 7-8) further passes to cascade condenser where heat transfer between two refrigerants takes place.

DESCRIPTION

DESCRIPTION

• Adiabatic and irreversible compression• Negligible pressure and heat drop in the piping or

system components.• Isenthalpic expansion of refrigerants in expansion

valves.• Heat transfer process in heat exchanger is isobaric.• Changes in kinetic and potential energy are negligible.

ASSUMPTIONS

EQUATIONS

Low evaporating temperature range (TE,LT) of -55˚C to -30˚C

Increasing the higher stage temperature of cascade system (TC,HT) from 30˚C to 55˚C

GRAPHS

Cascade condenser temperature (ΔTCC) is increased from 1˚C to 13˚C

Condensing temperature (TC,LT) increases from -30°C to 10°C

GRAPHS

• From the comparative assessment of different cascade refrigeration pairs; the R744-R717 pair has the maximum COP

• The cascade refrigerant pair R744-R717 has higher COP as compared to other refrigerants pairs R744-R134a, R744-R290 and R744-R404A for the same TC, TE and TCASC; other parameters remain constant

• R744-R717 pair has the higher COP as compared to other refrigerant pairs for cooling application

CONCLUSION

• World Academy of Science, Engineering and Technology International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering Vol:8, No:8, 2014[A. D. Parekh, P. R. Tailor]

• International Journal of Innovative Research in Science, Engineering and Technology(An ISO 3297: 2007 Certified Organization) Vol. 4, Special Issue 6, May 2015.

[ Gajendrasinh G. Parmar , Dr. R. G. Kapadia• Applied Thermal Engineering, Elsevier, 2009, 29 (8-9), pp.1577. <10.1016/j.applthermaleng.2008.07.006>. <hal-00581928>• GOOGLE SEARCH ENGINE• WIKIPAEDIA

REFERENCES