International Journal of Research in Engineering and Innovation Vol-3, Issue-5 (2019), 321-325 _______________________________________________________________________________________________________________________________________ International Journal of Research in Engineering and Innovation (IJREI) journal home page: http://www.ijrei.com ISSN (Online): 2456-6934 ___________________________________________________________________________________________ Performance evaluation of half effect LiBr-H 2 O vapour absorption systems using multi cascading of vapour compression cycles for low temperature applications Radhey Shyam Mishra Department of Mechanical, Production, Industrial and Automobiles Engineering, Delhi technological University, Delhi, India ________________________________________________________________________________________________________________________ Abstract _____________________________________________________________________________________________________________ 1. Introduction Vapour absorption cooling systems are environmental, clean and economically driven refrigerating cycles. By consuming very small electric power, they can use waste heat or solar energy for cooling. The half effect absorption systems have the advantage of using low temperature heat energy for cooling. The first law & second law performances (i.e. coefficient performance (COP) and the exergetic efficiency) of the half effect absorption systems are found as 0.45 and 0.24, respectively. Arivazhagan R, et.al [1] computed component’s irreversibilities and also are found most of the exergy destruction occurred in the evaporator and in the absorbers and concluded that the half effect absorption systems is the best for cooling driven by low temperature heat energy and the performance of the evaporator and the absorbers is very important for the cycle. In recent years, the fourth generation Hydrofluoro-olefins (HFOs)-R1234yf and R1234ze are being considered as alternative to R134a. A number of studies have been carried out using HFO 1234yf and HFO 1234ze. Although, R134a is a wide spread used refrigerant due to its commercial availability, similar properties to R12, less ODP value, excellent thermal stability, non toxic and non-flammability etc has high GWP value is more than 1300. The European Union (EU) regulation is phasing out the current generation HFCs like R134a due to its high GWP and environment consequences. The thermodynamic and environmental characteristics of refrigerants HFC 134a, HFO 1234yf & HFO 1234ze are shown in Table-1. The European Union (EU) regulation is phasing out the current generation HFCs like R134a due to its high GWP and environment consequences. A number of studies have been carried out using R1234yf and R1234ze [2]. In the notable studies [3-8], Yataganbaba et al. [3] performed exergy analysis on a two evaporator vapour compression refrigeration system using R1234yf, R1234ze and R134a as refrigerants. The two refrigerants R1234yf and R1234ze were good alternatives to R134a regarding their environment friendly properties. Sanchez et al. [8] compared five low GWP refrigerants R152a, R1234yf, R1234ze, R290 and R600a for the replacement of R134a using hermetic compressor in the experimental test rig and Most of the absorption cooling system use either LiBr-H2O or NH3-H2O solutions. The LiBr-H2O system can operate at a low generator temperature with better coefficient of performance than NH3-H2O system. However, COP of absorption system is relatively less as compared to the compression system. To improve its performances, several modifications have been made in the cycle. Therefore, this paper mainly deals with performance evaluations of half effect LiBr-H2O vapour Absorption Systems using multi cascading of vapour compression cycles for low temperature applications (at -100 o C) used for cryogenics applications and comparison at -50 o C evaporator temperature in the low temperature circuit using HFO refrigerants in the intermediate temperature circuit and found that half effect LiBr-H2O vapour Absorption Systems using multi cascading of vapour compression cycles for low temperature applications using HFC152a in intermediate temperature cycle and HFC-134a in LTC gives better thermodynamic performances than by using HFO refrigerants in intermediate temperature cycle & HFC-134a in low temperature cycle. The thermodynamic performances using HFO-1234ze in intermediate temperature cycle is better than using HFO-1234yf in intermediate temperature cycle. © 2019 ijrei.com. All rights reserved Keywords: Multi-Cascade systems, Half effect LiBr-H2O integrated absorption systems, HFO refrigerants Corresponding author: R.S. Mishra Email Address: hod.mechanical.rsm@dtu.ac.in 321 http://doi.org/10.36037/IJREI.2019.3506