Exergy and Exergoenvironmental Assessment and Optimization of Low GWP Refrigerant for Vapor Compression Heat Pump System
Published at : 07 Dec 2018
Volume : IJtech
Vol 9, No 6 (2018)
DOI : https://doi.org/10.14716/ijtech.v9i6.2369
Aisyah, N., Alhamid, M.I., Nasruddin, 2018. Exergy and Exergoenvironmental Assessment and Optimization of Low GWP Refrigerant for Vapor Compression Heat Pump System . International Journal of Technology. Volume 9(6), pp. 1256-1265
| Nyayu Aisyah | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Muhammad Idrus Alhamid | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Nasruddin | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
Scientists have worked assiduously to find low GWP refrigerants for HVAC systems that specifically address the environmental problems of ozone depletion and global warming. R1234ze and R1234yf were considered as potential alternatives to conventional refrigerants such as R410A. Thermodynamic analysis of 4 kW air conditioning systems was conducted to assess system performance of R1234ze and R1234yf. Furthermore, exergy and exergo-environmental analysis were carried out for the heat pump system using selected environmentally friendly refrigerants. Finally, by using a multi-objective genetic algorithm, the optimum operating condition, including evaporation temperature, condensing temperature and mass flow refrigerant was determined. The result showed that the optimum operating condition of 20oC evaporation temperature, 42.57oC condensation temperature and 0.02 kg/s mass flow rate, led to exergy efficiency of 51.92% and an exergo-environmental value of 101.925 mPts/h. R1234ze has a comparable performance to R410A or performs even better.
Exergo-environmental; Exergy; Heat pump; Low GWP refrigerants
The search for alternative refrigerants has been, and still remains, a prevalent topic in the history of Heating Ventilating Air Conditioning systems (HVAC systems) (Mohd-Ghazali et al., 2011; Alhamid et al., 2013). Chlorofluorocarbon (CFC), as the first refrigerant used in HVAC systems was banned by the Montreal Protocol in 1987 to be replaced by Hydrofluorocarbon (HFC) and Hydrochlorofluorocarbon (HCFC). In 1996, the phase-out of CFC refrigerants was completed, and HFC and HCFC were recommended as CFC alternatives because of their low Ozone Depletion Potential (ODP). However, in 1990 it was found that both of these low ODP refrigerants actually contribute to the global warming phenomenon. Consequently, the Kyoto Protocol, issued in 1997, aimed to reduce global warming by decreasing greenhouse gases with the use of low Global Warming Potential (GWP) refrigerants (Yildirim et al., 2017).
Many alternative refrigerants were introduced to replace conventional refrigerants. For example, due to its low GWP value, low flammability, and comparable performance, the R1234 refrigerant series was widely touted as a potential alternative to replace the conventional refrigerant R134a (Fukuda et al., 2014; Kondou & Koyama, 2015; Nawaz et al., 2017; Wu et al., 2018).
R32 and L41a have also been recommended as candidates to replace R410A because not only do they have a low GWP value, but they also closely resemble the characteristics of R410A and perform well. (Alabdulkarem et al., 2015; Cho et al., 2016; Yildirim et al., 2017; Botticella et al., 2018; Cremaschi et al., 2018).
Recently, some researchers have shown interest in pursuing a return to natural refrigerants as alternative to commercial refrigerants. Nasruddin et al. (2018) conducted research using a working fluid mixture of 86% R601 and 14% R744 for binary cycle systems. Yamaguchi et al. (2011) investigated the use of R744 for heat pump systems. Natural refrigerants such as hydrocarbons are considered non-toxic, non-flammable harmless working fluids, and furthermore, they do not contribute to global warming (Park et al., 2007; Sarkar & Bhattacharyya, 2009; Mohanraj et al., 2009; Antunes & Filho, 2016; Badache et al., 2018).
In order to ascertain whether an alternative refrigerant could be an option to replace conventional ones, a thermodynamic analysis is required. Park et al. (2007) conducted a thermodynamic analysis of a residential heat pump system using R433A as a replacement for HCFC22. R433A has zero ODP and a GWP of less than 5. The results revealed that the coefficient of performance for the system using R433A is 4.9% higher than a system using HCFC22. In conclusion, R433A is a good substitute for the conventional refrigerant has better performance (Park et al., 2007). Dopazo et al. (2009) also reported on the COP and exergy efficiency of a cooling system using alternative refrigerant R744 with an analysis and parametric study of the system. The result showed that the system has COP varied from 1.5–2.5 and can be increased 70% by doing optimization procedure. Nawaz et al. (2017) made a performance evaluation of a residential heat pump system in order to compare R600a and R290 refrigerants to HFC refrigerant, R134a. The analysis suggested that both refrigerants could be viable options with comparable performance (Nawaz et al., 2017).
But in previous literature that mentioned above, the analysis still not considers the effect of the system on the environment. So in this work, the exergoenvironmental analysis is discussed, and it becomes the novelty of this paper. The purpose of this work is to perform exergy and exergoenvironmental analyses of low GWP refrigerant R1234ze and R1234yf theoretically and compare it with R410A. After that, the multi-objective optimization is conducted by using the best refrigerant selected by exergy and exergoenvironmental analyses. From the result of the optimization procedure, the optimum condition including evaporation and condensation temperature, as well as the mass flow rate of refrigerant can be determined.
Exergy and exergo-environmental analysis and optimization were conducted in this study. The refrigerant R1234ze was chosen based on the evaluation of its thermophysical properties, the TEWI analysis method, and exergy and exergo-environmental analyses. After conducting this analysis, an optimization procedure was performed. By using a multivariable genetic algorithm, the system was optimized. In the optimization procedure, the exergy efficiency and exergo-environmental were choosen as the objective functions, while evaporating temperature, condensing temperature, and refrigerant mass flow rate were selected as constraints. The results showed that the heat pump system using environmentally friendly refrigerant R1234ze has a good performance with an exergy efficiency of 51.92% and a 101.925 mPts/h exergo-environmental value with an evaporating temperature of 20oC, a condensing temperature of 42.57oC, and a mass flow rate of 0.02 kg/s.
The authors gratefully
acknowledge Universitas Indonesia for supporting this research under the Tugas
Akhir Mahasiswa Doktor (TADOK) research grant 2018 number
1356/UN2.R3.1/HKP.05.00/2018 dated March 21, 2018.
Alabdulkarem, A., Eldeeb, R., Hwang, Y., Aute, V., Radermacher, R., 2015. Testing, Simulation and Soft-optimization of R410A Low-GWP Alternatives in Heat Pump System. International Journal of Refrigeration, Volume 60, pp. 106–117
Alhamid, M.I., Nasruddin, Darwin, R.B.S., Lubis, A., 2013. Characteristics and COP Cascade Refrigeration System using Hydrocarbon Refrigerant (Propane, Ethane and CO2) at Low Temperature Circuit (TC). International Journal of Technology, Volume 4(2), pp. 112–120
Antunes, A.H.P., Filho, E.P.B., 2016. Experimental Investigation on the Performance and Global Environmental Impact of a Refrigeration System Retrofitted with Alternative Refrigerants. International Journal of Refrigeration, Volume 70, pp. 119–127
Badache, M., Ouzzane, M., Eslami-Nejad, P., Aidoun, Z., 2018. Experimental Study of a Carbon Dioxide Direct-expansion Ground Source Heat Pump (CO2-DX-GSHP). Applied Thermal Engineering, Volume 130, pp. 1480–1488
Botticella, F., de Rossi, F., Mauro, A.W., Vanoli, G.P., Viscito, L., 2018. Multi-criteria (Thermodynamic, Economic and Environmental) Analysis of Possible Design Options for Residential Heating Split Systems Working with Low GWP Refrigerants. International Journal of Refrigeration, Volume 87, pp. 131–153
Cho, I.Y., Seo, H.J., Kim, D., Kim, Y., 2016. Performance Comparison between R410A and R32 Multi-heat Pumps with Sub-cooler Vapor Injection in the Heating and Cooling Modes. Energy, Volume 112, pp. 179–187
Cremaschi, L., Yatim, A.S., Mulugurthi, S.K., 2018. Experimental Study of Oil Retention in Microchannel Type Evaporators of Air-source Heat Pump Systems. International Journal of Refrigeration, Volume 91, pp. 158–166
Dai, B., Dang, C., Li, M., Tian, H., Ma, Y., 2015. Thermodynamic Performance Assessment of Carbon Dioxide Blends with Low-Global Warming Potential (GWP) Working Fluids for a Heat Pump Water Heater. International Journal of Refrigeration, Volume 56, pp. 1–14
Dincer, I., Rosen, M.A., Ahmadi, P., 2017. Optimization of Energy Systems. John Wiley & Sons Ltd., USA
Dopazo, J.A., Fernández-Seara, J., Sieres, J., Uhía, F.J., 2009. Theoretical Analysis of CO2-NH3 Cascade Refrigeration System for Cooling Applications at Low Temperatures. Applied Thermal Engineering, Volume 29(8-9), pp. 1577–1583
Fukuda, S., Kondou, C., Takata, N., Koyama, S., 2014. Low GWP Refrigerants R1234ze(E) and R1234ze(Z) for High Temperature Heat Pumps. International Journal of Refrigeration, Volume 40, pp. 161–173
Kondou, C., Koyama, S., 2015. Thermodynamic Assessment of High-temperature Heat Pumps using Low-GWP HFO Refrigerants for Heat Recovery. International Journal of Refrigeration, Volume 53, pp. 126–141
Mohanraj, M., Jayaraj, S., Muraleedharan, C., 2009. Environment Friendly Alternatives to Halogenated Refrigerants—A Review. International Journal of Greenhouse Gas Control, Volume 3(1), pp. 108–119
Mohd-Ghazali, N., Anwar, M., Settar, N.H.M.A., 2011. Thermoacoustic Cooling with No Refrigerant. International Journal of Technology, Volume 2(3), pp 234–241
Molés, F., Navarro-Esbri, J., Peris, B., Mota-Babiloni, A., Barragán-Cervera, Á., 2014. Theoretical Energy Performance Evaluation of Different Single Stage Vapour Compression Refrigeration Configurations using R1234yf and R1234ze(E) as Working Fluids. International Journal of Refrigeration, Volume 44, pp. 141–150
Nasruddin, Nasution, S., Aisyah, N., Surachman, A., Wibowo, A.S., 2018. Exergy Analysis and Exergoeconomic Optimization of a Binary Cycle System using Multi Objective Genetic Algorithm. International Journal of Technology, Volume 9(2), pp. 275–286
Nasruddin, Alhamid, M.I., Aisyah, N., 2017. Energetic, Economic and Environmental (3E) Optimization of Solar Assisted Heat Pump using Low GWP Refrigerant R1234ze(E) for High Temperature Application. In: 3rd International Conference on Power Generation Systems and Renewable Energy Technologies (PGSRET), Johor Bahru, 4-6 April, Malaysia, pp. 79–84
Nawaz, K., Shen, B., Elatar, A., Baxter, V., Abdelaziz, O., 2017. R1234yf and R1234ze(E) as Low-GWP Refrigerants for Residential Heat Pump Water Heaters. International Journal of Refrigeration, Volume 82, pp. 348–365
Park, K.J., Seo, T., Jung, D., 2007. Performance of Alternative Refrigerants for Residential Air-Conditioning Applications. Applied Energy, Volume 84(10), pp. 985–991
Sarkar, J., Bhattacharyya, S., 2009. Assessment of Blends of CO2 with Butane and Isobutane as Working Fluids for Heat Pump Applications. International Journal of Thermal Sciences, Volume 48(7), pp. 1460–1465
Wu, D., Hu, B., Wang, R.Z., 2018. Performance Simulation and Exergy Analysis of a Hybrid Source Heat Pump System with Low GWP Refrigerants. Renewable Energy, Volume 116(Part A), pp. 775–785
Yildirim, C., Özkan, D.B., Onan, C., 2017. Theoretical Study of R32 to Replace R410A in Variable Refrigerant Flow Systems. International Journal of Ambient Energy, Volume 39(1), pp. 87–92
Yamaguchi, S., Kato, D., Saito, K., Kawai, S., 2011. Development and Validation of Static Simulation Model for CO2 Heat Pump. International Journal of Heat and Mass Transfer, Volume 54(9-10), pp. 1896–1906