Effects of compressor speed and electronic expansion valve opening on the performance of R410a water chiller system
DOI:
https://doi.org/10.31185/ejuow.Vol8.Iss1.151Keywords:
Variable speed compressor, water chiller, EEV, degree of superheat, R410a.Abstract
Refrigeration and air conditioning systems consume high rates of electrical energy of the total global power consumption. The major part of this energy is used by compressor which is the main equipment in vapor compression refrigeration systems. In this study, the performance of a variable speed chilled water refrigeration system with electronic expansion valve (EEV) is experimentally investigated. The system is composed of variable speed rotary compressor, water cooled condenser, electronic expansion valve, and evaporator with refrigerant R410a for one tone cooling capacity. The results showed that the EEV opening was related to the compressor speed at limits of refrigerant subcool and system stability to achieve better performance. Refrigerant superheats increased with closing the EEV at constant compressor speed. Moreover, the degree of superheat was inversely proportional to the compressor speed at constant EEV opening. The coefficient of performance (COP) was improved by about 2.2 to 4.0% by controlling the EEV at constant compressor speed. Increasing compressor speed from 1200 to 3600 rpm resulted in decreasing system COP from 5.2 to 2.35 due to the increase of the power consumed by compressor.
References
Schibuola L, Scarpa M, & Tambani C, (2018). Variable speed drive (VSD) technology applied to HVAC systems for energy saving: an experimental investigation. Energy Procedia, 148: 806-813.
Khatri R, & Joshi A, (2017). Energy performance comparison of inverter based variable refrigerant flow unitary AC with constant volume unitary AC. Energy Procedia, 109: 18-26.
Binneberg P, Kraus E, & Quack H, (2002). Reduction in power consumption of household refrigerators by using variable speed compressors., in: International Refrigeration and Air Conditioning Conference, Purdue University, Purdue.
Cohen R, Hamilton J, & Pearson T, (1974). Possible energy conservation through use of variable capacity compressors., in: International Compressor Engineering Conference, Purdue University, Purdue.
Shimma Y, Tateuchi T, & Suglura H, (1985). Inverter control systems in the residential heat pump air conditioner. ASHRAE Trans.;(United States), 91(CONF-850606-).
Koury R, Machado L, & Ismail K, (2001). Numerical simulation of a variable speed refrigeration system. International journal of refrigeration, 24(2), 192-200.
Chang W, Liu D, Chen G, & Wu Y, (2004). The Components and Control Methods for Implementation of Inverter-Controlled Refrigerators/Freezers., in: International Refrigeration and Air Conditioning Conference, Purdue University, Purdue.
Aprea C, Mastrullo R, & Renno C, (2006). Experimental analysis of the scroll compressor performances varying its speed. Applied thermal engineering, 26(10), 983-992.
Taynara L, Claudia N, Luiz F, (2016). Experimental investigation on variable speed compressor with an electronic expansion valve in a refrigeration system, in: 16th Brazilian Congress of Thermal Sciences and Engineering, Brazil.
Tu Q, Zhang L, Cai W, Guo X, Yuan X, Deng C, & Zhang J, (2018). Control strategy of compressor and sub-cooler in variable refrigerant flow air conditioning system for high EER and comfortable indoor environment. Applied Thermal Engineering, 141, 215-225.
Pršić D, Vičovac A, & Stojanović V, (2016). The Static Characteristic of the Evaporator Superheat Control Loop. In Proceedings of the VIII XIII International SAUM Conference on Systems, Automatic Control and Measurements (pp. 242-245).
Moffat, R, (1988). Describing the uncertainties in experimental results. Experimental thermal and fluid science, 1(1), 3-17.
Xia Y, & Deng S, (2016). A Modeling Study on the Operational Stability of a Variable Speed Direct Expansion Air Conditioning System, in: International Refrigeration and Air Conditioning Conference.
Kuk F, & Hau O, (2017). Compression speed and cognition: A variable speed compressor for all. Hearing Review, 24(3), 40-48.
Xia Y, Ding Q, Jiang Z, Deng S, & Song M, (2019). Development of a superheat controller for mitigating hunting in a direct expansion air conditioning system. Energy Procedia, 158, 2085-2091.
Lei Z, & Zaheeruddin M, (2005). Dynamic simulation and analysis of a water chiller refrigeration system. Applied Thermal Engineering, 25(14-15), 2258-2271.
