Evaluation of two-phase suction, liquid injection and two-phase injection for decreasing the discharge temperature of the R32 scroll compressor

Abstract

R32 has been considered as an important alternative in the phase-out of hydrochlorofluorocarbons (HCFCs) due to its advantages such as relatively low global warming potential compared to R410A, favorable thermal properties. However, the increased discharge temperature of the R32 compressor, compared with R410A, is the main barrier affecting the wide and quick adoption. In this work, three promising methods to decrease the discharge temperature of R32 scroll compressor, namely, two-phase suction, liquid injection and two-phase injection, have been investigated. By considering the variations of motor efficiency and leakage rate, an improved distributed parameter model of the scroll compressor is rebuilt based on a previously developed one (Wang et al., 2008). By that model, the effectiveness of these three methods in decreasing discharge temperature and their influence on thermodynamic performance are researched.It is concluded that all the three methods show excellent potential in decreasing the discharge temperature of R32 scroll compressor. Besides, two-phase injection outperforms the other two methods in cooling capacity and COP by 11.8% and 4.8%, respectively.

Recent investigations in HFCs substitution with lower GWP synthetic alternatives: Focus on energetic performance and environmental impact

“…Shuxue et al (2013) quantified the discharge temperature reduction by the use of enhanced vapor injection between 10 and 20 K but Xu et al (2013) only measured energy performance improvement using this configuration at non-extreme cooling and heating conditions. Yang et al (2015) concluded that two-phase injection outperforms liquid injection ( Figure 11) and two-phase suction in both cooling capacity and COP by 12% and 5%. Contrary to other synthetic refrigerants, the use of IHX in R32 systems is not recommended because it reduces the COP and increases the discharge temperature (Park et al, 2015).…”

“…Barve and Cremaschi, 2012 Park et al, 2015Qv et al, 2017Shuxue et al, 2013Wu et al, 2016Xu et al, 2013Yang et al, 2015Zilio et al, 2015…”

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

“…In fact, an overly high discharge temperature and pressure of R32 under extremely high temperature conditions was a concern for the safe operation of the unit, and might be a concern for the compressor lifetime cycle; in addition, it has been the main barrier for the wide and quick introduction of this fluid in air conditioning systems where R410A has typically been used, as shown in Figure 6. Yang et al [59] proposed different cycles with modifications to reduce the discharge temperature. A two-phase injection outperforms a liquid injection and two-phase suction in terms of the cooling capacity and COPc by 12% and 5%, respectively, and significantly decreases the discharge temperature of the R32 scroll compressor (benefited by its significant amount of latent heat).…”

Effects of subcooling degree and injection super‐heating degree on performance of an air source heat pump with subcooler

“…For two‐phase injection, it is currently rarely studied because of test difficulties in metering injection mass flow rate . Yang experimentally demonstrated that three injection styles, ie, two‐phase suction injection, direct liquid injection, and two‐phase injection, obviously decreased the T d of the compressor, and the cooling capacity and COP with two‐phase injection were 11.8% and 4.8% higher than those with the other two injection styles, respectively. Kim et al built a mathematical model to forecast the influence of the liquid, vapor, and two‐phase injection on the heat pump performance.…”