Numerical investigation on thermal performance of absorption refrigeration system using MWCNT nanoparticle-enhanced 1-hexyl-3-methylimidazolium cation-based ionic liquids

Abstract

• Specific heat of HMIM cation based four different ionic liquids were investigated experimentally. • Increase concentration in the MWCNT nanoparticle enhanced ionic liquid improves the COP of the ARS. • The largest COP is presented by 1 wt% MWCNT [HMIM][Pf 6 ] NEIL, followed by 1 wt% MWCNT [HMIM][Tf 2 N] NEILs. In this investigation, the thermal performance of single-stage absorption refrigeration systems (ARSs) utilizing different MWCNT nanoparticle-enhanced 1-hexyl-3-methylimidazolium (HMIM) cation-based ionic liquids with R1234yf refrigerant were analyzed. The specific heats of the various MWCNT nanoparticle-enhanced [HMIM] cation-based ionic liquids were obtained experimentally at a temperature and a concentration of 303–383 K and 0–1 wt%, respectively, and were subsequently used for modeling the solubility and absorption refrigeration cycle. As a result, the maximum specific heats of all considered ionic liquids were examined at the highest temperature of 383 K. The solubility order of R1234yf refrigerant from highest to lowest was [HMIM][Bf 4 ], [HMIM][Pf 6 ], [HMIM][TfO], and [HMIM][Tf 2 N] RTILs. In addition, the maximum COPs of the ARSs were achieved at the temperature and concentration of 363 K and 1 wt%, respectively, which were 0.205, 0.242, 0.286, and 0.259 for the [HMIM][Bf 4 ], [HMIM][TfO], [HMIM][Pf 6 ], and [HMIM][Tf 2 N] MWCNT NEILs, respectively. By applying the proposed system could be simplified at high-temperature applications and prevent undesirable side effects of conventional working pairs such as metal incompatibility, toxicity, and chemical instability.