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

•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][Pf6] NEIL, followed by 1 wt% MWCNT [HMIM][Tf2N] 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][Bf4], [HMIM][Pf6], [HMIM][TfO], and [HMIM][Tf2N] 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][Bf4], [HMIM][TfO], [HMIM][Pf6], and [HMIM][Tf2N] 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.