CIRCE is a test facility designed and realized by the Italian agency ENEA to support the heavy liquid metal technology for nuclear fission plants. Within the H2020 projects MYRTE and SESAME, various experiments will be performed in this facility, using two different heat exchangers, resembling nominal operation and accident scenarios of a Liquid Metal Fast Reactor (LMFR). Simultaneously, within these projects different thermal-hydraulics models of CIRCE are created to gain experience in the modelling of such a facility and to help future development of LMFRs. At NRG, both an STH and CFD model of CIRCE in two different configurations, are created. These two models are to be coupled eventually. The present paper describes these two models. Results obtained with these models are, where possible, compared with experimental results, both for steady-state and transient conditions. For the steady-state, generally good agreement is found. The transient simulation performed recovers some of the main features of the experiment, however excessive cooling is found. The cause is currently under investigation, which is complicated due to the lack of experimental data.