This paper presents a review of methods for fluid-to-fluid modelling of the critical heat flux (CHF) in tubes, annuli, and rod-bundle geometries. Most CHF modelling techniques require identical values for the boiling number, negative inlet quality, liquid-to-vapour density ratio and L/D ratio. Various expressions have been proposed for modelling the mass flux, including purely empirical to theoretically derived expressions. Dimensionless CHF correlations and analytical CHF models are also examined. The accuracy of the various CHF modelling techniques are assessed for each geometry. Generally fluid-to-fluid modelling in simple geometries is reliable as the error in modelling is of the same magnitude as the scatter in the data. The best modelling results in bundle geometries were obtained after adjusting the mass flux scaling factors using identical bundle geometries. Modelling fluids also tend to rank the relative effects of rod spacing devices on CHF in the correct order. An assessment of the modelling of subchannel mixing and flashing is also included in this paper.