Quenching mechanism of spray cooling and the effect of system pressure

•Spray cooling tests are performed at various system pressures ranging from 0.1 MPa to 0.5 MPa in a practically oxygen-free environment.•Quenching occurs at higher temperature as the system pressure increases, mainly due to the increase in the saturation temperature.•The rate of heat transfer in the film boiling regimes increases with the system pressure due to the reduction of vapour film thickness.•Partial liquid-solid contact may take place even at sufficiently high surface temperatures.•Predictive models for the onset of quenching and heat transfer rate in the film boiling regime were assessed and found to agree with the experimental observations reasonably well.