The tunnel pasteuriser delivers beer that is safe for the consumer even after long periods of storage and it is essential that this machine achieves the desired PU while operating efficiently. This work develops a steady state model for the pasteuriser using a 2 layer model. The first layer represents a distributed tunable model of the bottle in order to correctly predict the delays of the core temperature where the PU is measured. The second layer integrates all the heating and cooling zones which are coupled to the bottle model. The model accurately predicts the behaviour of the bottle temperature and thus also PU and allows the determination of the heat duties required to obtain the optimal temperature profile.