| dc.description.abstract | Jet fires pose serious safety hazards in situations where pressurised gas tanks are stored close together. A jet fire originating from one tank will likely damage another and lead to additional fires and even explosions. To prevent this from happening, equipment has to built to be able to endure the high heat fluxes produced in jet fires. SP Fire Research has developed a test procedure where equipment can be tested for jet fires producing heat fluxes of 350 kW/m$^2$.
This thesis has worked towards implementing automatic control of the temperature in the oven of this test rig. The temperature inside the oven is regulated by fans supplying the oven with additional air, a change in fan frequency leads to a change in temperature. The oven has prior to this thesis been built in two different ways, resulting in two systems with different dynamics, one over ventilated and one under ventilated.
Mathematical models were created to decide the relationship between fan inputs and the oven temperature in both oven builds. This was done by modifying an existing compartment fire temperature model to accommodate the effects the jet fire has on the system, as well as the bigger openings in the compartment (oven). The resulting models were then verified by comparing simulations to data from previous tests. With satisfying comparison results, the models were used to test different control schemes through simulation. These simulations suggested that PI control should work in both builds. Consequently, PI control was tested in the over ventilated build. The results were conclusive with simulations, and the PI control was verified as a suitable control scheme for the over ventilated system. It is expected to work just as well in the under ventilated system, though it has not yet been tested.
In addition to the main objective of temperature control, some additional functionalities have been assessed. Reference control schemes are suggested, and a way to automatically detect and terminate faulty thermocouples. The advantages and disadvantages of the two builds were reviewed. The over ventilated build was suggested as the favorable choice, but should be continuously reviewed through changing weather conditions as it is more affected by weather than the under ventilated build, as the test rig is situated outside. | en |
